NLS2024027, Response to NRC Request for Additional Information Regarding Application for the Emergency License Amendment Request to Revise Technical Specifications 3 .3 .1.1, Reactor Protection (RPS) Instrumentation
| ML24094A331 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 04/03/2024 |
| From: | Dia K Nebraska Public Power District (NPPD) |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NLS2024027 | |
| Download: ML24094A331 (1) | |
Text
NLS2024027 April3,2024 H
Nebraska Public Power District "Always there when you need us" 50.90 50.91(a)(5)
Attention: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
Response to Nuclear Regulatory Commission Request for Additional Information Regarding Application for the Emergency License Amendment Request to Revise Technical Specifications 3.3.1.1, "Reactor Protection (RPS) Instrumentation" Cooper Nuclear Station, Docket No. 50-298, Renewed License No. DPR-46
Reference:
- 1. Email from Thomas Byrd, U.S. Nuclear Regulatory Commission, to Linda Dewhirst, Nebraska Public Power District, dated April 3, 2024, "Cooper - RAI Emergency LAR Turbine Stop Valve Limit Switch TS 3.3.1.1 (EPID L-2024-LLA-0037)"
- 2. Letter from Khalil Dia, Nebraska Public Power District, to the U.S. Nuclear Regulatory Commission, dated April 1, 2024, "Emergency License Amendment Request to Revise Technical Specifications 3.3.1.1, "Reactor Protection (RPS) Instrumentation"
Dear Sir or Madam:
The purpose of this letter is for the Nebraska Public Power District (NPPD) to respond to the Nuclear Regulatory Commission's (NRC) Request for Additional Information (RAI) (Reference
- 1) related to the Cooper Nuclear Station (CNS) "Emergency License Amendment Request to Revise Technical Specifications 3.3.1.1, "Reactor Protection (RPS) Instrumentation."
The response to the RAI is provided in Attachment 1 to this letter. Attachment 2 contains revised TS marked up pages. Attachment 3 contains revised ( clean) TS pages.
NPPD has reviewed the information supporting a finding of no significant hazards consideration and the environmental evaluation that were previously provided to the NRC in Reference 2. The additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration and does not affect the conclusion of the environmental evaluation.
There are no new regulatory commitments made in this submittal. If you should have any questions regarding this submittal, please contact Linda Dewhirst, Regulatory Affairs and Compliance Manager, at (402) 825-5416.
COOPER NUCLEAR STATION 72676 648A Ave/ P.O. Box 98 / Brownville, NE 68321 http://www.nppd.com
NLS2024027 Page 2 of2 I declare under penalty of perjury that the foregoing is true and correct.
Executed On: ApV.' I 3, Z,:, 2. L/
Date Sincerely, Site Vice President
/dv Attachments:
- 1. Response to Request for Additional Information
- 2. Proposed Technical Specifications Change (Mark-up)
- 3. Revised Technical Specifications Page cc:
Regional Administrator w / attachments USNRC - Region IV Cooper Project Manager w/ attachments USNRC - NRR Plant Licensing Branch IV Senior Resident Inspector w/ attachments USNRC-CNS Nebraska Health and Human Services w/ attachments Department of Regulation and Li censure NPG Distribution w/ attachments CNS Records w/ attachments
NLS2024027 Page 1 of 5 Response to Request for Additional Information Cooper Nuclear Station, Docket No. 50-298, Renewed License No. DPR-46 The Nuclear Regulatory Commission Request for Additional Information (RAI) regarding the Emergency License Amendment Request (LAR) for Cooper Nuclear Station (CNS) to revise the Technical Specifications (TS) TS 3.3.1.1 is shown in italics. The Nebraska Public Power District (NPPD) response to the request is shown in normal font., "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.
NPPD Response NPPD confirms that the commitment for the compensatory measures will continue until startup from Refueling Outage 3 3 with the clarification that the compensatory measures are required when the Turbine Stop Valve (TSV) position switches are required to be operable (i.e., 2: 29.5%
rated thermal power). During low power and shutdown conditions, the compensatory measures are not necessary because the position switches are not required to be operable. The proposed Note ( d) that is being added to TS Table 3.3.1.1-1 has been revised to include the implementation of the compensatory measures. See Attachment 2 for a markup of the TS page and Attachment 3 for a clean-typed version of the TS page.
RAf 2 The LAR does not discuss any changes to the lnservice Testing (1ST} Program at Cooper for the turbine stop valves for the duration of the LAR.
The licensee is requested to describe any adjustments to the 1ST Program activities that might impact the performance of the turbine stop valves as part of the LAR.
