[Federal Register: November 18, 2003 (Volume 68, Number 222)]
[Proposed Rules]
[Page 65119-65151]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18no03-26]
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Part II
Environmental Protection Agency
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40 CFR Chapter 1
Approaches to an Integrated Framework for Management and Disposal of
Low-Activity Radioactive Waste: Request for Comment; Proposed Rule
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Chapter 1
[FRL-7585-6]
RIN 2060-AL71
Approaches to an Integrated Framework for Management and Disposal
of Low-Activity Radioactive Waste: Request for Comment
AGENCY: Environmental Protection Agency (EPA).
ACTION: Advance notice of proposed rulemaking (ANPR).
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SUMMARY: This Advance Notice of Proposed Rulemaking (ANPR) requests
public comment regarding options to promote a more consistent framework
for the disposal of radioactive waste with low concentrations of
radioactivity (``low-activity''). Of immediate interest is low-activity
mixed waste (LAMW). This waste is both chemically hazardous according
to the Resource Conservation and Recovery Act (RCRA) and is radioactive
with low radionuclide concentrations under the purview of the Atomic
Energy Act of 1954 (AEA). Such waste is regulated and managed under
both authorities but under certain conditions, one authority may be
sufficient to provide public health and environmental protection. In
particular, given appropriate limits on radionuclide concentrations in
LAMW, disposal of LAMW in RCRA Subtitle C hazardous waste landfills,
with their prescribed engineering design and associated RCRA
requirements (e.g., waste treatment, waste form), may provide
protection of public health and the environment. This document focuses
on effective use of the RCRA-C disposal technology for the disposal of
LAMW. We (the Environmental Protection Agency) seek comment on
standards that would codify this approach and provide greater
flexibility for the safe disposal of LAMW.
Beyond LAMW, however, there is a wide variety of radioactive wastes
with relatively low concentrations of radioactivity; these wastes are
not considered mixed wastes because they are not regulated under both
RCRA and the AEA. Examples of such low-activity waste include certain
AEA radioactive wastes, certain wastes from the extraction of uranium
or thorium (such as those generated by the Formerly Utilized Sites
Remedial Action Program (FUSRAP)), a variety of wastes that fall into
the technologically enhanced naturally occurring radioactive materials
(TENORM) category, and certain decommissioning wastes. Some AEA wastes
are deferred from regulation, such as ``unimportant quantities'' of
source material with less than 0.05 percent uranium or thorium, and
would be characterized as another form of low-activity radioactive
waste (LARW, of which low-activity mixed waste would be a subset). Some
radioactive wastes are regulated strictly down to the last atom while
other low-activity wastes are regulated primarily for their chemically
hazardous constituents. Some of these wastes may be unregulated or
regulated under a framework lacking clarity and consistency. We seek
comment on possible regulatory and non-regulatory options to provide a
more coherent framework to manage LARW, and information to improve the
scientific characterization of such wastes.
We envision that any standards promulgated to address the use of
the RCRA-C disposal technology for LAMW (or, more broadly, LARW) would
offer a new disposal option for these wastes. This would provide the
flexibility to allow States, disposal facility operators, and waste
generators to account for specific State or local regulatory
constraints and economic considerations in determining whether they
would choose to implement this disposal option for protective
management and disposal of these wastes.
DATES: To ensure that your comments will be considered in future
actions related to this document, please submit your comments no later
than March 17, 2004.
ADDRESSES: Comments may be submitted by mail to: Air and Radiation
Docket, Environmental Protection Agency, EPA West Room B108, Mailcode:
6102T, 1200 Pennsylvania Ave., NW., Washington, DC 20460, Attention
Docket ID No. OAR-2003-0095. Comments may also be submitted
electronically, or through hand delivery/courier. Follow the detailed
instructions as provided in Unit I.B of the SUPPLEMENTARY INFORMATION
section. Please be aware that mail addressed to EPA headquarters may
experience delays in delivery resulting from physical security
screening. We will consider that fact when evaluating comments received
after the end of the comment period.
FOR FURTHER INFORMATION CONTACT: Dan Schultheisz, Radiation Protection
Division, Office of Radiation and Indoor Air, Mailcode: 6608J, United
States Environmental Protection Agency, Washington, DC, 20460-0001; telephone (202) 343-9300; e-mail schultheisz.daniel@epa.gov.
SUPPLEMENTARY INFORMATION:
I. General Information
A. How Can I Get Copies of Related Information?
1. Docket. EPA has established an official public docket for this
action under Docket ID No. OAR-2003-0095. The official public docket
consists of the documents specifically referenced in this action, any
public comments received, and other information related to this action.
Although a part of the official docket, the public docket does not
include Confidential Business Information (CBI) or other information
whose disclosure is restricted by statute. The official public docket
is the collection of materials that is available for public viewing at
the Air and Radiation Docket in the EPA Docket Center (EPA/DC), EPA
West, Room B102, 1301 Constitution Ave., NW., Washington, DC. The EPA
Docket Center Public Reading Room is open from 8:30 a.m. to 4:30 p.m.,
Monday through Friday, excluding legal holidays. The telephone number
for the Public Reading Room is (202) 566-1744, and the telephone number
for the Air and Radiation Docket is (202) 566-1742.
2. Electronic Access. You may access this Federal Register document
electronically through the EPA Internet under the ``Federal Register''
listings at http://www.epa.gov/fedrgstr/. It will also be available,
along with general information relevant to this ANPR, such as
Frequently Asked Questions (FAQ), through EPA's Radiation Program Home
Page at http://www.epa.gov/radiation/.
An electronic version of the public docket is available through
EPA's electronic public docket and comment system, EPA Dockets. You may
use EPA Dockets at http://www.epa.gov/edocket/ to submit or view public
comments, access the index listing of the contents of the official
public docket, and to access those documents in the public docket that
are available electronically. Once in the system, select ``search,''
then key in the appropriate docket identification number.
Certain types of information will not be placed in the EPA Dockets.
Information claimed as CBI and other information whose disclosure is
restricted by statute, which is not included in the official public
docket, will not be available for public viewing in EPA's electronic
public docket. EPA's policy is that copyrighted material will not be
placed in EPA's electronic public docket but will be available only in
printed, paper form in the official public
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docket. To the extent feasible, publicly available docket materials
will be made available in EPA's electronic public docket. When a
document is selected from the index list in EPA Dockets, the system
will identify whether the document is available for viewing in EPA's
electronic public docket. Although not all docket materials may be
available electronically, you may still access any of the publicly
available docket materials through the docket facility identified in
Unit I.A.1.
For public commenters, it is important to note that EPA's policy is
that public comments, whether submitted electronically or in paper,
will be made available for public viewing in EPA's electronic public
docket as EPA receives them and without change, unless the comment
contains copyrighted material, CBI, or other information whose
disclosure is restricted by statute. When EPA identifies a comment
containing copyrighted material, EPA will provide a reference to that
material in the version of the comment that is placed in EPA's
electronic public docket. The entire printed comment, including the
copyrighted material, will be available in the public docket.
Public comments submitted on computer disks that are mailed or
delivered to the docket will be transferred to EPA's electronic public
docket. Public comments that are mailed or delivered to the docket will
be scanned and placed in EPA's electronic public docket. Where
practical, physical objects will be photographed, and the photograph
will be placed in EPA's electronic public docket along with a brief
description written by the docket staff.
For additional information about EPA's electronic public docket
visit EPA Dockets online or see 67 FR 38102, May 31, 2002.
B. How and To Whom Do I Submit Comments?
You may submit comments electronically, by mail, or through hand
delivery/courier. To ensure proper receipt by EPA, identify the
appropriate docket identification number in the subject line on the
first page of your comment. Please ensure that your comments are
submitted within the specified comment period. Comments received after
the close of the comment period will be marked ``late.'' EPA is not
required to consider these late comments, but will do so at its
discretion.
1. Electronically. If you submit an electronic comment as
prescribed below, EPA recommends that you include your name, mailing
address, and an e-mail address or other contact information in the body
of your comment. Also include this contact information on the outside
of any disk or CD ROM you submit, and in any cover letter accompanying
the disk or CD ROM. This ensures that you can be identified as the
submitter of the comment and allows EPA to contact you in case EPA
cannot read your comment due to technical difficulties or needs further
information on the substance of your comment. EPA's policy is that EPA
will not edit your comment, and any identifying or contact information
provided in the body of a comment will be included as part of the
comment that is placed in the official public docket, and made
available in EPA's electronic public docket. If EPA cannot read your
comment due to technical difficulties and cannot contact you for
clarification, EPA may not be able to consider your comment.
i. EPA Dockets. Your use of EPA's electronic public docket to
submit comments to EPA electronically is EPA's preferred method for
receiving comments. Go directly to EPA Dockets at http://www.epa.gov/edocket
, and follow the online instructions for submitting comments. To
access EPA's electronic public docket from the EPA Internet Home Page,
select ``Information Sources,'' ``Dockets,'' and ``EPA Dockets.'' Once
in the system, select ``search,'' and then key in Docket ID No. OAR-
2003-0095. The system is an ``anonymous access'' system, which means
EPA will not know your identity, e-mail address, or other contact
information unless you provide it in the body of your comment.
ii. E-mail. Comments may be sent by electronic mail (e-mail) to a-and-r-Docket@epa.gov, Attention Docket ID No. OAR-2003-0095. In
contrast to EPA's electronic public docket, EPA's e-mail system is not
an ``anonymous access'' system. If you send an e-mail comment directly
to the Docket without going through EPA's electronic public docket,
EPA's e-mail system automatically captures your e-mail address. E-mail
addresses that are automatically captured by EPA's e-mail system are
included as part of the comment that is placed in the official public
docket, and made available in EPA's electronic public docket.
iii. Disk or CD ROM. You may submit comments on a disk or CD ROM
that you mail to the mailing address identified in Unit I.B.2. These
electronic submissions will be accepted in WordPerfect or ASCII file
format. Avoid the use of special characters and any form of encryption.
2. By Mail. Send your comments to: Air and Radiation Docket,
Environmental Protection Agency, EPA West Room B108, Mailcode: 6102T,
1200 Pennsylvania Ave., NW., Washington, DC 20460, Attention Docket ID
No. OAR-2003-0095.
3. By Hand Delivery or Courier. Deliver your comments to: Air and
Radiation Docket in the EPA Docket Center, EPA West Room B108, 1301
Constitution Ave., NW., Washington, DC, 20004, Attention Docket ID No.
OAR-2003-0095. Such deliveries are only accepted during the Docket's
normal hours of operation as identified in Unit I.B.
4. By Facsimile. Fax your comments to (202) 566-1741, Attention
Docket ID. No. OAR-2003-0095.
C. How Should I Submit CBI to the Agency?
Do not submit information that you consider to be Confidential
Business Information electronically through EPA's electronic public
docket or by e-mail. Send or deliver information identified as CBI only
to the following address: Dan Schultheisz, U.S. Environmental
Protection Agency, Office of Radiation and Indoor Air, Mailcode: 6608J,
1200 Pennsylvania Ave., NW., Washington, DC 20460, Attention Docket ID
No. OAR-2003-0095. You may claim information that you submit to EPA as
CBI by marking any part or all of that information as CBI (if you
submit CBI on disk or CD ROM, mark the outside of the disk or CD ROM as
CBI and then identify electronically within the disk or CD ROM the
specific information that is CBI). Information so marked will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2.
In addition to one complete version of the comment that includes
any information claimed as CBI, a copy of the comment that does not
contain the information claimed as CBI must be submitted for inclusion
in the public docket and EPA's electronic public docket. If you submit
the copy that does not contain CBI on disk or CD ROM, mark the outside
of the disk or CD ROM clearly that it does not contain CBI. Information
not marked as CBI will be included in the public docket and EPA's
electronic public docket without prior notice. If you have any
questions about CBI or the procedures for claiming CBI, please consult
the person identified in the FOR FURTHER INFORMATION CONTACT section.
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D. What Should I Consider as I Prepare My Comments for EPA?
You may find the following suggestions helpful for preparing your
comments:
1. Explain your views as clearly as possible.
2. Describe any assumptions that you used.
3. Provide any technical information and/or data you used that
support your views.
4. If you estimate potential burden or costs, explain how you
arrived at your estimate.
5. Provide specific examples to illustrate your concerns.
6. Offer alternatives.
7. Make sure to submit your comments by the comment period deadline
identified.
8. To ensure proper receipt by EPA, identify the appropriate docket
identification number in the subject line on the first page of your
response. It would also be helpful if you provided the name, date, and
Federal Register citation related to your comments.
Acronyms and Abbreviations
We use many acronyms and abbreviations in this preamble. For your
convenience and reference, they are:
AEA--The Atomic Energy Act
AEC--The Atomic Energy Commission
ANPR--Advance notice of proposed rulemaking
CED(E)--Committed effective dose (equivalent)
CERCLA--Comprehensive Environmental Response, Compensation, and
Liability Act (also known as Superfund)
CFR--Code of Federal Regulations
DOE--The United States Department of Energy
EPA--The United States Environmental Protection Agency
FR--Federal Register
FUSRAP--Formerly Utilized Sites Remedial Action Program
GTCC--Greater-Than-Class C low-level radioactive waste
HWIR--Hazardous Waste Identification Rule
LAMW--Low activity mixed waste
LARW--Low activity radioactive waste
LLRW--Low-level radioactive waste
MCL--Maximum Contaminant Level
MLLW--Mixed low-level radioactive waste
MW--Mixed waste
NESHAPS--National emission standards for hazardous air pollutants
NRC--The United States Nuclear Regulatory Commission
OMB--The Office of Management and Budget
ORIA--EPA's Office of Radiation and Indoor Air
OSW--EPA's Office of Solid Waste
OSWER--EPA's Office of Solid Waste and Emergency Response
RCRA--The Resource Conservation and Recovery Act
RCRA--C--Subtitle C of RCRA
TEDE--Total effective dose equivalent
TENORM--Technologically Enhanced Naturally Occurring Radioactive
Materials
TRU--Transuranic waste
TSCA--Toxic Substance Control Act
UMTRCA--Uranium Mill Tailings Radiation Control Act
USACE--United States Army Corps of Engineers
UTS--Universal Treatment Standards
What Do We Mean by Certain Terms?
Throughout this ANPR, we refer to ``Low-Level Radioactive Waste,''
``Mixed Waste,'' ``Low-Activity Low-Level Radioactive Waste,'' ``Low-
Activity Mixed Waste,'' and ``Low-Activity Radioactive Waste.'' Each of
these terms has a distinct meaning within the context of this document
(though not necessarily a regulatory or statutory definition). We want
to avoid confusion wherever possible, so we offer these definitions to
help you better understand the discussion.
When we say ``Low-Level Radioactive Waste'' (or LLRW), we always
mean a specific kind of radioactive material defined at section 2(16)
of the Nuclear Waste Policy Act as radioactive waste that is not spent
nuclear fuel, high-level waste, transuranic waste, or uranium and
thorium mill tailings. Under 10 CFR part 61, ``Licensing Requirements
for Land Disposal of Radioactive Waste,'' the NRC regulates disposal of
LLRW in near-surface disposal facilities. The NRC has defined three
classes of LLRW in part 61 (classes A, B, and C) based on their
radionuclide content and half-life. Under the part 61 waste
classification and disposal site design, siting, and waste acceptance
scheme, waste with radionuclide content that exceeds Class C still is
regulated as LLRW, but generally is not acceptable for near-surface
disposal. The Department of Energy (DOE) regulates LLRW under its own
AEA authority (see DOE Order 435.1).
When we say ``Mixed Waste'' (or MW), we always mean waste that is
regulated under both the Resource Conservation and Recovery Act (RCRA)
as hazardous waste and under the AEA as radioactive material. This
document is concerned only with MW containing LLRW, so-called mixed
low-level waste (MLLW). MLLW can include LLRW Classes A, B, and C, and
greater-than-class C. Non-AEA radioactive wastes mixed with hazardous
waste are not technically MW, although they may be managed in a similar
way.
We are introducing today the term ``low-activity'' to represent the
idea that some radioactive wastes may contain radionuclides in small
enough concentrations to allow them to be managed in ways that are
fully protective of public health and the environment but do not
require all of the radiation protection measures necessary to manage
higher-activity radioactive material. As used in this document, ``low-
activity'' is a conceptual term that does not have a statutory or
regulatory meaning. This document outlines and requests public comment
on methods that could be used in future actions to define ``low-
activity'' wastes. ``Low-activity'' wastes would be subsets of broader
waste categories, such as those defined previously. This document
discusses several types of ``low-activity'' waste, including:
[sbull] ``Low-activity'' LLRW;
[sbull] ``Low-activity'' MW (LAMW);
[sbull] ``Low-activity'' radioactive waste (LARW)--this is a broad
category that includes low-activity LLRW and LAMW, as well as other
wastes such as those primarily regulated at the State level (e.g.,
TENORM wastes, where the term ``technologically enhanced'' means that
human activity has concentrated the natural radioactivity or increased
the potential for human exposure).
Finally, when we say ``byproduct material'' we are using the
definition in section 11e of the AEA. The discussion in section III of
this document focuses on ``pre-UMTRCA byproduct materials'' not
regulated by the NRC. (``Pre-UMTRCA byproduct materials'' are tailings
or wastes produced by the extraction or concentration of uranium or
thorium from any ore processed primarily for its source material
content that NRC has concluded are outside its jurisdiction under
section 11e.(2) of the AEA. This is discussed further in section III.B
of this document. The FUSRAP cleanups address much of the pre-UMTRCA
byproduct material.)
Questions for Public Comment
Consistent with the purpose of an Advance Notice of Proposed
Rulemaking, we are asking many questions about the concepts described
in this document. Because this document covers a broad variety of
topics and possibilities, we note throughout the text the issues on
which we would like public comment. We
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have also collected questions at the end of sections II, III, and IV,
and additional questions may be found in the ``Request for
Information'' sections (see the ``Outline of Today's Action''). The
questions at the end of each section are focused on the material
presented in those sections; however, commenters may feel that
information in a later section is relevant to a question in an earlier
section, or vice versa. We encourage commenters to address the
questions as they believe most appropriate. Further, we welcome
comments on any aspect of the text, not just on those points for which
we specifically request comment. However, to facilitate our evaluation
of and response to public comment, we ask that commenters clearly
identify which issue(s) they are addressing and refer to relevant
portions of the text in their comment.
Outline of Today's Action
I. Why Are We Publishing Today's ANPR?
II. How Can the Disposal of LAMW be Simplified?
A. What Needs to be Done to Allow Protective Disposal of LAMW?
1. Assess Characteristics of LAMW
2. Assess Alternative Disposal Methods
a. RCRA Subtitle C Land Disposal
b. Establish a Risk or Dose Basis for Allowable Concentrations
3. Coordination with Nuclear Regulatory Commission
B. Why is There a Need to Simplify Disposal of LAMW?
1. Dual Regulatory Structure
2. Recent EPA Mixed Waste Actions
C. How Would the RCRA Regulatory Framework Support a Viable
Disposal Concept?
1. Technological Basis for Disposal (RCRA Hazardous Waste
Landfill Criteria)
2. RCRA Treatment Standards
3. RCRA Disposal Facility Operating Standards
4. How does AEA Licensing Compare to RCRA Permitting?
D. What Methods Could be Used to Assess the Risk of Disposing of
LAMW?
1. Modeling as a Basis for Establishing Risk or Dose Basis
2. Comparison of Risks from Radioactive and Hazardous Waste
Disposal
3. Modeling Scenarios
a. Situations to be Addressed
b. Long-term Disposal Cell Performance
i. General Discussion
ii. ``Wet'' and ``Dry'' Sites
iii. Modeling Timeframe
c. ``Off-Normal'' Events
d. Disposal Facility Worker
e. Transportation Worker
f. Post-Closure Site Use
4. Other Considerations Affecting Risk Analysis
a. Use of Part 61 Classification System
b. Waste Form and Packaging
c. Activity Caps
d. Unity Rule
5. Risk or Dose Basis for a LAMW Standard
E. What Legal Authority Does EPA Have Under the AEA?
F. What Regulatory Approaches Could NRC Take With Respect to
LAMW?
1. Regulatory Approaches That Could Apply to RCRA Facilities
2. Regulation of LAMW Generators
G. How Might DOE Implement a LAMW Standard?
1. DOE's ``Authorized Limits'' System
2. DOE's Radiological Control Criteria
H. How Would States Implement the Standard?
1. Would States be Required to Implement the Standard?
2. State Programs
a. Facility Permitting/Public Participation
b. Implementation at the Disposal Facility
c. Agreement States d. Non-Agreement States
3. Regional Low-Level Radioactive Waste Compacts
I. Request for Information: LAMW
J. Background Information Regarding LAMW
1. Commercial LAMW
2. DOE LAMW
K. Questions for Public Comment: Disposal Concept for LAMW
III. Is it Feasible to Dispose Other Low-Activity Radioactive Wastes
(LARW) in Hazardous Waste Landfills?
A. How Would the Proposed Disposal Concept Apply to Other Low-
Activity Radioactive Wastes?
1. From a Technological Perspective
2. Pre-UMTRCA Byproduct Material
3. TENORM
4. Low-Activity LLRW/Source Material Exempted by NRC
B. What Legal and Regulatory Issues Might Affect Applying the
RCRA-C Disposal Concept to Other Low-Activity Radioactive Wastes?
1. Lack of Federal Regulation
2. How They are Regulated Now
a. Pre-UMTRCA Byproduct Material (FUSRAP)
b. TENORM
3. Existing Federal Regulation (Low-Activity LLRW)
4. Potential for a New ``Class'' of Disposal Facilities
C. Request for Information: Other LARW
D. Background Information Regarding Other LARW
1. Pre-UMTRCA Byproduct Material (and FUSRAP)
2. TENORM
3. Low-Activity LLRW/Source Material Exempted by NRC
4. Decommissioning Wastes
E. Questions for Public Comment: Disposal of Other LARW in
Hazardous Waste Landfills
IV. What Non-Regulatory Approaches Might be Effective in Managing
LAMW and Other Low-Activity Radioactive Wastes?
A. General Discussion
1. Advantages and Disadvantages of Non-Regulatory Approaches
2. Examples of Existing EPA Non-Regulatory Programs
3. National Academy of Sciences Studies
B. Non-Regulatory Approaches for LAMW and Other Low-Activity
Radioactive Wastes
1. Develop Guidance
2. Partner with Selected Stakeholders to Develop Waste-Specific
``Best Practices'
C. Request for Information: Non-Regulatory Alternatives to Our
Disposal Concept
D. Questions for Public Comment: Non-Regulatory Alternatives to
Our Disposal Concept
V. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
I. Why Are We Publishing Today's ANPR?
Today's ANPR introduces a variety of approaches that might be
applicable to certain low-activity radioactive waste categories
(LARW).\1\ We (the Environmental Protection Agency) seek public comment
on the appropriateness of these approaches towards a coherent framework
assuring appropriate management and disposal of such a diverse set of
LARW. As discussed below, our intent is to develop a regulatory
framework applicable to all LARW, which could include disposal of LARW
at RCRA facilities, whether radioactive material addressed by the
Atomic Energy Act under the jurisdiction of NRC or not. Our more
immediate focus regards a simpler but protective approach to the
present dual regulatory system applicable to low-activity mixed waste
(LAMW). We seek comment on approaches that would reduce the burden of
the dual regulatory framework for LAMW. One possibility would be to
establish a regulatory framework to allow, under certain conditions,
the disposal of LAMW at hazardous waste landfills under the purview of
Subtitle C of RCRA. Under this approach, we and NRC could reach
agreement on the appropriate conditions under which such disposal could
take place. Ideally, the conditions that would apply to disposal of
low-activity waste would be much simplified over those requirements
that now apply to low-level waste disposal facilities which allow the
disposal of higher concentrations of radioactive material. Upon such
agreement, NRC would need to take regulatory action to allow AEA
material under its jurisdiction to be sent to Subtitle C landfills.
This would, in
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effect, expand the disposal options available for LAMW.
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\1\ It is important to understand that the term ``low-activity''
does not have a precise statutory or regulatory definition. We use
the term throughout today's action to refer to wastes in which the
radioactivity is low enough to potentially allow management
alternatives that do not incorporate the entire range of radiation
control practices, such as disposal at RCRA Subtitle C landfills.
The situations and conditions that would define ``low-activity''
waste are the subject of today's action and potentially future
rulemakings.
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We recently took a similar approach to minimize dual regulation for
mixed waste. Recognizing the compliance difficulties associated with
the dual regulatory framework applicable to mixed waste, we promulgated
subpart N to 40 CFR part 266 (``Conditional Exemption for Low-Level
Mixed Waste Storage, Treatment, Transportation and Disposal''). (See 66
FR 27218, May 16, 2001.) This conditional exemption provides for a
reduced regulatory burden for facilities that store, treat, transport,
or dispose of mixed low-level waste (MLLW). Under certain conditions,
certain mixed wastes are exempt from RCRA regulation, leaving only the
requirements of the AEA to govern their storage, treatment,
transportation.
