HERMISTON -- Incineration of chemical weapons is on hold at the Umatilla Chemical Depot while officials look into why a rocket caught fire as it was being destroyed Thursday evening.

The 8-foot M55 rocket had been drained of its GB sarin nerve agent, and the blades in what is called the rocket shear machine were making the fifth of eight cuts through the rocket's motor when the fire started, said Rick Kelley, spokesman for Washington Group International, which runs the incineration facility.

The fire occurred on the B line in the explosive containment room, which has massive concrete walls designed to withstand explosions.

"If something is going to happen, we know that it is going to happen in that room," Kelley said. "That is why it is built the way that it is."
Kelley said workers went into the room in high-level protective gear to repair damaged equipment Friday evening, but it could be Sunday before rocket destruction resumes.

The shutdown is the second caused by a mishap since incineration began in September.

In December, two workers opened an incorrect door to the facility's ventilation system and allowed a trace amount of sarin vapor to escape into a vestibule. The incident prompted a monthlong shutdown for examination and retraining.

In mid-October, two workers in mid-level protective gear accidentally entered a room that was potentially contaminated with nerve agent.

The incinerator has two separate rocket processing lines. Each takes rockets into a containment room, where they are drained of nerve agent and then cut into pieces before being dropped into an incinerator.

No people are in these rooms while work is going on and therooms are sealed to prevent the escape of any chemical vapor.

The fire occurred at about 5 p.m. Thursday, and a fire suppression system automatically shut off all air to the room to suffocate the flames, said depot spokeswoman Mary Binder.

A similar incident happened about a month ago at another weapons incinerator in Anniston, Ala., but a subsequent investigation could not determine what happened, Kelley said.

The Umatilla depot, which is 35 miles south of the Tri-Cities, had a fire on the A line in mid-November. That fire was caused by friction created while a rocket was being cut up after a nozzle designed to cool the blades was bumped out of place.

That incident did not cause the facility to shut down.

Kelley said he didn't think there was any connection between Thursday's fire and the one in November.

The depot started destroying rockets in September and had destroyed 10,871 rockets when the fire happened.