§ Mr. Leeasked the Secretary of State for the Environment what is the estimated maximum life of radioactivity of any of the various radioactive wastes at present disposed of within the United Kingdom; where such wastes are located; what is the quantity involved; and if he will make a statement.
§ Mr. Denis HowellThe longest lived radioactive waste comes from naturally occurring substances which have a very long half life, but a very low activity. The longest lived is thorium 232 which has a half life of 14,000,000,000 years. It is810W present in most building materials and is used in domestic products such as electric light filaments, but because activity is so low no control is normally necessary over disposal. Thorium is therefore likely to be present in refuse disposal sites throughout the country. Where the thorium is present in significant amounts in exceptionally high concentration it is disposed of at the special disposal site at Drigg.