United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 85-17, Supplement 1: Possible Sticking of ASCO Solenoid Valves

                                                  SSINS No.:  6835 
                                                  IN 85-17, Supplement 1 

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                    OFFICE OF INSPECTION AND ENFORCEMENT 
                           WASHINGTON, D.C. 20555 

                              October 1, 1985 

Information Notice No. 85-17, SUPPLEMENT 1:  POSSIBLE STICKING OF ASCO 
                                                SOLENOID VALVES 

Addressees: 

All nuclear power reactor facilities holding an operating license (OL) or a 
construction permit (CP). 

Purpose: 

This notice is to inform recipients of the results of followup 
investigations regarding the reasons for sticking of Automatic Switch 
Company (ASCO) solenoid valves used to shut main steam isolation valves 
(MSIVs) under accident conditions. Recipients are expected to review the 
information for applicability to their facilities and consider actions, if 
appropriate, to preclude similar problems occurring at their facilities. 
However, suggestions contained in this information notice do not constitute 
NRC requirements; therefore, no specific action or written response is 
required. 

Description of Circumstances: 

Information Notice No. 85-17, "Possible Sticking of ASCO Solenoid Valves," 
described the problem that occurred with ASCO Model HTX 832320V solenoid 
valves at Grand Gulf Unit 1. 

General Electric (GE) and ASCO conducted tests to determine the cause and 
any further corrective actions. The following is a summary of the GE and 
ASCO tests and analyses: 

     Two of the three solenoid valves which failed at the Grand Gulf Nuclear
     Station also sporadically failed to transfer during testing at elevated
     temperatures. These two valves were the only valves that failed during 
     these tests. However, these failures were not predictable. 
     Subsequently, five valves from Grand Gulf service were disassembled and 
     inspected. This inspection identified a microscopic foreign substance 
     on the lower core/plug nut interfaces on all five valves. 

     Further evaluations of this microscopic substance were inconclusive 
     because of the small foreign substance sample size. After cleaning and 
     reassembly of these valves, tests were conducted on four of these five 
     valves at elevated temperatures. These four valves functioned normally.
     ASCO felt certain that the valve failures resulted from 
     high-temperature sticking of the lower core-to-plug nut faces resulting 
     from a foreign substance or combination of substances collected at this 
     interface. 


8509260369 
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                                                     IN 85-17 Supplement 1 
                                                     October 1, 1985  
                                                     Page 2 of 2 

     A detailed dimensional analysis and comparison among the valves 
     returned from Grand Gulf indicated that all parts were within allowable 
     limits and differences were not enough to cause a failure to shift. 
     Therefore, this examination tended to relieve concerns related to a 
     generic design defect. 

     GE has attempted to locate additional foreign substance from other 
     valves of the same type in use at Grand Gulf to determine how the 
     foreign substance got in the valve, or where it originated. GE was able
     to scrape some small amounts of foreign substance from the lower 
     core-to-plug nut interface. However, there was not enough residue to 
     make a definitive identification of the nature of the foreign 
     substance. 

GE has recommended that the licensee replace the potentially contaminated 
MSIV solenoid valves and institute a periodic examination and cleaning of 
the MSIV solenoid valves. Grand Gulf has replaced the eight MSIV HTX832320V 
dual solenoid valves with fully environmentally qualified ASCO Model NP 
8323A20E dual solenoid valves. The environmentally qualified valve Model NP 
8323A20E was included in a control sample placed in the test ovens with the 
solenoid valves that stuck at Grand Gulf. The environmentally qualified 
model did not stick under the test conditions that cause sticking in the 
other solenoid valves. 

No specific action or written response is required by this information 
notice. If you have any questions about this matter, please contact the 
Regional Administrator of the appropriate regional office or this office. 


                                   Edward L. Jordan, Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 


Technical Contact:       Eric Weiss, IE 
                         (301) 492-9005 

Attachment: List of Recently Issued IE Information Notices 
Page Last Reviewed/Updated Tuesday, November 12, 2013