UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 

WASHINGTON, DC 20555 - 0001 

November 14, 2016 

The Honorable Stephen G. Burns 

Chairman 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

SUBJECT: REVIEW OF SECY-16-0106, PROPOSED FINAL RULE 10 CFR PART 61, 

“LOW-LEVEL RADIOACTIVE WASTE DISPOSAL” 

Dear Chairman Burns: 

During the 638th meeting of the Advisory Committee on Reactor Safeguards (ACRS), November 

3-5, 2016, we completed our review of SECY-16-0106, the staff’s proposed final rule, “LowLevel Radioactive Waste Disposal (10 CFR Part 61).” Our Subcommittee on Radiation 

Protection and Nuclear Materials discussed this matter during its meeting on October 18, 2016. 

Our meetings focused on issues raised by the ACRS in its past letter reports on this matter. 

During these meetings, we benefitted from discussions with the NRC staff and members of the 

public. We also had the benefit of the referenced documents. 

CONCLUSIONS AND RECOMMENDATIONS 

1. The approach in proposed final rule 10 CFR Part 61, “Low-Level Radioactive Waste 

Disposal” can ensure that facilities meet Commission public health and safety objectives. 

2. We remain concerned about the requirement that existing operating disposal facilities 

need to satisfy the new performance objectives even if they do not plan to add 

substantial long-lived waste for disposal, especially for already-buried waste. The final 

rule should retain the provision that allows compliance for existing facilities on a case-bycase basis. 

3. We prefer a regulatory approach consistent with that suggested in our previous reports 

making the site performance assessment with quantitative uncertainty analysis the basis 

for establishing the compliance and performance periods. The performance assessment 

results should inform qualitative requirements for periods exceeding the compliance 

period. 

 
-2- 

BACKGROUND 

10 CFR Part 61, “Licensing Requirements for Land Disposal of Radioactive Waste,” was 

promulgated by the NRC in 1982. The technical basis for the rule included analyses based on 

projections of low-level radioactive waste (LLRW) that were expected to be generated for the 

foreseeable future as determined at that time. Several changes to policy and practices have 

resulted in some LLRW streams which NRC did not include in the technical basis for the rule in 

1982, calling into question whether these waste streams can be appropriately disposed of in a 

shallow land disposal facility. 

The staff of the Office of Nuclear Materials Safety and Safeguard (NMSS) (or its predecessor 

organizations) has been working on the revision to 10 CFR Part 61, for more than ten years. 

The effort grew out of concern that arose during the staff review of an application to license the 

Louisiana Energy Services (LES) enrichment facility (now known as URENCO USA). The staff 

requested a Commission policy decision on how depleted uranium (DU) waste streams to be 

generated by the LES facility should be managed. 

The draft proposed final rule is intended to address DU waste streams, as well as others 

including blended low-level wastes, waste streams from spent nuclear fuel reprocessing, and 

radium-226 bearing wastes. A major concern for these waste streams involves whether they 

can meet the requirements for protection of an inadvertent intruder that are included in the final 

rule, primarily because the waste streams contain or will produce through radioactive decay 

(progeny) significant quantities of long-lived radionuclides which were not specifically evaluated 

in the original 10 CFR Part 61 technical basis, some of which only reach their maximum activity 

far in the future. 

We have followed this issue since 2010 and has made numerous recommendations and 

observations. A summary of our involvement with this issue is provided in Attachment 1 to this 

report. 

DISCUSSION 

The most difficult challenge in regulating radioactive waste disposal is providing reasonable 

assurance that the public will be protected long after institutional controls are terminated. The 

proposed final rule 10 CFR Part 61 establishes performance objectives which specify that doses 

to a member of the general public not exceed 25 millirem per year. The proposed final rule also 

specifies that doses to a postulated intruder who inadvertently interacts directly with the waste 

not exceed 500 millirem per year. The nominal compliance period for a disposal facility is 

defined as either 1,000 years or 10,000 years, depending on whether significant quantities of 

long-lived radionuclides exist in the waste inventory. 

