Chauncey Starr, 95; Physicist, Proponent of Nuclear Energy

Chauncey Starr, 95, a physicist and nuclear-energy pioneer who died of congestive heart failure April 17 at his home in Atherton, Calif., thought a great deal during his long professional life about what to fear and what not to.

While dean of the University of California at Los Angeles engineering school in 1968, he wrote a landmark paper on how to weigh the risks and social benefits of various technologies. That paper became the basis of modern risk analysis. "How safe is safe enough?" he wanted to know. Building on Dr. Starr's research, today's risk managers would ask, "What is acceptable risk?"

In his paper, published in 1969 under the title "Social Benefits versus Social Risks" in the journal Science, Dr. Starr examined a number of everyday activities and converted the social benefit of each into a dollar figure. He then calculated the cost of each activity as a function of the number of deaths associated with it. He discovered that when the activity is voluntary, people are more willing to take the risk, even if it's measurably more dangerous.

Driving versus flying is a good example. Writing in the Los Angeles Times in 2004, social psychologist David G. Myers noted that Americans in the second half of the 1990s were 37 times more likely to die in a vehicle crash than on a commercial flight. The key difference, as Dr. Starr recognized, is that the person driving is in control; on a commercial airline, someone else is.

"We are loath to let others do unto us what we happily do to ourselves," he was quoted as saying.

Dr. Starr was equally well-known as the founder, in 1973, of the Electric Power Research Institute, the electric industry's research and development collaborative. At the time of his death, he was still working 10 to 5, five days a week. He died in his sleep the day after a celebration in his honor at the institute, based in Palo Alto, Calif.

An enthusiastic proponent of nuclear power, he had worked in recent years on the concept of a power-generating and distribution system called the SuperGrid. It featured a network of air-cooled nuclear power plants that would be located underground for safety and security reasons. The power plants would be spaced about a hundred miles apart along a transcontinental "spine" of long-distance, superconducting cables routed through tunnels.

"I think in 30 to 50 years there will be systems like this," he told the New York Times in 2003. "I think the advantages of this are sufficient to justify it."

Dr. Starr was born in Newark and received an undergraduate degree in electrical engineering in 1932 and a doctorate in physics in 1935, both from Rensselaer Polytechnic Institute. He became a research fellow in physics at Harvard University.

In 1941, he was asked by the Navy's Bureau of Ships to establish an underwater electronic research group at the Navy laboratories in Carderock.

During World War II, he worked with J. Robert Oppenheimer on the Manhattan Project. An expert on the electromagnetic separation of uranium isotopes, Dr. Starr moved to Oak Ridge, Tenn., to direct the construction and operation of a plant designed to separate uranium 235 -- the isotope that causes a rapidly expanding fission chain reaction -- from the other more abundant uranium isotopes.

"From the point of view of being able to meet a time schedule to end World War II, I was one of the contributors on the basic weapons material," he told an electric industry publication in 2002. "From a patriotic point of view -- if you want to put it that way -- it was a major contribution. I was proud of that."