NPPD Response The TSV are non-essential valves and do not meet the scope requirements of IST A-1100 Scope of the ASME OM Code 2004/2006 Addenda, "These requirements apply to (a) pumps and valves that are required to perform a specific function in shutting down a reactor to the safe
NLS2024027 Page 2 of 5 shutdown condition, in maintaining the safe shutdown condition, or in mitigating the consequences of an accident." The control system would also be excluded under ISTC-1200 Exemptions, "External control and protection systems responsible for sensing plant conditions and providing signals for valve operation are excluded from the requirements of this Subsection." Therefore, no IST activities at CNS are impacted by this LAR.
RAl3 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.
NPPD Response The fuel vendor ran a sensitivity case for CNS Cycle 33, modeling the HPCIL8 event (inadvertent HPCI event) without crediting the reactor scram on TSV position. The results of the sensitivity case round to the same Operating Limit MCPR values as provided in the Cooper Cycle 33 Supplemental Reload Licensing Report.
RAl4 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.
NPPD Response The event referenced for the overpressure analysis in Section 3.3 of the request is based on the closure of all MSIVs, which is described in USAR Section IV-4.9.3. The event description in the request was not meant to refer to Chapter XIV-5.1.3.4, but a specific USAR section reference was not included in the original request. The event in Section IV-4.9.3 assumes that the scram off the position of the MSIV s ( direct scram) does not occur and the neutron flux signal scrams the reactor. The scram from the turbine stop valve position is not discussed. CNS agrees that the closure of all MSIV s is limiting for overpressure analysis of the reactor coolant pressure boundary and the event as described in USAR Section IV-4.9.3 is the most limiting event for
NLS2024027 Page 3 of 5 overpressure protection of the reactor coolant system boundary. As the issue with the stop valve position limit switches does not affect this event, the Cycle 33 Supplemental Reload Licensing Analysis results for this event remain the same if the scram signal from these switches does not occur.
RAIS 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 licensee's request for a review processed per 10 CFR 50.91 (a)(5).
NPPD Response As a result of the concern with channel independence, at 1437 on March 29, 2024, CNS entered a 12-hour action statement under TS 3.3.1.1, Condition A, and a 6-hour action statement under TS 3.3.1.1 Condition B, related to TS Table 3.3.1.1-1 Function 8. Resolution of the design concern cannot be accomplished within the completion time of the TS Limiting Condition for Operation Required Action without requiring a reduction in Reactor Thermal Power below 29.5% without a commensurate benefit in nuclear safety.
This change is needed sooner than can be issued under exigent circumstances because the Notice of Enforcement Discretion expires at 023 7 on April 6, 2024, and this license amendment request is considered timely considering the unplanned nature of this condition.
RAl6 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.
NPPD Response Surveillance Procedure 6.RPS.303 is performed during each refueling outage to complete the channel calibration of the TSV position switches, RPS channels Al, A2, Bl, and B2. This is Cdone by stroking the valves individually and verifying the applicable Reactor Protection System (RPS) relays drop out when the valve is at :=S10% CLOSED. This surveillance procedure
NLS2024027 Page 4 of5 is performed in Modes 4 or 5. The required frequency for this surveillance, as described in Appendix B of the Technical Requirements Manual (TRM) 3.3.1.1.12 Function 8, is 24 months.
This surveillance also satisfies the Logic System Functional Test surveillance requirement of TRM 3.3.1.1.13 Function 8 with a frequency of24 months as described in Appendix B of the TRM. It should be noted, the calibration can be performed in Mode 1 at reduced power, which was done in January 2024, by using work order instructions that were similar to the steps in Surveillance Procedure 6.RPS.303 and contained the same acceptance criteria.
Surveillance Procedure 6.RPS.302 is performed on a quarterly frequency to complete the channel functional test of the TSV position switches, RPS Channels Al, A2, Bl, and B2. This is done by either manual actuation of the position switch linkage and a visual inspection of the linkage or by stroking of the individual TSV one at a time. Both methods verify the applicable RPS relays drop out. To perform the method of stroking of the TSV, power must be less than or equal to 1693 MWt. Manual actuation of the TSV position switches can be performed at any power but is typically performed during a downpower to reduce dose. The required frequency for this surveillance as described in Appendix B of the TRM 3.3.1.1. 9 Function 8, is 92 days.
RAl7 Section 3.2 of the LAR states that the TSV#l position switch was replaced and calibrated in January 2024, but does not specify if both TSV#l position switches were replaced.
Please clarify which TSV#l position switches were replaced and calibrated in January 2024.
Please use the nomenclature of RPS Channel Al and RPS Channel A2 in your response.
NPPD Response Both of the position switches on TSVl (RPS Channels Al and A2) were replaced and calibrated in January 2024.
RAl8 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.
