05000443/LER-2018-002, Automatic Valve in Emergency Core Cooling System Inoperable
| ML18262A408 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 09/19/2018 |
| From: | Browne K NextEra Energy Seabrook |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SBK-L-18163 LER 2018-002-00 | |
| Download: ML18262A408 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4432018002R00 - NRC Website | |
text
September 19, 2018 10 CFR 50.73 Docket No. 50-443 SBK-L-18163 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Seabrook Station NEXTeraM EN~~~~
Licensee Event Report (LER) 2018-002-00 Automatic Valve in Emergency Core Cooling System Inoperable Enclosed is Licensee Event Report (LER) 2018-002-00. This LER reports an event that occurred at Seabrook Station on July 25, 2018. This event is being reported pursuant to the requirements of 10 CFR 50.73(a)(2)(i)(B) and 50.73(a)(2)(v)(D).
Should you require further information regarding this matter, please contact me at (603) 773-7932.
Sincerely, nn e
Licensing Manager cc:
D. Lew, Acting NRC Region I Administrator J. Poole, NRC Project Manager P. Cataldo, NRC Senior Resident Inspector NextEra Energy Seabrook, LLC P.O. Box 300, Seabrook, NH 03874
Enclosure to SBK-L-18163
NRC FORM 366 U.S. NUCLEAR REGULA TORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
3.Page Seabrook Station 05000 443 1
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- 4. Title Automatic Valve in Emergency Core Cooling System Inoperable
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Facility Name Docket Number Month Day Year Year Number No.
Month Day Year 05000 Facility Name Docket Number 07 25 2018 2018 -
002 -
00 09 19 2018 05000
- 9. Operating Mode
)
No Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
On 7/25/2018, it was discovered that the A Train Centrifugal Charging Pump (CCP) Flow Loop, 1-CS-F-7325, failed low which would have prevented CS-V-196, A Train CCP miniflow isolation valve from closing during a SI signal coincident with a charging pump flow greater than 122.5 gpm. Closing CS-V-196 directs the charging pump flow to Emergency Core Cooling (ECCS) injection. Failure of CS-V-196 to close diverts flow away from core cooling during a safety injection event. At the time of the event, the alternate train CCP, 1-CS-P-2B, was tagged out of service for maintenance for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and 28 minutes.
Technical Specification (TS) 3/4.5.2 requires two independent Emergency Core Cooling System (ECCS) subsystems OPERABLE which includes one OPERABLE CCP in each train. On 7/25/18 from 0629 to 1857, while 1-CS-P-2B was tagged out for maintenance, both trains were inoperable. TS Surveillance Requirement (SR) 3/4.5.2 requires that each automatic valve in the flow path be verified to actuate to the correct position. Since CS-V-196 would not have been capable of closing, it was incapable of meeting SR 4.5.2.e.
These conditions are reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specification and 50.73(a)(2)(v)(D) as a condition that could have prevented fulfillment of a safety function.
NRG FORM 366 (04-2018)
Event Description
On 07/25/18, with the plant operating at 100% power, Operations identified CS-P-2A flow loop 1-CS-F-7325 was indicating 0 gpm when it should have been indicating approximately 175 gpm. This indicated a potential failure of the flow loop. Review of previous trends indicated that the failure of the loop occurred on 07/08/18. On 07/26/18, l&C identified that the Westinghouse 7300 NLP (Nucana Loop Power Supply) printed circuit board, 1-CS-FQY-7325 had failed. The printed circuit board was energized, but had no output.
Loop 1-CS-F-7325 failing low would have prevented 1-CS-V-196 (1 -CS-P-2-A mini-flow isolation valve) from closing during a safety injection event, coincident with charging pump flow greater than 122.5 gpm. 1-CS-V-196 is required to close during a safety injection event in modes 1 through 4. Based on this Operations entered Technical Specification TS 3.5.2a action a: With one ECCS subsystem inoperable, restore the inoperable subsystem to Operable status within 7 days or be in at least Hot Standby with the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in 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 />.
TS 3.5.2 requires two ECCS trains to be operable. On 7 /25/18 from 0629 to 1857, when the B CCP (1-CS-P-28) was tagged out of service for maintenance and the A CCP (1-CS-P-2A) was determined to be inoperable, this TS was not met.
TS 3.0.3 requires that when an LCO is not met, within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> action shall be initiated to place in the unit in a MODE in which the specification does not apply. This resulted in the station being in a condition prohibited by Technical Specifications.
TS SR 3.5.2.e requires that each ECCS automatic valve in the flow path be verified to actuate to its correct position on (Safety Injection Actuation and Automatic Switchover to Containment Sump) test signals. Since CS-V-196 was unable to close, it was incapable of meeting the SR. For failure to meet this SR, SR 4.0.1 specifies that the Limiting Condition for Operation (LCO) is also not met.
Cause of Event
The low flow indication on loop 1-CS-F-7325 resulted in entry into Technical Specification Action TS 3.5.2a action a, was directly caused by the failure of 7300 NLP card 1-CS-FQY-7325 and was corrected by replacement of the printed circuit board.
Safety Consequence
The event is considered to be of very low safety significance. An_ engineering analysis was performed which concluded that with CS-V-196 open, the ECCS system would have provided sufficient flow to perform its cooling functions for the accidents where it is credited.
Corrective Actions
Loop 1-CS-F-7325 was repaired, restoring 1-CS-V-196 to operable status.
Previous Similar Events
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