Bulletin 74-010A: Failures in 4-Inch Bypass Piping at Dresden-2
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
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
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.
Page Last Reviewed/Updated Tuesday, September 01, 2015