In 1984, British Railways and the Central Electricity Generating Board intentionally crashed a train at 100m.p.h. into a steel flask carrying irradiated fuel rods from nuclear power stations. This was part of a £4m project to test the safety of nuclear fuel flasks. The flask, loaded with steel bars to simulate nuclear fuel rods, survived the impact with minimal damage. The crash was staged on a test track near Melton Mowbray, creating a carnival-like atmosphere with music and marquee tents. Despite successful results, concerns remained about potential leaks of radioactive material at destinations such as Sellafield.
https://www.therailwayhub.co.uk/67072/from-the-archive-operation-smash-hit-84/