Original classification rating: not rated. This clip chosen to be PG

Operation Blowdown’s simulated nuclear charge was composed of a large spherical mass of TNT, sourced from obsolete shells and filled into special containers, situated at the top of a high tower. On Thursday 18 July 1963 at 8:30 am the shot was fired. Observers were positioned in a bunker at Lamond Hill, 3.2 kilometres from the test site and 198 metres above it. After the explosion, troops and personnel went in to take readings and record observations. Analysis of the data, which took some months, revealed overpressure and dynamic pressure measurements along the blast line, as well as the effects of the blast on military material, field fortifications, supply points and foot and vehicle access.

Final checks are carried out on all instrumentation and the countdown begins. The explosion is shown, then the destruction of the forest is replayed in slow motion and from a number of different camera angles.

Thanks to the generosity of the rights holders, we are able to offer A 50-tonne explosion from the sponsored film Operation Blowdown as a high quality video download.

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