NLS2024027 Page 5 of 5 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 Al, RPS Channel A2, RPS Channel Bl, and RPS Channel B2 in your response NPPD Response a) The channel calibrations for TSV2 (RPS Channel Bl and RPS Channel B2) were last performed during refueling outage RE32 (November 9, 2022) per Surveillance Procedure 6.RPS.303. The channel function test for TSV2 (RPS Channel B 1 and RPS Channel B2) were last performed on March 2, 2024 during a quarterly downpower per Surveillance Procedure 6.RPS.302.
b) TS SR 3.3.1.1.4 is satisfied through the performance of Surveillance Procedures 6.1 RPS.314, RPS Channel Test Switch Functional Test (Div. 1) and 6.2RPS.314 RPS Channel Test Switch Functional Test (Div. 2) at a frequency of31 days. TS SR 3.3.1.1.12 is satisfied through the performance of 6.RPS.303 at a frequency of 2 years.
Surveillance 6.lRPS.314 6.RPS.303 Requirement 6.2RPS.314 3.3.1.1.4 X
3.3.1.1.12 X
c) TSVl (RPS Channel Al and RPS Channel A2) is inspected and tested at a frequency of 13 weeks through the performance of Surveillance Procedure 6.RPS.302.
d) This channel calibration is performed on both TSVl (RPS Channel Al and RPS Channel A2) and TSV2 (RPS Channel Bl and RPS Channel B2) on a 2-year frequency through the performance of Surveillance Procedure 6.RPS.303. This frequency will continue going forward. Both TSVl (RPS Channel Al and RPS Channel A2) and TSV2 (RPS Channel Bl and RPS Channel B2) will be calibrated during the upcoming refueling outage RE33 in the Fall of 2024. The channel function testing is performed on the position switches on both TSVl (RPS Channel Al and RPS Channel A2) and TSV2 (RPS Channel Bl and RPS Channel B2) on a 13-week frequency through the performance of Surveillance Procedure 6.RPS.302, Section 5, to manually actuate the position switches. This performance includes validation of linkages intact. This frequency will continue going forward during quarterly downpowers currently scheduled for May 2024 and August 2024.
NLS2024027 Page 1 of2 Proposed Technical Specifications Change (Mark-up)
Cooper Nuclear Station, Docket No. 50-298, Renewed License No. DPR-46 Revised Page 3.3-8
FUNCTION
- 7.
Scram Discharge Volume Water Level - High
- a.
Level Transmitter
- b.
Level Switch
- 8.
Turbine Stop Valve - Closure
- 9.
Turbine Control Valve Fast Closure, DEH Trip Oil Pressure -
Low
- 10. Reactor Mode Switch -
Shutdown Position
- 11. Manual Scram RPS Instrumentation 3.3.1.1 Table 3.3.1.1-1 (page 3 of 3)
Reactor Protection System Instrumentation APPLICABLE MODES OR OTHER SPECIFIED CONDITIONS 1,2 1,2 2: 29.5% RTP 2: 29.5% RTP 1,2 1,2 REQUIRED CHANNELS PER TRIP SYSTEM 2
2 2
2 2
CONDITIONS REFERENCED FROM REQUIRED SURVEILLANCE ALLOWABLE ACTION D.1 REQUIREMENTS VALUE G
SR 3.3.1.1.4 s 90 inches SR 3.3.1.1.9 H
G H
E E
G H
G H
SR 3.3.1.1.12(a,b)
SR 3.3.1.1.13 SR 3.3.1.1.15 SR 3.3.1.1.4 SR 3.3.1.1.9 SR 3.3.1.1.12 SR 3.3.1.1.13 SR 3.3.1.1.15 SR 3.3.1.1.4 SR 3.3.1.1.9 SR 3.3.1.1.12 SR 3.3.1.1.13 SR 3.3.1.1.15 SR 3.3.1.1.4 SR 3.3.1.1.9 SR 3.3.1.1.12 SR 3.3.1.1.13 SR 3.3.1.1.15 s; 90 inches s 90 inches s 90 inches SR 3.3.1.1.4 s 10% closed SR 3.3.1.1.9 SR 3.3.1.1.12 SR 3.3.1.1.13 SR 3.3.1.1.14 SR 3.3.1.1.15 SR 3.3.1.1.4 2: 1018 psig SR 3.3.1.1.9 SR 3.3.1.1.12(a,b)
SR 3.3.1.1.13 SR 3.3.1.1.14 SR 3.3.1.1.15 SR 3.3.1.1.11 SR 3.3.1.1.13 SR 3.3.1.1.11 SR 3.3.1.1.13 SR 3.3.1.1.9 SR 3.3.1.1.13 SR 3.3.1.1.9 SR 3.3.1.1.13 NA NA NA NA (a) If the as-found channel setpoint is outside its predefined as-found tolerance, then the channel shall be evaluated to verify that it is functioning as required before returning the channel to service.
