United States Nuclear Regulatory Commission - Protecting People and the Environment

LICENSEE: ILLINOIS POWER CO.                 
SITE: CLINTON 1                             EN NUMBER:31477
DOCKET: 05000461                         EVENT DATE: 12-17-96
RX TYPE: BWR                             EVENT TIME: 14:30
VENDORS: GE-6                           NOTIFY DATE: 12-18-96
EMERGENCY CLASS: N/A  REGION: 3 STATE: IL      TIME: 15:15
OPS OFFICER: DICK JOLLIFFE            
10 CFR SECTION: CCCC  21.21               UNSPECIFIED PARAGRAPH
UNIT  SCRAM   RX   INIT  INITIAL MODE     CURR   CURRENT MODE
      CODE   CRIT  PWR                    PWR
 1    N       N      0   REFUELING          0   REFUELING      

-CRD SYSTEM INOP DUE TO INCORRECT TORQUE VALUE OF CRD HCU HOLD   
DOWN BOLTS-                                                      
                                                                 
ON 11/19/96, WITH THE PLANT IN A REFUELING OUTAGE, THE LICENSEE  
IDENTIFIED THAT THE TORQUE VALUES SPECIFIED BY GENERAL ELECTRIC  
FOR THE 3/8-INCH HOLD DOWN BOLTS FOR THE CONTROL ROD DRIVE (CRD) 
HYDRAULIC CONTROL UNITS (HCUs) EXCEEDED THE MINIMUM YIELD        
STRENGTH OF THE BOLT MATERIAL.  THIS CAUSED THE CRD HCUs TO BE   
INOPERABLE BECAUSE THE TORQUE VALUE DID NOT MEET SEISMIC         
QUALIFICATION REQUIREMENTS FOR RESTRAINING THE CRD HCUs DURING A 
DESIGN BASIS EARTHQUAKE.  THE CRD HCU OPERATION WOULD ONLY BE    
AFFECTED IF A SEISMIC EVENT WERE TO OCCUR DURING PLANT OPERATION.
                                                                 
                                                                 
THERE ARE SEVEN 3/8-INCH BOLTS IN EACH OF THE 145 CRD HCUs FOR A 
TOTAL OF 1015 BOLTS.  THESE BOLTS ATTACH THE GENERAL ELECTRIC    
SUPPLIED CRD HCUs TO STRUCTURAL STEEL SUPPORTS IN THE CONTAINMENT
BUILDING WHICH WERE DESIGNED BY SARGENT AND LUNDY ENGINEERING,   
THE ARCHITECT ENGINEER FOR THE CONSTRUCTION OF THE POWER STATION.
 THIS CONDITION HAS EXISTED SINCE INITIAL LICENSING OF THE PLANT 
IN 1987.                                                         
                                                                 
ALL OF THE 3/8-INCH CRD HCU HOLD DOWN BOLTS HAVE BEEN REPLACED   
WITH NEW BOLTS AND RETORQUED TO THE PROPER VALUE.  A SAMPLE OF   
THE 3/8-INCH BOLTS THAT WERE REMOVED FROM THE CRD HCUs WILL BE   
TESTED TO DETERMINE WHETHER OR NOT THEY WOULD HAVE BEEN ABLE TO  
WITHSTAND A DESIGN BASIS EARTHQUAKE WHILE INSTALLED ON THE CRD   
HCUs.                                                            
                                                                 
THIS 10 CFR PART 21 REPORT ONLY APPLIES TO THE CLINTON POWER     
STATION.                                                         
                                                                 
IN ADDITION, THE LICENSEE HAS SUBMITTED LER #96-018 AND HAS      
INFORMED THE NRC RESIDENT INSPECTOR.                             

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