ML24330A050
| ML24330A050 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 11/12/2024 |
| From: | Ballard B Plant Licensing Branch III |
| To: | Kivi J, Mark Miller Northern States Power Co |
| Ballard, Brent | |
| References | |
| EPID L-2024-LLA-0067 | |
| Download: ML24330A050 (4) | |
Text
1 Brent Ballard From:
Brent Ballard Sent:
Tuesday, November 12, 2024 2:20 PM To:
Kivi, Jeffrey L; Miller, Michael A Cc:
Luis Cruz Rosado
Subject:
Request for Additional Information RE: Prairie Island, Units 1 and 2 - LAR to Revise TS Definition and Adopt Plant Specific Methods for RTT (EPID: L-2024-LLA-0067)
Attachments:
Prairie Island RTT LAR RAI-10392-R1-FINAL.docx HI Mike and Je, By letter dated June 3, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24155A220), Northern States Power Company, a Minnesota corporation (NSPM, the licensee), doing business as Xcel Energy, submitted a license amendment request for the Prairie Island Nuclear Generating Plant, Units 1 and 2. The proposed amendment would revise the Technical Speci"cation (TS) de"nition of REACTOR TRIP SYSTEM (RTS) RESPONSE TIME used in TS Surveillance Requirement 3.3.1.16 to allow allocation of response times in lieu of testing using methodologies proposed in the LAR, and revise applicability of SR 3.3.1.16 to RTS trip functions in TS Table 3.3.1-1.
The NRC sta has determined that additional information is needed to complete its review. Attached is NRC stas request for additional information (RAI).
A clari"cation call was held on November 7, 2024, with NSPM. Following the call, minor changes were made to RAI-EICB-3 for clarity. No changes were made to the scope of information requested. The NRC sta is requesting a response to the RAI within 30 days of the date of this email, which is December 12, 2024. Please let me know if you have any questions.
Thank you, Brent Brent Ballard Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 301-415-0680
1 REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PRAIRIE ISLAND 1 & 2 - LAR TO REVISE TS DEFINITIONS AND ADOPT PLANT SPECIFIC METHODS FOR RTT NORTHERN STATES POWER COMPANY PRAIRIE ISLAND, UNITS 1 & 2 DOCKET NO. 05000282, 05000306 ISSUE DATE: 11/12/2024
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Background===
By application of May 22, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24155A220), NSPM, the licensee for Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2, submitted a license amendment request (LAR) to change Technical Specification (TS). The proposed change would revise the definition of REACTOR TRIP SYSTEM (RTS) RESPONSE TIME used in TS Surveillance Requirement (SR) 3.3.1.16 to allow allocation of response times in lieu of testing using the proposed methodology. NSPM also proposes to revise TS Table 3.3.1-1 to apply SR 3.3.1.16 to the RTS trip functions for which the accident analyses include assumptions about time delays.
Regulatory Basis The regulatory requirements and guidance on which the NRC staff based its acceptance are:
General Design Criterion (GDC) 10 in 10 CFR 50 Appendix A, so far as it relates to fuel integrity during any condition of normal operation, including the effects of anticipated operational occurrences (AOOs).
GDC 15 requirement, so far as it relates to reactor coolant pressure boundary integrity during any condition of normal operation, including the effects of AOOs.
Chapter 15 of the NUREG-0800, Standard Review Plan (SRP) are relevant to the LAR.
Specifically, Chapter 15 discusses the AOOs and postulated accidents and associated criteria for evaluation of transient and accident analyses.
Enclosures 1 and 2 to the LAR provide the transient analysis information for the proposed RTS trip delay times, and addition or removal of SR 3.3.1-1 for RTS trip delay times testing to applicable RTS trip functions. The information addresses the departure from nucleate boiling ratio (DNBR) acceptance criteria defined in SRP Section 4.4, which includes GDC 10 requirements, and GDC 15 requirements for the reactor coolant pressure boundary limits.
During the review, the NRC staff identified that additional information is needed to complete its review and formulated the following request for additional information (RAI).
2 RAI-SNSB-1 The table in Section 3.1.5 of Enclosure 1 to the LAR of May 22, 2024, tabulates the proposed reactor trip delay times and the delay times assumed in the accident analyses for nine reactor trip system (RTS) functions. The last sentence in Section 3.1.5 indicates that the proposed delay time in all nine RTS functions is less than the delay time assumed in the accident analyses.
The table in Section 3.1.5 shows that the delay time of the power range high positive rate trip assumed in the accident analysis is 0.60 seconds. This delay time of 0.60 seconds is inconsistent with the equivalent delay time assumed in the design basis accident (DBA) analysis listed on page 14.3-4 of Prairie Island USAR Section 14 (Revision 36), which is 0.50 seconds.
a) Clarify which delay time (0.60 seconds or 0.50 seconds) is assumed in the DBA analysis for the power range high positive rate trip.
b) If the trip delay time assumed in the DBA analysis is 0.50 seconds, the proposed delay time of 0.501 seconds in the table of Section 3.1.5 of the LAR would exceed the value used in the accident analysis. Address acceptability of the proposed trip delay time of 0.501 seconds to meet the GDC 10 requirements for fuel integrity and GDC 15 requirements for the reactor coolant pressure boundary integrity.
RAI-EICB-2 In Criterion VI of Document Control of Appendix B to 10 CFR Part 50, it states, in part, that measures shall be established to control the issuance of documents, such as instructions, procedures, and drawings, including changes thereto, which prescribe all activities affecting quality. These measures shall assure that documents, including changes, are reviewed for adequacy and approved for release by authorized personnel. In Criterion III on Document Control of Appendix B to 10 CFR Part 50, it states, in part, that the verifying or checking process shall be performed by individuals or groups other than those who performed the original design, but who may be from the same organization.
However, the NRC staff found that the preparer and approver for Enclosure 2 of Proposed Methodology to Eliminate Protection Channel Response Time Testing for Prairie Island Nuclear Generating Plant is the same person. Please clarify if Enclosure 2 was issued and approved according to the licensees quality assurance program to meet Appendix B to 10 CFR Part 50 on Quality Assurance Criteria for Nuclear Power Plants.
RAI-EICB-3 10 CFR 50.36 (3) on surveillance requirements states that surveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.
On Page 9 of Proposed Methodology to Eliminate Protection Channel Response Time Testing for Prairie Island Nuclear Generating Plant, the NRC staff couldnt locate the basis for the time delays for the Lag Network NM-311 (135 ms) and Bistable Relay Driver NC-303 (65 ms) in Section 4.6 and 4.9 of WCAP-14036-P as stated for the Power Range High Positive Rate.
Please clarify or provide necessary information on delay times for devices which are used in the calculation of delay times in Enclosure 2 but are not included in the LAR itself or WCAP-14036-P.
3 RAI EICB-4 10 CFR 50.36 (3) on Surveillance requirements states that Surveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.
In the Table 5-1 on Page 45 of Attachment 6, Failure Modes & Effects Analysis and on Page 6 of Enclosure 2, the NRC staff found that the rising and falling response times for Baseline for RTL501 Module are not consistent with information provided in Section 5.0 of Attachment 6. The NRC staff also found that the rising and falling response times for Worst-Case Failures are not consistent either with information provided in Section 5.0 of Attachment 6. Please provide adequate additional information to support the calculation results of the final response times listed in Table 5-1.