The Situation at Mururoa And Fangataufa Atolls
Following a request by the French Government, the IAEA undertook to organize and manage an independent study of the radiological situation at the atolls of Mururoa and Fangataufa. The International Advisory Committee was established to provide scientific guidance and direction to the IAEA in carrying it out.
Background and History
By way of background, the atolls are located on the eastern edge of French Polynesia, some 1000 kilometers from Tahiti, and are about equidistant from the west coast of the United States and Latin America and the east coast of Australia. There were essentially two types of experiments carried out at Mururoa and Fangataufa: nuclear-weapon tests in which nuclear devices were exploded with release of fission energy, and nuclear-weapon safety trials — these involved nuclear devices that were subjected to simulated accident conditions and nuclear-weapon cores that were destroyed by conventional explosives with no or very little release of fission energy.
Most of the tests were conducted at Mururoa, the larger of the two atolls, and the rest, mostly the larger tests, were conducted at Fangataufa. Both the tests and the trials were conducted in the atmosphere as well as underground. There were 41 tests conducted in the atmosphere, 37 at Mururoa and four at Fangataufa, most of them by hanging the device from a balloon at a considerable elevation above the ground. There were 137 underground tests — 127 at Mururoa and ten at Fangataufa, the majority of which were conducted with devices lowered into holes drilled into the rock beneath either the rim or the lagoon of the atolls. There were fifteen safety trials in all — five conducted in the atmosphere and ten underground.
Since the evaluation of weapons testing is a scientifically difficult as well as a politically charged issue, the Study faced several enormous challenges. They included the need for independence, the need for a large number of competent scientists with an unusually wide range of skill and expertise, and the need for an organizational structure and efficiency required to complete the task in a thorough and timely manner. To that end, an International Committee of independent scientists, comprising highly qualified experts drawn from Member States and including ex officio experts selected by intergovernmental organizations was convened by the Director General of the IAEA to provide scientific guidance and direction to the IAEA on all matters related to the conduct ofthe Study. Apart from the International Advisory Committee and the IAEA staff, there were 55 experts from 21 countries involved in the Study. The work went far beyond a desk exercise as it also involved three campaigns of measurements and sampling at the atolls, whereby residual radioactive materials both in the terrestrial and in the aquatic environment were evaluated. Altogether, there were 18 laboratories in 12 countries involved in this campaign, which was led by the IAEA laboratories at Seibersdorf and Monaco.
The aims of the Study were to assess prospectively the situation at the two atolls and in the involved areas from the point of view of radiological safety, to ascertain whether there are any radiological hazards to people, and to make recommendations on the form, scale and duration of any remedial action, monitoring, or any other follow-up action that might be required. The specific objectives of the Study were to assess the residual radiological conditions at the atolls after the end of the nuclear testing and to cover both the present radiological situation and the potential long-term radiological situation.
It is important to understand these objectives because the Study was not designed to look retrospectively at past radiological situations, e.g., exposures caused by fallout during testing or occupational exposures of workers and military personnel during the testing period (it is the understanding of the International Advisory Committee that the French authorities will be publishing a report on this subject).
There will be no radiation health effects which could be either medically diagnosed in an individual or epidemiologically discerned in a group of people and which would be attributable to the estimated radiation doses which are being received or which would be received in the future by people as a result of the residual radioactive material at Mururoa and Fangataufa.
Overall, the expected radiation dose rates and mode of exposure are such that no effects on biota population groups could arise, although occasionally individual members of species might be harmed, but not to the extent of endangering the whole species or creating imbalances between species.
Given the measured and predicted radionuclide activity levels, and the low dose levels estimated for the present and for the future, and with account taken of international guidance, no remedial action at Mururoa and Fangataufa Atolls is needed on radiological protection grounds, either now or in the future.
Similarly, no further environmental monitoring at Mururoa and Fangataufa Atolls is needed for purposes of radiological protection.
Although many assumptions were made in the modelling of systems. the findings are robust: i.e. the expected extent of changes in the conclusions due to uncertainties in the parameters used in the modelling is slight. Furthermore, the predicted doses are so low that large errors (even of an order of magnitude) would not affect the conclusions. An important conclusion is also that future exposures are predicted to be less than today's exposures.
The Study further noted that a scientific programme of monitoring of the radionuclide concentrations in the rock and the nuclear test cavity-chimneys is under way at Mururoa and Fangataufa Atolls. Should this programme continue, the Study recommends that emphasis be placed on monitoring the migration behaviour of long-lived and relatively mobile radionuclides and radiocolloids because of its particular scientific interest. The scientific programme, supplemented by some monitoring of radionuclide levels in the biosphere, may also be useful in assuring the public about the continuing radiological safety of the atolls".
The Study took about two years to complete. It eventually engaged about 100 people in the effort and culminated in the production of comprehensive set of reports, special seminars in French Polynesia and Fiji. Upon the recommendations of the International Advisory Committee the IAEA convened an International Conference (30 June to 3 July 1998) to facilitate discussion of the results of the Study by the scientific community and other interested parties.