United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 85-26: Vacuum Relief System for Boiling Water Reactor Mark I and Mark II Containments

                                                         SSINS NO.:  6835 
                                                            IN 85-26 

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                    OFFICE OF INSPECTION AND ENFORCEMENT 
                           WASHINGTON, D.C. 20555 

                               April 2, 1985 

Information Notice No. 85-26:  VACUUM RELIEF SYSTEM FOR BOILING WATER 
                                  REACTOR MARK I AND MARK II CONTAINMENTS 
Addressees: 

All boiling water reactor (BWR) facilities having a Mark I or Mark II 
containment and holding either an operating license (OL) or construction 
permit (CP). 

Purpose: 

This notice is provided to alert recipients of potentially significant 
safety problems pertaining to the primary containment suppression 
chamber-to-reactor building vacuum relief system in BWRs with Mark I and 
Mark II containments. It is expected that recipients will review the 
information for applicability to their facilities and consider actions, if 
appropriate, to preclude similar problems occurring at their facilities. 
However, suggestions contained in this information notice do not constitute 
NRC requirements; therefore, no specific action or written response is 
required. 

Description of Circumstances: 

Early in 1980, General Electric (GE) was notified by Philadelphia Electric 
Company (PECO) of a safety concern regarding the installed condition of the 
torus-to-reactor building vacuum relief system at Peach Bottom 2 and 3. The 
concern involved the equipment safety classification and separation of the 
controls to the butterfly valves of the system. 

The butterfly valves of the torus-to-reactor building vacuum relief system 
in BWRs with Mark I containments perform the dual safety function of vacuum 
relief and containment isolation. Two identical system arrangements are 
provided, each of which can perform the vacuum relief function 
independently. In each line, the isolation function is provided by the 
normally closed air-operated butterfly valve and a check valve. Either or 
both of the safety functions have the potential for being jeopardized if the 
controls for the butterfly valves are inadequately separated or the valves 
and associated components are classified as non-safety related. 

Following a technical review, GE concluded that insufficient technical 
information exists within their organization to adequately evaluate this 
safety concern for the individual BWR plants. Although the design 
requirements pertaining to the torus-to-reactor building vacuum relief 
system are generally  



8503280045 
.

                                                           IN 85-26 
                                                           April 2, 1985  
                                                           Page 2 of 2 

addressed in the GE specifications, the actual system design is within the 
scope of the architect-engineer of a facility. Consequently design configur-
ation is not available within GE for their evaluation on a plant-specific 
basis. 

Discussion: 

After PECO notified GE of this safety concern, GE recommended to the BWR 
Owners' Group (BWROG) that facilities with Mark I containments upgrade their
designs. The concern was discussed in several BWROG meetings during 1981-82,
and it was concluded that any further action would only be appropriate on a 
plant-specific basis rather than on a generic basis. 

The NRC staff has discussed the safety concern with GE and BWROG representa-
tives and has concluded that the recommendations made to upgrade the designs
may not have been implemented for all affected Mark I BWRs. Furthermore, a 
similar problem of inadequate separation for controls and safety classifi-
cation also may exist in the suppression chamber-to-reactor building vacuum 
relief system for Mark II BWRs. 

No specific action or written response is required by this information 
notice; however, contingent upon the results of further staff evaluation, a 
Bulletin or a Generic Letter requesting specific licensee actions may be 
issued. If you have any questions about this matter, please contact the Re-
gional Administrator of the appropriate NRC regional office or this office. 



                                   Edward L. Jordan, Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response  
                                   Office of Inspection and Enforcement 

Technical Contact:  R. N. Singh, IE 
                    (301) 492-8985 

Attachment:  List of Recently Issued IE Information Notices 
Page Last Reviewed/Updated Tuesday, November 12, 2013