United States Nuclear Regulatory Commission - Protecting People and the Environment


LICENSEE: SIEMENS POWER CORPORATION          

SITE: SIEMENS POWER CORPORATION             EN NUMBER:32379

DOCKET: 07001257                         EVENT DATE: 05-22-97

RX TYPE:                                 EVENT TIME: 00:00

VENDORS:                                NOTIFY DATE: 05-22-97

EMERGENCY CLASS: N/A  REGION: 4 STATE: WA      TIME: 17:13

OPS OFFICER: BOB STRANSKY             

10 CFR SECTION: CDEG  21.21(c)(3)(i)      DEFECTS/NONCOMPLIANCE



CRITICAL HEAT FLUX DATABASE USED FOR 9x9 FUEL DESIGNS DOES NOT   

ADEQUATELY ESTIMATE UNCERTAINTIES.                               

                                                                 

THE FOLLOWING IS TEXT OF A FACSIMILE SUBMITTED BY THE VENDOR:    

                                                                 

"DURING NRC ENGINEERING INSPECTION 9990081/97-01, THE NRC        

DETERMINED THAT THE CHF [CRITICAL HEAT FLUX] DATA BASE FOR THE   

ATRIUM-9 (TM) FUEL DESIGN AND OTHER 9x9 FUEL DESIGNS WITH        

INTERNAL WATER CHANNELS WAS NOT EXTENSIVE ENOUGH TO ADEQUATELY   

ESTIMATE THE UNCERTAINTIES FOR THE ADDITIVE CONSTANTS USED IN    

SPC's (SIEMENS POWER CORPORATION) CHF CORRELATION. A STATISTICAL 

TREATMENT OF THE EXISTING RELEVANT CHF DATA WAS DEVELOPED TO     

ESTIMATE THE UNCERTAINTIES BEYOND THE ORIGINAL CHF DATA RANGES.  

THESE ESTIMATED UNCERTAINTIES ARE LARGER THAN THE ORIGINAL       

ADDITIVE CONSTANT UNCERTAINTIES. REVISED SAFETY LIMIT            

CALCULATIONS WITH THE LARGER ADDITIVE CONSTANT UNCERTAINTIES     

INDICATE THAT CERTAIN PLANTS MAY HAVE OPERATED WITH INCORRECT    

SAFETY LIMITS.                                                   

                                                                 

THE AFFECTED LICENSEES HAVE BEEN INFORMED OF THE INCREASE IN     

ADDITIVE CONSTANT UNCERTAINTIES AND OF THE POSSIBILITY THAT      

PREVIOUSLY CALCULATED SAFETY LIMITS MAY HAVE BEEN IMPACTED BY THE

LARGER UNCERTAINTIES. SAFETY LIMIT CALCULATIONS FOR CURRENT      

REACTORS WITH (THE) ATRIUM-9 FUEL DESIGN AND OTHER 9x9 FUEL      

DESIGNS WITH INTERNAL WATER CHANNELS HAVE BEEN PERFORMED WITH THE

INCLUSION OF PROJECTED HIGHER ADDITIVE CONSTANT UNCERTAINTIES."  

                                                                 

A LIST OF AFFECTED FACILITIES WAS NOT PROVIDED. THE VENDOR WILL  

CONTACT NRC REGION IV REGARDING THIS ISSUE.                      



Page Last Reviewed/Updated Thursday, March 29, 2012