ML25231A030
| ML25231A030 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/19/2025 |
| From: | Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| EPID L-2025-LRM-0106 | |
| Download: ML25231A030 (1) | |
Text
Sequoyah Nuclear Plant August 20, 2025 Pre-submittal Meeting for a License Amendment Request to Revise TS 5.5.3 Radioactive Effluent Controls Program Regarding Application of Potassium Hydroxide (KOH)
Agenda
- Introduction
- Purpose
- Regulations Applicable to Sequoyah ODCM
- Sequoyah Technical Specification Markup
- Proposed License Amendment
- Basis for Proposed Amendment
- NRC Questions from Previous Public Meeting
- Summary
- Schedule for Submittal 2
Introduction
- SQN is planning addition of KOH to control the pH of the primary side reactor coolant, a first of a kind application for a North American PWR.
- Background information provided during April 15, 2025 public meeting with NRC SQN was considering a potential exemption request History of rulemaking and regulatory precedents were presented NRC staff provided relevant questions which will be further discussed Meeting summary provided in ML25108A105
- SQN is now planning to propose a license amendment supporting application of KOH and performing a revision of the ODCM l 3
Purpose
- The purpose of this meeting is to discuss the need for an amendment to the operating licenses for SQN Units 1 and 2 related to KOH application Proposed amendment would revise TS 5.5.3 Radioactive Effluent Controls Program to allow for the application of specific ICRPs and FGRs in the determination of dose coefficients for KOH radionuclides Dose coefficients associated with KOH radionuclides are required to evaluate compliance with the requirements of 10 CFR Part 20 and 10 CFR Part 50, Appendix I
- Proposed license amendment would support a revision of the SQN ODCM that accounts for the additional radionuclides generated when using KOH l 4
Regulations Applicable to SQN ODCM 10 CFR Part 20 Standards for Protection Against Radiation 10 CFR Part 20.1302, Compliance with dose limits for individual members of the public 10 CFR Part 20 Appendix B, Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for Occupational Exposure; Effluent Concentrations; Concentrations for Release to Sewerage 10 CFR Part 50 Domestic Licensing of Production and Utilization Facilities 10 CFR Part 50 Appendix I, Numerical Guides for Design Objectives and Limiting Conditions for Operation to Meet the Criterion "As Low as is Reasonably Achievable" for Radioactive Material in Light-Water-Cooled Nuclear Power Reactor Effluents l 5
SQN Technical Specification Markup l 6 Proposed license amendment would not change any of the existing requirements of SQN TS 5.5.1
SQN Technical Specification Markup l 7
Proposed License Amendment Proposed license amendment for SQN Units 1 and 2 would be an allowance to use specific ICRP and FGR methodologies to calculate dose coefficients associated with KOH radionuclides ICRPs 72, 119, 144 and 151 along with FGR-12 and FGR-15 would be used to determine dose coefficients for radionuclides of Chlorine, Potassium and Argon only Dose coefficients used in the evaluation of compliance with requirements of 10 CFR Part 20, 10 CFR 50 Appendix I Proposed amendment would not apply to the determination of dose coefficients for any other radionuclides Proposed amendment would not limit SQN to using KOH as the only method for RCS pH control l 8
Basis for Proposed Amendment 10 CFR Part 20 and 10 CFR Part 50 Appendix I are based on ICRP 2 and ICRP 30 which do not account for KOH as an RCS pH control agent.
NRC has recognized that current regulations and guidance documents are static in relation to developments in standards such as ICRPs and others.
ICRPs 72, 119, 144, and 151 are industry standards.
FGR-12 and FGR-15 were developed jointly by the Environmental Protection Agency (EPA) and Oak Ridge National Laboratory (ORNL) for use in implementing radiation protection programs.
l 9
NRC Question Responses
- NRC asked if TVA determined if any of the new KOH radionuclides would be considered principal radionuclides Principal radionuclides are those that contribute greater than 1 percent of 10 CFR Part 50, Appendix I design objective dose when all radionuclides in the type of effluent are considered as outlined in RG 1.21 EPRI performed an activation analysis to evaluate KOH nuclide concentrations in the reactor coolant and potential effects on dose Only six KOH radionuclides have half-lives greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Cumulative increase in activity of these longer-lived radionuclides projected to represent less than 0.1% of the total activity in typical reactor coolant and subsequent effluents l 10
NRC Question Responses
- The NRC staff noted that the doses discussed during the meeting were to the public and asked TVA if there would be an occupational dose concern.
Occupational exposure trends at VVERs indicate that use of KOH for pH control is unlikely to be a major contributor to personnel exposure for PWRs For SQN, the addition of potassium in the primary coolant anticipated to increase letdown resin gamma dose rates Sodium impurities likely to lead to an initial transient increase in resin gamma dose rates in the first few days until it is removed Linear decrease in resin gamma dose rate expected over the course of the cycle concurrent with potassium removal from the coolant Potential for increase in gaseous waste generation due to accumulation and release of argon nuclides l 11
NRC Question Responses
- The NRC staff inquired about potassium-40 (K-40) and how TVA would distinguish between dose from naturally occurring K-40 and K-40 from an airborne event at the plant. The NRC staff also asked how TVA plans to distinguish between the K-40 from the plant and naturally occurring K-40 in its environmental monitoring program.
SQN has added historical K-40 data to the plant chemistry database that has been captured as part of the radioactive effluents monitoring program Newly collected data with results above two standard deviations in three consecutive samples would indicate a potential airborne event at the plant l 12
NRC Question Responses
- The NRC staff asked TVA how it plans to assess the food chain in RG 1.109, Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I, since it does not consider K-40 in the transference to milk.
SQN radioactive effluents monitoring program sampling does not include milking animals Food chain is assessed using guidance in NUREG-1301 where vegetation is sampled in lieu of milk SQN effluents sampling plan includes analysis for K-40 l 13
NRC Question Responses
- The NRC staff inquired if any changes would be needed to the plants pollution discharge elimination system permit.
SQN National Pollutant Discharge Elimination System (NPDES) Permit is TN0026450 Application of KOH in the RCS is not considered a Biocide/Corrosion Treatment (B/CTP) chemical. Therefore, it would not change the SQN compliance with NPDES permit Part IV.B.
KOH is not listed in 40 CFR Part 122, Appendix D and the notification levels of NPDES permit Part III.A.1 are not applicable.
NPDES permit application treatment code 2K authorizes the treatment method provided permit limitations and water quality standards are not exceeded l 14
Summary l 15 Recognized supply chain concerns for continued availability of Enriched LiOH SQN is working with EPRI to evaluate the use of KOH as an alternative to Enriched LiOH for reactor coolant pH control Use of KOH would introduce radionuclides not considered in the current licensing basis for SQN Existing regulations do not support use of newer ICRP and FGR methodologies needed for calculation of KOH radionuclide dose coefficients for inclusion in the ODCM for SQN Proposed license amendment to TS 5.5.3 would allow the identified ICRP and FGR methodologies to calculate KOH radionuclide dose coefficients and evaluate compliance with 10 CFR Part 20 and 10 CFR Part 50, Appendix I
Schedule for Submittal l 16
- TVA plans to submit the license amendment request to the NRC no later than September 30, 2025.