05000443/LER-2021-001, Pressurizer Safety Valve Outside of Technical Specification Limits Discovered During As-Found Set Point Testing

Pressurizer Safety Valve Outside of Technical Specification Limits Discovered During As-Found Set Point Testing

ML21140A411
Person / Time
Site:	Seabrook
Issue date:	05/20/2021
From:	Levander M NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-21053 LER 2021-001-00
Download: ML21140A411 (5)

LER-2021-001, Pressurizer Safety Valve Outside of Technical Specification Limits Discovered During As-Found Set Point Testing

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4432021001R00 - NRC Website

text

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Seabrook Station Docket No. 5 0-44 3 Seabrook Station NEXTeraM EN~C§~~

May 20, 2021 10 CFR 50.73 SBK-L-21053 Licensee Event Report (LER) 2021-001-00 Pressurizer Safety Valve Outside of Technical Specification Limits Discovered During As-Found Set Point Testing Enclosed is Licensee Event Report (LER) 2021-001-00. This LER reports an event that occurred at Seabrook Station on March 25, 2021. This event is being reported pursuant to the requirements of 10 CFR 50.73(a)(2)(i)(B).

Should you require further information regarding this matter, please contact me at (603) 773-7631.

Sincerely, NextEra Energy Seabrook, LLC Licensing Manager cc:

D. Lew, NRC Region I Administrator J. Poole, NRC Project Manager C. Newport, NRC Senior Resident Inspector NextEra Energy Seabrook, LLC P.O. Box 300, Seabrook, NH 03874

Enclosure to SBK-L-21053

NRG FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 (08-2020)

3. Page Seabrook Station 443 1 OF 3

05000

4. Title Pressurizer Safety Valve Outside of Technical Specification Limits Discovered During As-Found Set Point Testing

5. Event Date

6. LER Number

7. Report Date

8. Other Facilities Involved Month Day Year Year Sequential Revision Month Day Year Facility Name Docket Number Number No.

05000 03 25 2021 2021 -

001 -

00 05 24 2021 Facility Name Docket Number 05000

9. Operating Mode 110. Power Level 1

100

)

Abstract

On March 25, 2021, with Seabrook Station at 100% power, it was determined that one of the three Pressurizer Safety Valves (PSVs) had a low as-found set point pressure which was discovered during off site testing after the valve was removed from service during the previous refueling outage (04/01/20). Technical Specifications (TS) require three pressurizer safety valves to be operable, with a lift setting of+/- 3% in Modes 1, 2, and 3. One safety valve had an as-found set point of -4.2%, the other two were within the +/- 3% allowable tolerance. The cause of the set point pressure being out of the allowable band is attributed to set point drift. The planned Corrective Action is to replace the spring. Following the spring replacement, additional testing will be performed to ensure the valve will be suitable for continued service.

Event Description

During testing of the Pressurizer Safety Valves (PSV) (EEIS: RV) performed by an off-site vendor, the as-found set point for one of the three PSVs removed during the station's most recent refueling outage did not meet the Technical Specifications (TS) 3.4.2.2 requirement of being with +/- 3% of design lift pressure. The subject PSV had an as-found set point pressure that was -4.2%, which was validated on March 25, 2021. The PSV was last installed in the plant and returned to service from October 25, 2018 (Mode 4, power ascension after refueling outage), until April 01, 2020 (Mode 5, entering refueling outage) when it was then removed from service.

TS 3.4.2.2 has an action statement completion time of 15 minutes for one Inoperable Pressurizer Code Safety Valve, after which the plant must be in Hot Standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in at least Hot Shutdown within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Since it is assumed the condition existed prior to the as-found testing, and for a duration longer than the TS action completion time, it is assumed that the condition existed greater than the allowed out of service time and completion time. This event is being reported in accordance with 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications."

Safety Consequences

There were no actual safety consequences for this event. No safety system responses occurred.

A review of station parameters was completed and determined the actual Reactor Coolant System (RCS)(EEIS:AB) pressure was within normal operating limits and the Pressurizer Safety Valves were not required to open to mitigate an overpressure event during Cycle 20. At no point did the RCS pressure reach the as-found set point of 2380 PSIG. As the set point is below the required Technical Specification range of 2485 +I - 3%, it would have provided overpressure protection. As the valve never lifted during the cycle, it did not have a negative effect on actual plant operation. The condition was identified after the valve was removed from service, at an off site testing facility.

Cause of Event

Disassembly, inspection, and spring testing of the valve following the unsatisfactory test was performed at the vendor testing facility. All qualifying spring test and measurement data, as well as visual inspection notes were within prescribed acceptance criteria. Although the acceptance criteria was met, notable changes were evident in the measurement data between the 2015 spring tests and the 2021 spring tests. While acceptable, the vendor indicated that these changes between spring tests over time are not typical and may be indicative of changes to the material characteristics of the spring which could potentially correlate with inconsistent lift results. A combination of minor changes such as these over time, when not alongside of a single clear cause of a valve set point failure, is commonly considered "set point drift." The cause of this event is being attributed to set point drift.

Corrective Actions

The planned Corrective Action is to replace the PSV spring. After the new spring is installed, testing of the valve will recur to ensure that is suitable to be placed back in service.

Previous Similar Events

A similar event occurred at Seabrook Station, documented within Licensee Event Report (LER) Number 2018-001-00, where as-found PSV set point testing occurred and the results exceeded the requirements within the Technical Specifications for a period longer than allowed. The specific valve outlined within LER 2018-001-00 was not the same valve being reported within this LER.

The PSV is manufactured by Crosby Valve and Gage Co., Size 6M6, Style HB-BP 86. Page 3

of 3