Information Notice No. 85-83: Potential Failures of General Electric PK-2 Test Blocks
SSINS No.: 6835
IN 85-83
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
October 30, 1985
Information Notice No. 85-83: POTENTIAL FAILURES OF GENERAL ELECTRIC
PK-2 TEST BLOCKS
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or a
construction permit (CP).
Purpose:
This information notice is to alert recipients of a potentially significant
problem involving fractures of PK-2 test block terminal posts that could
lead to inoperability of essential electrical equipment. It is expected that
recipients will review this information for applicability to their
facilities and consider actions, if appropriate, to preclude a similar
problem occurring at their facilities. However, suggestions contained in
this information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances:
The Tennessee Valley Authority (TVA) reported to General Electric (GE) and
the NRC that the Sequoyah Nuclear Power Plant experienced fracture failure
of terminal posts on some PK-2 test blocks during routine testing of a cir-
cuit that was not safety related. TVA subsequently tested PK-2 blocks at the
Watts Bar Nuclear Plants and found that terminal post fractures could be in-
duced, in some cases, by wiggling by hand. No failures were identified by
TVA on PK-2 safety-related applications. GE is investigating to determine
the root cause of the failures. However, because of the broad usage of the
test blocks, GE has notified the NRC that GE is unable to determine all of
the possible PK-2 class IE installations and therefore is unable to assure
specific notification of the problem to each utility.
Discussion:
Failure of PK-2 test blocks could occur either during testing or at other
times. Failure during circuitry testing could result in the inoperability of
essential electrical equipment. In this case, the loss of the electrical
equipment would be detected during the testing. The possibility also exists
for the fracture failure to occur at the completion of the circuit testing
or as the result of bumping during other maintenance. Such an occurrence
would
8510250543
.
IN 85-83
October 30, 1985
Page 2 of 2
result in an open circuit and the unavailability of the associated
electrical equipment could go undetected in certain applications. Though the
failures noted by TVA were not safety related, the usage of PK-2 test blocks
includes safety related equipment such as emergency diesel generator relay
boards. In addition to the possible loss of safety related equipment there
is a potential personnel safety concern if an open circuit is developed on a
current transformer circuit during testing.
General Electric has recommended that, in addition to visual inspection, a
force of about five pounds in any direction perpendicular to the terminal
posts can be applied to detect incipient failures.
No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
Regional Administrator of the appropriate regional office or this office.
Edward L. Jordan,Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: James C. Stewart, IE
(301) 492-9061
Attachment: List of Recently Issued IE Information Notices
Page Last Reviewed/Updated Tuesday, March 09, 2021