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[Federal Register Volume 74, Number 120 (Wednesday, June 24, 2009)]
[Notices]
[Pages 30175-30179]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-14820]

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NUCLEAR REGULATORY COMMISSION

[NRC-2009-0257]

Notice of Public Workshop on a Potential Rulemaking for Safe 
Disposal of Unique Waste Streams Including Significant Quantities of 
Depleted Uranium

AGENCY: Nuclear Regulatory Commission.

ACTION: Notice of public workshop and a request for comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) plans to conduct 
two public workshops to solicit public input on major issues associated 
with a potential rulemaking for land disposal of unique waste streams 
including, but not limited to, significant quantities of depleted 
uranium in near-surface radioactive waste disposal facilities. The 
public workshops are intended to solicit the views of representatives 
of interests that may be affected by the rulemaking. Members of the 
public are invited to provide written comments on the issues presented 
in this notice and to attend the workshops to provide feedback on the 
potential rulemaking. The public workshops will be held in Rockville, 
Maryland on September 2-3, 2009 and in Salt Lake City, Utah on 
September 23-24, 2009.

DATES: Members of the public may provide feedback at the transcribed 
public workshops or may submit written comments on the issues discussed 
in this notice. Comments on issues for the agenda should be postmarked 
no later than August 1, 2009. Comments on the issues and questions 
presented in this notice and discussed at the workshops should be 
postmarked no later than October 30, 2009. Comments received after 
these dates will be considered if it is practical to do so. NRC plans 
to consider these stakeholder views in the development of a technical 
basis for the planned rulemaking. Written comments may be sent to the 
address listed in the ADDRESSES section. Questions about participation 
in the roundtable discussion at the public workshops should be directed 
to the facilitator at the address listed in the ADDRESSES section. 
Members of the public planning to attend the workshops are invited to 
RSVP at least ten (10) days prior to each workshop. Replies should be 
directed to the points of contact listed in the FOR FURTHER INFORMATION 
CONTACT section.
    The public workshops will be held in Rockville, Maryland on 
September 2, 2009, from 8 a.m. to 5 p.m. and on September 3, 2009, from 
8 a.m. to 5 p.m. and in Salt Lake City, Utah on September 23, 2009, 
from 8 a.m. to 5 p.m. and on September 24, 2009, from 8 a.m. to 5 p.m. 
The location of and final agenda for each public workshop will be 
noticed no fewer than ten (10) days prior to each workshop on the NRC's 
electronic public workshop schedule at http://www.nrc.gov/public-involve/public-meetings/index.cfm. Please refer to the SUPPLEMENTARY 
INFORMATION section for additional information on the issues proposed 
for discussion at the public workshops.

ADDRESSES: Submit written comments to the Chief, Rulemaking and 
Directives Branch, Division of Administrative Services, Office of 
Administration, U.S. Nuclear Regulatory Commission, Mail Stop TWB 
5B01M, Washington, DC 20555-0001, and cite the publication date and 
page number of this Federal Register notice, or by fax at 301- 492-
3446. Comments may also be submitted electronicallly at http://www.regulations.gov. Search on docket ID NRC-2009-0257.
    Questions regarding participation in the roundtable discussions 
should be submitted to the facilitator, Francis Cameron, by mail to 
Mail Stop O16-E15, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001, by telephone at 301-415-1006 or 240-205-2091, or by e-mail 
at [email protected].

FOR FURTHER INFORMATION CONTACT: Priya Yadav, Office of Federal and 
State Materials and Environmental Management Programs, U.S. Nuclear 
Regulatory Commission, Washington, DC 20555-0001, telephone 301-415-
6667; e-mail [email protected], or Christopher Grossman, Office of 
Federal and State Materials and Environmental Management Programs, U.S. 
Nuclear Regulatory Commission, Washington, DC 20555-0001, telephone 
301-415-7658; e-mail [email protected].
    The public may examine and have copied for a fee, publicly 
available documents at the Public Document Room, One White Flint North, 
11555 Rockville Pike, Rockville, Maryland. Publicly available documents 
created or received at NRC after November 1, 1999, are available 
electronically at the NRC's Electronic Reading Room at http://www.nrc.gov/reading-rm/adams.html. From this site, the public can gain 
entry into the NRC's Agencywide Documents Access and Management System 
(ADAMS), which provides text and image files of NRC's public documents. 
If you do not have access to ADAMS, contact the Public Document Room at 
1-800-397-4209, 301-415-4737, or by e-mail to [email protected].

