Two weeks ago marked the fifteenth anniversary of the last nuclear weapon test in French Polynesia, which took place on 27 January, 1996.
When the French military carried out 147 underground nuclear tests in the atolls of Moruroa and Fangataufa between June 1975 and January 1996, they wiped out all expressions of concern about the effect of the nuclear blasts for the structural stability of the atolls. Unfounded, unrealistic, alarmist and deliberately misleading were some of the adjectives used against against the nuclear test opponents. There was no risk of collapse, and no risk of leakage of radioactive substances into the Pacific Ocean, they said.
So I was interested today, when my attention was brought to the fact that on 27 January, coincidentally on the fifteenth anniversary of the last nuclear explosion in French Polynesia, the local newspaper Les Nouvelles de Tahiti revealed that during a guided tour on Moruroa for local Polynesian media, the Ministry of Defence's Delegate for nuclear safety recognized that the risk of collapse was real.
According to Les Nouvelles, the Ministry of Defence now envisages that -- depending on the characeristics of the geological damage -- "several dozen million cubic metres" or "hundreds of million cubic metres" could fall into the sea anytime now. According to the Ministry of Defence the collapse of a bloc of about 100 million cubic metres would create at the site a wave of less than three metres, hence hardly perceptible on the nearest inhabited atoll of Tureia. But the Ministry says also that if 600 million cubic metres were to crack, this would cause a tydal wave of six to eight metres, which according to the Ministry's calculation would still measure one to two metres when it reaches Tureia, a cosiderable height for a low-lying atoll. According to the Ministry's best bet a wave at the site of between ten and twenty metres can be expected, thus liable to flood the nearest inhabited atoll.
The Defence Ministry maintains the theory the radionuclides trapped in the basalt under the coral would not leak into the surrounding marine environment even in the worst geological scenario, because they were vitrified by the extreme temperature during the nuclear blasts. It is hard to find this argument convincing, though, because what it means is that at best the rock has become an unpackaged solid radioactive waste liable to leach out and which according to internationally accepted rules of radioprotection should not be dumped and left in the sea. And of course the argument is even less reassuring when you think that it is given by the very same people who, not long ago, were denying the possibility that blowing dozens of nuclear bombs under these atolls could ever affect their geological stability.