Intermediate level waste

This type of waste emits levels of radiation that can be a significant health hazard. These can be contained safely through the use of thick shielding to block the radiation or, for other types, by keeping it in sealed containers to prevent inhalation or ingestion.

Intermediate-level waste, or ILW, can be stored at room temperature without the need for cooling.

At Dounreay, intermediate-level waste typically consists of equipment in reactors, plant that has been used to handle spent fuel, fuel element cladding and so on. It also includes “fission products” – the burnt atoms of nuclear material that have been split open inside a nuclear reactor to release their energy.

The waste exists at Dounreay in the form of solids, liquids and sludges. Historically, there were three ways of dealing with this waste – by placing it in the shaft and silo, storing it as liquor in tanks or keeping it loose inside drums in above-ground stores.

During the course of the site closure programme, these historical wastes will be retrieved. Together with new arisings from the clean-out and dismantling of old plants, the waste will be mixed with cement to immobilise the waste inside steel drums or boxes.

This type of waste remains a hazard for thousands of years. There is no agreed long-term management strategy for conditioned intermediate-level waste in Scotland at the present time, however, so it will be held in secure, above-ground stores at the site. These stores are being designed with a lifespan of 100 years.

By 2025, when the site has been cleared, the volume of intermediate-level waste that will need to be managed is expected to up to 15,000 cubic metres. This is equivalent in volume to about 100 double-decker buses.

This waste will remain at Dounreay after all the old facilities have been cleared away, pending a national policy for its long-term management.

Review of ILW strategy

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Image: Intermediate level waste is generated from cleaning out old facilities such as this waste handling cell

Intermediate level waste is generated from cleaning out old facilities such as this waste handling cell

Image: Typical intermediate-level waste stored loose in a drum

Typical intermediate-level waste stored loose in a drum

Image: Workers sort solid intermediate-level waste inside shielded cells using remotely-operated equipment, before the waste is moved loose in drums to stores pending its conditioning in cement

Workers sort solid intermediate-level waste inside shielded cells using remotely-operated equipment, before the waste is moved loose in drums to stores pending its conditioning in cement

Image: Loading a drum to receive a mix of cement and radioactive liquor to create conditioned ILW

Loading a drum to receive a mix of cement and radioactive liquor to create conditioned ILW

Image: A cutaway showing a drum of intermediate-level waste after it has been conditioned with cement

A cutaway showing a drum of intermediate-level waste after it has been conditioned with cement