05000454/LER-2021-001-01, Pressurizer Safety Valves As-Found Lift Pressure Outside of Tech Spec Limit

Pressurizer Safety Valves As-Found Lift Pressure Outside of Tech Spec Limit

ML22243A193
Person / Time
Site:	Byron
Issue date:	08/31/2022
From:	Welt H Constellation Energy Generation
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BYRON 2022-0052 LER 2021-001-01
Download: ML22243A193 (5)

LER-2021-001, Pressurizer Safety Valves As-Found Lift Pressure Outside of Tech Spec Limit

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)
4542021001R01 - NRC Website

text

Constellation.

August 31, 2022 L TR:

BYRON 2022-0052 File:

1.10.0101 (10.101) 2.07.0100 (5A.108)

United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 1 Renewed Facility Operating License No. NPF-37 NRC Docket No. STN 50-454 Constellation Energy Generation, LLC (CEG)

Byron Station 4450 N. German Church Road Byron, IL 61010-9794 www constellat1onenergy com 10CFR50.73

Subject:

Licensee Event Report (LER) Supplement No. 454-2021-001-01 "Pressurizer Safety Valves As-Found Lift Pressure Outside of Tech Spec Limit" Enclosed is Byron Station Licensee Event Report (LER) Supplement No. 454-2021-001-01 regarding pressurizer safety valves as-found lift pressure outside of technical specification limit on Byron Unit 1.

This condition is being submitted in accordance with 10 CFR 50.73, "Licensee Event Report System."

There are no regulatory commitments in this report.

Should you have any questions concerning this submittal, please contact Ms. Zoe Cox, Regulatory Assurance Manager, at (815) 406-2800.

Respectfully, Harris Welt Site Vice President Byron Generating Station HW/ZC/mf

Enclosure:

LER 454-2021-001-01 cc:

Regional Administrator-NRC Region Ill NRC Senior Resident Inspector - Byron Generating Station

Abstract

IA pressurizer safety valve (PSV) was removed and tested during the Unit 1 fall 2021 refueling outage (B1 R24) under the lnservice Testing (1ST) program. The as-found lift setting was outside the Technical Specifications (TS) 3.4.10 and 1ST program limits. This required the removal and testing of the remaining two PSVs. The remaining two PSVs were also outside the TS and 1ST program limits.

The three PSVs were replaced during the outage. An engineering analysis on the effects of these valves lifting at the as-found settings concluded that all acceptance criteria in the Updated Final Safety Analysis Report Chapter 15 analyses are still met. This condition of multiple pressurizer safety valves being outside of their required lift setting tolerance band is reportable in accordance with 10 CFR 50.73(a)(2)(i)(b), "Any operation or condition which was prohibited by the plant's Technical Specifications... "

A. Plant Operating Conditions Before the Event

Event Date:

Unit: 1 September 19, 2021 MODE: 6 (Refueling)

Unit 1 Reactor Coolant System (RCS) [AB]:

YEAR 05000454 2021 Reactor Power: 000 percent SEQUENTIAL NUMBER 001 Ambient Temperature and Depressurized REV NO.

01 No structures, systems or components were inoperable at the start of this event that contributed to the event. The PSVs were not installed in the system when the condition was discovered.

B. Description of Event

Energy Industry Identification System (EIIS) codes are identified in the text as [XX].

Technical Specification (TS) 3.4.10, "Pressurizer Safety Valves" requires three pressurizer [PZR] safety valves (PSV)(RY) to be operable with lift settings greater than or equal to 2411 psig and less than or equal to 2509 psig.

This lift setting span is based on +/- 2 percent tolerance requirement of a nominal 2460 psig setpoint. TS Surveillance Requirement 3.4.10.1 requires each pressurizer safety valve (PSV) to be lift tested in accordance with the lnservice Testing (1ST) program. In accordance with the 1ST Code, expanding the scope of testing is required for two additional PSVs if a PSV as-found lift pressure exceeds +/- 3 percent of 2460 psig. The 1ST program requires one PSV to be tested each refueling outage, and it requires the remaining two PSVs to be removed and tested if the first PSV's as-found lift pressure exceeds the 1ST scope expansion criteria. Byron Station methodology for testing is to remove the PSV and replace it with an operable PSV and then send the removed PSV to an offsite testing vendor.

