United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for June 10, 2004

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Part 21 - 2004-0014-00 - Valve Actuator Switch Mechanisms




License No:

MR Number: H-2004-0013
Date: 05/28/2004

Source Document: Letter

Reviewer: Allan Barker


Part 21 - 2004-0014-00 - Valve Actuator Switch Mechanisms

On May 28, 2004, Rotork reported that the molded polyphenylene sulfide (PPS) components within the NA1 switch mechanism assemblies manufactured between 1978 and November 2001, have a low level of crystallinity. These assemblies are supplied either as a spare item or fitted in an NA1 type electric valve actuator. The vendor could not confirm that the affected components are to the same specification as those originally tested and qualified at Wyle in 1978 (refer to test report 43979-1 Rev A). Previously, the vendor notified customers of this condition for actuators manufactured during a more limited time frame, between January 1998 and November 2001. The molded PPS switch mechanism components with a low level of crystallinity could become distorted in extreme circumstances, inhibiting correct operation of the mechanism. For the distortion to occur, the following conditions must exist simultaneously:

1. The actuator is held in the fully open or fully closed position.

2. The temperature of the switch mechanism components is above 80 C (176 F).

Rotork NA4, NA5, NA1E and NA5E type electric valve actuators are not affected.

ADAMS ACCESSION Number ML041560010 "Rotork Part 21 Notification Dated May 28, 2004 - NAl Switch Mechanisms
Manufactured Between 1978 And November 2001"


Name Office Abbrev Phone No E-Mail
BARKER, ALLAN NRR (301) 415-4006 ARB3@nrc.gov
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