Part 21 Report - 1995-222
ACCESSION #: 9510310202 Automatic Switch Co. Manufacturers of ASCO DEPENDABLE CONTROL Since 1888 FLORHAM PARK, NEW JERSEY 07932 o N.J.-(201) 966-2000 / N.Y.-(212) 344- 3765 FAX-966-2628 October 24, 1995 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTN: David Skeen, NRR/PECB MAIL STOP: 0-11A1 Subject: Request for technical review of draft information notice regarding failure of main steam isolation valves caused by sticking solenoid pilot valves Dear Mr. Skeen, This will respond to the October 18, 1995 letter I received from Alfred E. Chaffee, Chief Events Assessment and Generic Communications Branch, concerning the subject information notice draft. After review of this draft we have the following comments: 1. Please consider adding a statement that extensive testing by ASCO of Nyogel 775A lubricant and similar silicone lubricants has shown no potential for them to develop the sticking forces necessary to prevent the shifting of ASCO NP8323 valves. Additionally, to our knowledge, no testing by utilities or others has ever indicated a propensity for these lubricants to develop any significant adhesion force. However, testing by ASCO, G.E., and others has confirmed that Loctite PST 550 and Neolube 100 thread sealants both have the potential to prevent shifting of a typical solenoid valve. 2. We would like to see a statement added to the information notice indicating that all NP8323 valves supplied by ASCO (from the time they were first introduced to the time when their manufacture was discontinued) incorporated silicone lubricants. However, ASCO never used Loctite PST 550, Neolube 100 or any similar anaerobic sealants in the manufacture of these valves. It should also be noted that LaSalle uses Loctite PST to seal pipe threads in their air supply system, and used Loctite PST to seal the thread connections on some of the failed valves. 3. The third paragraph on page two states, "Prior to installation, LaSalle returned the valves to ASCO for inspection and cleaning, and some lubricant was found on one of the returned valves". Some of us interpreted this sentence to mean that lubricant was found in the valves after they were cleaned by ASCO, when in fact we believe the sentence is meant to indicate that lubricant was found in one of the valves supplied to ASCO for inspection prior to its cleaning. For this reason, we would like to see this sentence reworded to make it clear that no lubricant was found subsequent to the cleaning by ASCO. 4. Please consider adding a statement that ASCO issued a field notification in 1989 advising that we would discontinue the manufacture of NP8323 valves. That notification recommended that utilities remove NP8323 valves from MSIV piloting applications as soon as possible, consistent with normal plant operation and maintenance schedules. Additionally, please consider adding that ASCO issued a field notification in 1995 recommending that any plant who is continuing to use the NP8323 valves reconsider this position. I believe you already have copies of both of these notifications. David Skeen -2- October 24, 1995 NRC We appreciate the opportunity you have given us to provide input into this information notice draft. Please feel free to contact me if you would like to discuss any of our comments. Sincerely, AUTOMATIC SWITCH COMPANY John R. Shank Director New Product Design & Development /ja Skeen. doc *** END OF DOCUMENT ***
Page Last Reviewed/Updated Wednesday, March 24, 2021
Page Last Reviewed/Updated Wednesday, March 24, 2021