SUPPLEMENTARY INFORMATION: 

I. Background

    The Low-Level Radioactive Waste Policy Amendments Act of 1985 (Pub. 
L. 99-240) sets forth the Federal policy, including responsibilities, 
for the disposal of low-level radioactive waste to ensure available 
disposal capacity for all classes of waste, as specified by Title 10, 
Sec.  61.55, of the Code of Federal Regulations (CFR). Existing NRC 
regulations in 10 CFR 61.55 specify criteria for determining the 
classification of low-level radioactive waste for land disposal at a 
near-surface facility. The original development of 10 CFR 61.55 did not 
explicitly consider the impacts resulting from the disposal of 
significant quantities of depleted uranium from the operation of a 
commercial uranium enrichment facility (``Draft Environmental Impact 
Statement on 10 CFR Part 61 Licensing Requirements for Land Disposal of 
Radioactive Waste,'' NUREG-0782, 1981, ADAMS Accession Nos. ML060930564 
(vol. 1), ML060930573 (vol. 2), ML060930577 (vol. 3), and ML060930583 
(vol. 4); ``Final Environmental Impact Statement on 10 CFR Part 61 
Licensing Requirements for Land Disposal of Radioactive Waste,'' NUREG-
0945, 1982, ADAMS Accession Nos. ML052590184 (vol. 1) and ML052920727 
(vol. 2)). When 10 CFR Part 61 was initially developed, there were no 
commercial facilities generating significant quantities of depleted 
uranium waste. As a result, the analysis only considered the types of 
uranium-bearing waste streams being typically

[[Page 30176]]

disposed by the NRC licensees at the time.
    The NRC issued licenses for two commercial uranium enrichment 
facilities in 2006 and 2007, which are expected to generate significant 
quantities of depleted uranium. Depleted uranium is source material, as 
defined by Section 11(z) of the Atomic Energy Act of 1954, as amended, 
and if treated as a waste would fall under the definition of a low-
level radioactive waste under 10 CFR 61.55(a). The NRC reaffirmed this 
waste classification in Memorandum and Order CLI-05-20 dated October 
19, 2005 (ADAMS Accession No. ML052930035). Consistent with its policy 
to increase the use of risk-informed decision-making in all regulatory 
matters (``Staff Requirements--COMSECY-96-061--Risk-Informed, 
Performance-Based Regulation (DSI 12)'', April 15, 1997, ADAMS 
Accession No. ML003671740), the NRC considered in a screening analysis 
(``Response to Commission Order CLI-05-20 Regarding Depleted Uranium,'' 
SECY-08-0147, October 7, 2008, ADAMS Accession No. ML081820762) whether 
quantities of depleted uranium at issue in the waste stream from 
commercial uranium enrichment facilities warrant amending the waste 
classification tables in 10 CFR 61.55(a) or amending 10 CFR 
61.55(a)(6). The NRC decided to pursue a limited rulemaking to specify 
a requirement for a site-specific analysis and associated technical 
requirements for unique waste streams including, but not limited to, 
the disposal of significant quantities of depleted uranium (``Staff 
Requirements--SECY-08-0147--Response to Commission Order CLI-05-20 
Regarding Depleted Uranium,'' SRM-SECY-08-0147, March 18, 2009, ADAMS 
Accession No. ML090770988). In pursuing this limited rulemaking, the 
NRC is not proposing to alter the waste classification scheme. However, 
for unique waste streams including, but not limited to, significant 
quantities of depleted uranium, there may be a need to place additional 
criteria on its disposal at a specific facility or deny such disposal 
based on unique site characteristics. Those restrictions would be 
determined via a site-specific analysis that satisfies the requirements 
developed through this rulemaking process.
    In advance of this planned rulemaking, NRC will conduct public 
workshops inviting representatives of the stakeholders affected by the 
rulemaking in a ``roundtable'' format. At these workshops, NRC plans to 
discuss with stakeholders the issues to be considered in the rulemaking 
and the technical parameters of concern for a site-specific analysis 
associated with the disposal of unique waste streams, including 
significant quantities of depleted uranium. NRC plans to consider these 
stakeholder views in the development of a technical basis for the 
planned rulemaking.
    In order to have a manageable discussion, the number of 
participants around the table will, of necessity, be limited. The NRC, 
through the facilitator of the workshop, will attempt to ensure broad 
participation by the spectrum of interests affected by the rulemaking, 
including citizen and environmental groups, nuclear industry interests, 
state, tribal, and local governments, and experts from academia and 
other federal agencies. Other members of the public are welcome to 
attend. Those not seated at the tables, including individual members of 
the public, will have the opportunity to provide feedback on each of 
the issues slated for discussion by the roundtable participants. 
Questions about participation in the roundtable discussion may be 
directed to the facilitator.
    Section II describes issues associated with disposal of unique 
waste streams in general, while Section III describes specific issues 
associated with technical parameters for a site-specific analysis for 
disposal of significant quantities of depleted uranium that were 
identified from the screening analysis (SECY-08-0147, October 7, 2008).

