ENS 53158

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v t e ENS Event
05:00 Oct 17, 2017
Title	Part 21 - Failure of Under-Voltage Release Mechanism
Event Description	The following is a synopsis of information received via E-mail: On October 17, 2017, Palisades alerted Curtiss-Wright of the failure of the under-voltage dropout mechanism in a molded case circuit breaker to trip the breaker in an under-voltage condition. The specific component was a Westinghouse / Eaton Cutler Hammer P/N KD2200U18, containing CAT# UVH3LB08, Style 1492D79G24 under-voltage release mechanism (manufactured prior to 1999). Six of these components were supplied to Palisades in 1992. Findings indicated that the under-voltage release mechanism's failure was a result of a misalignment of the solenoid due to excessive play in the design/manufacturing process which allowed the plunger to miss the target that would cause the breaker to trip in an under-voltage condition. Palisades identified this failure and mentioned two previous failures, one in 1996, and one in 2009. The under-voltage trip mechanism was redesigned in the 1997-1998 time frame. The new design has not exhibited any reported failures. The observed failure on a 1992 breaker having failed in the installed condition took 50 trials to repeat the failure. Given that the excessive play could be a result of combined tolerances, worn tooling, as well as the design itself, and since the OEM has redesigned this mechanism almost 20 years ago, Curtiss-Wright would recommend end users to conduct their own evaluation to determine if a defect, which could create a substantial safety hazard, exists.

ENS 53158 +/-
Where
Curtiss Wright Nuclear Division Cincinnati, Ohio (NRC Region 3)
Organization:	Curtiss Wright Nuclear Division
Reporting

10 CFR 21.21(d)(3)(i), Failure to Comply or Defect
Time - Person (Reporting Time:+2025.47 h84.395 days <br />12.056 weeks <br />2.774 months <br />)
Opened:	Timothy Franchuk 15:28 Jan 9, 2018
NRC Officer:	Donald Norwood
Last Updated:	Jan 9, 2018
53158 - NRC Website
v • d • e

v t e Emergency Notification System
Curtiss Wright Nuclear Division with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect
WEEKMONTHYEAR2017-10-17T05:00:00 [Table view]
[ENS list for Curtiss Wright Nuclear Division]

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