(b) The instrument channel setpoint shall be reset to a value that is within the as-left tolerance around the Limiting Trip Setpoint (L TSP) at the completion of the surveillance; otherwise, the channel shall be declared inoperable. Setpoints more conservative than the L TSP are acceptable provided that the as-found and as-left tolerances apply to the actual setpoint implemented in the Surveillance procedures (Nominal Trip Setpoint) to confirm channel performance. The Limiting Trip Setpoint and the methodologies used to determine the as-found and the as-left tolerances are specified in the Technical Requirements Manual.
(c) With any control rod withdrawn from a core cell containing one or more fuel assemblies.
(d) The Turbine Stop Valve - Closure function does not meet channel independence criteria. Conditions A and Bare not required to be entered for this condition. NPPD will implement compensatory measures described in NPPD letter NLS2024024, dated April 1, 2024 (ML24092A376), during the applicable specified condition for the position switches until startup from RE33. If the position switches are returned to OPERABLE status prior to startup from RE33, then these compensatory measures are no longer required.
Cooper 3.3-8 Amendment No.
NLS2024027 Page 1 of2 Revised Technical Specifications Page Cooper Nuclear Station, Docket No. 50-298, Renewed License No. DPR-46 Revised Page 3.3.8
FUNCTION
- 7.
Scram Discharge Volume Water Level - High
- a.
Level Transmitter
- b.
Level Switch
- 8.
Turbine Stop Valve - Closure
- 9.
Turbine Control Valve Fast Closure, DEH Trip Oil Pressure -
Low
- 10. Reactor Mode Switch -
Shutdown Position
- 11. Manual Scram RPS Instrumentation 3.3.1.1 Table 3.3.1.1-1 (page 3 of 3)
Reactor Protection System Instrumentation APPLICABLE MODES OR OTHER SPECIFIED CONDITIONS 1,2 1,2
- 29.5% RTP
- 29.5% RTP 1,2 1,2 REQUIRED CHANNELS PER TRIP SYSTEM 2
2 2
2 2
CONDITIONS REFERENCED FROM REQUIRED SURVEILLANCE ALLOWABLE ACTION D.1 REQUIREMENTS VALUE G
SR 3.3.1.1.4 s; 90 inches SR 3.3.1.1.9 H
G H
E E
G H
G H
SR 3.3.1.1.12(a,b}
SR 3.3.1.1.13 SR 3.3.1.1.15 SR 3.3.1.1.4 SR 3.3.1.1.9 SR 3.3.1.1.12 SR 3.3.1.1.13 SR 3.3.1.1.15 SR 3.3.1.1.4 SR 3.3.1.1.9 SR 3.3.1.1.12 SR 3.3.1.1.13 SR 3.3.1.1.15 SR 3.3.1.1.4 SR 3.3.1.1.9 SR 3.3.1.1.12 SR 3.3.1.1.13 SR 3.3.1.1.15 s; 90 inches s; 90 inches s; 90 inches SR 3.3.1.1.4 s; 10% closed SR 3.3.1.1.9 SR 3.3.1.1.12 SR 3.3.1.1.13 SR 3.3.1.1.14 SR 3.3.1.1.15 SR 3.3.1.1.4
~ 1018 psig SR 3.3.1.1.9 SR 3.3.1.1.12(a,b}
SR 3.3.1.1.13 SR 3.3.1.1.14 SR 3.3.1.1.15 SR 3.3.1.1.11 SR 3.3.1.1.13 SR 3.3.1.1.11 SR 3.3.1.1.13 SR 3.3.1.1.9 SR 3.3.1.1.13 SR 3.3.1.1.9 SR 3.3.1.1.13 NA NA NA NA (a) If the as-found channel setpoint is outside its predefined as-found tolerance, then the channel shall be evaluated to verify that it is functioning as required before returning the channel to service.
(b) The instrument channel setpoint shall be reset to a value that is within the as-left tolerance around the Limiting Trip Setpoint (L TSP) at the completion of the surveillance; otherwise, the channel shall be declared inoperable. Setpoints more conservative than the L TSP are acceptable provided that the as-found and as-left tolerances apply to the actual setpoint implemented in the Surveillance procedures (Nominal Trip Setpoint) to confirm channel performance. The Limiting Trip Setpoint and the methodologies used to determine the as-found and the as-left tolerances are specified in the Technical Requirements Manual.
(c) With any control rod withdrawn from a core cell containing one or more fuel assemblies.
(d) The Turbine Stop Valve - Closure function does not meet channel independence criteria. Conditions A and Bare not required to be entered for this condition. NPPD will implement compensatory measures described in NPPD letter NLS2024024, dated April 1, 2024 (ML24092A376), during the applicable specified condition for the position switches until startup from RE33. If the position switches are returned to OPERABLE status prior to startup from RE33, then these compensatory measures are no longer required.
Cooper 3.3-8 Amendment No.