-snip-
As laid out by the commission’s report to Congress and other sources, the event at the Nuclear Fuel Service factory was discovered when a supervisor saw a yellow liquid dribbling under a door and into a hallway. Workers had previously described a yellow liquid in a “glove box,” a sealed container with gloves built into the sides to allow a technician to manipulate objects inside, but managers had decided it was ordinary uranium.

In fact, it was highly enriched uranium that had been declared surplus from the weapons inventory of the Energy Department and sent to the plant to be diluted to a strength appropriate for a civilian reactor.

In a puddle, the uranium is not particularly hazardous, but if it formed a more spherical shape, the commission says, it could become a “critical mass,” a quantity and shape of nuclear fuel sufficient to sustain a chain reaction, in this case outside a reactor.

According to the letter sent by the lawmakers, the puddle, containing about nine gallons, reached to within four feet of an elevator pit. Had it flowed into the pit and reached a depth of several inches, it would have been in a shape that might have supported a chain reaction. The letter from the congressmen says the agency’s report suggests “that it was merely a matter of luck that a criticality accident did not occur.”

Read the full story here