ML24159A016
| ML24159A016 | |
| Person / Time | |
|---|---|
| Issue date: | 09/25/2024 |
| From: | Elijah Dickson NRC/NRR/DRA/ARCB |
| To: | Kevin Hsueh NRC/NRR/DRA/ARCB |
| References | |
| Download: ML24159A016 (1) | |
Text
September 25, 2024 MEMORANDUM TO: Kevin Hsueh, Chief Radiation Protection and Consequence Branch Division of Risk Assessment Office of Nuclear Reactor Regulation MEMORANDUM FROM: Elijah Dickson, Senior Reliability and Risk Analyst Radiation Protection and Consequence Branch Division of Risk Assessment Office of Nuclear Reactor Regulation
SUBJECT:
INCREASED ENRICHMENT RULEMAKING TECHNICAL BASIS FOR DRAFT REGULATORY GUIDE 1.183 REVISION 2 (2024)
GRADED RISK-INFORMED PERFORMANCE-BASE CONTROL ROOM DESIGN CRITERIA FRAMEWORK The purpose of this memorandum is to document the technical basis for the Increased Enrichment Rulemaking technical basis for draft Regulatory Guide 1425 (DG-1425), Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors.
DG-1425 is the proposed revision 2 of Regulatory Guide 1.183 Rev. 1 which does not have a graded risk-informed performance-based control room design criteria framework.
The U.S. Nuclear Regulatory Commission (NRC) is proposing to amend its regulations to facilitate the use of light-water reactor (LWR) fuel containing uranium enriched to greater than 5.0 weight percent uranium-235 (U-235) in title 10 of the Code of Federal Regulations (10 CFR) part 50, Domestic Licensing of Production and Utilization Facilities; 10 CFR part 51, Environmental Protection Regulations for Domestic Licensing and Related Regulatory Functions; 10 CFR part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants; and 10 CFR part 71, Packaging and Transportation of Radioactive Material.
This proposed rule would increase the numerical value of the control room design criteria in 10 CFR part 50, appendix A, General Design Criteria for Nuclear Power Plants, Criterion 19, Control Room (GDC-19), and 10 CFR 50.67(b)(2)(iii) from 5 rem to 10 rem (0.05 Sievert (Sv) to 0.10 Sv) total effective dose equivalent (TEDE) but range up to 25 rem (0.25 Sv) TEDE with a consideration of the plant-specific risk profile or risk information. If additional operational flexibilities are needed beyond 10 rem (0.10 Sv) TEDE, facility-specific risk profile or information could be leveraged to justify a higher numerical value up to 25 rem (0.25 Sv) TEDE. To justify a higher value, the NRC proposes a risk-informed, performance-based framework in DG-1425 to balance engineering analysis and judgment, including the principle of defense-in-depth and the incorporation of safety margins, with performance history.
CONTACTS: Elijah Dickson, NRR/DRA Sunil Weerakkody, NRR/DRA 301-415-7647 301-415-2870 Signed by Dicks on 09/13/24
K. Hsueh The purpose of this memorandum is to document the technical basis for the Increased Enrichment Rulemaking technical basis for draft Regulatory Guide 1425 (DG-1425), Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors.
DG-1425 is the proposed revision 2 of Regulatory Guide 1.183 Rev. 1 which does not have a graded risk-informed performance-based control room design criteria framework.
The U.S. Nuclear Regulatory Commission (NRC) is proposing to amend its regulations to facilitate the use of light-water reactor (LWR) fuel containing uranium enriched to greater than 5.0 weight percent uranium-235 (U-235) in title 10 of the Code of Federal Regulations (10 CFR) part 50, Domestic Licensing of Production and Utilization Facilities; 10 CFR part 51, Environmental Protection Regulations for Domestic Licensing and Related Regulatory Functions; 10 CFR part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants; and 10 CFR part 71, Packaging and Transportation of Radioactive Material.
This proposed rule would increase the numerical value of the control room design criteria in 10 CFR part 50, appendix A, General Design Criteria for Nuclear Power Plants, Criterion 19, Control Room (GDC-19), and 10 CFR 50.67(b)(2)(iii) from 5 rem to 10 rem (0.05 Sievert (Sv) to 0.10 Sv) total effective dose equivalent (TEDE) but range up to 25 rem (0.25 Sv) TEDE with a consideration of the plant-specific risk profile or risk information. If additional operational flexibilities are needed beyond 10 rem (0.10 Sv) TEDE, facility-specific risk profile or information could be leveraged to justify a higher numerical value up to 25 rem (0.25 Sv) TEDE. To justify a higher value, the NRC proposes a risk-informed, performance-based framework in DG-1425 to balance engineering analysis and judgment, including the principle of defense-in-depth and the incorporation of safety margins, with performance history.
The proposed guidance will align with Commission direction provided in Staff Requirements Memorandum (SRM)-SECY-98-144, Staff Requirements - SECY-98-144 - White Paper on Risk-Informed and Performance-Based Regulation, to take a risk-informed, performance-based approach to regulations and guidance. SRM-SECY-98-144 defines the terms and Commission expectations for risk-informed and performance-based regulation. As described in SRM-SECY-98-144, a risk-informed, performance-based regulation is an approach in which risk insights, engineering analysis and judgment including the principle of defense-in-depth and the incorporation of safety margins, and performance history are used to (1) focus attention on the most important activities, (2) establish objective criteria for evaluating performance, (3) develop measurable or calculable parameters for monitoring system and licensee performance, (4) provide flexibility to determine how to meet the established performance criteria in a way that will encourage and reward improved outcomes, and (5) focus on the results as the primary basis for regulatory decision-making.
The purpose framework enables a performance-based evaluation using traditional deterministic radiological consequence analysis methods within defined risk informed boundaries. These boundaries are defined by acceptable radiation exposure guidelines and Commission regulations for radiation workers during accident and emergency conditions and acceptable contemporary nuclear facility risk profiles using modern PRA methods. Such a framework is intended to provide flexibility when determining how to meet an established acceptance criterion in a way that encourages and rewards safety of the facility. In practice, the method produces a framework that leverages in part, its safe design, and operations to justify a higher control room design criterion with a lower plant-specific risk metric.
K. Hsueh The following attachments are included with this memo: : Method for Graded Risk-Informed Performance-Based Control Room Design Criteria Framework (see ADAMS ML24150A080)
ML24159A016 NRR-106 OFFICE NRR/DRA/ARCB NRR/DRA/ARCB: BC NAME EDickson KHsueh DATE 9/12/2024 9/25/2024