IE Circular No. 79-25 - Shock Arrestor Strut Assembly Interference
CR79025
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555
December 14, 1979
(Corrected)
MEMORANDUM FOR: B. H. Grier, Director, Region I
J. P. O'Reilly, Director, Region II
J. G. Keppler, Director, Region III
K. V. Seyfrit, Director, Region IV
R. H. Engelken, Director, Region V
FROM: Harold D. Thornburg, Director, Division of Reactor
Construction Inspection, IE
SUBJECT: IE CIRCULAR NO. 79-25 - SHOCK ARRESTOR STRUT ASSEMBLY
INTERFERENCE
The subject circular should be dispatched for action to all licensees and
holders of power reactor construction permits no later than December 20,
1979. The text of the circular and draft letter to licensees are enclosed
for this purpose.
Harold D. Thornburg, Director
Division of Reactor Construction
Inspection
Office of Inspection and Enforcement
Enclosures
1. Draft transmittal letter
2. IE Circular No. 79-25
CONTACT: W. Laudan, IE
49-27551
.
SSINS: 6830
Accession No: 7910250514
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
December 20, 1979
IE Circular No. 79-25
SHOCK ARRESTOR STRUT ASSEMBLY INTERFERENCE
The Bergen Paterson Pipesupport Corporation reported to the NRC a potential
problem with their mechanical shock arrestor - "Strut Assembly." The Bergen
Paterson, Part 2540 Strut Assembly, is being used as a rear bracket for
different sizes of Pacific Scientific Company (PSCO) mechanical shock
arrestors. Some of these shock arrestor sizes may not function as intended
due to insufficient clearances. The following problems were identified:
For PSCO shock arrestors sizes 15 and 50, the Bergen Paterson Part 2540
strut Assembly does not provide sufficient clearance for the shock arrestor
to function freely, when installed at an off axis angle greater than
83.
For PSCO shock arrestor size 120 there is insufficient clearance throughout
the 180 installation angle.
For PSCO shock arrestor sizes 50 and 120 with Bergen Paterson Adaptor Part
2103 the shock arrestor unit may sustain functional damage when the adaptor
unit comes in contact with the rear of the snubber, causing distortion of
the end dust cover.
PSCO shock arrestors sizes -.35, -.65, 1.5 and 6 do not have this
interference condition and therefore are not part of the potential problem
of this circular.
Bergen Paterson stopped shipment as of October 1979 of all Part 2540-15,
2540-50, and 2540-120 strut assemblies and is reviewing all applicable
design detail drawings, to identify all affected items and the facilities to
which those items have been delivered.
Licensees and holders of construction permits are advised to proceed with
the inspection of Pacific Scientific Mechanical Shock Arrestor installations
with Bergen Paterson Part 2540-15, 2540-50 and 2540-120 Strut Assemblies and
determine whether any of the following conditions are applicable:
1. The shock arrestor installation orientation presents a possible
interference problem.
2. Inspection of shock arrestors 50 and 120 with adaptor show damaged or
deformed snubber.
Corrective action should be coordinated with the Strut Assembly supplier
(Bergen Paterson) and appropriate resolutions promptly implemented.
.
(Corrected)
(Draft letter to all licensees and holders of construction permits)
IE Circular No. 79-25
Gentlemen:
The enclosed Circular 79-25, is forwarded to you for information. No written
response to this Circular is required. If you require additional information
regarding this subject, please contact this office.
Sincerely,
Signature
(Regional Director)
Enclosures:
1. IE Circular No. 79-25
2. List of IE Circulars
Recently Issued
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