Department for Energy Security and Net Zero written question – answered at on 17 November 2025.
Helen Maguire
Liberal Democrat Spokesperson (Primary Care and Cancer)
To ask the Secretary of State for Energy Security and Net Zero, what quantities of unprocessed plutonium remain within discharged irradiated spent nuclear fuel at (a) nuclear reactor sites and (b) Sellafield.
Michael Shanks
Minister of State (Department for Energy Security and Net Zero), Minister of State (Department for Business and Trade)
Plutonium is a by-product of nuclear fission, and it is present in small quantities in spent irradiated fuel. However, the quantities would vary based on the fuel and reactor type.
The Office for Nuclear Regulation publishes annual figures on estimated amounts of plutonium contained in spent civil reactor fuel in the UK. The most recently published data can be found at the following link: 2023 annual figures for holdings of civil unirradiated plutonium | Office for Nuclear Regulation
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Secretary of State was originally the title given to the two officials who conducted the Royal Correspondence under Elizabeth I. Now it is the title held by some of the more important Government Ministers, for example the Secretary of State for Foreign Affairs.
