United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 85-67: Valve-Shaft-to-Actuator Key May Fall out of Place When Mounted below Horizontal Axis

                                                          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 
Page Last Reviewed/Updated Tuesday, November 12, 2013