ENS 43836
ENS Event | |
|---|---|
14:55 Dec 11, 2007 | |
| Title | Loss of Rhr Room Cooler |
| Event Description | At 08:55 on 12/11/07 the division 1 RHR room cooler, V-AC-5 would not start. At approximately 10:00, troubleshooting determined that the cause of the failure was a blown line fuse on the B phase of the 480 VAC supply breaker. In accordance with plant procedures, a loss of this room cooler requires that the associated division 1 core spray pump and both division 1 LPCI pumps be declared inoperable. The result is entry into Technical Specification 3.5.1 Condition M due to having two or more ECCS injection/spray subsystems inoperable. This requires entry into LCO 3.0.3. At 10:53 on 12/11/07 the blown line fuse was replaced, the unit was tested and operability was restored. LCO 3.0.3 was exited at this time.
The Technical Specification bases for Technical Specification 3.5.1 Condition M states that when multiple ECCS subsystems are inoperable, as stated in Condition M, the Plant is in a condition outside of the accident analyses. As described in this bases section the plant is in an unanalyzed condition and pursuant to 10 CFR 50.72(b)(3)(ii) an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> report is being made. At this time, the station believes there was no loss of safety function. Further review of the event is in progress at the station. The station has informed the NRC resident inspector of this event.
After further review, the licensee is retracting this report based on the following: The notification was initiated due a TS Bases that stated the plant was outside of its accident analyses with multiple ECCS subsystems are inoperable. This was considered an unanalyzed condition. Further evaluation by plant staff has determined that for the conditions present at the time of the event the station was bounded by the accident analysis and therefore the event was not an unanalyzed condition. A review of Section 14 of the Updated Safety Analysis Report (USAR) determined that with one low-pressure ECCS division inoperable, the plant was not outside the ECCS accident analysis as described in the SAFER GESTR ECCS licensing topical report for Monticello and reflected in Chapter 14 of the USAR. The licensee informed the NRC Resident Inspector. Notified R3DO (Tom Kozak). |
| Where | |
|---|---|
Monticello  Minnesota (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+2.55 h0.106 days <br />0.0152 weeks <br />0.00349 months <br />) | |
| Opened: | Randy Sand 17:28 Dec 11, 2007 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Feb 8, 2008 |
| 43836 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |