Information Notice No.79-35 - Control of Maintenance and Essential Equipment

                              UNITED STATES                SSINS No.: 6870 
                       NUCLEAR REGULATORY COMMISSION        Accession No:  
                   OFFICE OF INSPECTION AND ENFORCEMENT     7910250510     
                          WASHINGTON, D.C. 20555

                             December 31, 1979

                                             Information Notice No. 79-35

CONTROL OF MAINTENANCE AND ESSENTIAL EQUIPMENT

Description of Circumstance:

Enclosed is a copy of a recent enforcement action against Duquesne Light 
Company. A copy of this action is being forwarded to all utilities with a 
power reactor operating license or a construction permit. This is being done
to apprise you of a serious condition which revealed an apparent weakness in
facility control of maintenance and essential equipment. 

You should review your existing procedures and control for independent 
verification of operability of redundant counterpart equipment when an 
essential component, subsystem, or system is determined inoperable. 
Operability is defined as follows:

     A system, subsystem, train, component or device shall be OPERABLE or 
     have OPERABILITY when it is capable of performing its specified 
     function(s). Implicit in this definition shall be the assumption that 
     all necessary attendant instrumentation, controls, normal and emergency
     electrical power sources, cooling or seal water, lubrication or other 
     auxiliary equipment that are required for the system, subsystem, train,
     component or device to perform its function(s) are capable of 
     performing their related support function(s).

If you have any questions regarding this matter, please contact the Director
of the NRC Regional Office in which your facilities are located. No written 
response to this Information Notice No. is required. 

Enclosures: 
1.   Letter to Duquesne Light Company
       from V. Stello, Jr., dtd, 12/5/79
2.   Recently Issued IE Information
       Notices