United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 84-03: Refueling Cavity Water Seal

                                                  SSINS No.: 6820          
                                                  OMB No.: 3150-0011       
                                                  Expiration Date: 04/30/85 
                                                  IEB 84-03                

                                UNITED STATES
                           WASHINGTON, D.C. 20555

                               August 24, 1984



All power reactor facilities holding an Operating License (OL) or 
Construction Permit (CP) except Fort St. Vrain. 


The purposes of this bulletin are to: (1) notify addressees of an incident 
in  which the refueling cavity water seal failed and rapidly drained the 
refueling cavity, and (2) request certain actions to assure that fuel 
uncovery during refueling remains an unlikely event. 

Description of Circumstances: 

On August 21, 1984, the Haddam Neck plant experienced a failure of the 
refueling cavity water seal with the refueling cavity flooded in preparation 
for refueling. The refueling cavity water level (23 feet) decreased to the 
level of the reactor vessel flange within 20 minutes which flooded the 
containment, with approximately 200,000 gallons of water. The seal assembly 
consists of an annular plate with two pneumatic seals (Figure 1). The 
assembly was recently redesigned by the licensee and had been used once 
previously. The seal was manufactured by Presray, Inc. The seal assembly was 
subject to a gross failure due to lack of an interference between the width 
of the seal annulus and the width of the opening, which allowed the seal to 
be significantly displaced. No fuel was being transferred at the time of 
this seal failure. If, however, fuel had been in transfer at the time, it 
could have been partially or completely uncovered with possible high 
radiation levels, fuel cladding failure and release of radioactivity. In 
addition, if the fuel transfer tube had been open, the spent fuel pool could 
have drained to a level which would have uncovered the top of the fuel. 

Action to be Taken by Plants Currently in Refueling: 

1. Evaluate the potential for and consequences of a refueling cavity water 
   seal failure and provide a summary report of these actions by August 31, 


                                                            IEB 84-03      
                                                            August 24, 1984 
                                                            Page 2 of 2    

Action To Be Taken By Plants Prior To Beginning Refueling Or Within 90 Days 
Of Receipt Of This Bulletin, Whichever Is Sooner: 

2.   Evaluate the potential for and consequences of a refueling cavity 
     water seal failure and provide a summary report of these actions. 

Such evaluations should include consideration of: gross seal failure; 
maximum leak rate due to failure of active components such as inflated 
seals; makeup capacity; time to cladding damage without operator action; 
potential effect on stored fuel and fuel in transfer; and emergency 
operating procedures. 

Written reports describing the above actions shall be submitted to the 
appropriate Regional Administrator under oath or affirmation under 
provisions of Section 182a, Atomic Energy Act of 1954, as amended. Also, the 
original copy of the cover letter and a copy of the report shall be 
transmitted to the U.S. Nuclear Regulatory Commission, Document Control 
Desk, Washington, D.C. 20555 for reproduction and distribution. 

This request for information was approved by the Office of Management and 
Budget under a blanket 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. 

If you have any questions regarding this matter, please contact the Regional 
Administrator of the appropriate NRC Regional Office or the technical 
contact listed below. 

                                   Richard C. DeYoung, Director 
                                   Office of Inspection and Enforcement 

Technical Contact:  H. Bailey, IE
                    (301) 492-7078

1.   Figure 1
2.   List of Recently Issued IE Bulletins
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