ENS 44295

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v t e ENS Event
15:00 Jun 13, 2008
Title	Part 21 Report Involving Commercial Grade Relay Contacts Containing Potential Defects
Event Description	The following Part 21 notification was received via fax: On June 13, 2008, AmerGen Energy Company, LLC (AmerGen) completed a reportability determination which concluded that relay contacts contained an underlying design vulnerability that created a failure mode, and were reportable under Part 21, since the underlying vulnerability could create a substantial safety hazard. The relay contacts are Commercial Grade items dedicated by AmerGen. The relay contacts are provided by Joslyn Clark Controls Inc. (formerly AO Smith) as Normally Closed (N/C) open top contact assemblies (part numbers KPM-44, KPM-46, KPM-6A, and KPM-4A). These contacts are used in safety related applications, primarily in the engineered safeguards actuation system (ESAS). They are also used in safety related applications in the makeup/high pressure injection (HPI) system, main steam system, and the heat sink protection system (HSPS). The underlying vulnerability associated with the N/C Joslyn Clark contact is the design of the nylon contact arm. The design allows the contact to become configured incorrectly during assembly or following maintenance. If installed improperly, the moving contactor can hang up on the lip of the slot in the nylon actuator. The hang up results in failure of the contact to fully close and perform its function. Following proper assembly, the N/C Joslyn Clark contacts will not become hung-up during normal relay operation. As a result of this exposed design vulnerability, the Commercial Grade Dedication (CGD) plans as well as the maintenance procedures have been enhanced to prevent a relay from being placed into service with an improperly configured contact. Extent of condition reviews performed to date on relays installed in the plant, have not identified any of these deficiencies. The NRC resident inspector was notified of this part 21 notification by the licensee.

ENS 44295 +/-
Where
Three Mile Island Pennsylvania (NRC Region 1)
Reporting

10 CFR 21.21
Time - Person (Reporting Time:+-2.92 h-0.122 days <br />-0.0174 weeks <br />-0.004 months <br />)
Opened:	Adam Miller 12:05 Jun 13, 2008
NRC Officer:	Steve Sandin
Last Updated:	Jun 13, 2008
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v • d • e

v t e Emergency Notification System
Three Mile Island with 10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation
WEEKMONTHYEAR2008-06-13T15:00:00 [Table view]
[ENS list for Three Mile Island]

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