Cause of Fatal Rockwell Blast Under Scrutiny : Inquiry: Government is seeking to determine if the scientists killed in 1994 explosion were disposing of toxic waste rather than conducting tests.

Federal agents are investigating whether two Rockwell International Corp. scientists killed in an explosion last year were actually blowing up toxic waste rather than conducting valid rocket fuel tests, government officials said Friday.

Burning off unneeded rocket fuel chemicals would violate federal environmental laws and breach cleanup contracts that paid Rockwell more than $1 million, the officials said.

“They were supposed to dispose of it in accordance with environmental regulations,” one federal investigator said. “By going out in the back yard and disposing of it, you are polluting the environment and causing harm to the government.”

Otto K. Heiney and Larry A. Pugh were killed and a third worker was hurt July 26, 1994, when the nitrocellulose and glycidal azide polymer they were handling blew up in their faces at the Rocketdyne division’s test lab near Simi Valley.

After the blast, Rockwell officials said the scientists had set up acoustic probes near the open-air test stand in Happy Valley. The rock-lined bowl is at the 2,700-acre Santa Susana Field Laboratory where the firm’s Rocketdyne division develops rocket engines.

The probes, Rocketdyne President Paul Smith has said, were used to record shock waves from what were supposed to be controlled explosions while the scientists waited in a safe bunker.

But one source said the blasts were nothing but “bucket tests,” Rockwell slang for illegal tests of no scientific value with only one goal--to get rid of the rocket fuel.

Rocketdyne spokesman Paul Sewell refused to comment Friday on the investigation or whether the scientists had died while trying to get rid of the rocket fuel.

Nor would he confirm whether Rocketdyne had contracts to dispose of the rocket fuel ingredients. Typically under federal contracts, Rockwell would be reimbursed for the cost of disposing of hazardous or toxic material by whatever agency issued the contract that generated the waste.

On Thursday, about 40 agents from the FBI, Environmental Protection Agency, National Aeronautics and Space Administration and the Departments of Defense, Energy, Air Force and Navy raided Rocketdyne’s field lab and Canoga Park headquarters, seizing files relating to the explosion.

Over the years, NASA, the Energy Department and the military agencies have all contracted with Rocketdyne for various research projects at the rugged Santa Susana Field Lab, ranging from nuclear reactor testing to development of space shuttle engines.

If the propellant isn’t disposed of properly, the government could be liable for the pollution, an investigator said.

Officials said they did not know whether burning off the toxic chemicals would create any health risk.

After the fatal blast, the California Division of Occupational Safety and Health Administration and Rocketdyne engineers launched investigations.

In January, Cal/OSHA levied $202,500 in fines against Rockwell International for four serious violations of worker safety rules that may have contributed to the blast.

Also, investigators found that Rocketdyne violated state regulations by failing to tell Cal/OSHA where and when the explosives were being made. Rocketdyne is appealing the citations.

Times staff writer Ralph Vartabedian contributed to this report.