ML24354A005
| ML24354A005 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/30/2024 |
| From: | NRC/NMSS/DREFS/EPMB1 |
| To: | |
| References | |
| Download: ML24354A005 (1) | |
Text
1 DRESDEN NUCLEAR POWER STATION SAMA REVIEW AUDIT REPORT Subject Audit of the Severe Accident Mitigation Alternatives (SAMA) analysis portion of the Dresden Nuclear Power Station (DNPS), Units 2 and 3, Subsequent License Renewal (SLR) Application Environmental Report (ER)
When September 30, 2024, 9:00 AM to 10:15 AM Eastern Time (SAMA Audit)
SAMA Audit Discussion Participants (may not be complete)
Angela Sabet U.S. Nuclear Regulatory Commission (NRC)
Chuck Molten NRC Tam Tran NRC Steve Short Pacific Northwest National Laboratory (PNNL)
Bill Ivans PNNL Hannah Pell Constellation Energy Generation (CEG)
Kristen Meek CEG John Hilditch CEG Annika Macleod CEG/Jensen-Hughes William Milne CEG/Jensen-Hughes Documents Reviewed on the Applicants Portal
- 1. Assessment of Significance for New Information relevant to Dresden Nuclear Power Station SAMAs, Revision 0, January 31, 2023.
- 2. DR-PSA-021.11, Dresden Fire PRA Summary & Quantification Notebook, Revision 3.
- 3. DR-MISC-033, Dresden High Winds and Tornado Risk Assessment, Revision 0 (Draft).
- 4. DR-LAR-008, External Hazards Assessment for Dresden Nuclear Power Station, Revision
- 0.
- 5. DR-PSA-013, Dresden PRA Summary Document, Revision 12.
- 6. TODI NF220695, Dresden 2 Cycle 29 Cycle Design Inputs and Requirements (CDIR),
Revision 0.
- 7. DR-PSA-014, Dresden Nuclear Power Station Probabilistic Risk Assessment Quantification Notebook, Revision 5.
Discussion On April 17, 2024 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML24108A008), the NRC received the Constellation Energy Generation, LLC (CEG or the applicant) application for subsequent renewal of the operating license for DNPS Units 2 and 3. In support of the application and in accordance with Title 10 of the Code of Federal Regulations (10 CFR) Part 51 and Part 54, CEG also submitted an ER for DNPS.
After a welcome and introductions on September 30, 2024, the plan and schedule for the audit were discussed. The goal of this portion of the audit was to review SAMA and postulated accident supporting information to complete the site-specific environmental impact statement for subsequent license renewal. During the audit, NRC, PNNL, and CEG/contractor (Jenson-Hughes) staff involved in the SAMA review discussed all the SAMA-related audit needs identified in the audit plan. Specifically discussed were the audit needs addressing the following topics:
2
- 1. Potentially new and significant information relevant to the SAMA analysis;
- 2. Assessment process of potentially new and significant information; and
- 3. Identification, qualitative pre-screening, and quantitative evaluation of risk reduction of industry and unimplemented Final Plant-Specific SAMAs.
As a result of the audit, NRC/PNNL staff identified requests for confirmation of information (RCIs) for which further information will be needed on the docket to complete the site-specific environmental impact statement for subsequent license renewal. No requests for additional information (RAIs) were identified. The following table summarizes the results of the audit by delineating the SAMA-related audit needs in the audit plan into: 1) those for which information is not needed on the docket; and 2) those for which supplemental information is needed on the docket as RCIs. The RCIs are provided below.
Audit Need Information Needed on the Docket SAMA-1 RCI SAMA-2 Not Needed SAMA-3 RCI SAMA-4 Not Needed SAMA-5 Not Needed SAMA-6 Not Needed SAMA-7 RCI SAMA-8 Not Needed SAMA-9 Not Needed Request for Confirmation of Information (RCI)
SAMA-RCI-1 [Info Need SAMA-1] Section 4.15.2.1 of the SLR ER provides risk estimates for internal events, including internal flooding as well as fire, seismic, external flooding, and high wind/tornado events. The extent to which other external events were considered and their basis for exclusion, if applicable, as new and significant information is not clear from the information documented within the ER. Confirm that such events were considered and determined to not represent new and significant information.
SAMA-RCI-2 [Info Need SAMA-3] Section 4.15.2.1 of the SLR ER provides a CDF estimate for high wind/tornado events that is estimated to be no more than 2.00E-05 per year per unit. The extent to which such events were considered as new and significant information relative to the SAMA analysis is not clear from the information documented within the ER. Confirm that such events were considered and determined to not represent new and significant information (i.e.,
would not result in a SAMA that yields a significant risk reduction).
SAMA-RCI-3 [Info Need SAMA-7] The dispositions for SLR SAMAs 48 and 54 within Table 4.15-5 of the ER state that the seismic PRA model failed to properly quantify and that the same reduction as the internal events model was assumed. The basis of this assumption is not clear from the information documented within the ER. Confirm that the evaluation of SAMAs 48 and 54 would yield the same conclusion (i.e., would not result in a SAMA that yields a significant risk reduction) had the seismic risk had been directly considered or quantified.
Requests for Additional Information (RAIs)
None