Information Notice No. 90-18: Potential Problems with Crosby Safety Relief Valves used on Diesel Generator Air Start Receiver Tanks

                                UNITED STATES
                           WASHINGTON, D.C.  20555

                                March 9, 1990

                                   RELIEF VALVES USED ON DIESEL GENERATOR 
                                   AIR START RECEIVER TANKS 


All holders of operating licenses or construction permits for nuclear power 


This information notice is intended to alert addressees to potential 
problems with Crosby safety relief valves that could result in a loss of 
starting air to the emergency diesel generators (EDGs).  It is expected that 
recipients will review the information for applicability to their facilities 
and consider actions, as appropriate, to avoid similar problems.  However, 
suggestions contained in this information notice do not constitute NRC 
requirements; therefore, no specific action or written response is required. 

Description of Circumstances: 

On March 13, 1989, Cooper Industries was made aware of circumstances at 
Perry Unit 1 that led to the Division I EDG being declared inoperable.  A 
Crosby safety relief valve on one of the two EDG starting air receiving 
tanks was inadvertently hit during maintenance activities.  The force of the 
impact caused the valve to open and blow down both air receiving tanks.  The 
safety relief valve did not reseat until approximately 30 psig below the EDG 
automatic start lockout signal.  On January 12, 1990, Cooper Industries 
learned that a similar event had occurred at Comanche Peak.  On January 17, 
1990, Cooper Industries submitted a 10 CFR Part 21 report on the affected 
safety relief valves (Crosby style JMBU and JRU safety relief valves). 

Discussion of Safety Significance: 

Although Crosby-style JMBU and JRU safety relief valves were designed to 
meet the requirements of Section VIII of the ASME Boiler and Pressure Vessel 
Code, they were not seismically qualified.  In addition, the blowdown 
characteristics of the valves were not consistent with the functional 
requirements of the system in which they were installed.  Cooper Industries 
has recommended replacing these valves with seismically qualified valves 
that have the proper blowdown reseat characteristics.


                                                            IN 90-18
                                                            March 9, 1990
                                                            Page 2 of 2

All licensees with Transamerica Delaval Inc. (TDI) diesel generators were 
notified of this problem by Cooper Industries via the Part 21 notification.  
However, Crosby safety relief valves (style JMBU, JRU, and possibly non-code 
style JMB) may be installed on EDGs manufactured by other vendors.  
Licensees may wish to verify that the relief valves installed in their EDG 
air start systems have appropriate qualifications and characteristics. 

This information notice requires no specific action or written response.  If 
you have any questions about the information in this notice, please contact 
the technical contact listed below or the appropriate NRR project manager. 

                              Charles E. Rossi, Director
                              Division of Operational Events Assessment
                              Office of Nuclear Reactor Regulation

Technical Contact:  John Thompson, NRR
                    (301) 492-1175 

Attachment:  List of Recently Issued NRC Information Notices

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