Scientists on Moruroa

Despite the continuing and con troversial French nuclear testing program on Moruroa, near Tahiti, radiation in the area is well below the world average, says the report just published by the party of Australian, New Zealand and Papua New Guinea scientists recently allowed to make a survey of the atoll.

Critics of their report say they were shown only what the French felt like showing them and that their conclusions are therefore invalid. The report does say that various restric tions were placed on the in vestigation but, in general, faci lities were considered sufficient to provide the scientific team

with good data.

The report was discussed at some length during the meeting of the South Pacific Forum at Tuvalu last month. Pacific na tions generally oppose the tes ting and support the campaign to have the Pacific Basin de clared a nuclear- free zone.

Australia’s foreign minister, Mr Bill Hayden, has said the conclusions of the scientific team showed that the French were using proper safeguards, but Australia remained firmly opposed to the French testing.

Australia’s objection was not based upon any health hazard which might, or might not, be caused, but on grounds that the program contributed to the

continuation of the nuclear arms race.

Australia would continue to work actively for a comprehen sive test ban treaty and was committed to pursue this objec tive in the conference on dis armament in Geneva and the UN General Assembly.

The report is highly technical, but sufficiently clear to a lay man to show a number of criticisms of certain French claims. Yet the overall conclu sion seems to be that radiation levels are a good deal lower than might have been expected and generally less than else where in the world.

On longer-term damage to the volcanic rock under the atoll where the subterranean tests are conducted the report is less sanguine, but still of the view that leakage of contaminated materials from the detonation chambers will not occur for 500 to 1000 years.

“The volcanic core in which the tests take place has been severely altered in zones sur rounding the detonation cham bers and the integrity of the coral limestones which form the upper section of Moruroa has been impaired by Assuring, sub sidence and submarine slides,” the report said. But the balance of available data suggests the overall integrity of the volcanic structures has not been im paired.

Nor were the scientists able to detect sufficient radiation in the region to justify assertions by political groups and others that hazards to human health had been created. Indeed “maximum annual doses in Pacific islands from radioactive fallout from atmospheric tests have remained less than one tenth the world average annual natural radiation exposure,” the report says.

“Ambient radiation levels in the base accommodation area of Moruroa atoll are generally lower than they are elsewhere in the world, and traces of fallout from atmospheric tests are detectable only at levels far below those of health signi ficance.

“Radiation doses to the French Polynesian population from natural radiation, and fall

out radioactivity are lower than world average levels, and do not lead to any expectation that radiation-induced diseases would be detectable.

“Cancer statistics for the re gion do not support any suggestion of elevated rates for types of cancer which might be associated with excessive expo sure to radioactive fallout.

“There is no geological evi dence of short-term leakage to date,’’the report says. The hydrology of limestones and volcanics is such as to suggest that leakage could occur in a time period of 500 to 1000 years.

“Venting of gaseous and volatile fission products from the underground test sites does occur at the time of detona tion,” said the report. “There is evidence that the amount is greater than would be expected simply through the back-pack ing of the placement bore being ‘less than perfect.’

“At the underground test sites water is available for leaching the radio-active material (which can be equated to high-level waste). Mechan isms exist for the transport of this contaminated water to the biosphere at least in the long term (greater than 500 years).

The radiological consequence of this leakage depends markedly on the depth of place ment of the weapons tested, and on their relative placement, one test to another. Precise details of placement are not known.

“Waste management at Moruroa was poor,” said the report. “It is now very good.

Only small quantities of radioactivity are now routinely discharged and they are not radiologically significant.

“There is transfer of dis solved plutonium from the la goon to the ocean; it is of only minor radiological importance. ”

The scientific team spent two months examining the environ mental and health aspects of the testing, at the invitation of the French government.

The report will not change Pacific attitudes towards the testing, although it is expected to take some of the fire out of the anti-nuclear campaign by reason of the report’s conclu sions that cancer rates are not increased, and that public health is not at risk.