ENS 40716

v t e ENS Event
19:57 Apr 29, 2004
Title	Identified Leakage Limit Exceeded for 5 Minute Period Due to Lifted Letdown Line Safety Valve
Event Description	D.C. Cook Unit 2 was performing post-maintenance testing on a solenoid valve associated with a letdown orifice valve and realigning letdown flowpath when safety valve 2-SV-51 (Regenerative Heat Exchanger Letdown Outlet Safety Valve) lifted on 4/29/04 at 15:57 EDT, relieving 323 gallons of water to the Pressurizer Relief Tank over a five (5) minute period before letdown was isolated. Average leak rate was approximately 65 gallons per minute, greater than the 25 gallon per minute identified leak rate limit for an Unusual Event [10CFR50.72(a)(1)(i)]. This was a rapidly concluded event of a five (5) minute duration. Time of discovery for leakage quantity and reportability was 17:10 on 4/29/04. Therefore, for a five (5) minute period, D.C. Cook Unit 2 met the conditions for an Unusual Event. However, this fact was discovered after leakage was stopped. Unit 2 is stable at approximately 100% reactor thermal power with the excess letdown system in service. An Unusual Event was NOT declared, but the conditions for an Unusual Event were met between 15:57 and 16:02 on 4/29/04. This ENS notification is being made within one hour of the discovery of the undeclared event. The licensee notified the NRC Resident Inspector.

ENS 40716 +/-
Where
Cook Michigan (NRC Region 3)
Reporting

Other Unspec Reqmnt
Time - Person (Reporting Time:+-1.8 h-0.075 days <br />-0.0107 weeks <br />-0.00247 months <br />)
Opened:	Bud Hinckley 18:09 Apr 29, 2004
NRC Officer:	Mike Ripley
Last Updated:	Apr 29, 2004
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v • d • e

v t e Emergency Notification System
Cook with Other Unspec Reqmnt
WEEKMONTHYEAR2006-04-29T14:56:00 [Table view]
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