§ Mr. Cotter
To ask the Secretary of State for the Environment, Transport and the Regions what his 629W estimate is of the length of time that a vessel could maintain traces of radiation having been used to dump nuclear waste at sea. 
§ Mr. Meacher
Vessels used for sea dump in the North Atlantic were subject to licence under the Dumping at Sea Act 1974. Such licences contained a provision requiring the ships, on completion of sea dump operations, to be monitored and, if necessary, cleaned by a qualified person until free from significant radioactive contamination to ensure the ships could be returned to unrestricted use with other cargoes. The statutory limits of residual non-fixed radioactive contamination and radiation levels applicable at the time remain essentially the same to date, ie non-fixed contamination limits of 4 Bq/cm2 (10-4 µCi/cm2) for beta/gamma and low toxicity alpha emitters, 0.4 Bq/cm2 (10-5 µCi/cm2) for all other alpha emitters, and a surface radiation limit of µ5 Sv/h (0.5 mrem/h).
Sea dump operations ceased in 1982 with the last operation of the MV Gem, which was certified free from significant radioactive contamination on 15 August 1982 by observers from the UK Atomic Energy Authority and the Nuclear Energy Agency of the OECD.