IE Circular No. 80-12, Valve-Shaft-to-Actuator Key May Fall out of Place When Mounted below Horizontal Axis
SSINS No.: 6830
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
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
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.
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