Same Hanford Tank Blew In ‘70s But Previous Problem Went Undetected Until Investigation Of May Explosion

The chemical tank that exploded on the Hanford nuclear weapons complex in May also blew its lid in the 1970s, U.S. Department of Energy officials revealed Friday.

But record-keeping was so poor in the past that Hanford officials didn’t learn about the 1970s explosion until recently, said Ron Gerton, lead investigator for DOE.

Investigators also say there is little doubt the May explosion was caused when the stainless steel of the storage tank was partially dissolved by the nitric acid it contained, Gerton said.

“Nitric acid will dissolve iron, chrome and nickel,” he said, listing the key components of stainless steel. “Any of these metals can act as a catalyst” to an explosion.

The latest revelations continue DOE’s policy of keeping the public informed, often in painful detail, about the investigation of the May 14 blast that sent eight workers to the hospital and blew the lid off the 400-gallon chemical tank, one of thousands at Hanford.

But they have also revealed a frightening disarray in the way dangerous chemicals are stored on the 560-square-mile nuclear reservation.

For more than four decades, Hanford made plutonium for nuclear weapons. As a result, it is now considered the nation’s most contaminated nuclear site and extensive cleanup is under way.

No radioactive materials were involved in the May blast.

A Hanford watchdog organization is demanding independent investigations of the May blast. Seattle-based Heart of America Northwest sent letters to two federal agencies Thursday criticizing the DOE’s probe at the Plutonium Finishing Plant.

The letter asks the Environmental Protection Agency and the Occupational Safety and Health Administration to jointly investigate the explosion.

In a telephone conference call, Gerton said the investigation is being conducted openly and nothing is being covered up.

“I have no problem sharing my facts with anybody,” he said.

Investigators recently found a document written in 1987 by a Hanford worker who had heard rumors of a chemical explosion at the plant in the 1970s, Gerton said.

The worker was apparently unable to find any accident reports on the 1970s explosion and it’s possible none exists, Gerton said.

But the worker contacted past Hanford workers and determined there was an explosion at storage tank A-109 in Room 40 of the Plutonium Finishing Plant.

That is the same tank that exploded in May.

The worker learned that a mixture of hydroxylamine nitrate and nitric acid in the tank exploded in the ‘70s, blowing a small lid off the tank into the ceiling of the room, Gerton said.

The May explosion, caused by an unstable mixture of the same two chemicals, blew the much-larger main lid of the storage tank into the ceiling, Gerton said.

Why Hanford workers did not heed the warnings of the 1987 report is unknown, Gerton said.

“We are finding out people do not understand very well these hazards,” he said.

The blast was made possible because water in the tank that was diluting the two chemicals evaporated, leaving an unstable mixture.

It is well known the two chemicals become unstable if allowed to concentrate, Gerton has said previously. Hanford officials inexplicably stopped monitoring the tank’s contents last year, allowing much of the water to evaporate, Gerton says.

It now appears that the nitric acid may have corroded some of the stainless steel, with heat from that chemical reaction causing the temperature inside the tank to rise to the point where it exploded, Gerton said.

The explosion, with 200 to 300 pounds per square inch of pressure, blasted off doors, drove a metal shaft into the ceiling of the room like an arrow and split open the roof of the building.

A chemical plume escaped the building, and eight workers who may have been exposed to it were treated at a local emergency room. Some have since complained of rashes, mental confusion and irritability. Hanford officials have agreed to monitor their symptoms for six months, and to have them examined at Harborview Medical Center in Seattle.

Gerton said Hanford operators have been ordered to dispose of any quantities of the two chemicals they are storing to prevent future problems.

The Savannah River plant in South Carolina, the government’s other plutonium production site, gets rid of the chemicals within five days, Gerton said. That policy apparently was imposed after two similar explosions there in the late 1980s, he said.