United States Nuclear Regulatory Commission - Protecting People and the Environment

LICENSEE: ABB COMBUSTION ENGINEERING NUCLEAR 
SITE: ABB COMBUSTION ENGINEERING NUC        EN NUMBER:31178
DOCKET:                                  EVENT DATE: 10-18-96
RX TYPE:                                 EVENT TIME: 15:15
VENDORS:                                NOTIFY DATE: 10-18-96
EMERGENCY CLASS: N/A  REGION: 1 STATE: CT      TIME: 15:10
OPS OFFICER: JOHN MacKINNON           
10 CFR SECTION: CDEG  21.21(c)(3)(i)      DEFECTS/NONCOMPLIANCE

REPORTING OF DEFECTS AND NONCOMPLIANCE                           
                                                                 
THE IDENTIFIED DEFECT INVOLVES THE APPLICATION OF CERTAIN ASPECTS
OF THE ABB COMBUSTION ENGINEERING (ABB-CE) RELOAD SAFETY ANALYSIS
METHODOLOGY.                                                     
                                                                 
SPECIFICALLY, THE IDENTIFIED DEFECT CONCERNS THE SCREENING       
METHODOLOGY USED BY ABB-CE TO ASSESS THE CONTINUED CONSERVATISM  
AND APPLICABILITY OF THE DEPARTURE FROM NUCLEATE BOILING RATIO   
(DNBR) PROBABILITY DISTRIBUTION FUNCTION (PDF) FROM              
CYCLE-TO-CYCLE.  THIS ASSESSMENT IN TURN PROVIDES ASSURANCE THAT 
THE FUEL DNBR SPECIFIC ACCEPTABLE FUEL DESIGN LIMIT (SAFDL) WILL 
NOT BE VIOLATED.  IT IS IMPORTANT TO POINT OUT THAT THE CURRENT  
ABB-CE THERMAL-HYDRAULIC STATISTICAL COMBINATION OF UNCERTAINTIES
(SCU) METHODOLOGY USED TO EXPLICITLY DETERMINE THE PDF INPUT TO  
THE DNBR SAFDL CALCULATION IS CORRECT.  RATHER, THE DEFECT       
INVOLVES THE EVALUATION CRITERION USED DURING CYCLE SPECIFIC     
SCREENING TO DETERMINE WHETHER OR NOT AN EXPLICIT SCU PDF        
RE-ANALYSIS IS REQUIRED TO VERIFY THE CONTINUED CONSERVATISM     
DURING THE UPCOMING CYCLE FOR THE DNBR SAFDL OF RECORD.  BASED   
UPON AN EVALUATION, ABB-CE HAS CONCLUDED THAT THE ABOVE DESCRIBED
SITUATION REPRESENTS A DEFECT AS DEFINED IN 10 CFR 21.3, "A      
CONDITION OR CIRCUMSTANCE ... THAT COULD CONTRIBUTE TO THE       
EXCEEDING OF A SAFETY LIMIT.."  THE FOLLOWING POWER PLANTS ARE   
POTENTIALLY AFFECTED BY THIS DEFECT:  ARKANSAS NUCLEAR ONE UNIT  
2; CALVERT CLIFFS UNITS 1 AND 2; PALO VERDE UNITS 1, 2, AND 3;   
SAN ONOFRE UNITS 2 AND 3; ST. LUCIE UNIT 2; AND WATERFORD STEAM  
ELECTRIC STATION UNIT 3.                                         

Page Last Reviewed/Updated Thursday, March 29, 2012