In addition to LAMW, there are a variety of wastes with relatively
low concentrations of radioactivity such as certain TENORM waste,
certain AEA materials and certain decommissioning wastes for which the
present institutional framework is less than clear. Some wastes are
tightly regulated from origin through final disposal while others are
presently unregulated. These wastes present a variety of radiological
risks and, ideally, wastes with similar risks should be managed
proportionately to the risk they represent. In this regard, there are a
variety of tools that may achieve acceptable risk levels, with
regulatory controls being one such tool. However, we recognize that
other tools, such as voluntary guidance, ``best practices,'' industry
standards, and the like have the potential to result in acceptable risk
levels. In section III of this document, we seek comment on the use of
these non-regulatory approaches for assuring and achieving acceptable
risk levels from the disposal of these various wastes and what role EPA
should play in creating a consistent and protective framework for
limiting risk. Just as importantly, our ANPR seeks information
regarding the characterization of wastes that fall in these categories,
or information on other wastes that might be considered in conjunction
with those named in this ANPR. Such information can only help to better
characterize the risk inherent in these waste categories and lead to a
more consistent, protective institutional framework.
We believe that the approach presented in today's action could
provide the necessary flexibility for the safe disposal of LAMW and
other LARW and might facilitate site cleanups. Informal discussions
with various stakeholders (commercial mixed waste generators, DOE,
disposal facility operators, State regulators, public interest groups)
suggest a broad level of interest in the potential advantages of this
approach. Today's document offers an opportunity for stakeholders to
provide detailed comment on a variety of concepts and possibilities
that could be used in a future rulemaking. If affected entities
demonstrate support for such a rulemaking and provide information
needed to develop technical and economic analyses, we would have a
strong basis to pursue this effort beyond the ANPR stage. Similarly,
NRC could use the approach described in this document to develop
regulations addressing the disposal of LAMW or other low activity
radioactive wastes from its (or Agreement State) licensees. In an
effort that may affect the disposal of LARW, NRC held a workshop on May
21-22, 2003, to discuss alternatives for safely controlling solid
materials that have no, or very small amounts of, radioactivity. One
alternative for that material is placement in a RCRA Subtitle C
(hazardous waste) or Subtitle D (solid waste) disposal facility.
Therefore, some of the issues discussed in that workshop may be similar
to some of the approaches discussed in this ANPR. Background materials
(including the information collection efforts conducted by NRC) and
current activities (including recent documents issued and plans for
stakeholder input), as well as transcripts of the workshop, can be
found at http://ruleforum.llnl.gov/cgi-bin/rulemake?source=SM_RFC&st=ipcr
.
II. How Can the Disposal of LAMW Be Simplified?
As noted above, we have recently promulgated regulations that
describe conditions under which RCRA defers to the NRC and Agreement
State requirements under the AEA for the storage, treatment,
transportation, and disposal of mixed low-level waste. We based this
deferral on our determination that the AEA requirements as addressed by
NRC's regulations for management of radioactive waste offered an
adequate degree of human health and environmental protection when
compared to that offered by RCRA for the hazardous components of MLLW.
Our RCRA authority is much more comprehensive and wide-ranging than our
AEA authority. Under RCRA, we define hazardous waste and regulate
hazardous waste generation, transportation, treatment, and disposal,
including the operation of facilities handling hazardous waste.
However, RCRA specifically excludes certain AEA material from its
jurisdiction (40 CFR 261.4(a)(4)). Under the AEA, for the protection of
the general environment, we can establish generally applicable
radiation protection standards that apply outside the boundaries of
locations under the control of persons possessing or using radioactive
material. NRC and DOE are responsible for establishing requirements for
disposal of AEA material by such persons. For example, we have used
this AEA authority to establish effluent release limits from facilities
comprising the uranium fuel cycle in 40 CFR part 190. In the case of
low-activity mixed waste a dual regulatory framework already exists to
address the storage, treatment, transportation, and disposal of such
waste. With the promulgation of subpart N to 40 CFR part 266, some of
these requirements are eased but widespread implementation of this rule
awaits adoption by the States before it can be implemented. (See 66 FR
27257, May 16, 2001.)
In an effort to further reduce the burden of this dual regulatory
framework for mixed waste, one option would be to promulgate a standard
(such as regulatory limits for radionuclides in the waste) in
coordination with the NRC allowing the disposal of LAMW in Subtitle C
(hazardous waste) RCRA landfills. We believe an appropriate rulemaking
by EPA and NRC of this nature will achieve the same level of
protectiveness while at the same time significantly reducing the effort
(and cost) otherwise required to comply with two separate regulatory
regimes. We focus on disposal because we are aware of a few thousand
small generators who store their mixed waste indefinitely because of
the lack of disposal options, or the high costs of disposal. We are
concerned that this situation may lead to mishandling, illegal dumping,
or the elimination of research on, and use of, medical diagnostic
techniques resulting in less than optimum health care. A protective
regulatory framework that is less expensive and less burdensome would
encourage prompt disposal of such waste, avoiding the risks of
mishandling and illegal disposal, while improving options for health
care. Some Subtitle C treatment standards for land disposal result in
stabilized, solidified, or vitrified treatment residues that will
immobilize radiological components, as well as hazardous constituents.
Also, RCRA requires landfills to have certain engineered barriers to
minimize infiltration and prevent releases. These factors make disposal
of LAMW in RCRA hazardous waste landfills an
[[Page 65125]]
attractive approach for a rulemaking. The key in this approach would be
to determine what concentrations of radioactivity in LAMW are
appropriate for disposal in a RCRA Subtitle C landfill. As the preamble
to subpart N to 40 CFR part 266 noted, an evaluation of the
requirements embodied in the respective regulatory frameworks for RCRA
and AEA revealed that both offer significant protections to human
health and the environment. (See 66 FR 27223, May 16, 2001.) In the
following sections, we discuss more fully the option of pursuing a
rulemaking allowing disposal of LAMW in a RCRA Subtitle C landfill.
A. What Needs To Be Done To Allow Protective Disposal of LAMW?
Because mixed waste contains both a hazardous chemical component
and a radioactive component, the safe disposal of low-activity mixed
waste must combine elements pertinent to both types of hazards. The
RCRA regulatory standards and permitting process provide for control of
the chemically hazardous waste components. If EPA pursues rulemaking
for the disposal of LAMW, we would focus on the controls necessary to
ensure protective disposal of the radioactive component of the waste.
We do not propose to change, either directly or indirectly, any of the
RCRA provisions regulating the disposal of the chemically hazardous
components of the waste. For the radioactive component of the waste,
limits on the concentration of radiological waste that can be disposed
of in a RCRA Subtitle C landfill may be the most straightforward method
to use. These limits would be protective of the public health and would
take into account the waste forms derived from the RCRA treatment
standards and the design and performance of engineered barriers
associated with such landfills.
1. Assess Characteristics of LAMW
The characteristics of low-activity mixed waste are important
factors in determining whether a given disposal concept will be
appropriate. By ``characteristics'' we mean the properties that will
influence our technical analysis of LAMW disposal, because they affect
the way the waste will behave in a Subtitle C disposal cell and
potential radiation exposure to people. Properties of interest will
include physical form and chemical composition of the wastes, and
radionuclide content (specific radionuclides and their concentrations).
There is limited information available on mixed waste, particularly
when compared to waste that is only low-level radioactive or RCRA
hazardous. The most comprehensive survey of commercial mixed waste was
conducted by NRC and EPA in 1992 (``National Profile on Commercially
Generated Low-Level Radioactive Mixed Waste,'' NUREG/CR-5938). A
summary of this survey is available at http://www.epa.gov/radiation/mixed-waste/nat-prof.htm.
NRC indicated that, based on 1990 practices,
commercial facilities generated about 3,950 cubic meters of mixed waste
annually and held another 2,120 cubic meters in storage. The profile
divides mixed waste properties and generation into five categories:
medical facilities, academic institutions, government institutions,
industrial facilities, and nuclear power plants. For various reasons,
such as improved waste management practices and information collected
by a few States, we believe the volumes of mixed waste being generated
today may be significantly lower than those described in NRC's profile.
For example, when developing our mixed waste rule of May 2001, our
discussions with mixed waste generators suggested that the industry has
recognized the limited progress in developing mixed waste treatment and
disposal capacity and taken steps to reduce mixed waste generation in
order to reduce the associated financial and regulatory burden.
Mixed waste (and therefore LAMW) is also generated by DOE. In fact,
DOE has a legacy of environmental and process wastes requiring disposal
and significant volumes are expected in the future as DOE sites undergo
continued cleanup. As discussed in more detail later (see section
II.J), DOE has indicated that tens of thousands of cubic meters of low-
level radioactive waste that is mixed waste (MLLW) may be considered
for disposal in commercial disposal facilities. Some fraction of this
waste may have concentrations low enough to qualify as LAMW. The
approach presented in this ANPR may also facilitate the cleanup of
contaminated DOE sites in a protective, expedited, and cost-effective
manner. We request comment on the application of a rulemaking based on
this approach to DOE LAMW.
We encourage mixed waste generators to give us their perspective on
the current status of mixed waste generation, storage, and disposal. In
particular, we would like to know whether generators believe the 1992
EPA/NRC profile accurately describes the state of mixed waste
generation today and how their mixed waste experience compares to that
profile. Further, since an approach using radionuclide concentration
limits to define LAMW for disposal at Subtitle C facilities may be the
most workable, we would like generators to tell us which radionuclides
are of most concern to them and the concentrations that would address a
significant portion of their waste (e.g., what concentration of a
particular radionuclide is found in 25%, 50%, 75% of a generator's
waste).
2. Assess Alternative Disposal Methods
Because we are focusing on simplifying disposal of LAMW, we must
assess the suitability of land disposal methods that have features that
could contribute to containment and isolation of low concentrations of
radionuclides or treated hazardous constituents. Disposal facilities
meeting this description would include:
[sbull] Low-level radioactive waste facilities licensed under 10
CFR part 61;
[sbull] Hazardous waste disposal facilities permitted under RCRA
Subtitle C;
[sbull] Uranium mill tailings facilities operating under 10 CFR
part 40; and
[sbull] Solid waste disposal facilities permitted under RCRA
Subtitle D.
Today's ANPR focuses on hazardous waste facilities permitted under
RCRA Subtitle C. We do not see a need to address low-level waste
facilities, which are licensed with conditions on acceptable
radionuclides and concentrations (which may vary for each licensed
facility). Further, the rule we issued in 2001 at 40 CFR part 266,
subpart N established conditions under which mixed waste could be sent
to an NRC or Agreement State licensed low-level waste facility without
requiring a RCRA permit. Similarly, while NRC has explored the
possibility of allowing mill tailings facilities to accept RCRA
hazardous and low-level radioactive waste, those facilities are not
generally able to accept either without site-specific licensing.
Finally, at this time, we do not expect to extend our disposal concept
to RCRA Subtitle D (non-hazardous solid waste) landfills. However, the
most recent EPA standards for such facilities (40 CFR part 258) require
them to have engineered features that are similar in many ways to
Subtitle C facilities. Further, our recent Hazardous Waste
Identification Rule (HWIR) effort was intended to identify levels at
which hazardous constituents pose a sufficiently low risk that they may
be sent to Subtitle D facilities. (See 66 FR 27266, May 16, 2001.) We
also note that NRC, in collaboration with the State of Michigan, has
recently concluded that certain very low-activity wastes from the
decommissioning of the Big Rock Point nuclear facility may be sent to a
[[Page 65126]]
Subtitle D landfill. (See 66 FR 63567-63568, December 7, 2001.) Other
States have also determined that Subtitle D facilities may offer
sufficient protection for certain types of radioactive material.\2\
Therefore, we request comment on the suitability of Subtitle D
facilities for low concentrations of radionuclides, under what
conditions such disposal would be appropriate, and how comparable
Subtitle D and Subtitle C facilities should be considered. We also
request comment on the suitability of other types of disposal
facilities not mentioned above.
