discuss the effects of nuclear tests at the South Pacific Atolls An International Conference on the Radiological Situation at the Atolls of Mururoa and Fangataufa will take place at the Vienna International Centre from 30 June to 3 July 1998. Convened by the IAEA, the Conference will scrutinize the results of a recent Study on the radiological conditions at the atolls.
The atolls, narrow rims of coral reef jutting a few metres above the ocean, located in French Polynesia in the middle of the South Pacific, were the site of nearly 200 nuclear tests carried out by France from 1966 until January 1996, when all French nuclear testing ceased. The Government of France requested the IAEA to undertake the Study in 1995. The IAEA in turn set up an International Advisory Committee of eminent scientists from various countries to supervise the Study. Fifty five experts external to the IAEA and 18 scientific laboratories co-ordinated by the IAEA's two laboratories in Seibersdorf, Austria, and Monaco, participated in the assessment. In total, 22 States and 3 international organizations were involved in the Study.
The Study was prospective in nature, i.e. it assessed the present radiological situation after the cessation of testing at the atolls, and the expected future consequences. However, the Study also summarized the extensive retrospective assessments of the past consequences of the nuclear testing era made by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) at the time of testing.
The Study conducted a comprehensive sampling and surveillance campaign to determine the levels of residual radioactive materials in the terrestrial and aquatic environments of the atolls. It also estimated the radioactive materials present underground beneath the atolls and assessed the potential movement of these materials through the geological formations into the atoll lagoons and directly into the surrounding seawaters, and their dispersion throughout the South Pacific Ocean.
A main finding of the Study's sampling and surveillance campaign is that concentrations of residual radioactive material present in the accessible environment of the atolls are in general very low. However, the Study also noted that there were several kilograms of residual plutonium in the sediments in the lagoon of each atoll; that particles containing plutonium were present on three islets of the Mururoa Atoll, and that levels of caesium-137 were somewhat elevated in small areas of the Fangataufa Atoll. However, the Study found that all these residual radioactive materials were of little radiological significance.
Through an independent assessment, the Study also found that a large amount of residual radioactive material remains deep in the rocks beneath the atolls and predicted its future migration through the geosphere. Moreover, the consequences of several major hypothetical disruptive events were also assessed. The most significant event considered was a major rock slide exposing the underground cavities where nuclear tests took place and causing a sudden release of radioactive materials into the ocean. Regional and large scale modelling was subsequently applied to assess the potential dispersion and dilution through the South Pacific Ocean of all radioactive material assumed to be released from the atolls. The hypothetical potential radiation dose for future populations in the South Pacific was estimated and found to be a negligible fraction of the natural background dose that people from the region will unavoidably incur.
The Study therefore concluded that there will be no radiological health effects which could be either medically diagnosed in an individual or epidemiologically discerned in a group of people and which could be attributable to radiation doses from the residual radioactive material remaining at the atolls.
The Study also assessed the implications of residual radioactivity in the lagoons for the local animal and plant life and concluded that no effects on marine ecosystems would arise.
The Study concluded therefore that neither remedial actions nor continuing environmental monitoring at Mururoa and Fangataufa are needed on radiological protection grounds. However, the Study noted that the French Government plans to continue some environmental monitoring at the atolls, and suggested that there could be scientific interest in supplementing this programme by additional monitoring of the underground migration of certain radionuclides and that the environmental monitoring programme may be useful in assuring the public about the continuing radiological safety of the atolls.
A summary of the Study's findings, conclusions and recommendations was presented during the first week of June to the South Pacific Forum (a regional organization of 15 South Pacific countries) in Suva, to representatives of the Forum's member states in Nandi, and to people and authorities of French Polynesia in Faa'a. The Executive Summary of the Study was presented to the IAEA Board of Governors at its June meeting; the Board requested its transmission to the forthcoming IAEA General Conference in September.
Several reports arising from the Study will be tabled at the Conference: a Main Report, which incorporates an Executive Summary; a Technical Report in six volumes ("Radionuclide Concentrations Measured in the Terrestrial Environment of the Atolls"; "Radionuclide Concentrations Measured in the Aquatic Environment of the Atolls"; "Inventory of Radionuclides Underground at the Atolls"; "Releases to the Biosphere of Radionuclides from Underground Nuclear Weapon Tests at the Atolls"; "Transport of Radioactive Material within the Marine Environment"; and "Doses due to Radioactive Materials Present in the Environment or Released from the Atolls") comprising a total of nearly 2000 pages of technical material; and a 90 page Summary Report.
The Conference is directed at the general scientific community. Invited papers by participants in the Study will be presented at the Conference, and time will be allowed for counterarguments and discussion, both during sessions and in a Round Table. Decision makers, advisors, government officials and policy makers having administrative responsibilities in areas involving radiation protection should find the Conference of interest and instructive. The Conference proceedings which will contain a record of the discussion, and an overall summary of the views and conclusions arising from the Conference will be published by the IAEA soon after the Conference.