ENS 52403

v t e ENS Event
05:00 Dec 8, 2015
Title	Part 21 - Pawl Fasteners Failed to Provide Sufficient Structural Support
Event Description	The following is an excerpt of a Part 21 received via email: On December 8, 2015, ATC Nuclear performed seismic qualification testing on an ATC Nuclear Assembly with a W-2 Electroswitch Switch, Part Number W2-45B640-84 and W2-45B640-85, for TVA Watts Bar 2. During the first Safe Shutdown Earthquake (SSE) test run, the pawl fasteners used to secure the assembly in a test fixture failed to provide sufficient structural support, rendering the switch assembly non-captive. Based on the testing and analysis, ATC Nuclear concluded that the minimum force required to maintain structural integrity cannot be achieved with the existing pawl fasteners installed in the ATC Nuclear Assembly. This condition, if left uncorrected, could potentially cause a failure of the switch assembly to maintain its mounting configuration during a seismic event. This information provides the basis to establish a deviation in the pawl fasteners provided with the ATC Nuclear assembly that could be considered a potential defect as defined in 10 CFR Part 21. It is worth noting that there have been no failures identified by customers associated with this potential defect. If you have any questions or need additional information regarding this matter, please contact Ray Chalifoux at (865) 384-0124.

ENS 52403 +/-
Where
Atc Nuclear Oak Ridge, Tennessee (NRC Region 1)
Organization:	Atc Nuclear
Reporting

10 CFR 21.21(d)(3)(i), Failure to Comply or Defect
Time - Person (Reporting Time:+8624.3 h359.346 days <br />51.335 weeks <br />11.814 months <br />)
Opened:	Ray Chalifoux 13:18 Dec 1, 2016
NRC Officer:	Jeff Herrera
Last Updated:	Dec 1, 2016
52403 - NRC Website
v • d • e

v t e Emergency Notification System
Atc Nuclear with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect
WEEKMONTHYEAR2019-05-29T04:00:00 [Table view]
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