05000333/LER-2022-003-02, Safety Relief Valves Lift Setpoint Found Out of Tolerance Low

Safety Relief Valves Lift Setpoint Found Out of Tolerance Low

ML23251A149
Person / Time
Site:	FitzPatrick
Issue date:	09/08/2023
From:	Timothy Peter Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
JAFP-23-0051 LER-2022-003-02
Download: ML23251A149 (1)

LER-2022-003, Safety Relief Valves Lift Setpoint Found Out of Tolerance Low

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function
3332022003R02 - NRC Website

text

Constellation.

JAFP-23-0051 September 8, 2023 United States Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 James A. FitzPatrick NPP P.O. Box 110 Lycoming, NY 13093 Timothy C. Peter Site Vice President-JAF James A. FitzPatrick Nuclear Power Plant Renewed Facility Operating License No. DPR-059 NRC Docket No. 50-333 Subject:

Dear Sir or Madam:

LER: 2022-003-02, Safety Relief Valves Lift Setpoint Found Out of Tolerance Low This report is being submitted pursuant to 1 O CFR 50.73(a)(2)(v)(D).

There are no new regulatory commitments contained in this report.

Questions concerning this report may be addressed to Mr. Mark Hawes, Regulatory Assurance, at (315) 349-6659.

Sin~~

im~e, Site~ie CPresident TCP/MH Enclosure:

LER: 2022-003-02, Safety Relief Valves Lift Setpoint Found Out of Tolerance Low cc:

USNRC, Region I Administrator USNRC, Project Manager USNRC, Resident Inspector INPO Records Center (IRIS)

Abstract

The As-Found test results for eleven Safety/Relief Valve (S/RV) pilot assemblies during the 2022 Refueling Outage at James A. FitzPatrick Nuclear Power Plant (JAF) identified five (5) S/RV pilot assemblies that lifted outside of the allowable tolerance required by Technical Specifications (TS) Surveillance Requirement 3.4.3.1. Five (5) three-stage S/RVs were found out of tolerance low. Therefore, the TS inoperability of the five (5) S/RVs resulted in a reportable condition pursuant to 10 CFR 50.73(a)(2)(v)(D).

This condition did not affect the S/RV safety function to relieve vessel overpressure in accordance with the transient analysis. All valves failed low (conservative direction). A low lift setpoint reduces the margin for inadvertent SRV actuation.

The failed S/RV pilot assemblies were replaced during the outage. The vendors initial investigation was inconclusive; however, the most probable cause is associated with subcomponents in the pilot stage. The investigation into the mechanistic cause will continue with expanded dataset research. JAF will analyze cause, vendor testing results, and inspect replacement SRVs prior to the Fall 2024 refuel outage.

(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)

(See Page 2 for required number of digits/characters for each block)

LICENSEE EVENT REPORT (LER)

=

Background===

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code requires the reactor pressure vessel be protected from overpressure during upset conditions by self-actuated safety valves. As part of the nuclear pressure relief system, the size and number of Safety/Relief Valves (S/RV) are selected such that peak pressure in the Reactor Coolant Pressure Boundary (RCPB) will not exceed the ASME Code limits.

The James A. FitzPatrick Nuclear Power Plant (JAF) used eleven (11) three-stage Target Rock S/RV [EIIS Identifier: SB] for emergency pressure relief during operating Cycle 25. These valves are located on the main steam lines between the reactor vessel and the first isolation valve within the drywell. Each S/RV discharges steam through a discharge line to a point below the minimum water level in the suppression pool.

The S/RVs can actuate by either of two modes: the safety mode or the relief mode. In safety mode (or spring mode of operation), the spring-loaded pilot valve opens when steam pressure at the valve inlet overcomes the spring force holding the pilot valve closed. Opening the pilot valve allows a pressure differential to develop across the main valve piston and opens the main valve. This satisfies the code requirement. The Technical Specification (TS) Surveillance Requirement (SR) 3.4.3.1 requires verification that the safety function lift setpoint of the required S/RVs is 1,145 +/- 34.3 psig. Following testing, lift settings shall be within +/- 1%.

The purpose of the lower setpoint tolerance is to ensure sufficient margin exists between the normal operating pressure of the system and the point at which the S/RVs actuate in the safety mode. The nominal operating pressure of the reactor pressure vessel (RPV), at power, is 1,040 psig. For the low tolerance as-found setpoint of -3 percent, the S/RV would lift at 1,110.7 psig and provide an operating margin of 70.7 pounds per square inch differential (psid) between the nominal reactor operating pressure and the lowest margin lift pressure.

This provides sufficient margin to prevent unwanted actuation of the S/RVs postulated to occur during pressurization transients.

