Bulletin 74-010B: Failures in 4-Inch Bypass Piping at Dresden-2
BL74010B
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555.
JAN 24 1975
J. P. O'Reilly, Director, Region I
N. C. Moseley, Director, Region II
J. G. Keppler, Director, Region III
E. M. Howard, Director, Region IV
R. H. Engelken, Director, Region V
IE BULLETIN NO. 74-10B - FAILURES IN 4-INCH BYPASS PIPING AT DRESDEN-2
The subject Bulletin should be dispatched for action to all BWR facilities
of jet-pump design with operating license by close of business today.
The Bulletin should also be dispatched for information to all other BWR
facilities with operating license or construction permit and to all PWR
facilities with operating license no later than close of business on January
27, 1975.
The text of the Bulletin and draft letters to licensees are enclosed for
this purpose.
John G. Davis, Deputy Director
for Field Operations
Office of Inspection and Enforcement
Enclosures:
As stated
.
(Draft letter for action to all BWR facilities of jet-pump design with
operating license)
IE Bulletin 74-10B
Gentlemen:
Enclosed is IE Bulletin 74-10B, which amends the description of the
circumstances discussed in RO Bulletin 74-10A and requests additional
actions by you.
Should you have questions regarding this Bulletin or the actions requested
of you, please contact this office.
Sincerely,
Director
Enclosure:
IE Bulletin 74-10B
Approved by GAO, B-180225 (R0072), clearance expires 7-31-77. Approval
was given under a blanket clearance specifically for identified generic
problems.
.
(Draft letter for information to all other BWR facilities with operating
license or construction permit and to all PWR facilities with operating
license.)
IE Bulletin 74-10B
Gentlemen:
Enclosed is IE Bulletin 74-10B which is forwarded to you for information. No
action is required of you if you do not have a boiling water reactor of
jet-pump design with operating license.
Should you have questions regarding this Bulletin, please contact this
office.
Sincerely,
Director
Enclosure:
IE Bulletin 74-10B
.
IE Bulletin No. 74-10B Date: 1/24/75
FAILURES IN 4-INCH BYPASS PIPING AT DRESDEN-2
(REFERENCE: RO BULLETIN NOS 74-10, Dated 9/19/74
AND 74-10A, DATED 12/17/74)
DESCRIPTION OF CIRCUMSTANCES (AMENDED):
Cracks similar to those described in RO Bulletins 74-10 and 74-10A have been
revealed during reexamination of the 4-inch bypass piping at five boiling
water reactor facilities (including Dresden-2) since mid-December 1974. All
the facilities are of jet-pump design. In each instance where cracks have
been revealed, the same welds had been examined previously (during
September-November 1974) and no cracks were revealed at that time.
A special study group, comprised of key-technical members of the Nuclear
Regulatory Commission staff, is currently studying the causes of the cracks
which have been experienced. Consultants from other government agencies are
also participating in the study.
In the interim, pending recommendations of the Commission's special study
group, additional actions are necessary by licensees to insure continued
close surveillance of reactor coolant leakage.
ACTIONS REQUESTED OF LICENSEES (AMENDED):
For all boiling water reactor facilities of jet-pump design with operating
license:
1. Upon completion of those actions described in RO Bulletin 74-10A,
implement the following reactor coolant leakage detection program:
If (within the sensitivity specified in paragraph C.5. of Regulatory
Guide 1.45) any reactor coolant leakage detection system indicates,
within a period of 4 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 (2.0) gpm or
more:
a. Initiate plant shutdown immediately, and
b. Determine the source of increased leakage prior to resuming
operation.
.
c. If there is evidence of leakage from the 4-inch bypass piping,
reexamine (by ultrasonic or other suitable volumetric inspection
technique), all accessible welds in the bypass piping lines.
(In no case, however, shall the rate of leakage exceed that
specified in the technical specifications without those actions
required by the technical specifications being taken.)
2. Notify this office, in writing within 10 days of your receipt of this
Bulletin, of your intent to implement the actions described in 1.,
above.
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