05000482/LER-2021-001-01, Re Entry Into Mode 4 with Excessive Containment Valve Leakage Resulted in a Condition Prohibited by Technical Specifications
| ML21077A135 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 03/17/2021 |
| From: | Bayer R Wolf Creek |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| WO 21-0012 LER 2021-001-01 | |
| Download: ML21077A135 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4822021001R01 - NRC Website | |
text
P.O. Box 411 l Burlington, KS 66839 l 620-364-8831 Robert J. Bayer Plant Manager March 17, 2021 WO 21-0012 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Docket No. 50-482: Licensee Event Report 2021-001-01, Entry into Mode 4 with Excessive Containment Valve Leakage Resulted in a Condition Prohibited by Technical Specifications Commissioners and Staff:
The enclosed Licensee Event Report (LER) 2021-001-01 is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.
This letter contains no commitments. If you have any questions concerning this matter, please contact me at (620) 364-4015, or Ron Benham at (620) 364-4204.
Sincerely, Robert J. Bayer RJB/rlt
Enclosure:
LER 2021-001-01 cc:
S. S. Lee (NRC), w/e S. A. Morris (NRC), w/e N. OKeefe (NRC), w/e Senior Resident Inspector (NRC), w/e
Abstract
Wolf Creek Generating Station 482 5
Entry into Mode 4 with Excessive Containment Valve Leakage Resulted in a Condition Prohibited by Technical Specifications 05 15 2018 2021 001 01 03 17 2021 4
N/A
Ron Benham, Director Nuclear and Regulatory Affairs (620) 364-4204
At 0510 Central Daylight Time (CDT) on May 15, 2018, Wolf Creek Generating Station (WCGS) entered Mode 4 as part of coming out of Refueling Outage 22 (RF22). At that time, the as-left maximum pathway leakage rate (MXPLR) for the containment isolation valves associated with the containment purge supply was greater than 0.6La (250,000 sccm). Technical Specification (TS) Surveillance Requirement (SR) 3.6.1.1 requires that containment penetration leak rate testing be performed in accordance with the Containment Leakage Rate Testing Program as defined in TS 5.5.16 and in Wolf Creek Nuclear Operating Corporation Procedure AP 29E-001. The as-left MXPLR leak rate being greater than 0.6La is contrary to the requirements of TS 5.5.16 and AP 29E-001. As such, TS SR 3.6.1.1 was not satisfied prior to entering Mode 4. TS Limiting Condition for Operation (LCO) 3.6.1, requires that containment be operable in Modes 1, 2, 3, and 4. Therefore, this event represents a condition prohibited by TS. Specifically, LCO 3.6.1 was not met, along with LCO 3.0.4 which prohibits entering into a mode of applicability when the LCO is not met unless the specified actions in the LCO have no time limit, a risk assessment is performed, or when specifically allowed by the Specification. This event was repeated when WCGS entered Mode 4 at 0850 CDT on November 2, 2019, coming out of RF23. Page of 05000-
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
SAFETY SIGNIFICANCE
The safety significance was low. The as-left leakage rate through GTHZ0007 was under the administrative limit in both events. In addition, though they could not be credited for meeting LCO 3.6.3, non-safety related (but seismically analyzed blind flanges had been installed on GTHZ0006 prior to entry into Mode 4 in both events. These blind flanges have since been qualified as safety-related and a license amendment request has been submitted to formally permit the use of blind flanges in meeting LCO 3.6.3, Condition D. Finally, except for the time between May 15, 2018 and August 8, 2018 (when it was discovered that a blind flange was being inappropriately used to meet LCO 3.6.3), GTHZ0007 was maintained shut and deactivated while WCGS was in Mode 1, 2, 3, or 4. As such, there is reasonable assurance that had a design basis accident occurred, containment integrity would have been maintained.
OPERATING EXPERIENCE/PREVIOUS EVENT There were 2 previous events that were related to the event described here. LER 2018-001-00, "Inappropriate Use of Blind Flange for Containment Isolation Valve Results in Condition Prohibited by Technical Specifications," dated October 4, 2018, described that blind flanges were inappropriately credited for meeting LCO 3.6.3 Condition D. LER 2020-001-01, "Plant Shutdown Due to Inoperable Containment Purge Isolation Valves," dated July 6, 2020, detailed a plant shutdown due to as-found excessive leakage measured in both GTHZ0006 and GTHZ0007.
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Wolf Creek Generating Station 482 2021 001 01