ENS 42224
ENS Event | |
|---|---|
03:25 Dec 23, 2005 | |
| Title | Eecw Temperature Control Valve Not Fully Open |
| Event Description | While performing Div. 1 & 2 Emergency Equipment Cooling Water (EECW)/Emergency Equipment Service Water (EESW) Valve Lineup Verification surveillance on 12/22/05, the temperature control valve (TCV) on both divisions of EECW were found to be approximately 95% open rather than their required full open position. The system design requires that the TCV, or the associated TCV bypass valve, be in the full open position during system startup to avoid a potentially damaging pressure transient from occurring. Both divisions of EECW and all supported systems (including HPCl, both divisions Core Spray, and both divisions of RHR) were declared INOPERABLE at 2225 EST. Multiple LCO Required Actions were entered, including entry into LCO 3.0.3. At 2250 EST, Div. 1 EECW was restored to OPERABLE status by fully opening the TCV bypass valve and isolating the TCV, and LCO 3.0.3 was exited. At 2252 EST, Div. 2 EECW was restored to OPERABLE status by fully opening the TCV bypass valve and isolating the TCV, and all associated LCO Required Actions were exited. Reactor power remained at 100% throughout the event. The NRC resident inspector has been notified. This report is being made pursuant to 10CFR50.72(b)(3)(ii)(B) as an unanalyzed condition and 10CFR50.72(b)(3)(v)(D) as a condition that at the time of discovery could have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident.
The licensee is investigating the cause of the valve not being fully open. The licensee notified the NRC Resident Inspector.
This is a retraction of NRC Event #42224. Based on further engineering review, it is concluded that no potential damage from a pressure transient would occur as a result of the TCV being approximately 95% open. System startup pressure transient concerns reflected in the operating procedures originated from a previously-experienced pressure transient resulting from void collapse against a closed TCV. System startup with the as-found TCV position still provides a sufficiently-open flow path to preclude void collapse against a closed boundary. Additionally, Engineering has determined that system operation with a 90% open TCV would have no significant impact on total system flow and the cooling function. Therefore, both divisions of EECW and all other supported systems (including HPCI, both divisions of Core Spray, and both divisions of RHR) were operable with the TCV in the approximately 95% open position. The licensee notified the NRC Resident Inspector. Notified R3DO (Ring). |
| Where | |
|---|---|
Fermi  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-1.05 h-0.0438 days <br />-0.00625 weeks <br />-0.00144 months <br />) | |
| Opened: | Michael Himebauch 02:22 Dec 23, 2005 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jan 5, 2006 |
| 42224 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |