Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
BL75005
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555
April 14, 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 75-05 - OPERABILITY OF CATEGORY I HYDRAULIC
SHOCK AND SWAY SUPPRESSORS
The subject Bulletin should be dispatched for action to all power reactor
facilities with operating license or construction permit by close of
business on April 14, 1975.
The text of the Bulletin and draft letter to licensees are enclosed for this
purpose.
John G. Davis
Deputy Director for
Field Operations
Office of Inspection
and Enforcement
Enclosures:
As stated
Distribution:
See page 2
.
(Draft letter for action to all power reactor facilities with operating
license or construction permit)
IE Bulletin No. 75-05
Gentlemen:
Enclosed is IE Bulletin No. 75-05 which requires action by you with regard
to your power reactor facility(ies) with an operating license or
construction permit. Also enclosed are copies of RO Bulletins 73-3 and 73-4
which are referenced in IE Bulletin 75-05.
Should you have questions regarding this Bulletin or the actions required of
you, please contact this office.
Sincerely,
Director
Enclosures:
IE Bulletin No. 75-05
RO Bulletin Nos. 73-3 and 73-4
Approved by GAO, B-180225 (R0072), clearance expires 7-31-77.
Approval was given under a blanket clearance specifically for
identified generic problems.
.
IE BULLETIN NO. 75-05 April 14, 1975
OPERABILITY OF CATEGORY I HYDRAULIC SHOCK AND SWAY SUPPRESSORS
DESCRIPTION OF CIRCUMSTANCES:
The Metropolitan Edison Company notified the Region I Office of Inspection
and Enforcement by telephone on March 21, 24 and 25, 1975, of the finding of
eight inoperable hydraulic shock suppressors on the main steam lines inside
containment at the Three Mile Island facility.
The licensee reported that these suppressors were removed for overhaul (seal
replacement) and testing during a planned maintenance program. The
suppressors were determined to be inoperable (suppressor lockup could not be
achieved) during, piston displacement tests performed by the licensee. The
tests were performed on a test rig which actuates the piston with air
pressure. These suppressors, representing equipment originally installed at
the facility, were specified to achieve lockup at a velocity not exceeding
10 in. per minute. The test rig at the facility was reported to have a
capability of testing at velocities up to 50 in. per minute. The specific
cause of the reported failures has not been determined. Spare suppressors
were installed as replacements after their acceptability was determined by
the licensee by test.
For your information, RO Bulletins 73-3 and 73-4, dated July 27, 1973 and
August 17, 1973 respectively (copies enclose) discuss some prior experience
concerning the operability of hydraulic suppressors.
In general, the installation of hydraulic suppressors provides a system for
the restraint of Category I systems and components against excessive
movement during seismic and fluid system transient conditions. Although in
such a restraint system the failure or inoperability of a single suppressor
would not normally defeat the design function of the restraint system, it is
desirable to provide for the periodic testing of a representative sample
from the total population of suppressors to assess the operational
capability of the restraint system on a continuing basis.
ACTION TO BE TAKEN BY LICENSEES:
1. For all power reactor facilities with an operating license:
Review the design and installation of your hydraulic restraint systems,
and provide the following information to this office in writing within
30 days of the date of this Bulletin:
a. The design requirements which the various suppressors are intended
to meet, such as velocity, acceleration, load, etc. Also, indicate
the margin available between the
.
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design requirements and the requirements specified for purchase of
these components.
b. Describe the testing of the hydraulic suppressors conducted by you
or your supplier (s) prior to installation to assure their
operation in accordance with design requirements.
c. Describe the surveillance (including testing) programs now
underway or planned by you to assure continued operability of the
hydraulic suppressors under the design. Conditions throughout the
life of the facility.
2. For all power reactor facilities with a construction permit:
Report to this office in writing within 60 days of the date of this
Bulletin or prior to completion of preoperational testing, whichever is
earlier, the information requested in Items 1.a. thru 1.c. above.
A copy of your response to items 1 and 2 above should also be sent to:
Assistant Director for Construction and Operations, Office of Inspection and
Enforcement, USNRC. Washington, D. C. 20555.