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\2\ The State of Texas allows certain radioactive material with
half-life less than 300 days to be disposed in solid waste
landfills. (See Texas Administrative Code, Title 25, Chapter 289,
Section 202(fff).) In 2001, the Radiation Focus Group of the
Association of State and Territorial Solid Waste Management
Officials (ASTSWMO) stated ``Currently, prohibitions against all
radioactive materials are too broad'' and that ``the list of
radioactive materials that should be excluded from landfills * * *
should include only wastes that are long-lived, and/or soluble, or
otherwise pose a significant hazard.'' (``Detection and Response to
Radioactive Materials at Municipal Solid Waste Landfills,'' Final
Report, July 18, 2001.)
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a. RCRA Subtitle C Land Disposal. The design requirements for RCRA
Subtitle C hazardous waste landfills include engineered barriers (e.g.,
liners, see 40 CFR part 264, subpart N) while the hazardous waste
itself must be treated to meet the land disposal restriction (LDRs)
requirements. (See 40 CFR part 268.) Determining when disposal of LAMW
at Subtitle C landfills is appropriate could involve deriving limiting
radionuclide concentrations in the waste through modeling the
performance of these disposal cells. We would consider the
effectiveness of the RCRA-permitted landfill disposal cells under a
variety of performance and release scenarios. These performance
scenarios would take these design and waste treatment requirements into
account and would anticipate the range of site-specific conditions at
disposal sites that may occur in practice. The scenarios could assess
performance of the RCRA Subtitle C design with respect to ground-water
contamination under various climatic and hydrogeological conditions.
Scenarios could also evaluate worker exposure situations, including
both the worker at the disposal site and the transportation worker.
RCRA facilities are highly regulated and implement measures to protect
workers against associated hazards. The personal protective equipment
provided to RCRA workers might be expected to offer some protection
against radiological constituents. Presuming low concentrations of
radionuclides (which we would expect would keep exposures well below
those allowable for workers at AEA-licensed disposal facilities), these
workers might not need to be considered as occupational workers for the
purposes of a radiation protection program under NRC regulations.
Indeed, if the benchmark for exposure is low enough, from a
radiological perspective, these workers would be more like members of
the general public in the exposures they would be likely to receive
(requirements related to RCRA hazardous waste would still apply). Other
scenarios could also be considered as appropriate to assure the
protection of the public health and the environment. Consequently, this
approach would establish concentration limits appropriate for RCRA
Subtitle C landfills accepting LAMW without requiring site-specific
performance assessments. As a point of reference, consistent with the
concept of LAMW (and ``low-activity'' waste in general), radionuclide
concentration limits would not exceed the values NRC has established
for Class A radioactive waste, as described in 10 CFR 61.55. (See 47 FR
57473, December 27, 1982.) See section II.D for a more detailed
discussion of our concept for modeling.
b. Establish a Risk or Dose Basis for Allowable Concentrations. The
basic modeling scenarios provide a method for identifying appropriate
risk-or dose-based concentration limits on radionuclides in LAMW.\3\
However, we still must consider the appropriate level of risk or dose
on which the concentrations would be based. We are considering a number
of factors in selecting an appropriate level, including other risk
management decisions for radiation protection. In this regard, we are
also working with NRC to understand how risk considerations will be
incorporated into NRC's selection of a regulatory approach. We give
more detail on these factors in section II.D.4.
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\3\ A ``risk-based'' limit would consider the probability that a
person being exposed to radiation would develop a health effect. A
``dose-based'' limit would consider the amount of radiation exposure
that person could receive. The correlation between risk and dose is
not the same for every radionuclide.
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3. Coordination With the Nuclear Regulatory Commission
Because a significant purpose of our proposed approach is to
address low-activity mixed waste generated by NRC licensees, we and NRC
will work closely together in modifying the existing regulatory
structure to encourage more flexibility in LAMW disposal. The lack of
facilities to treat and dispose of mixed waste has been the subject of
Congressional hearings and EPA and NRC were encouraged to devote
resources to develop a strategy to address these issues.\4\ Concern was
also expressed to the Council on Environmental Quality about this
problem, which ``has persisted for over 11 years [with] no resolution
in sight.'' \5\ The Council was asked what action was being taken to
create alternatives for dealing with these waste streams.\6\ We and NRC
have worked together in the past to develop guidance and regulatory
solutions for certain broad mixed waste issues.\7\
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\4\ Hearing Before the Subcommittee on Energy and Power of the
Committee on Commerce, House of Representatives, 104th Cong., 2d
Sess., Sept. 5, 1996, Serial Number 104-114.
\5\ Hearing Before the Subcommittee on Oversight and
Investigations, of the Committee on Energy and Natural Resources,
United States Senate, 104th Cong., 2d Sess., Sept. 26, 1996, Serial
Number 104-775, at 71.
\6\ Id.
\7\ EPA and NRC have issued joint guidance on mixed waste
testing (``Joint EPA/NRC Guidance on Testing Requirements for Mixed
Radioactive and Hazardous Waste,'' 62 FR 62079, November 20, 1997)
and disposal (``NRC/EPA Siting Guidelines for Disposal of LLMW,''
OSWER Directive 9480.00-14, June 1987; ``Joint NRC/EPA Guidance on a
Conceptual Design Approach for Commercial LLMW Disposal
Facilities,'' OSWER Directive 9487.00-8, August 3, 1987). These
documents are available at http://www.epa.gov/radiation/mixed-waste.
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In that vein, EPA and NRC view the disposal of LAMW in a Subtitle C
RCRA landfill as a viable approach deserving further examination
through a public notice and comment process. EPA and NRC believe this
approach has the potential to offer needed flexibility in the
regulation of mixed waste and be fully protective of the public health
and the environment. This approach would also be consistent with
actions taken by both agencies to address specific situations. Note
that the NRC, in consultation with us, has issued guidance such that,
under certain conditions, radioactively contaminated electric arc
furnace dust containing cesium-137 below specified levels--the result
of accidental melting of sealed sources by steel mills--appropriately
may be disposed of in commercially operated RCRA hazardous waste
facilities (62 FR 13176, March 19, 1997).
We anticipate that implementing the disposal option discussed in
today's action for all low-activity radioactive waste, including those
waste streams discussed in section III, will require regulatory action
by both agencies (although our respective responsibilities clearly vary
for the different waste streams). We invite commenters to provide their
perspective on the appropriate roles of the two agencies in developing
regulatory standards and implementing them for waste generators
[[Page 65127]]
and disposal facilities, including the appropriate level of Federal
and/or State oversight. What regulatory arrangement, including division
of responsibilities between EPA and NRC, would be most likely to
facilitate the safe management and disposal of these wastes? We would
also welcome suggestions as to the most effective ways to minimize the
effects of dual regulation.
In our discussions, NRC has identified several regulatory options
that it might apply to LAMW. We discuss these potential NRC regulatory
approaches to LAMW in section II.F, and have included some questions to
elicit public comment on those approaches. However, NRC will discuss
issues specific to NRC's regulatory system in greater detail as it
proceeds through its own rulemaking process. Our action today focuses
more on technical and policy questions surrounding the use of RCRA-C
technology and regulatory framework for disposal of LAMW, the
applicability of the RCRA-C technology to other low-activity
radioactive wastes, and non-regulatory approaches that might prove
effective in managing and disposing of low-activity wastes. We
encourage commenters to respond to all questions in today's action.
B. Why Is There a Need To Simplify Disposal of LAMW?
1. Dual Regulatory Structure
Mixed waste is regulated under both RCRA and the AEA. The need to
comply with two separate regulatory systems, each of which is targeted
to a different component of the waste, creates a certain regulatory and
economic burden on mixed waste generators. While many of the
requirements of the two systems have similar purposes (e.g.,
inspections), they can have the effect of creating two distinct
regulatory compliance infrastructures. Generators (as well as treatment
and disposal facilities) must achieve compliance with both systems. In
some cases, these requirements may appear to be duplicative.
Approximately 3000 small volume generators store mixed wastes, in
part because disposal options are extremely limited. Some estimates are
that the number of individual sites storing mixed waste could be
significantly higher, though there is greater uncertainty in these
estimates. The lack of disposal options for these generators causes
increased management costs. It also can result in mishandling and
perhaps illegal dumping of the waste. Some mixed waste has been in
storage for over a decade. These concerns are not limited to small
generators. The EPA rule discussed in section II.B.2 was largely driven
by power companies' concern over dual regulation of mixed waste. We
believe, in general, that treatment and permanent disposal of waste,
when available, is preferable to storage.
Also, we are concerned that the high costs and difficulty of
disposing of mixed waste will cause doctors, hospitals, and diagnostic
laboratories to suspend certain procedures, which could result in the
provision of less than optimum health care.\8\ There are reports that
the inability to store and dispose of radioactive waste has caused
researchers to avoid scientific procedures that are known to be
effective and to develop less effective alternatives.\9\ We also are
concerned that such problems indirectly may be hampering medical
research.
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\8\ Kaye, Gordon J, ``The Crisis in LLRW Disposal Short- and
Long Term Effects on the Biomedical Community,'' Newsletter for
Appalachian Compact Users of Radioactive Isotopes, June 1991.
\9\ Isaac, Peter G, et al., ``Nonradioactive Probes,'' Molecular
Biology, p 259-160, vol. 3, June 1995.
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We believe it is possible to alleviate the problem if more of the
facilities that can accommodate hazardous waste safely were allowed,
under certain conditions, to dispose of LAMW. Of the commercial
facilities currently permitted to dispose of hazardous waste under
RCRA, only one is also licensed to dispose of AEA radioactive waste
(and mixed waste). (This facility and one other that we are aware of
that has applied for a license to dispose of AEA radioactive waste are
special cases, as their original plans involved accepting radioactive
waste.) This situation may be due, in part, to the additional burden
faced by the RCRA disposal facility operators in applying for a site-
specific license under 10 CFR part 61 or its equivalent to establish a
full-fledged low-level radioactive waste (LLRW) disposal facility. Both
10 CFR part 61 and RCRA Subtitle C describe fairly lengthy, data
intensive, and costly processes for regulatory approval. The somewhat
different focus of the two systems (RCRA as ``technology based'', part
61 as ``performance based'') may also serve to limit the number of
facilities willing to demonstrate compliance under both regulatory
systems. (See section II.C for more detail on the licensing-permitting
issue.) A few commercial Subtitle C landfills have accepted non-AEA
radioactive waste with the approval of State authorities, which
supports our belief that, with the proper controls, the RCRA-C
technology can provide protective disposal of certain types of
radioactive material. Issues associated with non-AEA radioactive wastes
are discussed in section III.
We asserted RCRA authority over the hazardous portion of mixed
waste in the mid-1980s; however, section 1006 of RCRA states that the
AEA takes precedence over RCRA in cases where the regulatory
requirements are inconsistent. Because the approach we are considering
would rely on RCRA Subtitle C landfill technology, and because low-
activity mixed waste would have relatively low concentrations of
radionuclides, our approach would permit the disposal of LAMW if it met
RCRA-C regulations and practices. This implies that the risks to
workers, the public, and the environment (including ground water)
presented by the radioactive portion of LAMW would be effectively
minimized considering the controls already in place at the RCRA-C
landfills. Waste generators would also bear responsibility for ensuring
that their waste met conditions for disposal as low-activity mixed
waste.
This approach would take into account the practicalities of
implementing LAMW disposal at RCRA-permitted hazardous waste landfills,
rather than transforming them into more AEA-like facilities. We believe
that this will introduce sufficient flexibility as to allow LAMW
generators to take advantage of additional disposal options. Similarly,
the number of commercial facilities currently permitted under RCRA to
accept hazardous waste (roughly 20) is significantly higher than the
number licensed to accept low-level waste (3) or mixed waste (1),
offering the prospect of greater competition and disposal capacity.
Though this comparison is instructive, we do not want to limit our
focus to commercial disposal facilities. A significant number of
companies have been issued permits for their own ``captive'' or
privately-owned hazardous waste disposal facilities, which typically
accept waste only from generators owned by or affiliated with the
landfill operator. It is conceivable that mixed waste generators might
be among those with access to such facilities. These facilities must
meet the same RCRA permitting requirements as commercial facilities and
therefore, this approach should be equally appropriate for the receipt
of LAMW. We request comment on whether we should consider only a subset
(i.e., only the commercial or private sector) of the RCRA-C universe in
our analyses. On a related topic, should RCRA landfills operated by DOE
on its own sites be considered within the scope of this approach?