II. Issues With Disposal of Unique Waste Streams

    This section discusses issues associated with a regulatory 
definition of unique waste streams that should be considered before 
commencing regulatory activities related to technical requirements for 
a site-specific analysis for land disposal of unique waste streams in 
the near-surface. Each issue is assigned a number, a short title, and a 
list of questions and factors for consideration. These issues, 
questions, and factors are not meant to be a complete or final list, 
but are intended to initiate discussion. Interested stakeholders are 
welcome to recommend additions, deletions, or modifications to the key 
issues for consideration. These issues and factors will focus the 
discussion at the public workshops. All public feedback will be used in 
developing options for NRC consideration.

Issue II-1. Definition of Unique Waste Streams

    The NRC plans to propose a rulemaking in 10 CFR Part 61 to specify 
a requirement for a site-specific analysis for the disposal of unique 
waste streams including, but not limited to, significant quantities of 
depleted uranium. As part of this planned rulemaking, NRC will solicit 
stakeholder views on considerations for a regulatory definition for 
unique waste streams requiring a site-specific analysis.
    Question II-1.1--Should the NRC propose a regulatory definition to 
(a) specify general criteria that would capture both current and 
foreseeable unique waste streams; or (b) limit the definition to a 
known set of current unique waste streams including significant 
quantities of depleted uranium? What characteristics should NRC propose 
as defining for unique waste streams?
    Question II-1.2--What waste streams containing radionuclides listed 
in the waste classification tables at 10 CFR 61.55 are currently, or 
possibly in the foreseeable future, being disposed of in quantities 
significantly greater than initially considered in the development of 
10 CFR Part 61?
    Question II-1.3--What waste streams containing radionuclides that 
are not listed in the waste classification tables at 10 CFR 61.55 are 
currently, or possibly in the foreseeable future, being disposed of in 
concentrations or quantities significantly greater than initially 
considered in the development of 10 CFR Part 61?
    Question II-1.4--What waste streams that were not considered in the 
initial development of 10 CFR Part 61 should be considered under the 
definition of ``unique waste streams''?
    Question II-1.5--Should the NRC consider waste streams that result 
from spent fuel reprocessing and are not high-level or greater-than-
class C waste in the definition of ``unique waste streams''?
    Question II-1.6--Are there other characteristics besides 
concentration and quantity that NRC should consider when defining 
``unique waste streams''?