 
-3- 

The proposed final rule requires that a site-specific performance assessment be conducted to 

demonstrate compliance with the performance objectives. A performance assessment is an 

analysis that identifies the features, events, and processes that could affect the disposal site 

performance, and estimates the potential dose as a result of releases caused by all significant 

features, events, and processes including uncertainties. Behavior of a disposal site is 

influenced by the land disposal facility design, the characteristics of the wastes, and the 

geologic and environmental characteristics of the site. A performance assessment considers 

the characteristics of the site (e.g., hydrology, meteorology, geochemistry, biology, and 

geomorphology) and the degradation, or alteration processes of the engineered barriers and 

natural system that will occur over time. Furthermore, the performance assessment identifies 

and evaluates the interactions between the disposal site characteristics and engineered barriers 

that might impact the performance of the disposal site. 

The proposed final rule and its guidance, as currently structured, use the performance 

assessment primarily as a tool to identify scenarios that result in releases of radionuclides, to 

quantify their health effects to humans, and to thereby provide assurance that the facility is 

designed, managed, and left in a state that complies with the regulatory requirements. 

Section 10 CFR 61.13 of the proposed final rule requires the licensee use the performance 

assessment to demonstrate that a member of the general public will not receive more than an 

annual dose of 25 millirem over the 1,000-year or 10,000-year duration of the facility’s 

compliance period. The staff has briefed us on their basis for the 10,000-year period, which is 

founded on the projected radiotoxicity of DU. 

There are many sources of uncertainty associated with projecting the future radiological risks 

from disposal of LLRW, including natural, engineered, and societal sources. The time scales of 

concern can be so long that direct observations or measurements of temporal changes on the 

disposal system are of limited value. Thus, assessment of future site performance must be 

based on models and assumptions about the physical and chemical processes involved. The 

nominal analysis timeframes specified in the proposed final rule account for the general 

observation that behavior of natural systems tends to be relatively stable and predictable until 

tens of thousands of years, when geomorphologic processes become highly uncertain and 

human experience is limited. 

The staff notes that, by extending the analysis to 10,000 years, the dose from the DU decay 

chain would have built up to about 10% of its peak, sufficient to consider release pathway 

characteristics to inform the development of qualitative protective measures (i.e., defense-indepth measures) in these time periods where uncertainty in performance analysis results is very 

large. Therefore, despite the fact that DU’s peak radiological risk occurs after a million years, 

the staff has selected a nominal 10,000-year quantitative analysis time frame to avoid highly 

speculative and unreliable consequences. Though the impacts after 10,000 years would not be 

part of the compliance period calculations, they would be considered in the licensing process, 

and a licensee must demonstrate that the impacts after 10,000 years have been minimized to 

the extent reasonably achievable. The staff also noted that other domestic and international 

precedents support quantitative requirements that apply for time periods on the order of 10,000 

years. 

 
-4- 

Significant additions in the proposed final rule are the requirement to document the facility 

safety case and an explicit requirement to identify provisions for defense-in-depth. Section 10 

CFR 61.2 defines a safety case as a collection of information that demonstrates the assessment 

of the safety of a land disposal facility. This includes the required technical analyses, as well as 

conclusions on defense-in-depth and supporting evidence, and reasoning on the strength and 

reliability of the technical analyses and the assumptions made. The safety case also includes a 

description of the safety relevant aspects of the site, the design of the facility, and the 

managerial control measures and regulatory controls. Safety case, therefore, is a description of 

safety arguments that highlight the main evidence supporting the claim that the land disposal 

facility will provide long-term protection to health and safety of the public and environment. 

The defense-in-depth concept has been used implicitly in waste disposal regulations in the past. 

Those requirements are intended to ensure that safety does not depend on one single element 

of the facility and includes such considerations as remote siting, waste forms that limit 

radionuclide release, appropriate design of engineered features, and beneficial natural geologic 

features of the disposal site. In general, assessments of the adequacy of defense-in-depth in 

isolation can lead to ineffective conclusions. Thus, a risk-informed regulatory framework should 

apply tailored defense-in-depth considerations to mitigate the effects from large uncertainties 

that are identified during the performance assessment. 

The proposed final rule requires each operating facility to demonstrate compliance with the new 

performance objectives, even if the facility met the current 10 CFR Part 61 requirements at the 

time of burial and the facilities do not intend to add significant quantities of long-lived waste 

streams. We remain concerned about the requirement that existing operating disposal facilities 

need to satisfy the new performance objectives even if they do not plan to add substantial longlived waste for disposal, especially for already-buried waste. We understand the staff’s 

rationale, but it is essential to evaluate the feasibility and consequences of “remedial actions” 

available to those facilities which may not comply fully with the revised performance objectives. 

