Chemical Mix Blamed For Blast Evaporation In Tank Led To High Concentrations

An explosion at the Hanford nuclear reservation’s Plutonium Reclamation Facility apparently was caused by a spontaneous reaction of two chemicals stored in a tank, the U.S. Department of Energy said Monday.

A preliminary investigation concluded the 408-gallon tank contained less than 40 gallons of a liquid solution of hydroxylamine nitrate and nitric acid, said Ron Gerton, chairman of an Energy Department team investigating Wednesday’s blast.

Both chemicals were once used at the building to recover plutonium from waste materials.

Hanford officials initially had given conflicting accounts about the likely contents of the tank, with one saying it had contained hydroxylamine nitrate and another saying it instead contained only nitric acid.

One factor that apparently led to the explosion was evaporation that had occurred in the tank during storage, Gerton said. The evaporation caused higher concentrations of the two chemicals.

The reaction created steam and nitrogen gas, which blew the top off the tank without a fire, Gerton said.

The explosion also ruptured a fire sprinkler line that flooded the fourth-floor room and sent water down an elevator shaft to a parking lot before water and electricity to the building were shut off, acting Hanford manager Lloyd Piper said after the blast.

The blast caused a small amount of reddish-brownish gas to come out of the building’s smokestack, Energy Department spokeswoman Karen K. Randolph said. A small amount of the gas may also have been released into the atmosphere through two 6-inch holes that the explosion left in the roof, she said.

Air monitors on the 560-square-mile reservation have not detected any airborne contamination from the blast, Randolph said.

The investigation has turned up no signs of any release of radiation, and nine workers taken to a hospital as a precaution continue to show no ill health effects, Randolph said. The workers, who initially reported a metallic taste in their mouths, were examined and released a few hours after the blast.