As part of the fall 2021 Unit 1 refueling outage (B1 R24) activities, pressurizer safety valve 1 RY8010B was removed and sent to the vendor for testing as required by the 1ST program. The surveillance as-found acceptance criteria for PSVs are+/- 1.8 percent of 2460 psig. This is a+/- 2 percent tolerance with an additional restriction of 0.2 percent due to vendor instrumentation uncertainty.

On September 19, 2021, the vendor testing facility informed Byron Station that the 1 RY801 OB PSV (SIN: N56964-00-0094) failed the as-found lift pressure test. The as-found lift pressure was 2385 psig, which is outside the allowed Technical Specification (TS) and lnservice Testing (1ST) program limits. In accordance with the 1ST program, the remaining two installed Unit 1 PSVs were removed and sent to the vendor for testing. On September 28, 2021, Byron was informed that the 1 RY801 0A PSV (SIN: N56964-00-0030) failed the as-found lift pressure test. The as-found lift pressure was 2342 psig, which is outside the allowed TS and 1ST program limits.

On October 1, 2021, Byron was informed that the 1 RY8010C PSV (S/N: N56964-00-0090) failed the as-found lift pressure test. The as-found lift pressure was 2544 psig, which is outside the allowed TS and 1ST program limits.

As the removed valves were replaced with operable valves, no TS action condition applied at the time. However, the condition of multiple pressurizer safety valves being outside of their required lift setting tolerance band is reportable in accordance with 10 CFR 50.73(a)(2}{i)(b), "Any operation or condition which was prohibited by the plants Technical Specifications... "

C. Cause of Event

YEAR 2021 SEQUENTIAL NUMBER 001 The event is documented in station Issue Report (IR) numbers 04447391, 04450104 and 04450108.

REV NO.

01 The cause of the three PSV as-found lift pressure failures is set pressure drift during system operation. This failure mechanism aligns with industry operating experience (OPEX). This failure cause has been documented in EPRI Technical Report, "Nuclear Maintenance Application Center: Safety and Relief Valve Testing and Maintenance Guide, Revision 2", which describes set-pressure drift in the range of+/- 3 percent to+/- 5 percent where no mechanical defects or extenuating circumstances can be attributed. The three three PSVs all failed within this range.

D. Safety Consequences

The safety significance of this condition was minimal. The pressurizer safety valves provide, in conjunction with the Reactor Protection System, overpressure protection for the RCS. The safety valves are designed to prevent system pressure from exceeding the RCS safety limit of 2735 psig.

An engineering analysis on the effects of these valves lifting at the as-found settings concluded that all acceptance criteria in the Updated Final Safety Analysis Report Chapter 15 analyses were still met.

E. Corrective Actions

The removed PSVs were replaced with operable PSVs.

As part of the investigation into the failure of the PSVs to meet as-found lift pressure acceptance criteria the recertification process used by the vendor, NWS, was reviewed. Some enhancements were identified to the vendor valve inspection and recertification process to improve the stability of the lift setpoint pressure and mitigate potential setpoint drift. The revised valve inspection and recertification process was implemented for use for the three PSVs discussed in this LER.

The corrective action from the investigation is to review the vendor inspection and certification guidance to ensure the enhancements have been incorporated.

F. Previous Occurrences

No previous, similar Licensee Event Reports were identified at the Byron Station in the past three years.

G. Component Failure Data

Manufacturer Nomenclature Crosby Pressurizer Safety Valve Crosby Pressurizer Safety Valve Crosby Pressurizer Safety Valve Model N/AHB-BP-86 HB-BP-86 HB-BP-86 YEAR 2021 SEQUENTIAL NUMBER 001 Mfg. Part Number 1 RY801 OB PSV (S/N: N56964 0094)N/A 1 RY801 OA PSV (S/N: N56964 0030) 1 RY801 OC PSV (S/N: N56964 0090)

REV NO.

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