Staff Reports
NS&D Monitor
2/5/2016
Casting operations with highly enriched uranium were temporarily “paused” last month because of a perceived “deficiency” in nuclear criticality safety in a part of Building 9212 at the Y-12 nuclear weapons plant in Tennessee.
The issue was reported in an area associated with Stack 110, which is the primary ventilation system that supports uranium casting operations in Building 9212. Uranium casting involves the melting of uranium and pouring into molds to form shapes for various purposes – ranging from weapons components to cylinders or buttons for shipment and storage.
According to a recently released Jan. 8 activity report by Defense Nuclear Facilities Safety Board site staff, nuclear criticality safety engineers documented a safety deficiency after production personnel reported that about 2 feet of water had been found in the “discharge tube” below Stack 110’s dust collector.
The report said the discharge tube – which collects uranium dust that falls from the stack filters – has geometry that is nuclear-criticality safe.
“However, the criticality safety evaluation for the Stack 110 system requires the dust collector to limit water ingress such that water cannot accumulate to the cartridge filter housings above the discharge tubes,” the DNFSB report stated.
In this case, the water level did not approach the filter housings, but the report noted that it still represented an “off-normal condition” that necessitated nuclear criticality safety guidance “on the actions to be taken for recovery.”
The safety board’s activity report said casting operations in 9212 were paused while nuclear safety and systems engineers determined the location where water was entering the tubes and developed actions for recovery.
Asked if the casting operations had resumed, Y-12 spokeswoman Ellen Boatner said the operations were only suspended for a “brief time” while the situation was investigated. They have resumed, she said.
Boatner also provided a statement that said the water did not pose a safety issue, “but was considered an unusual condition.” She noted, “Additional efforts have been made to protect the tube from precipitation.”