The final rule should retain the provision that allows compliance for existing facilities on a caseby-case basis. 

An Alternative Regulatory Approach 

We remain concerned that the requirements in the proposed final rule are complex and 

unnecessarily burdensome. An alternative approach to the rule is possible by making greater 

use of site performance assessments with quantitative uncertainty analyses. Performance 

assessments are required by the proposed final rule. Modern methods of performance 

assessment have greatly advanced in recent years and allow an integrated evaluation of the 

effects of geology, hydrology, waste form, and waste barriers. The performance assessment 

together with a dose limit defined by the Commission (such as 25 millirem/year) to assure 

adequate protection of the public health and safety can be used to integrate parts of the current 

rule that now have an ad hoc appearance. In addition to providing assurance that the general 

public is protected, it has become traditional to assume there is an inadvertent intrusion into the 

site and its waste at some time following termination of institutional controls. The performance 

assessment can also readily incorporate an objective examination of this stochastic event, as 

well as a range of possible intruder activities. In this approach, the performance assessment 

would be used to structure the most appropriate methods to achieve the desired performance 

 
-5- 

objectives for a particular disposal site, rather than to simply demonstrate compliance with 

nominal regulatory requirements which may not be well-founded for the site, its waste forms, or 

protection strategies. 

Any performance assessment will be uncertain. The sources of these uncertainties can be 

identified and quantified. Defense-in-depth can be integrated explicitly into the performance 

assessment as a means to ameliorate the significant sources of uncertainty. This contrasts 

sharply with defense-in-depth being little more than an exposition of site attributes as it is in the 

proposed final rule. The systematic evaluation of defense-in-depth measures provides a more 

rational approach to minimize risk to the public. 

Waste emplaced in a disposal facility licensed under the current rule will need to be included in 

the performance assessment. Any need for remediation of the older waste under the proposed 

rule would be a decision of the licensee based on the results of the performance assessment 

and their interest in acceptance of future waste streams. Engineering trade-offs between 

remediation of the old waste and treatment of the new waste would be based, again, on the 

results of performance assessment and would consider the potential consequences of proposed 

remediation activities. 

The performance assessment can be used to define the compliance period based on the waste, 

waste form, geology, and hydrology of the site. The Commission may find it useful to define 

some minimal compliance period but this should not be a rigid limit. The performance 

assessment can also be used to show that large, sudden increases in the public dose do not 

occur following the period of compliance. Uncertainty quantification in the performance 

assessment can also be used to show when uncertainties grow sufficiently large that meaningful 

prognostications of waste behavior are no longer possible. Waste rules making greater use of 

performance assessments will facilitate future efforts to address new waste types such as 

‘greater than class C’ waste. 

While the proposed final rule 10 CFR Part 61 can ensure that facilities meet Commission 

objectives, it would do so in ways that add unnecessary complexity and burden to current 

licensees and applicants. As for the staff guidance provided in draft NUREG-2175, we received 

a briefing on aspects of the guidance at our meeting on November 3, 2016. We did not receive 

the actual document in time to complete our review. 

 Sincerely, 

 /RA/

 Dennis Bley 

 Chairman 

Attachment: 

As Stated 

 
-5- 

objectives for a particular disposal site, rather than to simply demonstrate compliance with 

nominal regulatory requirements which may not be well-founded for the site, its waste forms, or 

protection strategies. 

Any performance assessment will be uncertain. The sources of these uncertainties can be 

identified and quantified. Defense-in-depth can be integrated explicitly into the performance 

assessment as a means to ameliorate the significant sources of uncertainty. This contrasts 

sharply with defense-in-depth being little more than an exposition of site attributes as it is in the 

proposed final rule. The systematic evaluation of defense-in-depth measures provides a more 

rational approach to minimize risk to the public. 

Waste emplaced in a disposal facility licensed under the current rule will need to be included in 

the performance assessment. Any need for remediation of the older waste under the proposed 

rule would be a decision of the licensee based on the results of the performance assessment 

and their interest in acceptance of future waste streams. Engineering trade-offs between 

remediation of the old waste and treatment of the new waste would be based, again, on the 

results of performance assessment and would consider the potential consequences of proposed 

remediation activities. 

