ML24094A246
| ML24094A246 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 04/03/2024 |
| From: | Byrd T NRC/NRR/DORL/LPL4 |
| To: | Dewhirst L Nebraska Public Power District (NPPD) |
| Byrd T | |
| References | |
| L-2024-LLA-0037 | |
| Download: ML24094A246 (7) | |
Text
From:
Thomas Byrd (They/Them)
Sent:
Wednesday, April 3, 2024 11:40 AM To:
Dewhirst, Linda R.
Cc:
Unruh, Mark E.; Van Der Kamp, David W.
Subject:
RE: Cooper - RAI Emergency LAR Turbine Stop Valve Limit Switch TS 3.3.1.1 (EPID L-2024-LLA-0037)
Attachments:
FINAL RAI CNS Emergency LAR Turbine Stop Valve 04032024.pdf By letter dated April 1, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24092A376), Nebraska Public Power District (NPPD, the licensee) submitted a license amendment request (LAR) proposing emergency changes to the technical specifications (TSs) for the two turbine stop valves (TSVs) at Cooper Nuclear Station (Cooper).
The amendment would change TS 3.3.1.1, specifically adding a temporary footnote to TS Table 3.3.1.1-1, Reactor Protection System Instrumentation, that is applicable to Function 8, Turbine Stop Valve - Closure. The current design configuration of the Turbine Stop Valve position switches that input to the Reactor Protection System (RPS) does not meet the channel independence criteria. This temporary footnote would allow NPPD to not enter the TS 3.3.1.1, Condition A or B for the channel independence condition for a period ending no later than startup from Refuel Outage 33.
The licensee and NRC staff held a clarification call on April 3, 2024, which ensured the licensee understood the questions asked and were clear on their proposed responses. A publicly available version of this final RAI (attached with Draft removed) will be placed in the NRCs ADAMS system. As agreed, please provide a response to this RAI by 1700 Central Time April 3, 2024.
Thomas Byrd Project Manager - Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Office: (301) 415-3719 From: Thomas Byrd (They/Them)
Sent: Wednesday, April 3, 2024 9:33 AM To: Dewhirst, Linda R. <lrdewhi@nppd.com>
Cc: Unruh, Mark E. <m1unruh@nppd.com>; Van Der Kamp, David W. <dwvande@nppd.com>
Subject:
Cooper - RAI Emergency LAR Turbine Stop Valve Limit Switch TS 3.3.1.1 (EPID L-2024-LLA-0037)
By letter dated April 1, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24092A376), Nebraska Public Power District (NPPD, the licensee) submitted a license amendment request (LAR) proposing emergency changes to the technical specifications (TSs) for the two turbine stop valves (TSVs) at Cooper Nuclear Station (Cooper).
The amendment would change TS 3.3.1.1, specifically adding a temporary footnote to TS Table 3.3.1.1-1, Reactor Protection System Instrumentation, that is applicable to Function 8, Turbine Stop Valve - Closure. The current design configuration of the Turbine Stop Valve position switches that input to the Reactor Protection System (RPS) does not meet the channel
independence criteria. This temporary footnote would allow NPPD to not enter the TS 3.3.1.1, Condition A or B for the channel independence condition for a period ending no later than startup from Refuel Outage 33.
The Nuclear Regulatory Commission (NRC) staff reviewed the submittal and determined that additional information, as described in the attached draft request for additional information (RAI), is required for the staff to complete its review of the application. This RAI is identified as a draft currently to confirm your understanding of the information that the NRC staff needs to complete the evaluation. Please let me know if you would like to have a call with the NRC staff to clarify this request. If the request for information is understood, due to the emergency nature of this LAR please respond to this RAI today by 6:00pm EST (5:00pm CST).