[[Page 65128]]
2. Recent EPA Mixed Waste Actions
As described above, on May 16, 2001, we promulgated regulations
related to the storage, treatment, transportation, and disposal of
mixed low-level radioactive waste (subpart N of 40 CFR part 266). These
regulations describe conditions under which MLLW can be exempted from
certain RCRA hazardous waste requirements. In particular, a generator
of MLLW may store and treat the waste at the generator's facility
without obtaining a RCRA permit (required for hazardous waste
treatment, disposal, and on-site storage beyond 90 days), as long as
the storage and treatment take place in tanks or containers and conform
to the generator's AEA license conditions. Similarly, transportation to
an AEA-licensed low-level radioactive waste disposal facility, and
subsequent disposal, may also take place solely according to AEA
requirements. However, eligible MLLW must still meet the RCRA land
disposal treatment standards prior to transportation for disposal at a
licensed low-level waste disposal facility.
We believe our conceptual approach to disposal of low-activity
mixed waste is complementary to the regulations we promulgated in
subpart N. We believe that a significant proportion of MLLW could
qualify as low-activity mixed waste (just as most low-level waste is in
the lowest-activity class), depending on where the technical analyses
indicate the limits should be set. The approach we are outlining today
would also significantly increase disposal options, if fully
implemented. Compared to the three operating low-level radioactive
waste disposal facilities, there are roughly twenty commercial RCRA
Subtitle C disposal facilities operating today, with many more that
take waste from only a limited number of generators.
The approach we took in promulgating the subpart N disposal
requirements relied on a comparison of the RCRA and AEA requirements
for disposal. In that context, and recognizing that RCRA waste meeting
the treatment standards for land disposal would likely be significantly
lower in risk, we determined that AEA disposal requirements offered
sufficient protectiveness for the hazardous constituents in MLLW. Our
approach to establishing disposal standards for low-activity mixed
waste is similar in concept. For example, our approach would consider
the effects of waste form for the treated LAMW and containerization in
minimizing the availability of radionuclides in the waste for release
in the presence of water. However, our approach will rely on modeling
to determine when the risk to workers and the public from disposal of
radionuclides is acceptably low. The LAMW concentration limits
developed under this approach will be analogous to the RCRA
concentration-based treatment standards that reduce the toxicity and
mobility of hazardous constituents in the waste. Additional measures
that support and build public confidence in this determination, such as
ground-water monitoring for radionuclides, may be advisable.
There will be unavoidable overlap of the mixed waste eligible for
disposal under the two rules. Our subpart N regulations cover a broader
spectrum of MLLW, while we expect the LAMW concept to address only the
lower-activity portion of that MLLW spectrum. Generators with waste
eligible under both rules may make their disposal choice based on cost,
access to a disposal facility, and regulatory constraints.
C. How Would the RCRA Regulatory Framework Support a Viable Disposal
Concept?
We propose to rely to a large extent on the protections offered by
the RCRA hazardous waste disposal facilities for disposal of low-
activity mixed waste. We believe that the RCRA Subtitle C requirements
provide a uniform level of waste containment and isolation technology
that warrants confidence in their ability to address low concentrations
of radionuclides; although RCRA does not regulate on the basis of
radioactivity, there is no general prohibition on disposal of material
not regulated as hazardous in a hazardous waste facility, and some RCRA
facilities are permitted to accept certain types of TENORM waste. In
addition, requirements related to hazardous waste characteristics have
evolved over the life of the Subtitle C program to the point that they
are tightly controlled through application of treatment standards.
Below we discuss several points that we believe provide strong support
for the LAMW disposal approach.
1. Technological Basis for Disposal (RCRA Hazardous Waste Landfill
Criteria)
To assess the protectiveness of LAMW disposal at RCRA-C facilities,
we first need to understand how the disposal cell itself will
contribute to the isolation of radionuclides. It is recognized that
RCRA and AEA employ different regulatory philosophies. RCRA has
explicit engineering and construction criteria for Subtitle C
landfills. Therefore, any permitted RCRA-C facility is expected to meet
these basic criteria and they can be accounted for in the technical
analyses. In contrast, as discussed further in section II.C.4, AEA low-
level waste facilities in 10 CFR part 61 must meet certain performance
objectives to be licensed. Thus the AEA approach allows for some
variation among AEA facilities, depending upon factors such as climate
and site geology. This provides flexibility in facility design in that
it can be tailored to the hazard of the waste. Ultimately, the purpose
of both systems is to contain and isolate the waste in order to protect
public health and the environment.
We believe RCRA's uniformity of design, and the specific
engineering features required, provide assurance that RCRA-C facilities
can limit contact of waste with water (and subsequent leachate
generation) and should allow disposal of LAMW containing low
concentrations of radionuclides. The RCRA regulations describing
landfill attributes are located in 40 CFR part 264, subpart N. They
require, among other things, that a disposal facility have:
[sbull] A cap on the disposal cell that minimizes infiltration of
liquids, promotes drainage, minimizes erosion, accommodates settling
and subsidence, and has permeability no greater than that of the
disposal cell liner system or natural subsoils;
[sbull] A liner system beneath the disposal cell constructed of
materials of specified thickness, hydraulic conductivity, physical
strength, and chemical resistance;
[sbull] A leachate collection and removal system capable of
limiting leachate depth above the liner to 30 cm; and
[sbull] A leak detection system constructed with a specific slope
and materials of a certain thickness, hydraulic conductivity, physical
strength, and chemical resistance.
2. RCRA Treatment Standards
Besides having specific requirements for disposal cell
construction, RCRA also requires that hazardous waste be treated prior
to land disposal. This treatment may serve two purposes: First, it can
reduce the concentration of hazardous constituents in the waste, which
also reduces the associated risk; second, it may change the physical
form of the waste, which can change the volume of the waste, make the
waste easier to handle, reduce the likelihood of releasing hazardous
constituents from the waste, or reduce the likelihood that the waste
itself will migrate out of the disposal cell (e.g., as a liquid or
[[Page 65129]]
leachate) and reach ground water. (By contrast, NRC requirements
address waste characteristics, but NRC does not require specific
treatment methods for waste prior to disposal. However, low-level
radioactive waste is generally compacted, which reduces volume and
increases stability but also increases radionuclide concentrations on a
per unit volume basis. In addition, liquids and chelating agents must
be minimized or otherwise managed to limit their impact on facility
performance.)
The RCRA Universal Treatment Standards (UTS) are located in 40 CFR
part 268. Most are in the form of concentration limits of the
respective hazardous constituents, but some are in the form of
specified treatment technology (particularly in the case of hard-to-
treat wastes). The UTS are based on the level of reduction that can be
achieved by available technology, not on risk reduction. However, by
reducing the concentration of toxic constituents, the practical effect
is some reduction in risk. We would appreciate comments on the need for
measures, such as waste treatment to a specific waste form, that would
help ensure that radionuclide concentrations established under the
approach outlined today remain protective when implemented.
We expect this approach to require that low-activity mixed waste
comply with the RCRA UTS before allowing disposal at RCRA-C facilities,
in keeping with existing restrictions. To the extent that treatment
involves some kind of waste stabilization or solidification, we would
consider this advantageous to keeping radionuclides immobilized in the
disposal cell. We ask readers whether they believe there are situations
in which compliance with the UTS may be unnecessary or inadvisable for
wastes containing radionuclides. We request comment on the need to
require a certain waste form for LAMW and the desirability of having
standards (e.g., concentrations) that are dependent on waste form. We
also request comment on whether a rule should explicitly require
segregating treated LAMW meeting the UTS from untreated hazardous waste
(waste disposed of before treatment standards were required). This
would limit potential interactions with chemicals that could influence
the ability of radionuclides to move in the environment. We believe
this is probably not necessary, as disposal cells that were open prior
to the treatment requirements are likely to have been closed for some
time.
3. RCRA Disposal Facility Operating Standards
RCRA is also explicit about how the facility must approach
operational functions, both while the facility is operating and during
the closure and post-closure phases. In particular, facility operators
must follow specific procedures regarding (see 40 CFR part 264):
[sbull] Inspections--the facility operator must inspect equipment
and procedures in accordance with a written schedule (including
inspecting the installation of the liner and leachate collection
system), must inspect the operation of the landfill after storms, and
must inspect the leachate collection system regularly during operation
and post-closure;
[sbull] Recordkeeping--the facility operator must maintain
inspection records for at least three years and maintain records
detailing the location, dimensions, and contents of disposal cells;
[sbull] Monitoring/corrective action--the facility operator must
conduct a ground-water monitoring program and implement corrective
action when a hazardous constituent is detected in ground water at
concentrations that exceed those listed in the facility's permit;
[sbull] Closure/post-closure--the facility operator must install a
permanent cap on the disposal cell that complies with engineering
specifications, must have an approved closure plan that minimizes the
need for further maintenance, must perform maintenance that becomes
necessary throughout the post-closure period, and must submit a survey
plat showing the locations and contents of disposal cells.
4. How Does AEA Licensing Compare to RCRA Permitting?
Both the NRC and EPA have designed their disposal regulations with
the intent of isolating waste from the environment to minimize
exposures from the radiological or chemical constituents (in this
document, we are focusing on the NRC requirements for LLRW disposal
under 10 CFR part 61). There are a number of broad similarities between
the two regulatory approaches that could translate into ``simplified''
AEA oversight. For example, both the AEA and RCRA:
[sbull] Accept and regulate near-surface disposal as a means to
contain and isolate waste;
[sbull] Include measures to limit infiltration into the disposal
cell (such as a cover/cap);
[sbull] Require site monitoring during operations;
[sbull] Require continued maintenance after facility closure; and
[sbull] Recognize that there are certain site characteristics to be
avoided (such as floodplains and other geologic hazards).
However, there are also some noteworthy differences in the
technical requirements for waste disposal. Some of these differences
exist because of the way the regulations are written and implemented.
RCRA regulations are more prescriptive and design-based than are the
NRC requirements. Although both systems have basic requirements for
site selection, RCRA does not require a landfill seeking a hazardous
waste disposal permit to conduct performance assessments (site-specific
modeling) to assess how waste disposal at the facility will protect
human health and the environment after facility closure. Instead, by
requiring a uniform (minimum) level of technology designed to provide
containment and prevent releases, RCRA places the burden on the
technology to perform as expected and thereby protect the public and
environment. For example, RCRA requires that a disposal cell have a
double liner constructed of certain materials and a leachate collection
system capable of performing to certain specifications. RCRA
regulations say, in effect, ``this level of technology is protective.''
An important point is that, under RCRA, leachate from a hazardous waste
disposal cell is hazardous waste, and must be collected and treated
accordingly. Similarly, leachate containing radionuclides could be
newly generated mixed waste and be treated accordingly. We request
comment on how we should address radionuclides in the LAMW leachate,
particularly if the LAMW has been disposed of under some exemption from
NRC requirements.
On the other hand, NRC, in its regulations under the AEA, focuses
more on standards of performance, rather than on construction
specifications. The NRC has established a maximum dose level to the
public; however, the burden is on the facility operator to satisfy the
licensing authority that the facility, as sited and constructed, will
not allow that dose to be exceeded. Thus, the NRC regulations require a
detailed, site-specific operational and post-closure performance
assessment to show that the facility will perform adequately. NRC
regulations say, in effect, ``show that the level of technology you
select, combined with the characteristics of the site you have
selected, will meet this level of protection.'' License conditions,
often including monitoring facility performance, are then established
to
[[Page 65130]]
ensure that the level of protection is achieved.
The nature of the waste can also affect the time needed for the
hazard to diminish. RCRA establishes a minimum period of 30 years for
facility maintenance and monitoring after closure of the disposal cell
(with extensions as necessary to protect human health and the
environment). NRC assumes a minimum period of 100 years for active
maintenance, with control of the site continuing for an indefinite
period before license termination because of the variety and
concentration of radionuclides that could be disposed at such a site.
Performance assessments conducted to meet 10 CFR part 61 licensing
requirements include projections well beyond both the 30- and 100-year
active institutional control periods.
The environment in the disposal cell (e.g., pH, temperature,
moisture) can affect the decomposition of many hazardous constituents
(primarily organics, as many heavy metals persist essentially forever).
