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

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

ML21322A197
Person / Time
Site:	Byron
Issue date:	11/18/2021
From:	Kowalski J Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BYRON 2021-0076 LER 2021-001-00
Download: ML21322A197 (4)

LER-2021-001, Re 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)
4542021001R00 - NRC Website

text

Byron Generating Station

4450 North German Church Rd Exelon Generation,!) Byron. IL 61010-9794

www.exeloncorp.com

November 18, 2021

10CFR50.73 L TR: BYRON 2021-0076 File: 1.10.0101 (1D.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

Subject: Licensee Event Report (LER) No. 454-2021-001-00 "Pressurizer Safety Valves As-Found Lift Pressure Outside of Tech Spec Limit"

Enclosed is Byron Station Licensee Event Report (LER) No. 454-2021-001-00 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.

Respectful4,,L_

John J. Kowalski Site Vice President Byron Generating Station

JJK/ZC/mf

Enclosure: LER 454-2021-001-00

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

Abstract

~ pressurizer safety valve (PSV) was removed and tested during the Unit 1 fall 2021 refueling outage (81 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: September 19, 2021

Unit: 1 MODE: 6 (Refueling) Reactor Power: 000 percent

Unit 1 Reactor Coolant System (RCS) [AB]: Ambient Temperature and Depressurized

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 [AB] (RY) safety valves 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 In service 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 Qf 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 (81 R24) activities, pressurizer safety valve 1RY80108 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 RY80108 PSV (S/N: 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 (S/N: 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 RY801 0C 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

The event is documented in station Issue Report (IR) numbers 04447391, 04450104 and 04450108.

The cause for the failures is unknown. The station is working with the offsite vendor facility to investigate the cause, and the station is performing a Corrective Action Program Evaluation (CAPE). The results of the investigation are expected to be completed by December 30, 2021. A supplemental LER will be submitted to document the results.

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. Additional actions to prevent recurrence will be determined from the CAPE. Once these actions are known, a supplemental LER will be submitted to document the actions.

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 Mfg. Part Number

Crosby Pressurizer Safety Valve NIA N/A