ENS 49355
ENS Event | |
|---|---|
16:59 Sep 18, 2013 | |
| Title | High Pressure Coolant Injection System Declared Inoperable Due to Steam Leak |
| Event Description | On 9/18/13, during performance of the High Pressure Coolant Injection (HPCI) pump operability surveillance, a minor steam leak was discovered on the governor valve inspection cover flange. Due to the leak, HPCI was declared inoperable.
Actions taken: A 14-day LCO per TS 3.5.E.2 has been entered and corrective actions are in progress. The licensee has notified the NRC Resident Inspector.
After further evaluation, the gasket leak at the flange was determined to have no impact on the operability of the HPCI system, and therefore the HPCI system was able to perform all safety functions with the identified condition. The immediate determination, made on September 18, 2013, that the HPCI system was inoperable was revised based on the results of an analysis of the HPCI room heat up rate. The heat up rate was modeled using a calculated steam leak rate based on actual measurements of the damaged gasket after removal from the HPCI turbine flange. The time to heat up was based on the first set point at which isolation due to a temperature increase would occur. It was determined that the existing gap in the gasket represented approximately one-tenth of the approximate size of a steam leak that would be expected to result in an isolation, therefore the existing flange leak had no impact on operability of the HPCI system or its ability to mitigate the consequences of an accident. The licensee has notified the NRC site Resident Inspector. Notified R1DO (Krohn). |
| Where | |
|---|---|
Vermont Yankee  Vermont (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:+1.82 h0.0758 days <br />0.0108 weeks <br />0.00249 months <br />) | |
| Opened: | James Kritzer 18:48 Sep 18, 2013 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Oct 31, 2013 |
| 49355 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |