Bulletin 74-010A: Failures in 4-Inch Bypass Piping at Dresden-2


RO Bulletin No. 74-10A                                      Date: 12/17/74 



The Commonwealth Edison Company notified the Region III Office of the 
Directorate of Regulatory Operations by telephone on December 13, 1974 of 
the finding of additional through-wall cracks in the 4-inch diameter bypass 
loop around the discharge valve of the "B" recirculation pump at the 
Dresden-2 facility. The circumferential cracks were located adjacent to the 
heat affected zone of a weld which joins the "B" bypass loop piping to a 
weldolet fitting on the 28-inch diameter main coolant recirculation piping. 

The cracks were revealed during a planned ultrasonic reexamination of the 
bypass piping as a part of the inservice inspection program at Dresden-2. 
Similar ultrasonic examination of the same weld in mid-September 1974 
revealed no evidence of cracks at that time. 

The Dresden-2 facility is currently shut down for refueling. All welds in 
the 4-inch bypass piping are to be reexamined during this shutdown. The 
licensee is evaluating the significance of the cracks which have been 
detected as well as procedures for their repair. 


For all boiling water reactor facilities of jet-pump design with operating 

1.   Reevaluate the results of ultrasonic and other examinations conducted 
     previously in response to RO Bulletin 74-10 or as part of the baseline 
     inservice inspection for those facilities not examined in response to 
     RO Bulletin 74-10. 

     Notify this office by telephone by December 23, 1974, and reaffirm in 
     writing by December 30, 1974, of the results of your reevaluation. 

2.   Reexamine (by ultrasonic or other suitable volumetric inspection 
     technique) all accessible welds in the bypass piping lines around the 
     recirculation pump discharge valves at the earliest of the following 

    a.   If presently at cold shutdown and scheduled to remain in this 
          condition for 48 hours or more, prior to resuming power operation.

     b.   If presently at a condition other than cold shutdown, at such time
          that (within the sensitivity specified in paragraph C.5. of 
          Regulatory Guide 1.45) any reactor coolant leakage detection 
          system indicates, within a period of four hours or less, either an 
          increase in unidentified leakage to twice the determined normal 
          rate of unidentified leakage or an increase in the rate of 
          unidentified leakage by two (2) gpm or more. (In no case, however,
          shall the rate of leakage exceed that specified in the technical 
          specifications without those actions required of the technical 
          specification being taken.) 

     c.   Next cold shutdown, regardless of duration. 

          Notify this office in writing, within 10 days following their 
          completion, of the results of the reexaminations conducted in 
          response to this Bulletin. Your written notification should also 
          include a brief description of the examination technique and 
          procedures employed, as well as a description of any special 
          engineering disposition or repairs necessitated by the results of 
          these reexaminations. 

     A copy of all written notifications to this office (including all 
     attachments) should be sent to the Assistant Director for Construction 
     and Operations, Directorate of Regulatory Operations, AFC Headquarters 
     in Washington, D.C. 

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