Radionuclides, however, break down more predictably than do hazardous
constituents. A radionuclide remains radioactive, and will take the
same time to decay, regardless of its physical and chemical
environment. Because some radionuclides take hundreds or thousands of
years to decay, under the AEA, facilities are not expected to maintain
perfect containment for these long periods until the waste is no longer
radioactive. In fact, evaluations of AEA facilities typically include
situations in which the disposal system does not perform as well as
expected, with resulting limited releases. These projected limited
releases become the basis for performance assessments used to make
compliance or licensing decisions. Under NRC regulation, the
combination of engineered barriers, waste form requirements, and
natural site characteristics are evaluated to assure that the
concentration of radionuclides reaching the accessible environment does
not exceed regulatory limits. Although AEA regulatory practice focuses
on preventing infiltration, if the cell cover degrades it is preferable
for infiltrating water to move quickly out of the disposal cell in
order to minimize contact time with the waste (avoiding a ``bathtub''
situation). Thus, this approach of recognizing the potential for
limited releases delays and spreads out the releases over time and
minimizes peak doses. In practice, many long-lived radionuclides will
not move with ground water, but will remain within the general area of
disposal because of their chemical characteristics. (Assumptions and
knowledge about the mobility of individual elements in various
environments influence the selection of modeling parameters. Typically,
conservatism is introduced into performance assessments to help account
for uncertainties in long-term modeling. It should also be noted that
the behavior of a particular element in the environment will be
essentially the same whether it is radioactive or not.) In this vein,
NRC regulations expect the evaluation of a potential disposal site for
``at least a 500 year time frame'' while also considering the
``indefinite future.''\10\
---------------------------------------------------------------------------
\10\ 10 CFR 61.7(a).
---------------------------------------------------------------------------
There are several fundamental issues to be considered in
determining the feasibility of an approach involving simplified NRC
oversight for RCRA-C facilities, particularly where NRC requirements
are more extensive than RCRA requirements. Areas of overlap in which
one regulatory regime would take primacy also are important. These
issues include:
[sbull] Post-Closure Care: Should operators be required to maintain
the facility for periods longer than the minimum 30 years required by
RCRA? (RCRA has discretion to extend this period, and some States have
done so.) What about for 100 years, with the expectation of longer site
control, as NRC requires?
[sbull] Land Ownership: RCRA allows private ownership of disposal
sites, with the possibility of future sale. NRC licensing under 10 CFR
part 61 is contingent on eventual ownership of the site by a Federal or
State government entity.
[sbull] Financial Assurance: AEA disposal facilities generally put
up a higher initial financial assurance than RCRA facilities to account
for longer periods of care.
[sbull] Ground-Water Monitoring and Corrective Action: If there are
releases of hazardous constituents, RCRA authorizes corrective action
(corrective action for hazardous constituents might be effective for
AEA materials combined with the hazardous constituents). RCRA
regulations have specific requirements for ground-water monitoring of
hazardous constituents (40 CFR 264.92-94), which are incorporated into
the facility permit. While NRC regulations have general requirements
for site monitoring ``capable of providing early warning of releases of
radionuclides from the disposal site before they leave the site
boundary'' (10 CFR 61.53), they do not contain separate ground-water
standards. Detailed monitoring requirements may be developed in the
facility license.
This ANPR addresses the possibility of alternate disposal methods
for LARW. We will work with NRC to develop appropriate concentration
limits that are protective of the general public and that minimize the
need for additional NRC requirements. However, NRC may decide that
additional requirements on generators or disposal facilities are
necessary for NRC to meet its obligations under the AEA. We request
comment on these issues.
D. What Methods Could Be Used To Assess the Risk of Disposing of LAMW?
1. Modeling as a Basis for Establishing Risk or Dose Basis
Mathematical modeling is a fundamental tool of radioactive waste
management. It assists regulators in assessing expected releases (and
subsequent doses) to the environment from disposal facilities over
periods of hundreds to thousands of years. However, these projections
over time should not be viewed as firm predictions. Instead, they can
give regulators and the public confidence that certain limits will not
be exceeded. Actual ``proof'' of performance would involve active
measures such as facility monitoring.
2. Comparison of Risks From Radioactive and Hazardous Waste Disposal
The public may not have a good understanding of the relative risks
from radiation and hazardous waste. It is probably true that many
people would consider radioactive waste to be more of a danger than
hazardous waste. It is important that the public be informed of the
risks involved in our approach and be satisfied that those risks are
managed appropriately. We have included a general discussion of risks
from both types of waste below.
The risk from radioactive material depends on the type of radiation
emitted and the path(s) of exposure. Gamma radiation is most
significant for external exposures. Alpha emissions are of most concern
for inhalation. NRC requirements for land disposal typically put limits
on radiation doses to the public. Dose can be converted to risk,
although risk can also be calculated directly from exposures; the
results tend to differ for the two methods, and dose itself can be
expressed in several ways that may not be equivalent (a more detailed
discussion of various dose standards is located in section II.D.5). As
discussed above, facilities seeking an NRC radioactive waste disposal
license
[[Page 65131]]
must satisfy the licensing authority that they can meet these limits
through long-term performance assessments. The performance assessment
evaluates the projected inventory of radionuclides in the disposal cell
at closure and models the movement of those radionuclides in the
environment using site-specific conditions.
RCRA considers risk when deciding which wastes should be defined as
hazardous. RCRA evaluates how individual constituents, when land
disposed, will behave in the environment over long periods of time.
Listed wastes (those designated by F, K, P, or U waste codes)
automatically include substances that have a lifetime cancer risk of
10-\4\ or higher to a nearby receptor (i.e., exposures to
the contaminant would cause a fatal cancer to one person or more in a
population of 10,000). RCRA lists substances with a lifetime cancer
risk between 10-\4\ and 10-\6\ on a case-by-case
basis. It does not list those substances with a lifetime cancer risk
less than 10-\6\ (i.e., fewer than one in 1,000,000). For
non-cancer toxic effects, if the concentration of the constituent in
leachate exceeds the drinking water treatment standard for that
constituent (i.e., the ``Hazard Quotient'' is greater than or equal to
1), the waste is listed as hazardous. Toxicity characteristic wastes
(designated by the D waste code) are defined at the concentration that
corresponds to a 10-\5\ lifetime fatal cancer risk. In
determining whether to list a waste as hazardous, RCRA does not focus
on individual site characteristics, but conducts generalized
assessments that consider climatological and hydrogeological variations
around the country along with how much of a particular waste is
generated and how many sites across the country might accept such
waste, and does not credit the engineered features required in the
regulations (as we would expect to do for LAMW).
Since 1998, hazardous waste must meet the Universal Treatment
Standards (UTS) in 40 CFR part 268 before being land disposed. The UTS
are constituent-specific concentration or treatment technology
standards that effectively reduce the toxicity, although the waste must
still be disposed of as hazardous. Our recent Hazardous Waste
Identification Rule (HWIR) effort is intended to establish risk-based
constituent concentrations at which listed hazardous wastes could
``exit'' regulation under Subtitle C. They could then be disposed of as
``solid waste'' under Subtitle D.
In sum, both the NRC and RCRA approaches serve to limit the risk to
the public from waste disposal. Although we plan to conduct modeling of
the disposal cell (that may combine aspects of the site-specific and
generalized approaches), we will also examine the NRC and RCRA disposal
regulations to support the modeling efforts.
3. Modeling Scenarios
The modeling effort would have two aims. The first aim would be
simply to assess the performance of the generic RCRA-C design in terms
of long-term radionuclide containment. The second aim would be to
derive limits for radionuclide concentrations in the wastes to be
disposed of in such a facility. Both NRC and EPA will have to be
satisfied with the modeling to successfully implement this approach.
EPA's modeling approach is detailed below and will be coordinated with
the NRC.
a. Situations to be Addressed. The initial step in a risk or dose
assessment is to determine how a person might be exposed to the
material in question. If there is no exposure, as for the period when
waste is contained and isolated within an intact disposal cell, the
risk or dose will be zero. There are four situations that could result
in human exposures to the radionuclides in low-activity mixed waste:
[sbull] The gradual degradation of the disposal cell through
expected natural processes, which results in radionuclide releases over
long periods of time (100 years or more);
[sbull] Releases caused by ``off-normal'' events, such as unusually
high precipitation over a period of years;
[sbull] Exposures to RCRA disposal facility workers handling LAMW;
and
[sbull] Exposures caused by human activity that disrupts the
disposal site.
These scenarios are discussed in more detail in the following
sections. We request comment on the adequacy of these scenarios and
whether there are others we should consider. We recognize that similar
scenarios could be used to describe potential exposures to the
hazardous constituents already handled at the facilities under
consideration, and that such exposures may be of equal or greater risk
than would be presented by radionuclides; however, our purpose in this
discussion is to determine the best way to demonstrate that the RCRA
technology is adequately protective for radionuclides.
b. Long-term Disposal Cell Performance. i. General Discussion. To
model the long-term performance of the RCRA hazardous waste disposal
cell, assumptions must be made about the initiation of failure of the
cap and liner system to allow water to enter the cell, interact with
the wastes, and exit the disposal cell to the surrounding area. Once
released from the disposal cell, contaminated water would percolate
downward through the unsaturated zone above the local water table,
eventually reaching the water table and migrating laterally in the
direction of ground-water flow toward a receptor at some distance from
the disposal facility. For this conceptual model, the receptor is a
person living close to the facility who receives doses from the use of
contaminated ground water. Other pathways of exposure would include the
surface transport of waste accidentally spilled during operation of the
disposal facility.
With this simple conceptual model, potential releases from the
disposal cell can be calculated for assumed waste concentrations by
specifying the other parameters involved in contaminant transport
calculations. Important factors for consideration in the modeling
calculations include:
[sbull] Rainfall rates;
[sbull] Thickness of the unsaturated zone under the disposal cell;
[sbull] Distance from the disposal cell to the well supplying water
to the receptor;
[sbull] Drinking water consumption rate from the contaminated well
and amounts of contaminated food consumed;
[sbull] Ground-water flow rates;
[sbull] Effectiveness of the cap in controlling water infiltration
and the liner in retarding contaminant movement;
[sbull] Radionuclide retardation effects (primarily sorption into
the geologic media and solubility constraints); and
[sbull] Radioactive decay along the flow paths.
To test the performance of the disposal cells, we would model a
wide range of site-specific conditions in arid and humid climatic
settings as well as variations in hydrogeologic conditions, such as
variations in the thickness of the unsaturated zone below the disposal
facility and ground-water flow rates in the saturated zone. Variations
in all these parameters will affect the exposures incurred by the
receptor for the scenarios analyzed. We would expect to base our
modeling on data available for actual sites in order to capture the
variation in various site parameters. We could use the data for DOE
sites, because they represent a wide range of climatic and
hydrogeologic conditions across the nation, and because they are
relatively well-characterized and a good data base of site-specific
conditions is available for them. We also could use site data
[[Page 65132]]
from RCRA-C facilities across the nation; the most comprehensive
approach would probably be to create a combined data set to ensure that
the modeled sites reasonably address the range of potential waste
disposal facilities subject to RCRA-C landfill requirements. We would
expect to adopt a conservative approach to selecting model parameters,
as described in more detail later. Additional sensitivity studies would
be done to identify the variables that most prominently control
disposal cell performance and exposures to the hypothetical receptor
outside the facility.
We expect to address a variety of site characteristics and exposure
scenarios in the analyses described below. These analyses will
encompass a broad range of potential conditions from which waste
concentrations could be derived for uniform waste acceptance criteria
nationwide. It is possible that some hazardous waste landfills could
dispose of waste containing higher concentrations of radionuclides than
would be appropriate for the ``average'' facility while maintaining the
appropriate level of protection for the public and environment. For
example, waste acceptance criteria could be derived by explicitly
examining site characteristics, such as annual precipitation levels.
Alternatively, disposal facilities with unique features, such as very
deep ground-water tables, may be able to safely contain wastes with
higher radionuclide content than the levels defined in a broadly
applicable standard. Therefore, we request comment on whether
individual disposal facilities should be given the opportunity to
demonstrate that they can accept waste with radionuclide concentrations
that exceed those that would be established by such a standard.
The basic scenario to model would be an expected performance case,
in which the disposal cell degrades over time and radionuclide releases
from the bottom of the cell infiltrate the underlying unsaturated zone
and move into the saturated zone. From that point, the ground-water
flow in the saturated zone carries radionuclides laterally to a well
supplying the water needs of a defined receptor (person) living near
the former disposal cell. The modeling would allow us to calculate
exposures to the receptor from direct ingestion of drinking water and
ingestion of food produced using contaminated ground water from
hypothetical wells. We could also examine the impact of volatile
radionuclides, such as might be encountered during irrigation. These
radionuclides can sometimes give significant exposures through
inhalation. However, we would expect ingestion exposures from various
ground-water uses to be much higher than those from inhalation of
volatile radionuclides.
We believe that the modeling approach should be appropriately
conservative. By ``conservative,'' we mean that we would select
modeling parameters so that releases from the disposal cell are more
likely to be over-estimated than under-estimated. This approach helps
to account for uncertainty by incorporating an additional margin of
safety. However, it would not be appropriate to be overly conservative.
