Fast Cold Starts of Diesel Generators (Generic Letter 83-41)

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                          WASHINGTON, D. C.  20555 

                              December 16, 1983

TO ALL LICENSEES OF OPERATING REACTORS 

Gentlemen: 

SUBJECT: FAST COLD STARTS OF DIESEL GENERATORS 
          (Generic Letter 83-41) 

Widespread concern has been expressed by the industry that fast cold start 
surveillance testing of diesel generators (i.e., starts with rapid 
acceleration and loading without prelubrication and warmup) may result in 
premature diesel engine degradation.  The NRC staff is also concerned about 
the possible deleterious effects of fast cold starts on diesel generators. 
However, we require additional information about the extent and effects of 
this practice before we can make a determination as to whether the number of
fast cold starts should be reduced. 

Accordingly, we are requesting your voluntary participation in providing 
responses to the following questions: 

1.   How many times in the past year (December 1, 1982 to December 1, 1983) 
     have your emergency diesel generators been subjected to a fast cold 
     start (without prelubrication and warmup of any moving parts of the 
     diesel generators)? Provide your data on a per machine basis, for each 
     of the following three categories: (a) surveillance testing, (b) 
     maintenance activities, and (c) actual demands. 

2.   What is your assessment of the effects of frequent fast cold starts on 
     diesel generator reliability and availability?  Do you believe that 
     they significantly degrade reliability and availability? 

This request for information was approved by the Office of Management And 
Budget under clearance number 3150-0011 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. 

As the results of this effort will be used to make selected licensing 
decisions, we request your responses be received by the staff prior to 
January 6, 1984.  The results of this and other efforts will be factored 
into our diesel generator reliability program.  Your participation in this 
data collection effort is appreciated. 


                          Darrell G. Eisenhut, Director 
                          Division of Licensing 



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