Thomas Byrd Project Manager - Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Office: (301) 415-3719
Hearing Identifier:
NRR_DRMA Email Number:
2450 Mail Envelope Properties (BLAPR09MB633948E39C67EF0FDAD6AE99FA3D2)
Subject:
RE Cooper - RAI Emergency LAR Turbine Stop Valve Limit Switch TS 3.3.1.1 (EPID L-2024-LLA-0037)
Sent Date:
4/3/2024 11:39:38 AM Received Date:
4/3/2024 11:39:00 AM From:
Thomas Byrd (They/Them)
Created By:
Thomas.Byrd@nrc.gov Recipients:
"Unruh, Mark E." <m1unruh@nppd.com>
Tracking Status: None "Van Der Kamp, David W." <dwvande@nppd.com>
Tracking Status: None "Dewhirst, Linda R." <lrdewhi@nppd.com>
Tracking Status: None Post Office:
BLAPR09MB6339.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 3535 4/3/2024 11:39:00 AM FINAL RAI CNS Emergency LAR Turbine Stop Valve 04032024.pdf 117505 Options Priority:
Normal Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
REQUEST FOR ADDITIONAL INFORMATION EMERGENCY LICENSE AMENDMENT RENEWED FACILITY OPERATING LICENSE NO. DPR-46 NEBRASKA PUBLIC POWER DISTRICT COOPER NUCLEAR STATION DOCKET NO. 50-298 EPID L-2024-LLA-0037
1.0 INTRODUCTION
By letter dated April 1, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24092A376), Nebraska Public Power District (NPPD, the licensee) submitted a license amendment request (LAR) proposing emergency changes to the technical specifications (TSs) for the two turbine stop valves (TSVs) at Cooper Nuclear Station (Cooper).
The amendment would change TS 3.3.1.1, specifically adding a temporary footnote to TS Table 3.3.1.1-1, Reactor Protection System Instrumentation, that is applicable to Function 8, Turbine Stop Valve - Closure. The current design configuration of the Turbine Stop Valve position switches that input to the Reactor Protection System (RPS) does not meet the channel independence criteria. This temporary footnote would allow NPPD to not enter the TS 3.3.1.1, Condition A or B for the channel independence condition for a period ending no later than startup from Refuel Outage 33.
The NRC staff has determined that additional information is needed to support its review. The following is the NRC staffs request for additional information (RAI).
2.0 REGULATORY BASIS Title 10 of the Code of Federal Regulations (10 CFR), Section 50.91, Notice for public comment; State consultation, contains procedures that the Nuclear Regulatory Commission (the Commission) will use for applications requesting an amendment to an operating license under 10 CFR Part 50. Regarding emergency amendment requests, 10 CFR 50.91(a)(5) states, in part, Whenever an emergency situation exists, a licensee requesting an amendment must explain why this emergency situation occurred and why it could not avoid this situation, and the Commission will assess the licensee's reasons for failing to file an application sufficiently in advance of that event.
The regulation in 10 CFR 50.36, Technical specifications, provides the regulatory requirements for the content of the TS. Specifically, Section 50.36(c)(3) states, surveillance requirements [SRs] 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.
Cooper was designed and constructed to meet the principal design criteria described in the Atomic Energy Commissions (AEC) proposed rule, General Design Criteria [GDC] for Nuclear Power Plant Construction Permits, published in the Federal Register on July 11,1967 (32 FR
10213). The degree of conformance to the 1967 proposed GDC is described in Appendix F, Conformance to AEC Proposed General Design Criteria, to the Updated Safety Analysis Report for Cooper. GDC 20, Protection System Functions, is the subject of this emergency LAR regarding channel independence for the position switches of the turbine stop valves at Cooper.
Criterion 14, Core Protection Systems: Core protection systems, together with associated equipment, shall be designed to act automatically to prevent or to suppress conditions that could result in exceeding acceptable fuel damage limits.
Criterion 20, Protection Systems Redundancy and Independence: Redundancy and independence designed into protection systems shall be sufficient to assure that no single failure or removal from service of any component or channel of a system will result in loss of the protection function. The redundancy provided shall include, as a minimum, two channels of protection for each production function to be served. Different principles shall be used where necessary to achieve true independence of redundant instrumentation components.
3.0 REQUEST FOR ADDITIONAL INFORMATION RAI 1, List of Commitments, to the LAR specifies two sets of commitments for compensating measures to provide assurance of the capability of the turbine stop valves at Cooper to perform their safety functions for the duration of the LAR. Attachment 2 indicates continuing compliance for these commitments.
