ML093140090

Notification of Potential Part 21 on Failure Which Occurred

ML093140090
Person / Time
Site:	LaSalle
Issue date:	11/06/2009
From:	Barry R Flowserve Corp
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML093140090 (4)

Text

Flow Control Division Anchor/Darling Valves FLOWSERVE BW/IP Valves Edward Valves Valtek Control Products Worcester Valves November 6, 2009 US Nuclear Regulatory Commission Document Control Desk 11545 Rockville Pike Rockville, MD 20852-2746

Subject:

USNRC 10CFR Part 21 Notification Ref: Flowserve Size 3/4 Figure 848Y Disk/Disk Nut Separation LaSalle Station Exelon PowerLabs, LLC Project Number: LAS-62808 Flowserve Complaint Report 4914 Flowserve Evaluation Report No. 10 CFR 21-50 Gentlemen, This is to notify the US Nuclear Regulatory Commission, in accordance with the provisions of 10CFR-Part 21 of a deviation identified by Flowserve Corporation.

Background

On September 8, 2009, Flowserve Corporation was notified by Exelon - LaSalle Nuclear Power Station of a failure which occurred and was initially communicated via Flowserve Complaint Report

1. 4914.

The Referenced Complaint Report describes an anomaly with a Size 3/4 Figure 848Y bolted bonnet valve at the LaSalle Nuclear Power Station.

The subject valve was in service at the time of disassembly. The disassembly revealed that the disk nut, which captures the valve stem in the valve main disk, had separated from the main disk.

The valve in question is a manually operated, non active valve. The safety function of this valve is to retain system pressure. This safety function was not affected by separation of the stem nut from the valve disk.

Flowserve U S Inc Raleigh Operations Toll Free: 1-800-225-6989 Flow Control Division PO Box 1961 1900 South Saunders Street Phone: 1-919-832-0525 Facsimile: 1-919-831-3369 /9 Raleigh, NC 27603 www.flowserve.com

US NRC November 6, 2009 Page 2 of 4 However, other Figure 848 valves may have different safety related functions that could be affected by this type of failure. See Discussion and Conclusion below.

Discussion Figure 1 provides an illustration of the stem/disk assembly in the Size 3/4 Figure 848 valye. The "Old Design" is typical of the valve that is the subject of this discussion. The valve stem has a collar on the very end. After the stem is inserted into the disk, the disk nut is threaded into the disk to retain the stem. A lock weld is then created to prevent the disk nut from unthreading out of the disk.

In about 1990, the design was changed to that shown as the "New Design" in Figure 1. The disk nut was eliminated, and the disk retained on the end of the valve stem using a piece of wire inserted into a groove located half in the valve stem and half in the disk.

NWr an ~mm NEW EESlID Figure 848 Figure A848 Figure 1 Stem/Disk Assemblies for Old Design and New Design Figure 848 / A848 Valves.

US NRC November 6, 2009 Page 3 of 4 For the case of the "Old Design" valve at LaSalle, once the disk nut has unthreaded out of the disk, the stem and the disk are no longer connected. The valve will then operate as a stop-check valve. The valve will open in response to normal forward flow, and close in response to normal reverse flow.

Because the disk nut is a solid piece assembled around the valve stem, the disk nut cannot fall off of the valve stem and become a loose part in the piping system.

After unthreading from the disk, the disk nut will sit on top of the disk. The valve will be able to open only partially, because the disk nut will interfere with the ability of the valve to open fully.

The amount that the valve can open will depend on the size of the valve. For the Size 3/4 valve at LaSalle, the disk would be able to open less than 1/8 of an inch. The amount that other valve sizes would be able to open is different, but all would be reduced.

In operation, the valve would function as a stop-check valve rather than a stop valve. If the handwheel is used to close the valve, the valve will remain closed. If the handwheel is used to retract the valve stem, differential pressure in the normal forward flow direction will open the valve and allow flow through the valve.

The valve handwheel will operate as though there is no problem, even though the disk is no longer connected to the valve stem.

The valve drawing does not provide a flow direction arrow, although a flow direction arrow is provided on the side of the valve body forging. If the installation was performed using the drawing as a guide, there is no guarantee that the valves were not installed backwards.

Figure 848 manually operated valves are not typically used as active safety-related devices.

Based on the above, different safety scenarios for the valve are described below:

Scenario Impact on Safety-Related function Valve has no safety-related function. None Safety-related function is to retain pressure Safety-related function is to remain closed. Safety-related function is not affected.

Safety-related function is to close against reverse flow.

Safety-related function is to pass a minimum amount of flow in the normal forward flow direction.*^,.

• ..* .. ......... *..... .. .... Safety-related function may be affected.

,dIltLy-l IdLCU IUIHILLIUI I 1. LU P=0 C1 11111111IUlll amount of flow in the normal reverse flow direction.

US NRC November 6, 2009 Page 4 of 4 Conclusion Based on the above, the Nuclear Industry needs to be notified concerning the potential defect, and encouraged to inspect the operation of their valves, especially if they have a safety-related function in the plant that may be adversely affected.

The valves affected are Size 2 and smaller Edward Figure 848 valves manufactured by Rockwell International at the Sulphur Springs, Texas, and the Raleigh, North Carolina, manufacturing facilities prior to 1991. These valves may be tagged "Rockwell", "Rockwell Edward" or "Edward".

The valves affected have the "Old Design" stem/disk assembly shown in Figure 1.

Valves with Figure Number A848 incorporate the "New Design" stem/disk connection and are not affected.

The total number of valves affected and their installed locations are not known.

Respectfully submitted, Robert D. Barry Manager, Quality Assurance Flowserve Corporation Flow Control Division 1900 S. Saunders St.

Raleigh, N.C. 27603