Issue II-2. Time Period of Performance

    While a period of 10,000 years was initially considered in NUREG-
0782 (1981), 10 CFR Part 61 does not specify a period to evaluate 
performance of a near-surface low-level radioactive disposal facility, 
in part due to the effects of site and waste characteristics on the 
timing of projected radiological doses. NRC continues to consider 
10,000 years a sufficient period, with some exceptions, to capture (i) 
the risk from the short-lived radionuclides, which comprise the bulk of 
the activity disposed; and (ii) the peak radiological doses from the 
more mobile long-lived radionuclides, which tend to bound the

[[Page 30177]]

potential radiological doses at time frames greater than 10,000 years 
(``A Performance Assessment Methodology for Low-Level Radioactive Waste 
Disposal Facilities'', NUREG-1573, 2000, ADAMS Accession No. 
ML003770778). Internationally, selection of a time frame for evaluation 
of facility performance has generally considered the hazard and 
longevity of the waste, the analysis framework (i.e., scenarios, 
receptors, and pathways), socioeconomic uncertainties, and uncertainty 
in extending models and data to times beyond those for which the 
underlying assumptions can be justified (``Safety Assessment for Near 
Surface Disposal of Radioactive Waste'', Safety Standards Series No. 
WS-G-1.1, International Atomic Energy Agency, 1999, available 
electronically at http://www-pub.iaea.org/MTCD/publications/PDF/Pub1075_web.pdf; ``The Handling of Timescales in Assessing Post-
closure Safety--Lessons Learnt from the April 2002 Workshop in Paris, 
France'', Organization for Economic Co-operation and Development 
Nuclear Energy Agency, 2004, available electronically at http://www.nea.fr/html/rwm/reports/2004/nea4435-timescales.pdf). As part of a 
planned rulemaking, NRC is soliciting stakeholder views regarding a 
time period to evaluate the performance of near-surface disposal of 
unique waste streams.
    Question II-2.1--Should the NRC (a) specify a single time period to 
evaluate the performance of facilities disposing of all unique waste 
streams in the near-surface; (b) specify criteria requiring the 
consideration of how the hazard for each unique waste stream evolves 
over time; or (c) permit a licensee to justify a period of performance?
    Question II-2.2--If NRC were to specify a single time period for 
site-specific analysis of facilities disposing of unique waste streams 
in the near-surface, what would be an appropriate period? What factors 
should NRC consider in determining a single time period of performance?
    Question II-2.3--If NRC were to specify criteria requiring the 
consideration of how the hazard evolves over time for each unique waste 
stream, what factors should NRC consider in determining these criteria?
    Question II-2.4--If NRC were to permit a licensee to justify a time 
period of performance, what factors should NRC consider when evaluating 
a licensee's justification?
    Question II-2.5--If NRC were to specify criteria requiring the 
consideration of how the hazard evolves over time, or permit a licensee 
to justify a time period of performance, should the NRC consider 
limiting the maximum extent of the time period considered? If so, what 
factors should NRC consider when specifying a maximum period of 
performance?
    Question II-2.6--What other approaches might NRC consider when 
specifying criteria for a period of performance for facilities 
disposing of unique waste streams in the near-surface?

Issue II-3. Exposure Scenarios for a Site-Specific Analysis

    Disposal of radioactive waste in near-surface disposal facilities 
has several performance objectives, specified at 10 CFR Part 61, 
including protection of the general population from releases of 
radioactivity and protection of individuals from inadvertent intrusion. 
In developing the waste classification scheme in 10 CFR Part 61, NRC 
performed an analysis (NUREG-0782, 1981; NUREG-0945, 1982) applying 
several assumptions with respect to exposure scenarios and potential 
receptors. Following the period of active institutional control, the 
member of the public was assumed to engage in residential, 
agricultural, or other activities at the boundary of the 100 meter (330 
feet) buffer zone surrounding the disposal area that circumscribes the 
disposal units. These assumed activities were consistent with regional 
practices current at the time of the analysis. Additionally, the 
analysis assumed that an inadvertent intruder engaged in activities on 
the disposal site rather than outside the buffer zone following the 
period of active institutional control. The inadvertent intruder 
exposure scenario assumed the exposure via either disruption of waste 
during the excavation and construction of a residence on the disposal 
site (i.e., intruder-construction) or occupation of a dwelling located 
on the disposal site and ingestion of food grown in contaminated soils 
(i.e., intruder-agriculture) if the waste had degraded to an 
unrecognizable form. As part of a planned rulemaking NRC is considering 
whether to specify criteria or provide guidance for appropriate 
exposure scenarios for site-specific analyses associated with disposal 
of unique waste streams.
    Question II-3.1--Should NRC specify technical criteria for, or 
permit licensees to justify, site-specific exposure scenarios for 
demonstrating compliance with the performance objective protecting 
members of the public for unique waste streams? What factors should NRC 
consider in specifying technical criteria or reviewing licensee 
justifications for exposure scenarios associated with members of the 
public?
    Question II-3.2--Should NRC specify technical criteria for, or 
permit licensees to justify, site-specific exposure scenarios for 
demonstrating compliance with the performance objective protecting 
individuals from inadvertent intrusion for unique waste streams? What 
factors should NRC consider in specifying technical criteria, or 
reviewing licensee justifications, for inadvertent intruder exposure 
scenarios?

