ENS 50848

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v t e ENS Event
05:00 Jan 22, 2015
Title	Abb K-Line Circuit Breaker Secondary Close Latch Binding
Event Description	The following was received from the licensee via email: Pursuant to 10 CFR Part 21, this is a non-emergency notification by Dominion Nuclear Connecticut, Inc. (DNC) concerning a defect identified in ABB K-Line secondary close latches at Millstone Power Station Unit 3 (MPS3). A written report to the NRC will follow within 20 days. On January 12, 2015, during the overhaul of an ABB K600 load center circuit breaker at MPS3, a defect in a new safety-related secondary close latch (Part No. 716610K01, Batch No. 0000150471) was identified when the latch did not fit properly into the breaker mechanism. The vertical piece on the front edge of the latch was contacting the manual close lever. Upon closer inspection, it was found that the angle of the bend in the secondary close latch was not correct, causing it to bind on the manual close lever when actuated. When the manual close lever was actuated, it too would bind due to the secondary latch pressing it into the left mechanism side sheet. Of the eight (8) additional secondary close latches in stock in the Millstone warehouse, all four (4) latches from Batch No. 0000150471, as well as two (2) latches from Batch No. 0000153854, were found to have improper bends. The two (2) remaining latches from Batch No. 0000119420 were found to have the correct bend angle. DNC determined that the defect meets the criteria of a substantial safety hazard since it could prevent a breaker from staying open following a trip signal. DNC notified ABB of this defect on January 22, 2015. Following this notification, one of the defective latches was returned to the vendor for evaluation.

ENS 50848 +/-
Where
Asea Brown Bovari Millstone, Connecticut (NRC Region 1)
Organization:	Dominion Nuclear Connecticut, Inc.
Reporting

10 CFR 21.21(d)(3)(i), Failure to Comply or Defect
Time - Person (Reporting Time:+821.4 h34.225 days <br />4.889 weeks <br />1.125 months <br />)
Opened:	Marylou Calderone 10:24 Feb 25, 2015
NRC Officer:	Daniel Mills
Last Updated:	Feb 25, 2015
50848 - NRC Website
v • d • e

v t e Emergency Notification System
Asea Brown Bovari with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect
WEEKMONTHYEAR2015-01-22T05:00:00 [Table view]
[ENS list for Asea Brown Bovari]

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