Hercules Bacchus West officials continue to probe a May 29 blast at the rocket motor propellant mixing facility, but as yet they have no answers.

"Information available to us at this juncture seems to rule out either human error or electrostatic discharge as the causes," said Ruth L. Novak, vice president and general manager of the Bacchus Works.Hercules and government investigators are now focusing their efforts on the mixer itself.

"We have very slowly and methodically probed the debris left from the incident so that we could examine as much data as possible," Novak said. "There is strong evidence that people were following procedures and that the procedures were adequate."

Production workers were in a remote control facility several hundred yards from the mixing building. The 12:05 a.m. blast occurred in an 1,800 gallon mixing bowl that contained more than 12 tons of solid rocket fuel.

No one was injured.