ML20055G824
| ML20055G824 | |
| Person / Time | |
|---|---|
| Issue date: | 08/07/2020 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| Eudy M | |
| Shared Package | |
| ML20009D873 | List: |
| References | |
| DG-1363, RG-1.105, Rev 4 | |
| Download: ML20055G824 (2) | |
Text
REGULATORY ANALYSIS DRAFT REGULATORY GUIDE DG-1363 SETPOINTS FOR SAFETY-RELATED INSTRUMENTATION (Proposed Revision 4 of Regulatory Guide 1.105, dated August 2020
- 1.
Statement of the Problem The NRC staff is considering whether to revise Regulatory Guide (RG) 1.105, Setpoints for Safety-Related Instrumentation, in order to provide licensees and applicants with an updated method to demonstrate compliance with the 10 CFR 50.36(c)(1)(ii)(A) requirements for determining limiting safety system settings. The proposed revision of RG 1.105 would endorse the American National Standards Institute (ANSI)/International Society of Automation (ISA)
Standard 67.04.01-2018, Setpoints for Nuclear Safety-Related Instrumentation. The previous revision of RG 1.105 (Revision 3) endorsed ISA S67.04-1994 with several clarifications and exceptions.
In June 2014, the NRC staff issued for public comment Draft Regulatory Guide (DG)
DG-1141, Setpoints for Safety-Related Instrumentation (ADAMS Accession No. ML081630179), which evaluated the 2006 revision of the ANSI/ISA 67.04.01 standard. DG-1141 described several concerns with the 2006 revision of the standard. These concerns included the need for additional definitions, analytical limit avoidance probability, use of the technical specification allowable value as a metric for determining instrument channel functionality and operability, and what to consider as an appropriate statistical confidence level.
The ANSI/ISA S67.04 Standards Committee addressed these NRC staff concerns, as well as comments provided by industry stakeholders, and issued a revision to the ANSI/ISA standard in December 2018. The NRC staff elected not to finalize DG-1141 as a revision to RG 1.105 and chose instead to evaluate the 2018 ANSI/ISA standard revision for endorsement. If the staff were to endorse the 2018 ANSI/ISA standard, then the staff would issue DG-1363 as a replacement for DG-1141. The staff notes that DG-1363 would consider and address technical issues and public comments related to the issuance of DG-1141.
- 2.
Objective The objective of this regulatory analysis is to assess whether to update the RG to endorse ANSI/ISA Standard 67.04.01-2018 or take an alternative approach to address the regulatory problem.
- 3.
Alternative Approaches The NRC staff considered the following alternative approaches:
- 1. Do not revise Regulatory Guide 1.105
- 2. Withdraw Regulatory Guide 1.105
- 3. Revise Regulatory Guide 1.105 to address the current methods and procedures.
Alternative 1: Do Not Revise Regulatory Guide 1.105 Under this alternative, the NRC would not revise the current guidance, and the current guidance (Revision 3) would be retained. This alternative is considered the no-action alternative and provides a baseline condition from which any other alternatives will be assessed.
However, the no-action alternative would not address identified concerns with the current version of the regulatory guide. The NRC would continue to review each new application and license amendment request on a case-by-case basis.
Alternative 2: Withdraw Regulatory Guide 1.105 Under this alternative the NRC would withdraw this regulatory guide. This would eliminate the problems identified above regarding the regulatory guide. It would also eliminate the only readily available description of the methods the NRC staff considers acceptable for demonstrating compliance with 10 CFR 50.36(c)(1)(ii)(A)..
Alternative 3: Revise Regulatory Guide 1.105 Under this alternative, the NRC would revise Regulatory Guide 1.105. This revision would incorporate the latest information in safety-related nuclear instrumentation setpoint determination, supporting guidance, and review practices. By doing so, the NRC would ensure that the NRC guidance available in this area is current and accurately reflects the staffs positions.
The impact to the NRC would be the costs associated with preparing and issuing the regulatory guide revision. The impact to the public would be the voluntary costs associated with reviewing and providing comments to NRC during the public comment period. The value to NRC staff, applicants, and licensees would be the benefits associated with enhanced efficiency and effectiveness in using a common guidance document as the technical basis for license applications and other interactions between the NRC and its regulated entities.
Conclusion Based on this regulatory analysis, the NRC staff concludes that revision of Regulatory Guide 1.105 is warranted. The action will enhance safety-related setpoint determination by providing endorsement of the latest industry standard. It could also lead to cost savings for the industry, especially pertaining to new and advanced reactors developing a setpoint methodology.
Revising this Regulatory Guide 1.105 to endorse portions of a consensus standard is consistent with the NRC policy of evaluating the latest versions of national consensus standards to determine their suitability for endorsement by regulatory guides. This approach also will comply with the NRCs Management Directive 6.5, NRC Participation in the Development and Use of Consensus Standards (ML100600460). This is also in accordance with Public Law 104-113, National Technology Transfer and Advancement Act of 1995 and the Office of Management and Budget Circular No. A-119, Federal Participation in the Development and Use of Voluntary Consensus Standards and in Conformity Assessment Activities.