The licensee is requested to confirm that the commitments for the compensating measures for the performance of the turbine stop valves will continue until the end of the refueling outage in the fall of 2024 and, if so, be included in the note of TS Table 3.3.1.1-1.
RAI 2
The LAR does not discuss any changes to the Inservice Testing (IST) Program at Cooper for the turbine stop valves for the duration of the LAR.
The licensee is requested to describe any adjustments to the IST Program activities that might impact the performance of the turbine stop valves as part of the LAR.
RAI 3
Section 3.3 of the LAR states that the fuel damage is avoided by setting the most limiting operating Minimum Critical Power Ratio (MCPR) analyzed for the cycle, which is the Inadvertent High Pressure Coolant Injection (HPCI) event from the date of the LAR to the end of Cycle 33. It is unclear whether the Inadvertent HPCI event being limiting for MCPR assumes the TSV position switches are not operable and a scram signal from the TSV position does not occur.
Please provide details on the limiting MCPR event assuming the TSV position switches are inoperable.
RAI 4
Section 3.3 of the LAR states that the reactor coolant boundary analysis is based on the Main Steam Isolation Valve (MSIV) closure event with a flux scram. This event is analyzed in Chapter XIV, Section 5.1.3.4 of the CNS USAR, and states that the reactor vessel pressure rise for the event is limited since steam can flow to the main turbine and bypass valves through the other three main steam lines.
Please provide additional details on why closure of one MSIV event is chosen as the limiting event among the pressure rise events listed in Chapter XIV Section 5.1 of the USAR, when other events are more severe; such as, the Closure of All MSIVs event, where the reactor pressure rises to the relief valve setpoints.
RAI 5
Section 2.2 of the LAR describes the reason for the proposed change. However, it does not contain a discussion of why an emergency request is necessary.
Please provide further justification to support the licensees request for a review processed per 10 CFR 50.91(a)(5).
RAI 6
The LAR refers to Procedure 6.RPS.302, Main Turbine Stop Valve Closure and Steam Valve Functional Test, in describing its compensating measures for the performance of the turbine stop valves at Cooper. In a separate document, the licensee referred to Procedure 6.RPS.303 in describing the testing and calibration of the switches for the turbine stop valves.
The licensee is requested to provide a brief synopsis of these two procedures and their implementation that provides confidence in the performance of the turbine stop valves for the duration of the LAR. Clarify which procedure ensures proper calibration of the limit switch by stroking the TSV while verifying proper limit switch lever arm movement. Identify the plant conditions that need to be present when this calibration is performed. Identify the required surveillance frequency applied to assure performance of each of these procedures.
RAI 7
Section 3.2 of the LAR states that the TSV #1 position switch was replaced and calibrated in January 2024, but does not specify if both TSV #1 position switches were replaced.
Please clarify which TSV #1 position switches were replaced and calibrated in January 2024.
Please use the nomenclature of RPS Channel A1 and RPS Channel A2 in your response.
RAI 8
Section 3.2 of the LAR states that the TSV #2 position switches are examined and actuated every 13 weeks but does not describe the frequency in which the TSV #1 switches are examined and actuated. Please provide the following:
a.) Identify the date that the TSV #2 switches were last calibrated versus last functionally tested.
b.) Identify the Cooper calibration and functional test procedures that fulfill TS SR 3.3.1.1.4 (Perform a functional test of each RPS channel test switch) and SR 3.3.1.1.12 (Perform CHANNEL CALIBRATION.) Also please specify the surveillance frequency that is applicable to each of these surveillances.
c.) Clarify if the TSV #1 position switches are also examined and actuated every 13 weeks.
d.) Provide the schedule for the TSV #1 and TSV #2 calibrations or functional tests going forward until Refuel Outage 33, and describe how the examination and actuation is performed. Please use the nomenclature of RPS Channel A1, RPS Channel A2, RPS Channel B1, and RPS Channel B2 in your response.