III. Issues With Disposal of Significant Quantities of Depleted Uranium

    This section discusses major issues to be considered before 
commencing regulatory activities related to requirements for a site-
specific analysis for near-surface land disposal of significant 
quantities of depleted uranium, a unique waste stream. Each issue is 
assigned a number, a short title, and a list of questions and factors 
for consideration. These issues, questions, and factors are not meant 
to be a complete or final list, but are intended to initiate 
discussion. Interested stakeholders are welcome to recommend additions, 
deletions, or modifications to the key issues for consideration and 
propose implementation considerations. These issues and factors will 
serve as the basis for discussion at the public workshops. All public 
feedback will be used in developing implementation options for NRC 
consideration.

Issue III-1. Definition of Significant Quantities

    The NRC plans to propose a rulemaking in 10 CFR Part 61 to specify 
a requirement for a site-specific analysis for the disposal of 
significant quantities of depleted uranium (SRM-SECY-08-0147, March 18, 
2009). As part of this rulemaking, the NRC intends to define 
``significant quantities'' of depleted uranium in the regulation. 
Recently, the NRC performed an analysis that confirmed that small 
quantities of depleted uranium (approximately 1-10 metric tons) may be 
disposed of at shallow depths and meet the performance objectives 
specified in 10 CFR Part 61. This result is consistent with the 
conclusions of an earlier analysis that the types of uranium-bearing 
waste streams typically disposed of by NRC licensees in limited 
quantities do not present a significant hazard to warrant limitation on 
the concentration of this naturally occurring material (NUREG-0945, 
1982). Because small quantities and lower concentrations of uranium 
were

[[Page 30178]]

previously evaluated and recently re-affirmed, the rulemaking will 
focus on ensuring additional disposal considerations are taken for 
depleted uranium based on the quantity and concentration of material at 
issue.
    Question III-1.1--Should NRC specify a lower quantity limit in the 
definition of ``significant quantities'' for near-surface disposal? If 
so, what factors should NRC consider in setting an appropriate lower 
threshold for near-surface disposal?
    Question III-1.2--Should NRC specify an upper quantity limit in the 
definition of ``significant quantities''? If so, what factors should 
NRC consider in setting an appropriate upper threshold for near-surface 
disposal?
    Question III-1.3--Are there alternative methods NRC should consider 
when specifying criteria to define ``significant quantities''?

