ML24303A083
| ML24303A083 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 10/28/2024 |
| From: | Montgomery B Nuclear Energy Institute |
| To: | Office of Administration |
| References | |
| NRC-2024-0151, 89FR78917 00002 | |
| Download: ML24303A083 (1) | |
Text
PUBLIC SUBMISSION As of: 10/29/24, 8:48 AM Received: October 28, 2024 Status: Pending_Post Tracking No. m2t-83na-hqoo Comments Due: October 28, 2024 Submission Type: Web Docket: NRC-2024-0151 Contamination Control, Radiological Survey, and Dose Modeling Considerations to Support License Termination at Sites with Environmental Discrete Radioactive Particle Contamination Comment On: NRC-2024-0151-0001 Draft Interim Staff Guidance: Contamination Control, Radiological Survey, and Dose Modeling Considerations To Support License Termination at Sites With Environmental Discrete Radioactive Particle Contamination Document: NRC-2024-0151-DRAFT-0003 Comment on FR Doc # 2024-22003 Submitter Information Email:atb@nei.org Organization:Nuclear Energy Institute General Comment See attached file(s)
Attachments 10-28-24_NRC_NEI Comment letter on DUWP-ISG-03 10/29/24, 8:48 AM blob:https://www.fdms.gov/0530ee9f-77a5-45a6-b7c2-882021ae6f97 blob:https://www.fdms.gov/0530ee9f-77a5-45a6-b7c2-882021ae6f97 1/1 SUNSI Review Complete Template=ADM-013 E-RIDS=ADM-03 ADD: Amy Snyder; Sarah Achten, Mary Neely Comment (2)
Publication Date:
9/26/2024 Citation: 89 FR 78917
Bruce Montgomery Director, Decommissioning and Used Fuel Phone: 202.406.0054 Email: bsm@nei.org October 28, 2024 Jane Marshall Director, Division of Decommissioning, Uranium Recovery, and Waste Programs Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
Subject:
NEI Comments on NRC Draft Interim Staff Guidance: Contamination Control, Radiological Survey, and Dose Modeling Considerations to Support License Termination at Sites with Environmental Discrete Radioactive Particle Contamination (Docket ID NRC-2024-0151)
Project Number: 689
Dear Ms. Marshall:
The Nuclear Energy Institute (NEI)1 appreciates the opportunity to comment on this draft interim staff guidance (DUWP-ISG-03). As evidenced during recent decommissioning projects, the discovery of discrete radioactive particles (DRPs) during final status surveys can result in significant delays in project completion.
NEI agrees that with appropriate isolation and control of radioactive contamination during decommissioning activities, the potential for introduction of DRPs to the environment can be reduced.
Measures such as work area compartmentalization, ventilation controls, and robust housekeeping will minimize the spread of DRPs to clean areas. In-process radiological surveys during decommissioning activities and confirmatory surveys during the final status survey phase will provide reasonable assurance that risk-significant DRPs do not remain in the environment following unrestricted release of the site.
The draft ISG proposes a methodology along with a new dose term and concept to correlate postulated DRP size and activity with the health effects of the particle in a variety of biological exposure scenarios.
This work is relevant to the understanding of the detectability of such particles using accepted radiological survey methods and current instrument technology. NEI believes that when reasonable assumptions are 1 The Nuclear Energy Institute (NEI) is responsible for establishing unified policy on behalf of its members relating to matters affecting the nuclear energy industry, including the regulatory aspects of generic operational and technical issues. NEIs members include entities licensed to operate commercial nuclear power plants in the United States, nuclear plant designers, major architect and engineering firms, fuel cycle facilities, nuclear materials licensees, and other organizations involved in the nuclear energy industry.
Ms. Jane Marshall October 28, 2024 Page 2 Nuclear Energy Institute applied to the new dose concept proposed in the draft ISG, it can be shown that all risk-significant DRPs can be easily detected with existing survey methods and removed for disposal.
NEI comments on the draft guidance are included in the attachment to this letter. Fundamentally, NEI observes that except for radiation workers covered by 10 CFR Part 20, the regulatory framework does not establish dose acceptance criteria for exposure to radioactive particles. There are many complexities involved in the development of new, interim criteria for non-occupational exposures, which this ISG attempts to do. Consequently, great care must be taken in this effort.
Additionally, NEI has undertaken preliminary efforts to examine the dose model/concept proposed by NRC. The results of this work are provided for your consideration in the attached comments. We believe these results demonstrate the need for additional dialog prior to the issuance of final guidance.
Suggestions on areas for technical changes that may be helpful in continuing this dialog are included.
Please contact me with any questions regarding our comments.
Sincerely, Bruce Montgomery Director, Decommissioning and Used Fuel
Attachment:
NEI Comments on NRC Draft Interim Staff Guidance: Contamination Control, Radiological Survey, and Dose Modeling Considerations to Support License Termination at Sites with Environmental Discrete Radioactive Particle Contamination c:
Ms. Jennifer Whitman, NMSS/DUWP Ms. Amy Snyder, NMSS/DUWP/RDP Ms. Cynthia Barr, NMSS/DUWP/RTAB
ATTACHMENT NEI Comments on NRC Draft Interim Staff Guidance: Contamination Control, Radiological Survey, and Dose Modeling Considerations to Support License Termination at Sites with Environmental Discrete Radioactive Particle Contamination
- 1. The draft ISG introduces a new dose term and dose concept (Localized Dose Equivalent, LDE) which is not recognized in 10 CFR Part 20. This term represents the same abbreviation (LDE) as the lens dose equivalent limit prescribed by 10 CFR Part 20, which could result in confusion by licensees. Most importantly, the NRC should not introduce a new dose concept outside of the U.S.
and international regulatory framework without the benefit of review and concurrence by the scientific community.
