ENS 49613
ENS Event | |
|---|---|
17:48 Dec 6, 2013 | |
| Title | |
| Event Description | At 1248 EST, Unit 2 High Pressure Coolant Injection (HPCI) system was being tested for routine quarterly flow verification using surveillance test procedure SO-252-002. When HPCI turbine speed was lowered to approximately 2400 RPM, oscillations on turbine speed, flow and discharge pressure were observed. HPCI turbine speed was raised to approximately 2700 RPM and the oscillations stopped.
Unit 2 HPCI system had been declared inoperable and LCO 3.5.1 entered at 1200 EST for the surveillance test. [This is a 14 day LCO.] Review by Engineering determined that cause of the oscillations warrant further evaluation and HPCI remains inoperable. HPCI is a single train Emergency Core Cooling Safety system. This event results in the loss of an entire safety function which requires an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> ENS notification in accordance with 10CFR50.72(b)(3)(v). There are no other ECCS systems presently out of service. The licensee notified the NRC Resident Inspector.
NUREG-1022, Revision 3, states, 'if the retraction or cancellation of a report under this criterion is due to a revised operability determination, the retraction or cancellation should discuss the basis for why the operability determination was revised, and why it is believed that system operability was never lost (i.e., in lieu of the initial determination).' As indicated in the initial report, Engineering determined that the cause of the oscillations required further evaluation and HPCI remained inoperable. Additional evaluation by Engineering resulted in a conclusion that HPCI was OPERABLE with the observed oscillations at the low flow conditions. Details are as follows: HPCI speed/flow oscillations at low flow conditions can occur due to inherent instability at these conditions. This phenomenon is understood and documented in industry OE [Operating Experience], EPRI [Electric Power Research Institute] maintenance guidelines, and station procedures. HPCI system operation and control during the surveillance were as expected and demonstrated proper response and stable operation, with the only exception being the described oscillations at the low flow condition. This was confirmed by a review of the system response on the start-up traces. A system walkdown confirmed no abnormality with the control system equipment or governor setting. No tuning adjustments were considered to be necessary based on the low magnitude of the oscillations and their negligible impact on system operation. Unit 2 HPCI was declared OPERABLE and LCO 3.5.1 was cleared at 2308 [EST] on December 6, 2013. Based on the above additional information, PPL [Pennsylvania Power and Light] is retracting this report. The licensee has notified the NRC Resident Inspector. Notified the R1DO (Rogge). |
| Where | |
|---|---|
Susquehanna  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+0.07 h0.00292 days <br />4.166667e-4 weeks <br />9.5886e-5 months <br />) | |
| Opened: | Darvin Duttry 17:52 Dec 6, 2013 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jan 17, 2014 |
| 49613 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (99 %) |