United States Nuclear Regulatory Commission - Protecting People and the Environment

Clarification of TMI Action Plan Item II.k.3.31 (Generic Letter No. 83-35)


                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                          WASHINGTON, D. C. 20555 
                                     
                             November 2, 1983  

TO ALL LICENSEES OF OPERATING REACTORS, APPLICANTS FOR OPERATING LICENSES 
AND HOLDERS OF CONSTRUCTION PERMITS 

Gentlemen: 

SUBJECT: CLARIFICATION OF TMI ACTION PLAN ITEM II.K.3.31 
          (GENERIC LETTER NO. 83-35) 

NUREG-0737 Item II.K.3.31 requires all licensees to submit plant-specific 
small-break-loss-of-coolant accident (SBLOCA) analyses using evaluation 
models revised per II.K.3.30. 

NUREG-0737 Item II.K.3.30 requires that each licensee revise its current 
ECCS SBLOCA models.  However, the currently approved models are still 
considered acceptable and in conformance with Appendix K to 10 CFR 50 
provided the results from the revised model confirm the acceptability of the 
current model results.  Unless a revised model shows a previously approved 
model to be nonconservative, then the previously approved models would 
remain in compliance with Appendix K to 10 CFR 50.  The ECCS analyses 
performed with the previous model would also remain valid and meet the 10 
CFR 50.46 criteria.  Therefore, the requirements of II.K.3.31 can be 
satisfied by each licensee by submittal of a plant-specific analysis that 
demonstrates that current SBLOCA analyses using previously approved 
evaluation models are more limiting than analyses using the revised 
(II.K.3.30) models.  This bounding demonstration can be done on a generic 
basis through the owners groups or vendors and submitted individually by 
each licensee. 

                           Sincerely, 


                           Darrell G. Eisenhut, Director  
                           Division of Licensing  




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