Freeman Dyson and TRIGA

Freeman Dyson, a true polymath — mathematician, physicist, theoretician, inventor, experimentalist, philosopher, ethicist, essayist, advocate, and heretic — died last week in Princeton, N.J. He was 96.

Freeman Dyson

I recommend the conventional obituaries, particularly in the New York Times and the Washington Post. My 2012 book, Too Dumb to Meter, has a chapter – “Flatulence in Space” – dealing with one episode, the Orion project, from Dyson’s long and rich career. Orion was a project Dyson led to try to develop space travel using a series of nuclear explosions to propel a spacecraft. It died in 1965, when Dyson’s expressed regret. In 1980, asked if he would like to revive the project, Dyson said, “My answer is an emphatic no…I would not now wish to fly about in a ship that dumps radioactive debris upon the heads of passengers in our other spaceship, Spaceship Earth.” In 2010, he was quoted in an article in the Atlantic, “The starship was like an existence theorem in math. I was to prove you could do it. I never really believed it.”

But the conventional obits have largely ignored a positive project that Dyson led and has been a commercial success and familiar to those who follow the history of civilian atomic energy: the TRIGA reactor. Working under the legendary Edward Teller at General Atomics in San Diego, Dyson led a team that in 1956 developed a pool-cooled nuclear reactor using a uranium zirconium hydride (UZrH) fuel with a strong negative coefficient of reactivity. As the temperature goes up, the nuclear reaction slows down.

Teller challenged the General Atomics team to come up with a reactor design that “could be given to a bunch of high school children to play with without any fear that they would get hurt.” The result was TRIGA, which stands for “Training, Research, Isotopes, General Atomics.”  According to GA, the reactors “operate at thermal power levels from less than 0.1 to 16 megawatts, and are pulsed to 22,000 megawatts.”

TRIGA has been a complete success, with 66 reactors installed at universities, government and industrial laboratories, and medical centers in 24 countries. TRIGA reactors are used in applications that included production of radioisotopes for medicine and industry, treatment of tumors, nondestructive testing, basic research on the properties of matter, and for education and training.”

So the beautiful mind of Freeman Dyson not only produced major theories in physics, beautiful essays and books, and provocative views on many issues of science and technology, but also perhaps the most practical, versatile, and safest nuclear reactor in history.

— Kennedy Maize