nuclear-news

Earthquakes, radioactive waste and that nuclear plant on Southern California’s coast
What are the risks at closed San Onofre during a temblor? Well, it depends, Orange County Register By TERI SFORZA | tsforza@scng.com July 8, 2019   The answer, of course, depends on exactly where the quake is centered and how much the ground beneath the plant shimmies and shakes. But one horrific scenario can be ruled out, despite frequent comparisons of San Onofre to Chernobyl and Fukushima:There can be no core meltdowns at San Onofre, because its reactors have been shut down for seven years. Nuclear fuel has been removed from them. Atoms are no longer split at the site.Instead, the risks at San Onofre center on how its 3.6 million pounds of highly radioactive waste — produced over some 40 years of generating electricity for California — are stored and safeguarded.

Currently, the majority of San Onofre’s radioactive waste cools in spent fuel poolsadjacent to the reactor domes. Those pools are far more vulnerable to the elements than the dry storage systems that will eventually house the waste, and where it will likely remain for decades until the federal government finds it a permanent home — but that’s another story.

‘Concrete monolith’

While pools require electricity and water to keep fuel cool, dry storage systems do not. Earthquake-inspired power outages could cripple pools, but not dry storage systems, which are deemed “passive.”

San Onofre’s dry storage employs massive slabs of concrete designed to withstand more than twice the ground-shake as the spent fuel pools and the reactor itself. Inside those dry systems — designed by Holtec and Areva — nuclear waste is housed in steel canisters.

The thickness of those canisters continues to be a matter of some debate, but experts say that the sooner nuclear waste moves to dry storage, the safer Southern California will be.

“I am more worried about the spent fuel left in the pools at San Onofre than about the fuel that has been transferred to dry casks,” said Edwin Lyman, acting director of the Nuclear Safety Project with the nonpartisan and nonprofit Union of Concerned Scientists in Washington, D.C.

“If a large earthquake tore the liner of a pool, causing a rapid loss of cooling water, there is a risk of a spent fuel pool fire that could cause a large dispersal of radioactive material,” he said. “Although the risk decreases as the spent fuel cools and the pools empty out, it does not go to zero as long as there is fuel in the pools.”………

“Bottom line — I am not worried about a seismic threat to spent fuel at San Onofre,” Lochbaum said via email. “I believe sabotage to be the primary hazard, especially now that SCE and NRC have taken steps to lessen the hazard from self-inflicted events (i.e., the shim pin and near canister drop events.)” https://www.ocregister.com/2019/07/08/earthquakes-radioactive-waste-and-that-nuclear-plant-on-the-orange-county-coast/