HERMISTON -- Another fire erupted Friday evening at the Umatilla Chemical Agent Disposal Facility, the fourth such fire since the plant began agent operations in September of 2004.

The fire occurred in Explosive Containment Room (ECR) B at about 9:16 p.m. while processing the 188th M55 GB rocket of the day, according to Mary Binder, public affairs officer for the Umatilla Chemical Depot (UMCD). No agent readings were detected outside of the ECR.

'B' line was the only line being utilized at the time of the fire, Binder said. 'A' line was shut down for routine maintenance.

The fire started after the fifth of seven shears when the rocket motor section ignited. The fire protection system put in place for just such an event suppressed the fire. The rocket that ignited is part of a group which were manufactured in August 1963. A combination of that lot and the lots from previous three fires were already in the facility before the Deactivation Furnace System agent trial burn was completed, waiting to be destroyed, which is why those rockets were being processed this past week.

According to Binder, the only item that was damaged was a hinge pin on the arm that pushes the rockets to the shear arm.

After following their checklist to ensure everything is in working order, UMCDF's 'A' line resumed rocket processing at 5 p.m. Saturday. 'B' line started up again at around 3 Sunday morning.

There are several items that need to be checked off before processing can resume, says Binder.

"There is a protocol and procedure checklist that has to be gone through," Binder said. "The DPE (Demilitarization Protective Ensemble) suits have to be put on, cameras need to be checked, the electronics are checked to make certain they are functioning. It all takes time."

The fire is the fourth fire that has happened in an ECR room. The first occurred on April 7, another on April 23 and on May 18. After the May 18 fire, the Oregon Department of Environmental Quality shut down rocket processing until a cause could be determined for the fires. After thorough investigation, it was determined that there was no root cause for the fires.

Rocket motors were sent to Picatinny Arsenal in New Jersey for testing. Preliminary reports indicate that nitroglycerin in the rocket's propellant had separated and pooled on the propellant grains. The rockets are safe to handle and move, however a fire can result when the shear blade hits the nitroglycerin. The ECRs were built for just such an incident.

As of July 27, 24,366 M55 GB rockets have been destroyed, which amounts to 26.7 percent of the GB rocket stockpile at the UMCD. More than 251,800 pounds of agent have been destroyed as of July 27 and eight storage igloos have been emptied.

The agent trial burn for the Liquid Incinerator (LIC) 1 was completed on July 23. The trial burn was a demonstration of the plant's capabilities to operate without exceeding permitted pollution levels.