ENS 45361
ENS Event | |
|---|---|
14:30 Sep 18, 2009 | |
| Title | Inoperability of Both Edg'S Due to Valve Found Out of Position |
| Event Description | At 02:00 on Friday, September 18, 2009, the Unit 2 AB Emergency Diesel Generator (EDG) Air Jet Assist Control Air Shutoff valve, which is required to be open, was discovered closed. At 10:30 on Friday, September 18, 2009, it was determined that with the valve closed, the EDG Air Jet Assist may not be able to support the EDG fast speed start to meet the EDG's Operability requirements. This condition renders the Unit 2 AB EDG inoperable. The valve was repositioned and verified open at 02:15 on Friday, September 18, 2009, restoring the EDG to operable status. Similar valves were verified to be in the correct position on all other EDGs in both Units.
The Unit 2 AB Emergency Diesel Generator Air Jet Assist Control Air Shutoff valve was last confirmed open on July 21, 2009. The time the valve became closed is not known. Since July 21, 2009, there have been 3 periods of inoperability for Unit 2 CD EDG, the redundant Emergency Diesel Generator. During each of these periods, both of the Unit 2 EDGs are assumed to be inoperable. The periods are as follows: August 10, 2009 at 09:31 until August 10, 2009 at 23:00 August 11, 2009 at 07:30 until August 11, 2009 at 23:16 September 9, 2009 al 00:02 until September 9, 2009 at 04:40 This notification is being made in accordance with 10 CFR 50.72 (b)(3)(ii)(B) due to the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. The licensee has notified the NRC Senior Resident Inspector.
At 02:00 on Friday, September 18, 2009, the Unit 2 AB Emergency Diesel Generator (EDG) Air Jet Assist Control Air Shutoff valve, which is required to be open, was discovered closed. At 10:30 on Friday, September 18, 2009, it was determined that with the valve closed, the EDG Air Jet Assist may not be able to support the EDG fast speed start to meet the EDG's Operability requirements. This condition renders the Unit 2 AB EDG inoperable. The valve was repositioned and verified open at 02:15 on Friday, September 18, 2009, restoring the EDG to operable status. Since the last time the Turbocharger Air Jet Assist Control Air Shutoff valve was confirmed open, July 21, 2009, there were three periods where the redundant EDG was inoperable for planned maintenance and surveillance testing. During each of these periods, both of the Unit 2 EDGs are assumed to be inoperable. As such, Cook Nuclear Plant (CNP) submitted Event Notification 45361 in accordance with 10CFR50.72(b)(3)(ii)(B) due to the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. On September 25, 2009, CNP conducted two EDG fast speed starts, one with the Turbocharger Air Jet Assist Control Air Shutoff valve closed, and one with the valve open. Based on a review of the data collected and observed performance of the EDG, the determination has been made that having the Turbocharger Air Jet Assist Control Air valve closed does not adversely impact operability of an EDG. The circumstances discussed in the notification did not result in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. The licensee has notified the NRC Resident Inspector. Notified R3DO (Lara). |
| Where | |
|---|---|
Cook  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+1.98 h0.0825 days <br />0.0118 weeks <br />0.00271 months <br />) | |
| Opened: | Ben Huffman 16:29 Sep 18, 2009 |
| NRC Officer: | John Knoke |
| Last Updated: | Oct 1, 2009 |
| 45361 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 525442017-02-04T01:24:0004 February 2017 01:24:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Unaccounted Loads in Safe Shutdown Analysis ENS 453612009-09-18T14:30:00018 September 2009 14:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Inoperability of Both Edg'S Due to Valve Found Out of Position ENS 439672008-02-07T00:20:0007 February 2008 00:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Train "a" 250 Vdc Cable Passes Through Train "B" Switchgear Room 2017-02-04T01:24:00 | |