ENS 47288
ENS Event | |
|---|---|
18:52 Sep 22, 2011 | |
| Title | Salt Service Water Pump Inoperability During Postulated Degraded Voltage Conditions |
| Event Description | On Thursday, September 22, 2011 at 1452 [EDT], with the reactor at 100% core thermal power and steady state conditions, Pilgrim Nuclear Power Station (PNPS) conservatively declared both Salt Service Water (SSW) subsystems inoperable when engineering analysis determined that inrush current on pump restart may exceed the thermal overload trip relay settings during certain degraded voltage conditions. A 24-hour Limiting Condition for Operation action statement was entered.
Entergy/Pilgrim is in the process of implementing temporary modifications to correct this issue. This potential concern has no impact on public health and safety. This 8-hour notification is being conservatively reported in accordance with 10 CFR50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified. The licensee will notify the Massachusetts Emergency Management Center.
Event Notification 47288 was conservatively made to ensure that the Eight-Hour Non-Emergency reporting requirements of 10 CFR 50.72 were satisfied pending further evaluation of Salt Service Water (SSW) subsystem operability during certain degraded voltage conditions. Pilgrim Station has subsequently evaluated the impact of the Salt Service Water (SSW) pump motor operating load; potential degraded voltage conditions on thermal overload settings; and pump motor restart requirements; and determined that reasonable assurance of SSW subsystem operability existed. Both SSW subsystems were evaluated to be capable of satisfying the system safety function of providing cooling water to the Reactor Building Closed Cooling Water System heat exchangers during accident and transient conditions. Pilgrim 's evaluation considered manufacturer's data for the thermal overload relays, site specific shop testing, and reliable grid conditions which minimize the potential for extended operation with 4 kV buses operating at just above degraded voltage relay trip settings. This past operability evaluation concluded that the SSW pumps would support continuous operation of the SSW subsystems. Therefore, the initial 50.72 report is being retracted. The licensee will notify the NRC Resident Inspector. Notified the R1DO (Caruso). |
| Where | |
|---|---|
| Pilgrim Massachusetts (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+3.47 h0.145 days <br />0.0207 weeks <br />0.00475 months <br />) | |
| Opened: | Mike Hettwer 22:20 Sep 22, 2011 |
| NRC Officer: | Vince Klco |
| Last Updated: | Nov 20, 2011 |
| 47288 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Pilgrim with 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
WEEKMONTHYEARENS 532872018-03-25T20:16:00025 March 2018 20:16:00
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