United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 83-04: Failure of The UnderVoltage Trip Function of Reactor Trip Breakers

                                                  SSINS No.:  6820 
                                                  OMB No.: 3150-00012 
                                                  Expiration Date: 04/30/85 
                                                  IEB 83-04 

                               UNITED STATES 
                           WASHINGTON, D.C. 20555 

                               March 11, 1983 

                         REACTOR TRIP BREAKERS 


All pressurized water nuclear power reactor facilities holding an operating 
license (OL) except those with Westinghouse DB type breakers for action and 
to other nuclear power reactor facilities for information. 


The purpose of this bulletin is to inform CP holders and licensees about 
recent failures of General Electric AK-2 type circuit breakers to trip open 
during testing of the undervoltage (UV) trip function and to require action 
of operating pressurized water reactors to assure proper operation of all 
reactor trip breakers in the future. 

Description of Circumstances: 

On March 11, 1983, Southern California Edison reported that during testing 
on March 3 and 8, 1983 of reactor protective system (RPS) breakers at San 
Onofre Nuclear Generating Station (SONGS) Units 2 and 3, three reactor trip 
breakers on Unit 2 and one reactor trip breaker on Unit 3 failed to open on 
activation of the undervoltage trip coil. Both units were shutdown at the 
time of the tests. The SONGS RPS systems are designed such that a reactor 
trip signal energizes the shunt trip coil and deenergizes the undervoltage 
trip coil. All tests of the reactor trip breakers using the shunt trip coil 
were satisfactory. A reactor scram would have occurred if an automatic or 
manual signal had been generated during operation from the redundant 
undervoltage and/or the shunt coils. 


In some RPS designs, the automatic protection signals are fed only to the 
undervoltage (UV) trip attachment of the reactor trip breakers. Other plants
may actuate both the UV device and the shunt trip coil on RPS trip. 

As described above, four RPS breakers at the SONGS Units 2 and 3 failed to 
open during testing. Other failures involving the GE type UV trip attachment
to the RPS have been reported to the NRC. These failures were due to either 
binding or 


                                                            IEB 83-04  
                                                            March 11, 1983 
                                                            Page 2 of 3 

out-of-adjustment within the linkage mechanism of the UV trip device 
installed in General Electric (GE) type AK-2 (i.e., AK2A-15, 25, 50, 75, 
100) circuit breakers. Failures have occurred at ANO-1, Crystal River-3, 
Oconee Units 1 and 3, TMI-1, and St. Lucie. As a result of these events, the 
NRC issued IE Bulletin No. 79-09 dated April 17, 1979 and I-E Circular, 
81-12 dated July 20, 1981. Subsequently, failures have been reported at 
ANO-1 and Rancho Seco. 

Required Actions for Holders of Operating Licenses for Pressurized Water 

PWR licensees with other than W DB type breakers in Reactor Protective 
System applications are requested to: 

1.   Perform surveillance tests of undervoltage trip function independent of
     the shunt trip function within 5 days of receipt of this Bulletin 
     unless equivalent testing has been performed within 10 days. Those 
     plants currently shutdown should complete this item before resuming 
     operation or within 10 days, whichever is sooner. Those plants for 
     which on-line testability is not provided should complete this item at 
     the next plant shutdown if currently operating. 

2.   Review the maintenance program for conformance to the latest 
     manufacturer's recommendation, including frequency and lubrication. 
     Verify actual implementation of the program. If maintenance does 
     not conform, initiate such maintenance within 5 days of receipt of this
     bulletin or provide an alternate maintenance program. Repeat the 
     testing required in item 1 prior to declaring the breaker OPERABLE. 

3.   Notify all licensed operators of the failure-to-trip event which 
     occurred at Salem (see IE Bulletin 83-01) and the testing failures at 
     San Onofre Units 2 and 3 described above. Review the appropriate 
     emergency operating procedures for the event of failure-to-trip with 
     each operator upon his arrival on-shift. 

4.   Provide a written reply within 10 days of receipt of this bulletin: 

     a.   Identify results of testing performed in response to item 1. 
          Plants without on-line testability should report the date and 
          results of the most recent test. 

     b.   Identify conformance of the maintenance program to manufacturer's 
          recommendation and describe results of maintenance performed 
          directly as a result of this Bulletin in response to item 2. 

IE Bulletin 79-09, dated April 17, 1979, had as an attachment an 
extract of General Electric (GE) Service Advice Letter No. 175(CPDD)9.3 
which is applicable to GE type AK-2 breakers. 

                                                       IEB 83-04  
                                                       March 11, 1983  
                                                       Page 3 of 3 

     c.   Provide a statement that provisions are in place to notify 
          licensed operators of the Salem and San Onofre events and bring to 
          their attention appropriate failure-to-trip emergency procedures 
          upon their arrival on-shift. 

     d.   Provide a description of all RPS breaker malfunctions not 
          previously reported to the NRC. 

     e.   Verify that procurement, testing and maintenance activities treat 
          the RPS breaker and UV devices as safety related. Report the 
          results of this verification to the NRC. 

5.   Any RPS breaker failure identified as a result of testing requested by 
     this bulletin should be promptly reported to the NRC via the emergency 
     notification system, regardless of the operating mode of the plant at 
     the time of the failure. 

The written report required shall be telefaxed to Richard C. DeYoung, 
Director, Office of Inspection and Enforcement within 10 days of receipt of 
this bulletin. At the same time, the report shall be submitted to the 
appropriate Regional Administrator under oath or affirmation under 
provisions of Section 182a, Atomic Energy Act of 1954, as amended. The 
original copy of the cover letters and a copy of the reports shall be 
transmitted to the U. S. Nuclear Regulatory Commission, Document Control 
Desk, Washington, D.C. 20555 for reproduction and distribution. 

This request for information was approved by the Office of Management and 
Budget under a blanket clearance number 3150-00012 which expires April 30, 
1985. Comments on burden and duplication may be directed to the Office of 
Management and Budget, Reports Management, Room 3208, New Executive Office 
Building, Washington, D.C. 20503. 

If you have any questions regarding this matter, please contact the Regional
Administrator of the NRC Regional Office or the technical contact listed 

                              Richard C. DeYoung, Director 
                              Office of Inspection and Enforcement 

Technical Contact:  I. Villalva, IE     V. Thomas, IE 
                    301-492-9635        301-492-4755 

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