United States Nuclear Regulatory Commission - Protecting People and the Environment

Safety Concerns Associated with Pipe Breaks in the BWR Scram System (Generic Letter 81-35)



                               UNITED STATES 
                        NUCLEAR REGULATORY COMMISSION
                           WASHINGTON, D.C. 20555

                               August 31, 1981

TO ALL BWR APPLICANTS FOR CP's, HOLDERS OF CP's, AND APPLICANTS FOR OL's 

Gentlemen: 

SUBJECT:  SAFETY CONCERNS ASSOCIATED WITH PIPE BREAKS IN THE BWR SCRAM 
          SYSTEM (GENERIC LETTER 81-35) 

In April 1981 the NRC staff sent a letter to each BWR license applicant 
requesting certain information on this subject. We indicated that this item 
must be resolved prior to issuance of an operating license. Subsequently, on
July 7, 1981 the NRC staff sent a letter to all BWR licensees informing them
that the generic review of this issue had been completed. We indicated that 
a NUREG report describing the results of this letter would be issued. 

This letter forwards NUREG-0803, "Generic Safety Evaluation Report Regarding
Integrity of BWR Scram System Piping," dated August 1981. Section 5 of 
NUREG-0803 presents the staff's generic conclusions on this issue. Briefly, 
the staff has concluded that the SDV piping system design is acceptable, 
provided certain conditions are satisfied on a plant specific basis. The 
staff further concluded that the safety concerns associated with a 
postulated failure of the SDV piping system do not represent a dominant 
contribution to the risk of core melt, provided certain assumptions used in 
the risk assessment are validated on a plant specific basis. 

NUREG-0803 provides the staff's guidance and schedule for implementation. As
provided in our April 1981 letter, cited above, plant specific responses 
should be provided for all plants with Mark I and Mark II containments to 
support issuance of an operating license. Plant specific responses 
conforming to the guidance contained in NUREG-0803 will satisfy the 
information requested in our April 1981 letter. This letter is being 
provided to applicants with Mark III containments for information purposes, 
since the staff has concluded that this is not a safety issue for the Mark 
III containment design. 

                              Sincerely, 


                              Darrell G. Eisenhut, Director 
                              Division of LIcensing 
                              Office of Nuclear Reactor Regulation 

Enclosure:
  As stated

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