The performance assessment can be used to define the compliance period based on the waste, 

waste form, geology, and hydrology of the site. The Commission may find it useful to define 

some minimal compliance period but this should not be a rigid limit. The performance 

assessment can also be used to show that large, sudden increases in the public dose do not 

occur following the period of compliance. Uncertainty quantification in the performance 

assessment can also be used to show when uncertainties grow sufficiently large that meaningful 

prognostications of waste behavior are no longer possible. Waste rules making greater use of 

performance assessments will facilitate future efforts to address new waste types such as 

‘greater than class C’ waste. 

While the proposed final rule 10 CFR Part 61 can ensure that facilities meet Commission 

objectives, it would do so in ways that add unnecessary complexity and burden to current 

licensees and applicants. As for the staff guidance provided in draft NUREG-2175, we received 

a briefing on aspects of the guidance at our meeting on November 3, 2016. We did not receive 

the actual document in time to complete our review. 

 Sincerely, 

 /RA/

 Dennis Bley 

 Chairman 

Attachment: 

As Stated 

Accession No: ML16312A116 Publicly Available Y Sensitive N

Viewing Rights: NRC Users or ACRS Only or See Restricted distribution 

OFFICE ACRS SUNSI Review ACRS ACRS ACRS 

NAME DWidmayer DWidmayer MLBanks/GS ADVeil ADV for DCB 

DATE

OFFICIAL RECORD COPY 

 
Attachment 

During the 570th meeting of the ACRS, March 4-6, 2010, we first heard from the staff regarding 

the status of rulemaking for DU and other unique waste streams. Our letter report, dated March 

18, 2010, contained the following recommendation: 

 

The staff should continue their efforts to risk-inform the regulations for disposal of DU based on 

site-specific, realistic performance assessments with appropriate consideration of uncertainties. 

We received briefings on this proposed rulemaking during our 585th meeting on July 

13-15, 2011, and our 586th meeting on September 8-10, 2011. Our letter report, dated 

September 22, 2011, contained the following conclusions and recommendations: 

1. 10 CFR 61 should not be amended in accordance with the staff’s recommendations. 

Rather, the staff should develop a risk informed, performance based LLW site 

assessment methodology using realistic characterizations of disposed radioactive 

materials; the features, events, and processes that can disrupt disposed waste; natural 

and engineered barriers; environmental transport mechanisms; and subsequent human 

exposure scenarios. 

2. Implementation guidance for Part 61 should not specify an a priori period of 

performance. Rather, the performance assessment should develop a period of 

performance based on the features, events and processes specific to the 

geohydrological features of a candidate site, the technologies used to isolate wastes, 

and the controls used to isolate wastes from the environment and humans. 

3. The approaches in recommendations 1 and 2 are equally applicable to the disposal of 

depleted uranium as well as other low-level waste. 

4. Compliance with performance objectives of the disposal system after the institutional 

control period ends, as well as the possible doses to hypothetical intruders, should be 

evaluated considering the natural features, events, and processes for a given site for a 

period of time commensurate with the risk for a specific facility and site. 

The Commission issued Staff Requirements Memorandum (SRM)-COMWDM-11-

0002/COMGEA-11-0002 on January 19, 2012, providing direction to the staff to revise the 

proposed rulemaking and supporting regulatory basis and submit it to the Commission within 18 

months. The SRM directed the staff to revise both the performance assessment and intruder 

analysis requirements: 

1. Allowing licensees the flexibility to use ICRP dose methodologies in a site-specific 

performance assessment for the disposal of all radioactive waste. 

2. A two tiered approach that establishes a compliance period that covers the reasonably 

foreseeable future and a longer period of performance that is not a priori and is 

established to evaluate the performance of the site over longer timeframes. The period 

of performance is developed based on the candidate site characteristics (waste 

package, waste form, disposal technology, cover technology and geo-hydrology) and the 

peak dose to a designated receptor. 

 
-2- 

3. Flexibility for disposal facilities to establish site-specific waste acceptance criteria based 

on the results of the site’s performance assessment and intruder assessment. 

During the 606th meeting of the ACRS, July 9-12, 2013, we reviewed draft SECY-13-0075, the 

staff’s proposal to revise 10 CFR Part 61 and the associated draft implementation guidance. 

