Is It Safe To Store Nuclear Waste At San Onofre? The Science Behind It
Wednesday, June 19, 2019
Photo by Shalina Chatlani
Southern California Edison will soon resume storing spent nuclear fuel at San Onofre Nuclear Generating Station. The move comes almost a year after a near-miss accident, when one of the canisters that contained the spent nuclear fuel nearly fell 18 feet.
Resuming storing the fuel has also reignited concerns from residents who live around San Onofre on whether storing 1,700 tons of nuclear waste next to the beach is safe.
Residents still worried
Many of those concerned residents, like Peter McBride of Oceanside, attend regular meetings of the San Onofre Community Engagement Panel.
“Nobody has talked about the half-life of the nuclear waste that’s there," he said at a June meeting. "Some of (the nuclear waste) goes quickly. But some of it goes 24,000 years. We’re talking about canisters … that are going to hold it for 10 to 60 years. It’s ridiculous.”
McBride and others at the meeting said the canisters are too thin, and with the salt air, they will corrode and break open. Some also said rising ocean levels could smother the canisters in water and cause them to breach.
“I’m worried about the fact that not only this area but other areas of the country face the same kind of irresponsibility with this potentially disastrous material,” McBride said. “I’m worried about our children, my grandson.”
San Onofre’s senior nuclear engineer Randall Granaas said residents shouldn't be concerned. He recently led KPBS on a tour of the station and said any danger would come from heat and radiation.
Right after being removed from the reactor, fuel rods are extremely hot. They are then put in cooling ponds for five to seven years.
“After five years then we can transfer it into this dry storage system,” he said. “And that’s adequate, using the natural convection to cool the fuel.”
Granaas said vents on the canisters allow cold air to come in, so the heat can circulate out.
There is, however, still the issue of radiation. Even spent nuclear fuel is highly radioactive. Part of that radiation can go through some materials, like aluminum, but not through steel or concrete. The radiation, known as gamma, can take years to dissipate.
“So if you had no shielding between our fuel and yourself, it could be fatal in a relatively short amount of time. So it is important to maintain that shielding,” Granaas said. “But if you fast-forward several hundred years from now you can walk up to one of those fuel assemblies for a short period of time and you’ll be fine.”
But we can't fast forward — that has residents such as McBride worried. What would happen if the shielding suddenly went away?
Storage is structurally sound, officials say
At San Onofre's spent fuel site, a thick concrete slab acts as a 35,000-pound lid. It sits on top of a 20-foot crevice, where the fuel canisters are stored. Officials say this system can withstand massive amounts of stress.
Still, some scientists are skeptical.
Physicist Tom English told KPBS he thinks there are a number of ways this operation could go wrong.
“They’re basically going to put the stuff in a thin storage container, which probably will have some problems with corrosion given this ocean environment here,” he said. “The second idea is they’re going to store it such that it will be about 100 feet from the water and a few inches above the groundwater table, which is totally ridiculous. As the sea level rises, what will happen is the bottom of the containers will corrode.”
But, Jim Conca, a nuclear waste storage expert and consultant for Southern California Edison, said many of the disaster scenarios around San Onofre are unlikely.
“These are totally fireproof,” he said of the storage containers. “Flooding isn’t going to do anything. Terrorism is the least issue. Each of these weighs 150 tons. Also, you can’t make a bomb out of spent fuel.”
He also said the containers are designed to sustain earthquakes.
“These are also low to the ground and in the ground,” he said. "All earthquake damage is a function of distance above the ground.”
And when it came to sea level rise, Conca wasn’t phased either.
“It’s going to take a long time for that sea level to rise anywhere near this,” said Conca.
Southern California Edison documents show these canisters can withstand 55 pounds per square inch of pressure in case of flooding. So, the chance of a breach from flooding is slim, officials said.
Another issue brought up by residents is corrosion of the canisters. When KPBS took a tour, all around the plant there was rust on the metal exposed to the air. Conca, however, said the fuel canisters are made of a special thick stainless steel that resists rust.
San Onofre is not the Egyptian Pyramids
Ted Quinn, the former president of the nonprofit American Nuclear Society, said he is confident the canisters would be fine in a number of disaster scenarios: earthquakes, tsunamis, fires, explosions and terrorism.
“The (Nuclear Regulatory Commission) has stated there’s no credible accident that can occur with our dry casks with the age of our fuel,” he said.
There is, however, a caveat, Quinn said. San Onofre wasn’t built to store spent nuclear fuel in the long term. While the fuel is safe for now, it still has to be looked over, which means there need to be people on site as long as the fuel is there.
The possibility that those personnel will not be there in the future is the real risk, he said.
“The role of San Onofre is done. It’s being taken down. And the only thing that will be left will be the canisters," Quinn said. "And there’s no reason for them to be there if the federal government fulfills its role."
Conca, the Southern California Edison consultant, agreed.
“Eventually you want to get it to some place where you’re going to get it in the ground," he said. "And that’s because, I love the pyramids, they’re great, but that’s the only thing humans that have made that have lasted as much as geological time."
The federal government was supposed to provide a solution decades ago, but it still hasn’t.
What’s preventing a permanent safe solution for San Onofre — and plants around the country — is less scientific, and more political, these experts said.
Editor's note: This story was updated to clarify that Southern California Edison has not yet resumed storing the spent fuel.
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