Event Description During the JAF Refuel Outage 25, at 0 percent power in Plant Mode 5, work scope removed 6 S/RVs for replacement from locations B, D, F, G, H, and L and were shipped to testing vendor NWS Technologies for as-found testing.

On September 29, 2022, the test found that B S/RV failed its as-found pressure setpoint. Two additional valves C and J were selected as the expanded testing scope; these two S/RVs were removed and shipped to NWS for testing. On October 1, 2022, the G and D failed as-found testing which resulted in all 11 S/RVs needing to be tested. On October 2, 2022, J failed as-found testing and on October 9, 2022, the A failed.

Five of the eleven three-stage S/RV pilots failed low. As-found failed test results are tabulated below: U.S. NUCLEAR REGULATORY COMMISSION (09-01-2023)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 09/30/2023

1. FACILITY NAME 050

2. DOCKET NUMBER

3. LER NUMBER James A. FitzPatrick Nuclear Power Plant 05000333 YEAR SEQUENTIAL NUMBER REV NO.

052 2022

- 003

- 02 Page 3 of 4 (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)

Table 1 - As-Found Test Results In-service Location Pilot Serial Number First Test (psig)

Acceptance Range (1110.7 - 1179.3 psig) 02RV-71A 119 1109 Unsat - Low 02RV-71B 90 1094 Unsat - Low 02RV-71D 97 1105 Unsat - Low 02RV-71G 27 1100 Unsat - Low 02RV-71J 21 1099 Unsat - Low Event Analysis The TS inoperability of the five (5) S/RVs is a reportable condition in per 10 CFR 50.73(a)(2)(v)(D). The one component within the S/RVs that would cause a low setpoint lift is the pilot stage. A Disassembly and failure analysis was performed at NWS Technologies in support of the investigation. This evaluation was not able to identify a single sub-component that would cause the setpoint drift. There is a potential of an aggregate effect; however, there is insufficient data to form a conclusion. There is no firm evidence for when the setpoint drift exceeded the requirement during the previous cycle. Additional investigation into the mechanistic cause is ongoing in the Corrective Action Program and with the NWS vendor which includes collecting more test data from the industry.

Cause The most probable cause of the 5 S/RVs failing low out of tolerance during testing is associated with subcomponents in the pilot stage.

FAILED COMPONENT IDENTIFICATION:

Manufacturer:

Target Rock Manufacturer Model Number:

0867F-001 Manufacturer Code:

T020 Component Code:

RV FitzPatrick Component ID:

02RV-71A, 02RV-71B, 02RV-71D, 02RV-71G, 02RV-71JU.S. NUCLEAR REGULATORY COMMISSION (09-01-2023)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 09/30/2023

1. FACILITY NAME 050

2. DOCKET NUMBER

3. LER NUMBER James A. FitzPatrick Nuclear Power Plant 05000333 YEAR SEQUENTIAL NUMBER REV NO.

052 2022

- 003

- 02 Page 4 of 4 (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)

Corrective Actions Completed Actions Replaced all 11 S/RVs prior to refuel outage startup with refurbished and certified components.

The 5 failed S/RVs were sent to NWS Technologies for further investigation.

Planned Actions Vendor investigation with a larger dataset from other sites and manufacturer to support a cause determination.

Review results of S/RV as-found pressure testing results from Fall 2024 refuel outage.

Submitted TS Amendment Request to adjust the acceptable low out-of-tolerance value in SR 3.4.3.1 from -3% to -5%. The Fall 2022 test results were within this proposed tolerance. Implementation planned prior to Fall 2024 Refuel Outage.

Safety Significance Nuclear safety - There were no actual consequences caused by this condition. This condition does not affect the ASME overpressure transient analysis. The potential consequence of a low out-of-tolerance S/RV setpoint is inadvertent S/RV lifting during normal operating pressure or early lifting during postulated accident scenarios. The lowest as-found test B of 1094 psig has 54 psig margin to the nominal operating pressure.

References Issue Reports:

IR 04525986, B SRV test result exceeded TS limit, dated September 30, 2022 IR 04526277, D SRV test result exceeded TS limit, dated October 2, 2022 IR 04526278, G SRV test result exceeded TS limit, dated October 2, 2022 IR 04526428, J SRV test result exceeded TS limit, dated October 3, 2022 IR 04528295, A SRV as found test outside TS limit, dated October 10, 2022 IR 04527149, Safety Relief Valve As-Found Testing Failure Roll-up, dated October 5, 2022 Letter, License Amendment Request to Modify Technical Specification Surveillance Requirement (SR) 3.4.3.1 Safety Relief Valves (S/RVs) Setpoint Lower Tolerance, JAFP-23-0038, dated July 28, 2023