John Dobken, Media Relations Manager, Southern California Edison
At a coffee klatch in San Clemente, the first question I got was a bit surprising. “Is it really Chernobyl in a Can?” The person was asking about the spent nuclear fuel canisters located at the San Onofre Nuclear Generating Station. Actually, the canisters couldn’t be any more different than Chernobyl.
The Chernobyl reactors are Soviet RBMKs, modeled on military weapons reactors, which were designed to make a lot of plutonium. Operators were using the Chernobyl Unit 4 reactor for a test and placed it in a configuration it shouldn’t have been, and things went very wrong. The reactor, with no containment structure, saw a power spike, steam explosion, melted down and spewed radioactive contamination across the land.
Because the Soviet government didn’t immediately tell anyone about the disaster or take protective measures, some people ingested radioactive material, such as iodine-131 (I-131), and did real damage to their health. But the source of that contamination was hot fuel from a working reactor, not spent fuel seven-plus years removed from the reactor core.
The spent fuel at SONGS no longer even contains I-131. With a half-life of eight days, all the I-131 disappeared approximately two months after the spent fuel was removed from the reactor. And unlike an operating reactor, a spent fuel canister (by design) has no way of sustaining the criticality needed to generate enough heat to recreate a Chernobyl or Fukushima-like event.
Some isotopes in spent fuel take longer to decay, such as cesium-137 and strontium-90. But there isn’t much of them in used nuclear fuel. The shielding of the dry cask system (5/8-inch stainless steel and reinforced concrete) protects us from gamma radiation. Ingesting any of the fission-product isotopes is out of the question: they are locked into a solid fuel pellet, inside a sealed zirconium steel tube, inside a stainless steel canister that is welded shut.
Now, there may be the same amount of radioactivity in a dry cask as was released at Chernobyl. But with no motive force (energy) to drive radioactive contamination into the environment, it’s not really relevant. Unless you simply want to scare people.