ENS 50200
ENS Event | |
|---|---|
08:52 Jun 13, 2014 | |
| Title | Loss of Both Trains of Control Structure Chilled Water |
| Event Description | On 6/13/2014 at 0417 [EDT], Limiting Conditions of Operation were entered on SSES Units 1 and 2 for an inoperable Train of Control Structure Chilled Water for planned maintenance. During clearance order application at 0452 on 6/13/2014, a switching move caused the in service [Division 1] Control Structure Chilled Water Train to trip and be declared inoperable. It was realized that a prior switching move had already rendered the standby train [Division 2] inoperable. There was no equipment failure or misoperation associated with this event. The trip of the running Control Structure Chiller was in accordance with its control logic scheme. This was not identified during the planning phase of this evolution.
During this time both divisions of Control Structure Chillers were inoperable and were not available to perform the required safety function. This condition also resulted in the inoperability of Control Room Emergency Outside Air Supply System due to the relationship between some of the equipment. This is a condition that, at the time of discovery, could have prevented fulfillment of Safety Functions and is reportable under 50.72(b)(3)(v)(D) as an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> notification. The loss of safety functions are based on 1) the SSC is inoperable in a required mode of operation, 2) the inoperability is due to procedural deficiency, and 3) there was no redundant equipment in the same system that was operable. One Train of Control Structure Chilled Water and Control Room Emergency Outside Air Supply System were restored to operable status at 0503 on 6/13/2014. The licensee notified the NRC Resident Inspector. |
| 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:+3.03 h0.126 days <br />0.018 weeks <br />0.00415 months <br />) | |
| Opened: | Ron Fry 11:54 Jun 13, 2014 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Jun 13, 2014 |
| 50200 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (99 %) |
| After | Power Operation (99 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |