FRANCE has started to demolish its nuclear test facilities on Mururoa and
Fangataufa atolls in the South Pacific. The French government last week insisted
that it is returning the islands to the civil authorities of French Polynesia in
a pristine condition. But independent scientists say the island may be
dangerously contaminated.
France exploded at least 123 nuclear bombs in the volcanic rock underneath
Mururoa between 1975 and 1996, and eight under Fangataufa. Earlier this year,
France said it would stop nuclear weapons tests. It is legally bound to hand the
atolls back, clean and safe, to the civil authorities of French Polynesia, and
says it will achieve this by 1998.
Jean-Eric Winckler, head of the French army鈥檚 press office, claims that
鈥渘othing is contaminated at Mururoa鈥�. All buildings and concrete are being
removed, except for a road, a testing laboratory and housing for 30 members of
the French Foreign Legion who will remain.
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However, during atmospheric nuclear tests over the atolls in the 1960s, a
bomb crashed onto Mururoa. The debris was covered with asphalt which, says
Winckler, was 鈥減ut in special containers and buried鈥� on the atoll. But Roger
Clark, a geologist at the University of Leeds who specialises in nuclear issues,
describes this method of dealing with high-level waste as 鈥渃avalier鈥�. He points
to the 鈥渕ajor technical problems鈥� facing the US at its proposed waste repository
in Nevada, where plans are being drawn up to bury high-level waste inside a
mountain. That project could yet be abandoned because of safety fears. And
unlike Mururoa, Nevada has no groundwater problems to worry about.
The underground tests have also created cavities in the rock which some
scientists believe pose a more serious danger. According to Winckler, there is
no risk because the radioactive material 鈥渋s all vitrified in the rock鈥�. Shafts
drilled to sample rock near the cavities have been plugged with concrete, he
says. But Manfred Hochstein of the University of Auckland says residual heat
from the explosions could create convection currents, increasing the flow of
water through the rock towards the surface. He points out that sediment from
Mururoa lagoon sampled by the explorer Jacques Cousteau in 1985 contained
isotopes that could only have come from underground nuclear tests (This Week, 1
September 1990, p 12). 鈥淲hat we don鈥檛 know is whether enough can escape to pose
a problem of toxicity,鈥� he says. Richard Anstiss of the Auckland Institute of
Technology says Cousteau鈥檚 data and models of the atoll show that convection
could cause enough leakage to be toxic.
To investigate the dangers, an international team led by the UN鈥檚
International Atomic Energy Agency is now taking samples on the atolls. Alan
Poletti of the University of Auckland, a member of the team, says the scientists
are free to take as many samples as they need. The team will report its findings
in December.
Hochstein says that monitoring should continue because convection cells can
take 30 years to develop. But Winckler says that once the UN has completed its
report, further monitoring will be done by France and not by independent
scientists. 鈥淭here is no question of some foreign outfit coming and
诲颈驳驳颈苍驳.鈥