Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 85-67
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
August 8, 1985
Information Notice No. 85-67: VALVE-SHAFT-TO-ACTUATOR KEY MAY FALL OUT
OF PLACE WHEN MOUNTED BELOW HORIZONTAL
AXIS
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or a
construction permit (CP).
Purpose:
This information notice is provided to alert recipients of a potentially
significant problem pertaining to the renewed possibility of the
valve-shaft-to-actuator key falling out of place when the motor operator is
mounted below the horizontal axis. It is expected that recipients will
review the 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.
Background:
On January 17, 1980 the Tennessee Valley Authority notified the NRC (NCR
19P) of the failure of a containment isolation valve to operate properly at
their Sequoyah Nuclear Plant Units 1 and 2. The utility's investigation
indicated that the failure was caused by the key, which locks the Bettis
actuator to the Henry Pratt valve shaft, falling out of place.
On May 1, 1980, the Henry Pratt Company notified the NRC of this condition.
The company indicated that they had alerted all of their nuclear customers
of the problem and that they had provided their customers with
recommendations for field modifications to correct the problem.
On the basis of the above notifications and a belief that other
manufacturers may be using a similar connection method, the NRC issued IE
Circular No. 80-12, "Valve-Shaft-to-Actuator Key May Fall Out of Place When
Mounted Below Horizontal Axis," on May 14, 1980.
Description of Circumstances:
On December 14, 1984 the Arizona Nuclear Power Project notified the NRC (DER
84-101) of the failure of a containment isolation system valve to operate
properly at their Palo Verde Nuclear Generating Station Units 1, 2, and 3.
The utility's investigation indicated that the failure was caused by the
key, which locks the Limitorque actuator to the Henry Pratt valve, falling
out of place.
8508050453
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IN 85-67
August 8, 1985
Page 2 of 2
On May 23, 1985, the Henry Pratt Company notified (Part 21 Report No.
85-267) the NRC of this condition and indicated that they had alerted all of
their nuclear customers of the problem. The company indicated that they had
recommended that their customers inspect the actuator to shaft connections
and that they had provided their customers with recommendations for changes
to their valve installation, repair, and replacement procedures. These
procedure changes recommended that ". . . Loctite 242 (formerly designated
as CV) or 271 (formerly designated as AV) should be applied to all four
sides of the key prior to reassembly if valve/operator connection is broken
for any reason. Loctite Grade 277 is also acceptable although its higher
shear strength may make its disassembly more difficult." Henry Pratt also
recommended that the NRC issue a supplement to IE Circular No. 80-12 to
emphasize ". . . that when actuators of any type and manufacture are removed
from Pratt valves and reinstalled in the field . . ." Loctite should be
used. Because circulars are no longer issued, this recommendation is being
met by this information notice.
It must be noted that this type of problem can occur not just in valves
manufactured by Henry Pratt, but in any valve that uses a key to attach the
actuator to the valve shaft when the actuator is mounted below the
horizontal axis. While the NRC cannot recommend the use of Loctite on valves
manufactured by companies other than Henry Pratt, it does suggest that each
utility contact its valve manufacturers to determine the appropriate method
of preventing the keys from falling out.
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: Richard J. Kiessel, IE
(301) 492-8119
Edward R. Schweibinz, RIII
(312) 790-5542
Attachment: List of Recently Issued IE Information Notices
