The science of nuclear energy
The science of nuclear energy

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The science of nuclear energy

2.3.3 Decommissioning at Dounreay

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After 35 years of service, Dounreay power station was finally decommissioned in 1994. But nearly 20 years later, it's still full of radioactive waste.
Nuclear reactors always produce radioactive waste, and this can range from the contents of the actual core, where the reaction happens, to really anything in the entire plant that becomes contaminated with radiation. Now, current figures show that right now in the UK, we've got well over 160,000 tonnes of the stuff, and something needs to be done with it.
Here at Dounreay, a 2.9 billion pound cleanup is well underway. But after six years, they're still dealing with the lowest level waste. Contaminated paper, rags, tools, which all must be sealed into steel drums and painstakingly analysed.
There's far more low-level waste here than anything else, and some of it's barely radioactive. But inside the reactor itself lies a far more serious challenge.
Literally where I'm walking now below my feet is the Dounreay reactor. Now, it's not in use anymore, but inside the core just down there is some very hazardous radioactive material that still remains - uranium, and plutonium. And the big challenge is to get all that stuff out and make it safe.
This final stage of the cleanup is due to start next year. Handling this waste will be so hazardous, they're now installing robots ready to do the entire job remotely.
The core on this reactor is going to be radioactive for hundreds and hundreds of years. First thing you would do is remove the fuel from the reactor. This is a very sophisticated mast, and it has 14 different tools on it. Tools can go into the reactor and cut free the elements.
So it's like a big Swiss army knife of multi-tools that can rotate on a mast.
It's a huge Swiss army knife that is designed to work remotely and reliably. That gets rid of all the fuel that's in the system.
Once extracted, the fuel rods will be transferred into a cell containing an automated dismantling robot. For now the robot's practising with dummy fuel rods, but once active, it'll be handling the plant's most radioactive waste.
So once it's on, once it starts, you're in production as it were, that's it. Nobody will be in here again.
Unlikely we'll ever put anybody in here again.
From here, another robot will transfer the individual fuel pellets into stainless steel drums, before sealing them in turn inside heavily shielded containers.
These drums of waste would go into an underground repository under very controlled conditions, and they would be stored there forever.
End transcript
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The video shows the progress made, by 2011, of the decommissioning of the Dounreay power station in the north of Scotland, UK.

The task of dealing with the waste continues. The end date for the entire process is given as 2022–25, that is about 30 years after the last reactor closed in 1994.

You can learn more at the Dounreay decommissioning [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] website (Dounreay Site Restoration Ltd, n.d.).

Next week you’ll consider the decommissioning of reactors that have malfunctioned.


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