Our letter report, dated July 22, 2013, contained the following conclusions and 

recommendations: 

 

1. The proposed rule significantly expands the regulatory requirements for the licensing of 

low-level waste facilities and increases regulatory burden without sufficient justification. 

2. Our primary concerns about the proposed changes to 10 CFR Part 61 are the 

requirements to demonstrate compliance for 10,000 years and protection of the 

inadvertent intruder. 

3. We plan to hold additional meetings to better understand the technical justification for 

the elements of concern in the proposed rule. 

4. Previously disposed wastes should not be subjected to additional compliance 

evaluations as proposed by the staff. 

During the 611th meeting of the ACRS, February 5-7, 2014, we completed our review of the 

staff’s proposed revisions. Our letter report, dated February 19, 2014, contained the following 

conclusions and recommendations: 

1. In our continuing assessment, we affirm the conclusions and recommendations in our 

earlier letter reports on this matter. 

2. In the two-tiered assessment approach, the compliance period covering a reasonably 

foreseeable future should not exceed 1,000 years. 

3. Wastes disposed in accordance with the existing Part 61 rule at the time of disposal 

should not be subjected to additional compliance evaluations. We have found no 

deficiencies in the existing regulations that warrant imposing new disposal requirements. 

4. The proposed revisions to Part 61 contain excessive implementation detail. These 

details should be provided in guidance documents rather than in the rule. 

The Commission issued SRM-SECY-13-0075 on February 12, 2014, providing direction to the 

staff to revise the proposed rulemaking and supporting regulatory basis in several ways, and 

requested further review of the rule requirements and implementation guidance by interested 

stakeholders. In the SRM, the Commission stated: 

1. The Advisory Committee on Reactor Safeguards (ACRS) is encouraged to continue to 

provide their independent review and recommendations on the technical basis supporting 

this rule, and the accompanying draft guidance, during the rulemaking period. 

 
REFERENCES 

1. U.S. Nuclear Regulatory Commission, SECY-16-0106, “Final Rule: Low-Level 

Radioactive Waste Disposal (10 CFR Part 61) (RIN 3150-AI92),” September 15, 2016 

(ML16188A290). 

2. U.S. Nuclear Regulatory Commission, Draft NUREG-2175, “Guidance for Conducting 

Technical Analyses for 10 CFR 61,” October 2016 (ML14357A072). 

3. U.S. Nuclear Regulatory Commission, SECY-08-0147, “Response to Commission Order 

CLI-05-20 Regarding Depleted Uranium,” October 7, 2008 (ML081820762). 

4. Advisory Committee on Reactor Safeguards, “Status of Staff Rulemaking Efforts for 

Depleted Uranium and Other Unique Waste Streams,” March 18, 2010 (ML100760264). 

5. Advisory Committee on Reactor Safeguards, “Proposed Rulemaking to Introduce a SiteSpecific Performance Assessment and Human Intrusion Analysis Requirement to 10 

CFR Part 61,” September 22, 2011 (ML11256A191). 

6. U.S. Nuclear Regulatory Commission, Staff Requirements Memorandum-COMWDM-11-

0002/COMGEA-11-0002, “Revision to 10 CFR Part 61,” January 19, 2012 

(ML1210190360). 

7. U.S. Nuclear Regulatory Commission, SECY-13-0075, “Proposed Rule: Low-Level 

Radioactive Waste Disposal (10 CFR Part 61) (RIN 3150-AI92),” July 18, 2013 

(ML13129A268). 

8. Advisory Committee on Reactor Safeguards, “Revisions to Low-Level Radioactive 

Waste Disposal Requirements (10 CFR Part 61),” July 10, 2013 (ML13203A078). 

9. U.S. Nuclear Regulatory Commission, Staff Requirements-SECY-13-0075, “Proposed 

Rule: Low-Level Radioactive Waste Disposal (10 CFR Part 61) (RIN 3150-AI92),” 

February 12, 2014 (ML14043A371). 

10. Advisory Committee on Reactor Safeguards, “10 CFR Part 61 - Revisions to Low-Level 

Radioactive Waste Disposal Requirements,” February 19, 2014 (ML14041A152). 

11. International Commission on Radiological Protection, ICRP Publication 81, “Radiation 

Protection Recommendations as Applied to the Disposal of Long-Lived Solid 

Radioactive Waste,” Annals of the ICRP, Vol. 28, No. 4, 2000.