Bulletin 74-010A: Failures in 4-Inch Bypass Piping at Dresden-2
BL74010A RO Bulletin No. 74-10A Date: 12/17/74 FAILURES IN 4--INCH BYPASS PIPING AT DRESDEN-2 (REFERENCE: RO BULLETIN NO. 74-10, DATED 9/19/74) DESCRIPTION OF CIRCUMSTANCES (AMENDED): 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. ACTIONS REQUESTED OF LICENSEES (AMENDED): For all boiling water reactor facilities of jet-pump design with operating license: 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 conditions: . 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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