![]() ![]() ![]() Of the 15 safety trials, all of which were carried out at Mururoa Atoll, 5 were atmospheric safety trials and 10 were underground safety trials. Forty-one of the nuclear tests were atmospheric nuclear tests which took place - 37 at Mururoa Atoll and 4 at Fangataufa Atoll - between July 1966 and September 1974, and 137 were underground nuclear tests which took place - 127 at Mururoa Atoll and 10 at Fangataufa Atoll - between June 1975 and January 1996. The expériences nucléaires were of two types: 178 were nuclear tests, in which nuclear devices were exploded with large releases of fission energy, and 15 were safety trials, in which more or less fully developed nuclear devices were subjected to simulated accident conditions and the nuclear weapon cores were destroyed by means of conventional explosives, with no or - on a few occasions - very small releases of fission energy. Driven by heat from the tectonic rocks, there is slow migration of relatively deep water from the ocean inwards, rising through the basalt basements and carbonate formations towards the lagoons. The carbonate formations are heterogeneous and fairly porous and the basalt basements are of lower permeability, but all are saturated with sea water. Therefore, in vertical structure, each atoll consists essentially of two rock sequences: an igneous volcanic basalt basement and, capping it, sedimentary carbonate formations hundreds of metres thick. Mururoa and Fangataufa Atolls have evolved from extinct submarine volcanoes, and each rests upon a massive volcanic substratum capped by a coral reef platform and surrounded by ocean water thousands of metres deep. Mururoa and Fangataufa Atolls are situated at 21 o 50 / S, 138 o 54 / W and 22 o 14 / S, 138 o 45 / W, respectively, in the middle of the South Pacific Ocean, halfway between Australia and South America they belong to the Pitcairn-Gambier island chain at the southeastern extremity of the Tuamotu archipelago in French Polynesia. Below are some edited excerpts from that report providing background information, radioactivity source terms, features of sampling and modelling procedures, and evaluations of the disposition and impact of the nuclear materials. #Bikini atoll map fullA full report on the radiological situation at the atolls of Mururoa and Fangataufa was released by the IAEA (1998). ![]()
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