05000482/LER-2020-001, Shutdown Due to Inoperable Containment Purge Isolation Valves
| ML20092N985 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 04/01/2020 |
| From: | Wolf Creek |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20092N983 | List: |
| References | |
| WO 20-0023 LER 2020-001-00 | |
| Download: ML20092N985 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) |
| 4822020001R00 - NRC Website | |
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NRC FORM 366 (04-2018)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
(See Page 2 for required number of digits/characters for each block)
(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/)
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
NRC FORM 366 (04-2018) 05000
- 3. Page 1
OF
- 4. Title
- 5. Event Date Month Day Year
- 6. LER Number Year Sequential Number Rev No.
- 7. Report Date Month Day Year
- 8. Other Facilities Involved Facility Name Docket Number 05000 Facility Name Docket Number 05000
- 9. Operating Mode
- 10. Power Level
- 11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply) 20.2201(b) 20.2201(d) 20.2203(a)(1) 20.2203(a)(2)(i) 20.2203(a)(2)(ii) 20.2203(a)(2)(iii) 20.2203(a)(2)(iv) 20.2203(a)(2)(v) 20.2203(a)(2)(vi) 20.2203(a)(3)(i) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.36(c)(1)(i)(A) 50.36(c)(1)(ii)(A) 50.36(c)(2) 50.46(a)(3)(ii) 50.73(a)(2)(i)(A) 50.73(a)(2)(i)(B) 50.73(a)(2)(i)(C) 50.73(a)(2)(ii)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(iii) 50.73(a)(2)(iv)(A) 50.73(a)(2)(v)(A) 50.73(a)(2)(v)(B) 50.73(a)(2)(v)(C) 50.73(a)(2)(v)(D) 50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(ix)(A) 50.73(a)(2)(x) 73.71(a)(4) 73.71(a)(5) 73.77(a)(1) 73.77(a)(2)(i) 73.77(a)(2)(ii)
Other (Specify in Abstract below or in Page of 05000-
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
REPORTABILITY
This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(A) for the completion of a nuclear plant shutdown required by the plants TS. WCGS entered Mode 3 (Hot Standby) at 2154 CST on 2/1/2020. Event notification 54508 was made in accordance with 10 CFR 50.72(B)(2)(i) as a four-hour notification for initiation of a plant shutdown required by TS at 2206 CST on 2/1/2020.
This event is also being reported in accordance with 10 CFR 50.73(a)(2)(v) as an event or condition that could have prevented fulfillment of the safety function(s) of structures or systems that are needed to (C) control the release of radioactive material, and (D) mitigate the consequences of an accident. The leakage rate measured from the containment shutdown purge penetration on 2/1/2020 was greater than the allowed TS leak rate for containment. Therefore, containment integrity was not maintained and as such, containment was declared inoperable at 1845 on 2/1/2020.
CAUSE
The root cause investigation for this event is still ongoing. The cause will be documented in the supplement to this LER.
CORRECTIVE ACTIONS
Initial corrective actions included repairing both GTHZ0006 and GTHZ0007 to restore them to operable status.
Additionally, the surveillance procedure was revised to account for installed blind flanges and a voluntary surveillance was performed early in March of 2020 to validate acceptable leakage limits were being maintained. Additional surveillances are planned to be performed in April 2020 and again in May 2020 to further monitor the condition of the valves. Further corrective actions will be documented in the supplement to this LER.
SAFETY SIGNIFICANCE
The actual safety significance was low. During the time that GTHZ0006 was out of service, the blind flange associated with this valve had been installed. While this blind flange is not safety-related, and as such, cannot be credited for completing Required Action D.1 of TS LCO 3.6.3, it is bounded by the seismic analysis performed for the piping associated with this containment penetration. The only credible failure mechanism is a seismic event; therefore, in a seismic event, the blind flange would likely still have maintained actual containment integrity. In addition, there are no design basis accidents (DBAs) which would have impacted the ability of the blind flange to limit containment leakage to within acceptable limits.
OPERATING EXPERIENCE/PREVIOUS EVENT None 4
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