Focusing on ``worst case'' conditions leads to reliance on unrealistic
modeling results. Major areas of conservatism could include:
[sbull] The distance from the disposal cell to the receptor well
could be assumed to be short--
--Prevents expected dilution of the contamination plume with larger
volumes of ``clean'' ground water
--Less radionuclide retardation by soils along ground-water flow path
--Institutional control over site may prevent a well close to the
disposal cell
--Early detection of radionuclide release could trigger facility
closure and corrective action
[sbull] Radionuclide retardation parameters could be selected for
less retardation and faster transport
[sbull] Disposal facility cap and liner could be assumed to fail
sooner than normally anticipated after facility closure
--Cap and liner designed to exceed RCRA 30-year post-closure monitoring
period
--Assumption of failure introduces infiltration and flow through
disposal cell earlier than normal, when radionuclide inventories are
highest.
As stated above, a primary purpose of modeling the long-term
performance of the RCRA-C disposal cell would be to derive radionuclide
concentrations in wastes that would assure that exposures from any
disposal cell releases would be at acceptably low levels to support a
simpler NRC regulatory process for the disposal of low-activity
radioactive waste at RCRA-permitted hazardous waste landfills. We
expect that modeling will show that some radionuclides reach the
receptor well within the modeling period. For these radionuclides,
waste concentration limits would likely be calculated by simply scaling
the exposures calculated in the modeling exercise to the acceptable
level of protection (we request comment on the appropriate level of
protection to consider for this approach in section II.D.5). These
limits would function as waste concentration limits for implementing
the RCRA-C disposal option. Wastes with radionuclide concentrations
higher than established in the rule would not be eligible for disposal
in the RCRA-C disposal cell, although consideration could be given to
including in the rule specific additional conditions that would permit
such disposal (essentially, a ``graded'' approach in which more
extensive radiation protection measures are applied as radionuclide
concentrations increase). Another alternative would be to allow a
disposal facility to petition to have higher waste concentration limits
based upon the results of site-specific performance assessments.
However, this would make it more difficult for NRC to pursue a
simplified regulatory approach.
ii. ``Wet'' and ``Dry'' Sites. We believe that using a conservative
modeling approach will incorporate a significant margin of safety
sufficient to compensate for any uncertainties in the eventual
performance of the RCRA-C disposal design. Assessing just how
significant the margin of safety will be depends on how waste
radionuclide concentrations will be applied to disposal facilities. We
see two basic approaches, discussed generally below. We request comment
on these and other potential approaches.
The first option (``Option 1'') would be to have all disposal
facilities use the same waste concentration limits regardless of the
projected disposal cell performance. Experience tells us we would
expect to see significant variation in performance under the wide range
of climatic and hydrogeologic conditions that we model. Essentially,
Option 1 imposes the concentration limits determined for the worst case
disposal cell we would model on all potential disposal sites,
regardless of the relative merits of any particular site conditions.
Option 1 would thus add an additional level of conservatism to an
already conservative approach. This approach has the potential to
significantly decrease the usefulness of the rule by placing additional
limitations on the waste streams addressed by our proposal (i.e., waste
concentration limits based on a ``worst case'' situation). An advantage
of Option 1 is that it is simple to implement, in the sense that no
variations in the waste concentration limits would be permitted.
Option 2 would allow different concentration limits to be used
depending on the projected performance of the disposal facility. For
example,
[[Page 65133]]
performance modeling might indicate that sites with lower rainfall and
deeper ground-water tables perform significantly better with respect to
limiting off-site doses from radionuclides that can be transported away
from the disposal cells by infiltrating ground water. Such a result
would not be surprising, simply because the travel time for
radionuclides to produce an off-site dose to individuals is likely to
be longer if infiltration is less and it takes longer to reach ground
water in the first place. For these ``dry'' sites, higher waste
concentrations for those radionuclides readily transported with ground
water could apply to the disposal facility while still meeting the same
exposure limits as the ``wet'' sites (with higher rainfall and
shallower ground-water tables). For both options, the exposure limits
which underlie the rule would be the same. If site conditions leading
to superior overall performance were clearly seen in the modeling,
Option 2 would take advantage of that projected performance, whereas
Option 1 would not.
Should Option 2 prove preferable, we would then face the challenge
of defining desirable site conditions that would allow disposal of
waste with higher radionuclide concentrations in some subset of RCRA-C
facilities. In general, annual precipitation is an important parameter
(and is also one for which data can be obtained easily), but often
varies too much to be used by itself to characterize site behavior.
Experience in modeling the movement of radionuclides through the
environment, as well as empirical observation, indicate that the depth
from the bottom of the disposal cell to the ground water is another
important parameter that also is measured easily. Although depth to
ground water also can vary (e.g., with seasonal variation in
precipitation), we believe that it could be possible to use
precipitation and depth to ground water, in combination with other
parameters, to distinguish sites that can accept higher concentrations
of some radionuclides without presenting undue hazards to human health
and the environment. This approach essentially favors sites that have
long travel times from the disposal cell to the ground-water table
(generally through some combination of deep ground water and soil types
that tend to slow the movement of infiltrating water) and limited
infiltration of water through the cap to the waste layer (generally
through a combination of low precipitation and high
evapotranspiration).
We recognize that there are many other parameters that affect
radionuclide transport. However, it may be difficult to obtain the
necessary information, and necessarily more complex to devise a method
to combine the parameters. We encourage public comment on the concept
of distinguishing among sites, as well as ideas on methods to make that
distinction. As an initial point of review for interested commenters,
we have examined this issue for relatively small Subtitle D facilities
in remote locations. Because many of these facilities are in
communities with limited resources, we determined that ground-water
monitoring could be limited if annual precipitation (including
evapotranspiration) was less than roughly 25 inches, as long as there
is no evidence of ground-water contamination. We also developed a
screening tool for Subtitle D facilities seeking no-migration variances
that considers precipitation, depth to ground water, net infiltration,
evapotranspiration potential, and permeability of the unsaturated zone.
This approach implicitly estimates travel time from the disposal cell
to the ground water. See ``Preparing No-Migration Demonstrations for
Municipal Solid Waste Disposal Facilities: A Screening Tool,'' EPA530-
R-99-008, February 1999 (available at http://www.epa.gov/osw).
We are aware that the approach embodied in Option 2 is somewhat
different from that taken by existing RCRA regulations. RCRA is a
national program and we have written regulations accordingly. In
practice, this means that all members of the regulated community have
to meet the same standard, whether it is numeric or technological
(i.e., a site with ``good'' transport characteristics does not get to
accept higher concentrations of hazardous constituents than sites with
relatively poorer characteristics). Under certain conditions, the
standard may be adjusted to meet the regulated party's specific
circumstances (e.g., through a delisting petition or variance). In
these cases, we create a process that an applicant can use to justify
an alternative standard. This would be somewhat analogous to allowing a
disposal facility operator to calculate site-specific concentration
limits, as we discussed earlier in this section.
Another option would be to set other restrictions on site
characteristics for RCRA-permitted landfills accepting low-activity
mixed waste for disposal. We believe the modeling should be conducted
with the intent that any facility that could be sited and permitted
under RCRA Subtitle C could safely dispose of LAMW. However, some
commenters may believe that some locations would not be appropriate for
radionuclide disposal without additional conditions or site-specific
analysis, especially if these locations have relatively poor overall
transport characteristics or geologic features such as fractures in the
subsurface that might provide faster transport pathways to the ground
water. If we were to identify such criteria that go beyond the existing
RCRA criteria (i.e., if simply having a RCRA permit is not sufficient),
what should they be? If a site did not meet the basic eligibility
criteria, should there be an alternative ``qualification'' process
(e.g., through the type of site-specific analysis discussed earlier in
this section)? For purposes of an implementable standard, the basic
eligibility criteria would need to be clearly defined in the rule
itself (NRC may or may not require additional conditions or
restrictions on waste streams under its authority before RCRA-C
facilities could accept those wastes). We also would need to clearly
relate these specific characteristics to a performance objective.
Therefore, we also ask that commenters provide supporting technical or
scientific information that describes how their recommendations would
improve facility performance, and how they would define ``good''
performance. The criteria could include climatological characteristics
such as annual precipitation, transport characteristics of the
unsaturated zone, depth to ground water, or proximity to other features
that affect site suitability. These minimum criteria then would be
factored into the basis for deriving radionuclide concentrations from
off-site exposures.
We also note that RCRA authorized States can issue standards that
are more stringent than the national program. This means that some
States could already have siting criteria for RCRA facilities that
explicitly address some of the factors mentioned above. We would
welcome comments that identify such criteria and indicate the technical
and scientific basis for their adoption. As we have stated before, we
believe that the modeling should be sufficiently conservative to
account for reasonably anticipated variations in site performance, so
that special conditions would not be necessary.
iii. Modeling Timeframe. Another factor in modeling the long-term
performance of a disposal cell is the time period covered by the
modeling. We believe that a 1,000 year modeling period may be
appropriate, although we
[[Page 65134]]
also expect to examine performance over longer times (e.g., up to
10,000 years) to see how well a 1,000 year modeling period captures the
behavior of most radionuclides. There is no consensus on the most
appropriate time for performance assessments. Periods from 100 years to
10,000 years have been used in assessments for various waste disposal
methods. While NRC regulations do not specify a time period in 10 CFR
part 61, NRC guidance in ``A Performance Assessment Methodology for
Low-Level Radioactive Waste Disposal Facilities,'' NUREG-1573 (2000),
endorses a 10,000-year modeling period for licensed LLRW sites.
However, NRC generally uses a 1,000-year period for assessing the dose
consequence of residual radioactive material at the time of license
termination. NRC has its radiological criteria for license termination
in 10 CFR part 20, subpart E. The 1,000-year period is typical for
evaluations of low-level waste disposal (as opposed to high-level waste
or spent fuel disposal, which generally focus on much longer time
periods), and is specified by DOE for performance assessments at its
disposal facilities (DOE Manual 435.1-1, ``Radioactive Waste Management
Manual''). However, some believe that modeling for low-level
radioactive waste must also look at periods well beyond 1,000 years (to
10,000 years or longer) to fully address the possibility of significant
change to the site from erosion or other long-term or cyclic processes.
Others believe that a modeling period of 1,000 years or longer
stretches the credibility of what modeling can reasonably project, and
that at most it is possible to examine with confidence only a few
hundred years (particularly with near-surface facilities, which are
more easily affected by climatic or geologic changes than are deep
subsurface facilities). We believe that 1,000 years may be appropriate
because it is likely that the rule will involve such low radionuclide
concentrations that the value of modeling over longer periods becomes
more questionable in the light of expected changes in surface
conditions over longer periods. It may also be appropriate to consider
periods on the order of 100 years as more consistent with the RCRA
approach to post-closure site care. We request comment on the
appropriate timeframe for modeling.
c. ``Off-Normal'' Events. In assessing the long-term performance of
the disposal cell, we typically use fairly well defined climatic
conditions (e.g., precipitation rates) and incorporate assumptions
about the behavior of the engineered cap and liner. However, we must
also consider what happens when the system departs from ``normal''
behavior. Situations to be examined would include heavier than normal
precipitation over a period of years (or possibly the indefinite
future), alternative cap and liner degradation scenarios, and the
possibility that the rate of water entering into the disposal cell
would exceed the rate exiting the cell, causing water levels to rise
inside the cell. In such a situation (also known as the ``bathtub
effect''), waste remains in contact with water and radionuclide
concentrations can build up in the water collected in the disposal
cell, so that when releases to the subsurface occur, radionuclide
concentrations are higher than they would be if the water spent less
time in contact with the waste. Alternatively, continued heavy
precipitation could cause the water level to overflow the disposal
cell, providing a surface pathway for radionuclide transport.
d. Disposal Facility Worker. For radionuclides that remain immobile
under the off-site exposure modeling described above (i.e., those that
do not reach the receptor well within the modeling period, even with
conservative transport assumptions), there must be another means of
developing waste concentration limits. One approach that might be
considered is the possible exposure that workers at the RCRA disposal
facility might receive because of radiation from the waste material. In
this case, exposures to the RCRA-C worker would also serve as a
benchmark for public exposures, both during the facility's operational
life and after final closure. Assessing worker dose will allow
estimations of exposures to the public without relying on excessively
speculative exposure scenarios; as discussed below, we believe that
anyone who is not directly handling the waste will receive much lower
exposures than would be expected of a worker.
