Deep Isolation aiming for disposal site within decade
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Muller, in an interview for the World Nuclear News podcast, said that a combination of the need to tackle climate change and the geopolitics of energy means "more and more countries are eager to move forward with new nuclear power" with an "increasing urgency for solving the waste problem".
The traditional 50 to 100 year time frames for disposal (rather than storage) of nuclear waste is changing, she said, with a number of locations around the world "now interested in seeing nuclear waste disposal happen in that five to ten year time frame. So that's who we're working with … I'm very confident that within the next decade we will have a disposal site that is up and running. I'm targeting five years for first disposal somewhere in the world".
Listen to the full interview, from 22 minutes, 40 seconds in the latest World Nuclear News podcast.
Deep Isolation’s system is to use directional borehole disposal of nuclear waste, building on some of the "incredible innovations that have taken place in the past 20 to 30 years in the drilling industry where it’s now inexpensive and routine to go down three quarters of a kilometre in depth and to have horizontal sections two, three or four kilometres in length".
Berkeley, California-based Deep Isolation's solution for the management of used nuclear fuel and high-level radioactive waste involves emplacing it in corrosion-resistant canisters placed in deep horizontal drillholes. The technology uses existing directional drilling technology. The waste can be retrieved during a determined time frame or permanently secured. In 2019, Deep Isolation publicly demonstrated its concept when it successfully placed and then retrieved a prototype nuclear waste canister hundreds of metres underground via a borehole.
The horizontal storage means that the waste can be disposed of in suitable geological conditions in many different places, including close to, or at proposed or existing sites where the waste is produced, Muller says: "If you're looking at only 500 metres of depth, it's harder to find a good location. If you're looking at 1000 metres, it's significantly easier to find a good location, and if you're looking at 1.5 kilometres or even deeper then I think most locations would probably qualify. We will, of course have to do a detailed analysis and study and testing to make sure … it meets the requirements for safety and environmental protection."
A further advantage of horizontal storage, she says is: "You can get more storage space for a given depth. You can follow a particular rock formation. There's no direct potential pathway through the vertical shaft to the surface and it's also easier to retrieve waste. You can retrieve waste potentially in vertical holes as well, but you need a structure because waste is so dense that it can compact and and crush any structure that it's in whereas when you're horizontal, you don't have that problem, it's just laid out end-to-end."
If it is permanent, how long would it be necessary to make the waste retrievable?
"So for how long it's required is a bit of a grey zone for mined repositories, most people think it is 50 years that it needs to be retrievable, but it is usually just the amount of time that the repository is open, so it is very possible that for borehole disposal it will only need to be retrievable for a couple of years as opposed to 50 years, and we think retrievability will be pretty straightforward for 20 years."
She said there are ways to have retrievability for up to 100 years "if you really want it, but I think the question is how long do you really want it for, and I think five to twenty years is probably going to be sufficient".
Muller, who was an environmentalist and climate change expert and academic before starting Deep Isolation, said the motivation for the business was her concern "that the things we are talking about doing when it comes to climate change aren't enough ... if we really want to stop climate change, we have to do bigger things and that led to my interest in nuclear power".
"I think the industry has done a very good job of explaining why that shouldn't be a barrier to the future of nuclear and yet the public has not really been receptive to talking about how safe it is now and how little waste there is compared to other industries. And so it seemed to me, let's just solve the nuclear waste problem. It can't be that hard ... it's the responsible thing to do anyway."
The drilling itself could take a matter of months “so we are not talking about 20 to 30 years to build a repository” with emplacement also taking a matter of months. "Because we're using smaller holes, we don't need people underground. We don't need air underground. This means that we can go deeper than is possible in mined repositories," she explains. She estimates that once there is a customer and a location it might take three years to get through the licensing process, but she hopes that will “get easier and faster for second locations and third locations … so we’re really looking three to five years to waste disposal from the time that we have a government and location that are interested in disposal.”
A new nuclear power plant, with a lifetime of about 50 years, would need about 15 boreholes, she estimates. The company is talking to countries taking steps into new nuclear as well as new advanced reactor developers about adopting deep borehole disposal.
A key part of work is meeting with communities in areas which have nuclear power plants. One of the challenges faced by past efforts to choose sites for permanent disposal of nuclear waste has been finding a site which was acceptable to communities.
Muller says that their research and public engagement has found that people object to nuclear waste being brought into their community or the idea of hosting a national repository, but if they already have some waste there then they tend to be open to the idea of disposing of the waste at the location where it already is.
She says their system is modular so can be put at the reactor site itself "which I think solves one of the biggest problems" governments have faced with disposal - "the reluctance to bring nuclear waste into someone’s backyard".
Last month Deep Isolation signed a Memorandum of Agreement with technical and engineering services provider Amentum to cooperate on the commercialisation of its radioactive waste disposal technology around the world.
The companies said initial targets for joint work include countries in Europe and the Pacific that "represent a combined addressable market for geologic disposal of spent fuel and high-level waste worth more than USD30 billion".
