ML20010F632
| ML20010F632 | |
| Person / Time | |
|---|---|
| Issue date: | 01/17/2020 |
| From: | Matthew Leech NRC/NRR/DRA/ARCB |
| To: | |
| Matt Leech | |
| References | |
| Download: ML20010F632 (5) | |
Text
Revision to IMC 0609 Appendix G The revision to Appendix G series includes 4 procedures:
- IMC 0609, Appendix G Shutdown SDP is the main base document
- IMC 0609, Appendix G, Attachment 1 is the Screening and Initial Characterization of Findings (Phase 1 screening)
- IMC 0609, Appendix G, Attachment 2 is the Phase 2 SDP template for PWR during shutdown
- IMC 0609, Appendix G, Attachment 3 is the Phase 2 SDP template for BWR during shutdown 1
Revision to IMC 0609 Appendix G Background info about Appendix G Shutdown Significance Determination Process (SDP)
Appendix G for the shutdown SDP has 3 phases
- Phase 1 Initial Screening and Characterization - is a quick screen with a series of questions
- (If necessary) Phase 2 SDP templates for the next phase of screening using pre-solved event trees, and worksheets
- (if necessary) Phase 3 is a detailed risk evaluation if it wasnt screened to Green during Phase 2 (typically performed by HQ staff)
- Procedure is set up this way since we dont have many plant-specific shutdown SPAR models 2
Revision to IMC 0609 Appendix G
- The revision doesnt change the way Appendix G assesses risk
- It is mostly an editorial clean-up
- AP1000 plants will not go through Appendix G for a Phase 2 risk assessment, instead analysts are directed to the AP1000 shutdown SPAR model.
- An informational section was added to Appendix G, Attachment 1 to highlight relevant shutdown information for the AP1000 design.
3
Revision to IMC 0609 Appendix G Reasons for the revision:
- There is a requirement to periodically review and maintain the IMC procedures up-to-date. In the case of Appendix G, Attachments 2 and 3 had not been updated since 2005.
- The revision was mostly an editorial clean-up, designed to bring the formatting up to current standards, correct typos, make terminology more consistent, procedure easier to use, etc.
- The revision incorporates several ROP feedback forms.
- The revision now includes guidance on how to handle AP1000 shutdown risk assessment.
- Incorporates the counting rule worksheet into Appendix G.
4
Impact to Appendix G
- IMC 0609 Appendix G is more consistent within the various attachments of Appendix G, formatting is more consistent, definitions are the same, terminology is aligned.
- IMC 0609 Appendix G feedback forms are addressed.
- AP1000 is now addressed.
5