The worker exposure analysis being considered would serve two
functions. First, it would limit potential exposures to the general
public in a manner that is generally consistent with the risk
management approach for radiation exposure to members of the general
public that EPA uses in its regulatory programs and NRC uses at fully-
licensed low-level waste disposal facilities. We would expect exposures
to people not directly handling waste to be much less than the
exposures considered as a reference level for modeling. We believe that
this will ensure that actual exposures to true members of the general
public, such as visitors during the operating life of the facility,
will be minimal. We believe such an approach is appropriate for the
disposal of low-activity mixed waste under this proposal. Second, it
should provide a reasonable basis for NRC, and Agreement States, to
determine whether significant additional worker protection requirements
beyond those of RCRA are necessary. Specifically, whether NRC should
consider requiring inclusion of training, personal dosimetry, record
keeping and reporting, in its regulatory approach. The goal is to
identify radionuclide concentrations that are low enough for the NRC to
conclude that it is unnecessary to consider RCRA workers as
occupational workers under NRC regulations. We also note that workers
handling AEA material are subject to NRC's occupational radiation
standards, rather than Occupational Safety and Health Administration
(OSHA) standards. Workers handling non-AEA material are subject to the
ionizing radiation standards issued by OSHA, which are found in 29 CFR
1910.1096. We anticipate that NRC's consideration of worker protection
requirements would be likely to address the necessary elements of the
OSHA requirements.
We emphasize that we do not intend to set a standard for worker
exposure. However, we are considering modeling several worker exposure
scenarios to assist in setting the radionuclide concentration limits
for LAMW. Some scenarios might assume that the waste already has been
treated and stabilized in a cement/concrete mixture, or in a less dense
medium such as polyethylene. This would mean that the radionuclides
most likely to be limited by a worker scenario are those that emit
strong gamma radiation. Alpha, beta, and weak gamma emissions are not
as likely to be able to escape the stabilized waste form to expose the
worker. However, we are also considering scenarios involving bulk waste
that is neither solidified nor containerized. These scenarios would
present a greater risk of waste becoming airborne, leading to exposure
by inhalation or ingestion. In such cases, the alpha, beta, and weak
gamma emissions would be of more importance than for stabilized waste
forms. We seek comment on the proportion of bulk waste that might be
disposed under this rulemaking.
e. Transportation Worker. It might be necessary to consider
exposures to a worker involved in transporting waste to the RCRA
disposal facility. The transportation worker would most likely be
exposed through pathways similar to a disposal facility worker who
handles waste containers within the facility. In
[[Page 65135]]
such a case, we would make assumptions about how close the worker is to
the waste and for what length of time. We would also consider
Department of Transportation requirements for transportation of
radioactive material.
f. Post-Closure Site Use. The worker exposure modeling we envision
would also help assure limited exposures to the public in the future,
when all waste is buried and the site is closed. Because existing
regulations allow RCRA sites to remain privately owned, it is possible
that a site could be made available for some limited (surface) use
after closure. People who casually traverse the site, or even spend
hours at a time engaged in an activity, would not be expected to
receive doses that exceed those calculated for the worker, and
therefore such doses should be acceptable.
When a Subtitle C disposal facility closes, RCRA requires that the
owner/operator file a survey plat with the local land-use authorities
and the EPA Regional Administrator that shows the location of all
hazardous waste units.\11\ The survey plat must note that the future
use of the land is restricted in accordance with applicable
regulations. The deed to the property also must state that it has been
used to manage hazardous waste and must cite the appropriate
restrictions on future use. At a minimum, use of the property that will
disturb the integrity of the final cover, the liner, or other parts of
the containment system is not permitted unless necessary to protect
human health and the environment, or if such use will not increase the
potential hazard to human health and the environment.
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\11\ 40 CFR part 264, subpart G.
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The facility's owner or operator must construct the final closure
cap to minimize infiltration and erosion and accommodate settling or
subsidence with little maintenance (40 CFR 264.310, although active
maintenance would be possible during the post-closure care period).
Even in the event of some noticeable erosion of the cap, which would
not occur until well after final closure, doses to an exposed person
should remain well within acceptable public dose limits. Because of the
multi-layer cap construction, erosion by itself should not be
sufficient to expose the waste. We believe that the controls
established by RCRA will be adequate to prevent intrusion, more
extensive use, or disruption of the site. NRC may apply the 10 CFR part
20, subpart E, unrestricted use standard of 25 mrem to RCRA sites
chosen for disposal of low-activity mixed waste. If subpart E is
applied, NRC might not impose additional facility requirements. On the
other hand, NRC could decide that additional controls for such sites
are necessary. Specifically, NRC could impose extended post closure
care, restricted access after closure, limitations on land use and
restricted site ownership requirements to such disposal sites. In this
ANPR, we are assuming that such additional requirements will not exist.
Although we believe limited use of an undisturbed LAMW disposal
site is not likely to present a significant risk to members of the
public, we must consider the possibility of more extensive use
involving a disturbance of the disposal cell. A common scenario for
such an analysis involves a person who builds a house on the disposal
site, where the construction involves excavation of some portion of the
disposal cell, disturbing the waste layer and scattering of the
contaminated material on the surface. The foundation and basement could
be constructed at some depth in the disposal cell, and the resident
could engage in small-scale crop production or raise some livestock on
the contaminated site. Further, in locating water to support the
resident, it might be assumed that a well is drilled through the
disposal cell, involving some exposure to the driller(s) as
contaminated material is brought to the surface.
This last possibility introduces the prospect that some disturbance
of the cell would enhance transport of radionuclides to the off-site
receptor. In past actions (e.g., geological disposal) we have addressed
a person who uses heavy equipment, such as a drill rig, to penetrate
the waste layer and cell liner, essentially creating a pathway for
radionuclides to move through the unsaturated zone to the aquifer. If
one assumes this type of drilling scenario, how would such a
disturbance affect the release and transport of radionuclides? The most
likely effect would be to create a pathway for the transport of
material containing radionuclides through the unsaturated zone into
direct contact with the aquifer. We would expect that only a very small
volume of waste would be affected by such action. Whether the waste is
solidified or not, the bulk of the radioactive material would be likely
to stay within the confines of the original disposal cell. It is also
clear that there would be no change in the way radionuclides are
released from the waste material remaining in the cell. Once a
radionuclide is released, however, the penetration may provide a
preferred pathway that decreases the travel time through the
unsaturated zone.
If they could occur, the types of site disturbances described above
would happen at some time in the future beyond the end of the RCRA
post-closure period. We do not consider such disturbances to be very
likely, given the site controls prescribed by RCRA regulations,\12\ but
must examine them as an extreme scenario. In its rulemaking for 10 CFR
part 61, NRC concluded that the possibility of extensive inadvertent
intrusion activities at near surface disposal facilities was not
credible for waste in a structurally stable waste form (that is, as
long as the waste remained in a form recognizably man-made, either in a
stabilizing medium or container, intruders would determine that it
should not be disturbed).\13\ If we assume that the intrusion occurs
after any solidified waste has broken down or containers have degraded,
this would likely be several hundred years beyond site closure,
suggesting that shorter-lived radionuclides will have decayed. We note
that hazardous constituents that do not degrade over time, such as
heavy metals, will still be present in the disposal cell and may
present a risk comparable to or greater than the risk from
radionuclides. We also note that the closure requirements described
above apply to Subtitle C facilities. As commenters consider the
applicability of this approach to Subtitle D facilities (see section
II.A.2), it would be appropriate to consider whether the same post-
closure exposure scenarios would apply to those facilities.
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\12\ 40 CFR part 264.
\13\ See Draft Environmental Impact Statement on 10 CFR part 61,
NUREG-0782, Vol. 2, page 4-53, Sept. 1981.
---------------------------------------------------------------------------
4. Other Considerations Affecting the Risk Analysis
a. Use of Part 61 Classification System. For LLRW, the NRC system
defines three waste classes (A, B, C) by the concentration of each
radionuclide. Class A has the lowest concentrations of short- and long-
lived radionuclides and is the least restrictive in terms of packaging
requirements. Classes B and C have more stringent packaging and
stabilization requirements. Class C waste must be located at least 5
meters below ground. NRC does not consider low-level radioactive waste
that exceeds Class C concentrations (``Greater-than-Class C'' waste) to
be generally suitable for disposal in a near-surface facility. Some
radionuclides do not move easily with ground water (or are very short-
lived) and may also not be significant contributors to worker or post-
closure
[[Page 65136]]
public exposure. This means that the limiting concentrations could be
very high if we relied solely on the various modeling scenarios we have
identified. In some cases the limiting concentrations from modeling may
exceed the maximum concentrations established by the NRC for Class A
low-level radioactive waste (see 10 CFR 61.55). In these cases, we
believe that it might be appropriate to set the concentration limit
equal to the Class A maximum value.
It is important to use credible modeling scenarios to the extent
possible to establish the capability of the RCRA-C technology for
radionuclide containment and isolation, and not to rely on the Class A
restriction or other such considerations, except in special cases. We
are concerned that it could be very difficult for us and NRC to justify
a ``simplified'' regulatory approach if a significant number of
radionuclides were at their Class A maximum values. That is, it would
be less likely that the resulting concentration limits would be
appropriate for disposal in RCRA-C facilities in the absence of
significant NRC licensing criteria. In any event, it would defeat the
purpose of simplifying LAMW disposal to require RCRA-C facilities to
undergo a complicated licensing process.
b. Waste Form and Packaging. An important factor in this analysis
is waste treatment prior to disposal. Mixed waste must undergo
treatment for its hazardous constituents to comply with the RCRA land
disposal restrictions of 40 CFR part 268. Treated RCRA waste often is
solidified or stabilized in some type of encapsulating medium to
prevent migration of the remaining hazardous constituents. Cement/
concrete is the most common encapsulating medium because of its ready
availability, cost, and experience in its use. Other encapsulating
technologies, such as vitrification or use of polymers or ceramics, are
less common but may be more effective than cement/concrete at binding
mobile constituents. There are no such treatment requirements for Class
A LLRW, other than restrictions on liquid content (although LLRW must
be treated ``to reduce to the maximum extent practicable'' the hazard
from non-radiological material). The modeling is expected to consider
various waste forms. Of the available encapsulating technologies, we
would consider use of cement/concrete as the most conservative case.
Though a common practice, stabilization is not necessarily a
requirement for compliance with land disposal restrictions. If
solidification or stabilization is not the treatment standard for a
particular hazardous constituent, RCRA requires that the solidified
waste form be tested to show that it meets the prescribed treatment
standard. We request comment on whether it is reasonable to assume a
stabilized waste form as a treatment of choice for LAMW and whether a
rule should require waste stabilization. Such a requirement, however,
could make the disposal of bulk low-activity waste in RCRA C landfills
prohibitively expensive. (Bulk wastes could include such items as soil,
demolition debris, and slag or other industrial process residuals.)
Alternatively, it may be appropriate to have a different set of
concentration limits for disposal of bulk wastes.
As stated earlier, we request comment on the possibility of
individual disposal facilities developing alternative concentration
limits. The performance of less-common encapsulating technologies could
be a factor in permitting such alternative calculations. However, there
are limited data available compared to the extensive literature
available on cement/concrete. In addition to comment, we request
information regarding the long-term performance of encapsulating
technologies, particularly as they pertain to radionuclides.
Waste containers also provide a barrier against radionuclide
releases, as well as adding structural stability to the waste form.
Containers are typically drums or boxes, made of metal or polymer. It
is not unusual for RCRA treatment to result in a waste form that is
solidified inside a container (for example, mixing ash or other
treatment residue with cement). NRC regulations require Class B and C
LLRW to be in containers; if Class A waste is not in containers, it
must be segregated from the waste that is in containers. We request
comment on the need to specify container requirements in the rule.
c. Activity Caps. As stated above, under our basic concept, wastes
with radionuclide concentrations higher than established in the rule
would not be eligible for disposal in the RCRA-C disposal cell.
However, waste with higher concentrations might be acceptable if the
total number of curies in the disposal cell remained below a certain
level (in conjunction with or in lieu of concentration limits). This
could mean placing limits on the total curies of radionuclides disposed
of at a site, inventory limits on specific radionuclides, or waste
volume limitations (as an indirect and more conservative method to
limit activity, since not all the waste would be expected to contain
the maximum radionuclide concentrations). Further, because modeling the
performance of facilities over the long term involves estimates of the
inventory of radionuclides present at site closure, limits of this type
would help reduce uncertainty in those estimates. We request comment on
this issue. We also request comment on how facilities could demonstrate
compliance with such activity limits, how such demonstrations might
relate to on-going operations at a RCRA-C facility, and the limitations
to such an approac