In August 2009, the Palo Verde nuclear plant in Arizona suffered a failure of a thermostatic valve element in an Emergency Diesel Generator at the plant. Subsequent investigation showed that the failure was a manufacturer’s defect, specifically, brass shavings which had gouged an element in the thermostat.
The part was manufactured by Engine Systems (ESI), Inc., in Rocky Mount, North Carolina. ESI’s investigation assessed the significance of the defect:
“This defect could affect operability of the thermostatic valve within the diesel engine cooling water and/or lube oil system, resulting in elevated fluid system temperatures during engine operation. Engine performance and/or load carrying capability could be impacted with the possibility of eventual engine failure, thereby preventing the emergency diesel generator from performing its safety related function.”
Today’s update included a list of nuclear plants for which ESI provided the same thermostatic valve element. The list includes South Texas Nuclear Project.
Here’s the complete list:
Site – Thermostatic Valve – System:
Braidwood – 6HAS – Lube
Byron – 6HAS – Lube
Nine Mile Point – 6HAS- Lube
Oconee – 4HAS & 6HAS – Water
Palo Verde – 6HAS – Lube & Water
South Texas Project – 6HAS – Lube & Water
Susquehanna – 6HAS – Lube & Water
Waterford – 5HAS & 6HAS – Lube & Water
No corrective action is planned.