Fire investigators on Friday said equipment failure during a cold fusion experiment probably caused a laboratory explosion that killed a researcher.
The blast at SRI International, which injured three others, occurred after an automatic pressure-release valve failed on a sealed canister, fire officials said.
"One of the experimenters tried to open it manually to release the pressure valve and that's when it blew up," said Menlo Park Fire Capt. Jim Lichtenstein. "We're pretty sure that's the cause of the explosion now." Both fire and laboratory officials said the explosion did not release any harmful chemicals or radiation.
Andrew Riley, 33, of Woodside, was killed in the explosion. He died of massive head and upper body injuries, said San Mateo County Chief Deputy Coroner Steve Hortin.
Riley and Steven Crouch-Baker, who received minor wounds in the blast, were contract scientists with Electric Power Research Institute of Palo Alto, which funds most of the cold fusion research in the United States.
Stuart Smedley, 48, and Michael McKubre, 43, were treated for face and arm injuries at Stanford University Hospital on Thursday. They worked for SRI on the $2-million project, said Barbara Klein, an Electric Power Research Institute spokeswoman.