# The Nuclear Installations (Prescribed Sites and Transport) Regulations 2018, Schedule 1: Limits on mass of fissile material


Fissile material
Mass
Plutonium as Pu 239 or Pu 241 or as a mixture of plutonium isotopes containing Pu 239 or Pu 241
150 grams
Uranium as U233
150 grams
Uranium enriched in U 235 to more than 1% but not more than 5%
500 grams
Uranium enriched in U 235 to more than 5%
250 grams

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Source: https://www.legislation.gov.uk/uksi/2018/42/schedule/1 (the official version)
Page: https://openlegislation.uk/nuclear-installations-prescribed-sites-and-transport-regulations-2018/schedule-1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.