IE Circular No. 80-12, Valve-Shaft-to-Actuator Key May Fall out of Place When Mounted below Horizontal Axis

                                                            SSINS No.: 6830 
                                                            Accession No.: 
                                                            8005050052

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C.  20555

                                May 14, 1980

                                                     IE Circular No. 80-12 

VALVE-SHAFT-TO-ACTUATOR KEY MAY FALL OUT OF PLACE WHEN MOUNTED BELOW 
HORIZONTAL AXIS 

Description of Circumstances: 

Tennessee Valley Authority has identified and reported to the NRC a 
nonconformance on a Bettis Robot-arm actuator installed on a Pratt Butterfly
Valve at the Sequoyah nuclear plant. 

It is reported (ref. attached 10 CFR 50.55e report) that a valved became 
inoperable when the valve-shaft-to-actuator key fell out place.  It is 
further noted that the orientation of this valve assembly was such that the 
operator was on the bottom of the valve (below the horizontal axis). 

The Pratt Butterfly Valve furnished with Bettis actuator is designed with a 
press-fit keyway connection valve/actuator.  We believe other manufacturer's
connections may be of similar construction and therefore subject to this 
failure mode. 

On May 1, 1980, Pratt Company sent letters to their customers who have these
connections (enclosed list).  They recommended that their customers review 
their installation of such connections, and if the keyway is oriented below 
horizontal, make one of the following field modifications: 

1.   Add a spacer bushing, or shim plate to fill the void between the top of
     the shaft and the indicating plate on the actuator. 

2.   Locally upset the end of the valve shaft in the area of the keyway 
     using a hand punch in such a way that the key could not work loose. 

3.   Install new keys of longer length which extend above the end of the 
     valve shaft whereby the key is up to the actuator plate and could not 
     slip down if inverted. 

Recommended Action for Licensee Consideration: 

We request that all plants make the above recommended inspection of all 
connections similar to the above described Bettis/Pratt connection, whether 
or not supplied by those particular manufacturers.  If connections are found 
that are susceptible to failure, on of the above recommended actions or 
other appropriate action should be taken to correct the potential problem. 
.

IE Circular No. 80-12                                       May 14, 1980 
                                                            Page 2 of 2 

No written response to this Circular is required.  If you desire additional 
information regarding this matter, contact the Director of the appropriate 
NRC Regional Office.