I recently attended a talk by Dr. Jonathan Turner who’s the Chief Geologist with Radioactive Waste Management (RWM). The talk pertained to an overview of the methods of dealing with nuclear waste in the UK.
Deep geological disposal facility (GDF) are the solutions to this waste problem. Unlike some chemical toxic waste which stays toxic forever, nuclear waste decays over time. The decay to safe levels is still extremely long. This means that the facility needs to be stable for +100,000 years post closure.
As the diagram on the left shows, this GDF will be buried very deep in the ground as far away from any activity whether that be human or natural. The space where the facility will sit will literally stay unaffected for millions of years. Geologically stable.
Well what is actually all this “waste” and how much is there?
There are three main types of waste:
- LLW: Low Level Waste, which is made up building material, personal protective equipment, this waste will stay radioactive for a few thousand years but is defined by the radioactivity.
- ILW: Similar waste as the LLW, but is more irradiated. Can have been in close contact with the fuel rods.
- HLW: Spent fuel, reprocessing waste. Heat producing and extremely high activity. There is enough HLW in the UK to fill the Big Ben.
The UK alone as of April 1st 2019 has 5.1 million tonnes of radioactive waste, according to the UK Radioactive Waste Inventory. The pie chart shows the portions in metric tonnes.
Is there geology in the UK suitable for this kind of project you may ask…
The answer is yes. There are many sites in the UK that are potentially suitable for a GDF site.
So why don’t we have a GDF yet if we have so much waste?
People’s opinion and approval is very important especially in the UK where the siting process is volunteer based. The country has been through many iterations of their disposal siting program, all of which have failed so far. As a result RWM has been employed by the government to manage the legacy waste as well as all the new waste produced by the new generation of power plants. They will dispose of the high level rad waste. The company is transitioning from research to delivery. In the midst of their change they plan on changing the cultural perception of the GDF and the process associated with it. This is one of the reasons why Dr. Turner came out to talk to us. They are all about the safety of the community.
Currently 70% of waste is stored in interim storage at Sellafield. 30% sits around the UK in decommissioned facilities.
The ILW is crushed and mixed with alkaline grout and filled into 500l drums. Four of which will be stored in one crate and each crate will be stacked on top of each other filling the repository.
Currently Finland is storing their high level waste in these copper canisters in the picture on the right. The UK may adopt this style of storage, but will possibly end up using stainless steel canisters instead as it is a lot cheaper. These canisters whether they be copper or stainless steel will be placed inside the GDF and into the ground and surrounded by bentonite rings. The rings wrap around the canister and are made up of a special clay mixture that will swell when in contact with groundwater, making the canisters impenetrable to water. It is important to note that the waste is heat producing and will need to be spaced apart when stored. If the temperature becomes too hot, reactions with the canister may occur as well as with the bentonite which starts to lose its swelling properties at a high temperature.
RMW started engaging communities for private confidential discussions in 2018. They are private to avoid conflicts with other parts of the community when the project hasn’t been fully discussed with the interested party. Once the interested party and RMW feel like this is a potential project to continue it gets made public in form of working groups. This is the the section “Forming Groups” in the diagram below. As the wider community is involved low cost surveys of the area in question are carried out. If the area is still promising the more cost intensive studies are carried which will involve drilling boreholes. Before the project is confirmed there is one final point where the community is asked before the “volunteer” part of the process stops. At all points in these 20 years the community has the right to withdraw their interest.
It is important to mention that RMW defines the UK as England, Wales and Northern Ireland and not Scotland. Scotland hasn’t chosen a disposal solution as of yet, so can not be part of the site selection process.
The big problem is that many communities do not want to host a GDF. I mean who wants to have radioactive waste under the house? Understandable. Making communities aware of the reality that the GDF will be safe for millions of years is the goal of RWM. The communities today will see a rise in jobs as well as finical support from the government of 1 million pounds a year for the first 5 years and then more after that, just for partaking in the volunteering process. 20-50 billion pounds are allocated for the project and the jobs associated with building the GDF and monitoring will be around for at least 200 years.
Building a GDF offshore means the comfort of not having it under anyone’s house. There is no scientific benefit of having it on the mainland. As long as the geology is right then there is no issue with it being under the ocean. The birds eye view diagram below shows my impression of how an offshire GDF would look like. The two big storage room correspond to the different ways the waste has to be stored. 80% of the inventory goes into the smaller space and 20% of the inventory consisting of HLW goes into the larger footprint area, due to the thermal spacing of the canisters.
The drift will be a 25km slope where large vehicles will transport the goods after they were checked at the entrance and accepted. They will then be checked again when they arrive at the offshore facility and then allocated a spot in the repository. The GDF will likely be able to process a max rate of two loads a week.
“no intent to retrieve” this is what it says in the governments white paper on GDFs. The moment you build retrievability into the system the integrity of the GDF is reduced. You are trying to isolate the GDF from the outside world and not allow things to be able to pass in and out of it. Retrievability makes the GDF less safe.
Permafrost needs to considered as well. Ice ages in the next 100,000 plus are inevitable so the GDF needs to be deep enough to not be affected by them.
With all the talk of climate change and sea level rise especially on the coasts of the UK, what are we supposed to do? Well as long as we can ensure that the facility stays dry for the next 200 years while it is operational it doesn’t matter as it will be completely back-filled and sealed up.
Many communities only want to their GDF to contain legacy waste and not new waste produced by the new generation of power plants. This point is taken on by green peace and friends of the earth who are also pro storage of legacy waste, but fear that a store will enable more nuclear power plant projects to go ahead in the future.
Watch this great video from the British Geological Survey for more details.
Leon's Geology 