- 2. Except for the CEDE (referenced in the dose limits as TEDE), all other dose factors are provided as dose rates per unit activity (Sv/Bq-hr). The document suggests, for several dose scenarios, that an exposure duration must be selected to calculate a dose. Selection of an exposure duration is arbitrary, particularly for a hypothetical individual in the future, unless the exposure time can be correlated with the predicted behavior/movement of particles in the affected organ after uptake.
- 3. For the site referenced in Appendix A, the particle activity corresponding to the applicable dose limit associated with activated metal and a fuel DRP is calculated in this response. In each case, this activity is calculated using the following:
Equation 1
() =
1 3.74
()
Where:
o Lp is the proposed dose limit for exposure pathway p, Sv, o fi is the activity fraction of radionuclide i, o tp is the exposure time for pathway p, hr, (for CEDE DCFs, this value is not used or set to 1), and o DCFi,p is the dose factor for nuclide i and exposure pathway p, Sv/Bq-hr or Sv/Bq (for CEDE)
The draft ISGs proposed dose limits for each pathway and the respective exposure times are shown in Table 1.
Attachment Page 2 Table 1: Proposed dose limits and exposure times DRP Dose Pathway Proposed Limit, Sv Exposure
- Duration, h
LDE Upper Resp. Tract 0.500 24 EDE Upper Resp. Tract 0.001 24 LDE Sm. Intestine 0.500 4
LDE Large Intestine 0.500 24 CEDE f1=0 0.001 1
SDE 0.500 24 EDE Skin 0.001 24 The activity fractions for each particle type and exposure pathway in the cases cited in Appendix A of the draft ISG are as follows:
Table 2: Activity Fractions of the two principal Particles Identified in Appendix A Particle Type Radionuclide Activity Fraction Fuel Sr-90 4.09E-01 Cs-137 2.57E-01 Pu-238 6.81E-02 Pu-239 9.81E-03 Pu-240 9.81E-03 Am-241 2.08E-01 Cm-244 3.85E-02 Activated Metal Co-60 3.04E-01 Ni-59 5.05E-03 Ni-63 6.91E-01 Using Equation 1 with the activity fractions in Table 1 and the proposed dose factors in the draft ISG for each dose pathway and for a 100 m diameter particle, the activity for each pathway and radionuclide is provided in Table 2 where the principle gamma emitter for soil scanning is highlighted. This shows that the maximum activity associated with the proposed dose limits generally range from 0.2 Ci to approximately 3 Ci except for the EDE Upper Respiratory tract dose pathway where the corresponding activity is approximately.0005 Ci, which is well below any field scanning detection capability.
This activity level is likely caused in part by the following:
o The dose model is non-anatomical and assumed the particle is 100% stationary for the exposure duration (whereas it is reasonable to adopt an assumption that a particle will continuously move and irradiate different portions of the URT), and
Attachment Page 3 o The dose model uses the lung dose weighting factor from ICRP26/30 for the entire lung which assumes that the whole lung is uniformly irradiated (rather than adopting an assumption of a heterogeneous dose distribution to a portion of the lung from a DRP).
Table 3: DRP Activities (Ci) corresponding to the proposed dose limits in proportion to the Activity Fractions from Table 1 using Equation 1.
Particle Type Nuclide LDE Upper Resp.
Tract Ci at Dose Limit EDE Upper Resp.
Tract, Ci at Dose Limit LDE Sm.
Intestine, Ci at Dose Limit LDE Lg.
Intestine, Ci at Dose Limit CEDE f1=0, Ci at Dose Limit SDE, Ci at Dose Limit EDE, Ci at Dose Limit Fuel Sr-90 3.48E-01 8.57E-04 3.55E+00 1.07E+00 4.04E+00 4.16E+00 4.08E+00 Cs-137 2.19E-01 5.39E-04 2.23E+00 6.76E-01 2.55E+00 2.62E+00 2.57E+00 Pu-238 5.80E-02 1.43E-04 5.92E-01 1.79E-01 6.74E-01 6.94E-01 6.81E-01 Pu-239 8.34E-03 2.06E-05 8.52E-02 2.58E-02 9.70E-02 1.00E-01 9.80E-02 Pu-240 8.34E-03 2.06E-05 8.52E-02 2.58E-02 9.70E-02 1.00E-01 9.80E-02 Am-241 1.77E-01 4.36E-04 1.81E+00 5.46E-01 2.06E+00 2.12E+00 2.08E+00 Cm-244 3.28E-02 8.07E-05 3.34E-01 1.01E-01 3.81E-01 3.92E-01 3.85E-01 Act. Metal Co-60 2.59E-01 6.38E-04 2.64E+00 7.99E-01 3.01E+00 3.10E+00 3.04E+00 Ni-59 4.30E-03 1.06E-05 4.39E-02 1.33E-02 5.00E-02 5.15E-02 5.05E-02 Ni-63 5.87E-01 1.45E-03 6.00E+00 1.81E+00 6.83E+00 7.04E+00 6.90E+00
- 4. Section 4.2.3.3 uses the highest mean residence time for exposure durations for the small and large intestines (4 and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> respectively) as a time interval corresponding to a static condition for these intervals. We believe these intervals are not representative of a particles behavior and the exposure intervals should be much smaller as most particles will continue to move rather than remain stationary for these periods. Given that the ICRP GI tract dose model assumes homogeneous mixing of distributed activity within the contents of this organ, the proposed model is not applicable to DRP exposure. We believe a more realistic dose model should be developed for particles within the GI tract.