Issue III-2. Time Period of Performance for a Site-Specific Analysis

    In addition to the issue described earlier in Section II for unique 
waste streams, generally, the following questions are provided to focus 
discussion on the disposal of significant quantities of depleted 
uranium.
    Question III-2.1--If NRC were to specify a single time period for 
the site-specific analysis of near-surface disposal of unique waste 
streams (see Question II.2.1), what factors associated with disposal of 
significant quantities of depleted uranium should NRC consider in 
determining a single time period of performance for unique waste 
streams, including significant quantities of depleted uranium?
    Question III-2.2--If NRC were to specify criteria requiring the 
consideration of hazards for each unique waste stream evolving over 
time (see Question II.2.1), what factors should NRC consider in 
determining these criteria for disposal of significant quantities of 
depleted uranium?
    Question III-2.3--If NRC were to permit a licensee to justify a 
time period of performance (see Question II.2.1), what factors should 
NRC consider when evaluating a licensee's justification for disposal of 
significant quantities of depleted uranium?
    Question III-2.4--If NRC were to specify criteria requiring the 
consideration of how the hazard evolves over time, or permit a licensee 
to justify a reasonable time period of performance (see Question II-
2.1), should the NRC consider limiting the maximum extent of the time 
period considered for disposal of significant quantities of depleted 
uranium? If so, what factors should NRC consider when specifying a 
maximum period of performance?
    Question III-2.5--What other approaches might NRC consider when 
specifying criteria for a period of performance for near-surface 
disposal of significant quantities of depleted uranium?

Issue III-3. Exposure Scenario(s) for a Site-Specific Analysis

    In addition to the issue described earlier in Section II for unique 
waste streams, generally, the following questions are provided to focus 
discussion on the disposal of significant quantities of depleted 
uranium.
    Question III-3.1--What factors specific to disposal of significant 
quantities of depleted uranium should NRC consider in specifying 
criteria or reviewing a licensee's justification for exposure scenarios 
for protection of members of the public?
    Question III-3.2--What factors specific to disposal of significant 
quantities of depleted uranium should NRC consider in specifying 
criteria or reviewing a licensee's justification for exposure scenarios 
for the protection of individuals from inadvertent intrusion?

Issue III-4. Source Term Issues for a Site-Specific Analysis

    Depleted uranium can have a variety of chemical and physical forms 
which are dependent on enrichment and deconversion processing. For 
instance, depleted uranium is commonly stored as a hexafluoride gas 
byproduct material. Depleted uranium hexafluoride gas may also be 
deconverted to an oxide form. Recently, the NRC performed a screening 
analysis (SECY-08-0147, October 7, 2008) that confirmed that small 
quantities of depleted uranium (approximately 1-10 metric tons) may be 
disposed of at shallow depths and meet the performance objectives 
specified in 10 CFR 61. This screening analysis assumed that depleted 
uranium would be disposed of in an oxide form following deconversion. 
NRC is seeking stakeholder views on modeling source terms in a site-
specific analysis for near-surface disposal of significant quantities 
of depleted uranium.
    Question III-4.1--Should NRC specify or permit licensees to propose 
physical or chemical forms (e.g., UF6, 
U3O8, metal) for disposal of significant 
quantities of depleted uranium? If so, what factors should NRC consider 
in specifying criteria for or developing guidance to review an analysis 
of physical or chemical forms?
    Question III-4.2--Should NRC specify criteria for, or permit 
licensees to justify, stabilizing admixtures (e.g., grout) for disposal 
of significant quantities of depleted uranium? If so, what factors 
should NRC consider in specifying criteria for, or developing guidance 
to review, an analysis of admixtures?
    Question III-4.3--What other factors should NRC consider when 
specifying criteria, or developing technical guidance, regarding waste 
forms for disposal of significant quantities of depleted uranium in 
near-surface facilities?
    Question III-4.4--Should NRC require a site-specific analysis to 
capture previously disposed quantities of depleted uranium? If so, what 
factors should NRC consider when specifying criteria, or developing 
technical guidance, regarding previously disposed quantities of 
depleted uranium?

Issue III-5. Modeling of Uranium Geochemistry in a Site-Specific 
Analysis

    The NRC plans to propose a rulemaking in 10 CFR Part 61 to specify 
a requirement for a site-specific analysis for the disposal of 
significant quantities of depleted uranium. Recently, the NRC performed 
a screening analysis (SECY-08-0147, October 7, 2008) that confirmed 
that small quantities of depleted uranium (approximately 1-10 metric 
tons) may be disposed of at shallow depths and meet the performance 
objectives specified in 10 CFR Part 61. The results of this analysis 
noted the dependence of disposal facility performance on site-specific 
geochemical conditions. Geochemical conditions were represented in the 
screening analysis as epistemic uncertainty over a broad range of 
disposal sites and conditions. In reality, many of these parameters may 
be constrained at a particular disposal facility.
    Question III-5.1--Should NRC specify regulatory criteria for, or 
permit licensees to justify, site-specific geochemical parameters for 
the analysis of disposal of significant quantities of depleted uranium?
    Question III-5.2--If NRC should specify regulatory criteria, then 
what factors should NRC consider in developing criteria for geochemical 
parameters for a site-specific analysis for disposal of significant 
quantities of depleted uranium?
    Question III-5.3--If NRC should permit licensees to justify site-
specific geochemical parameters, then what factors should NRC consider 
when reviewing a licensee's justification?
    Question III-5.4--What new or alternative approaches should NRC 
consider regarding the incorporation of

[[Page 30179]]

geochemical parameters in a site-specific analysis for disposal of 
significant quantities of depleted uranium?

Issue III-6. Modeling of Radon in the Environment in a Site-Specific 
Analysis

    Over time, the uranium isotopes comprising depleted uranium decay 
to multiple progeny radionuclides. Many of these progeny radionuclides 
are different elements, and differ from depleted uranium in their 
radiotoxicity and mobility in the environment. Among the progeny 
radionuclides exhibiting these differing characteristics, radon-222 is 
of particular interest because it exists as a gas under typical 
environmental conditions and presents a unique challenge to evaluate in 
a site-specific analysis of the performance of a near-surface, low-
level radioactive waste disposal facility. Analyzing the mobility of 
radon-222 in the environment involves demonstrating a reasonable 
understanding of the emanation of the radon gas from the depleted 
uranium solids, and migration to the surface of the disposal facility. 
Additionally, NRC anticipates that radon migration may require policy 
considerations of societal uncertainties in developing appropriate 
exposure scenarios.
    Question III-6.1--What new approaches for modeling radon emanation, 
migration, and exposure pathways, including the effects of differences 
in the physical and chemical properties between radon and its progeny, 
should NRC consider?
    Question III-6.2--Should NRC require licensees to evaluate the 
effects of radon in a site-specific analysis for disposal of 
significant quantities of depleted uranium in near-surface facilities?
    Question III-6.3--Should NRC specify by regulation, or develop 
guidance on, the technical parameters for evaluating radon emanation, 
migration, and exposure in a site-specific analysis of significant 
quantities of depleted uranium?
    Question III-6.4--If NRC should specify by regulation the technical 
parameters for evaluating radon emanation, migration, and exposure, 
what factors should NRC consider in specifying technical parameters for 
a site-specific analysis for significant quantities of depleted 
uranium?
    Question III-6.5--If NRC should develop guidance on the technical 
parameters for evaluating radon emanation, migration, and exposures to 
accompany regulatory criteria, then what factors should NRC consider in 
the development of guidance for evaluating technical parameters for a 
site-specific analysis for disposal of significant quantities of 
depleted uranium?
    Question III-6.6--What societal uncertainties should NRC consider 
when developing guidance for scenarios of exposure to radon gas 
released from the disposal of significant quantities of depleted 
uranium?
    Question III-6.7--What alternative methods should NRC consider when 
developing guidance on evaluating the impacts of radon gas exposures? 
For instance, U.S. Environmental Protection Agency standards at 40 CFR 
Part 192 for the control of residual radioactive materials from 
inactive uranium mill tailings sites specify that releases of radon-222 
to the atmosphere will not exceed an average release rate of 20 
picoCuries per square meter per second or increase the annual average 
concentration of radon-222 in air at or above any location outside the 
disposal site by more than 0.5 picoCuries per liter.

    Dated at Rockville, Maryland this 16th day of June, 2009.

    For the Nuclear Regulatory Commission.
Patrice M. Bubar,
Deputy Director, Environmental Protection and Performance Assessment 
Directorate, Division of Waste Management, and Environmental Protection 
Office of Federal and State Materials, and Environmental Management 
Programs.
[FR Doc. E9-14820 Filed 6-23-09; 8:45 am]
BILLING CODE 7590-01-P
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