Armed Japanese vessels were on stand-by as the Pacific Teal gave up 210 kilograms of mixed oxide plutonium and uranium (MOX) after a three-month journey along a secret 20,000-mile route.
The arrival of the Teal, and its sister ship Pacific Pintail, has provoked controversy in Japan since this newspaper's disclosure that some safety checks on MOX pellets, manufactured in Britain, had been faked.
Yesterday's cargo was made by the French reprocessing plant run by Cogema at La Hague, but the Pintail's MOX was made by British Nuclear Fuels at Sellafield in Cumbria. It was there the company admitted 22 quality control data sheets had been fabricated on a separate consignment. When that arrives at a plant in Takahama run by the Kansai Electric Power Company in a few days more protests are expected.
Yesterday, 10 inflatables were launched from the Greenpeace ship Arctic Sunrise, carrying protesters bearing banners in Japanese that read: "Plutonium Kills".
Greenpeace has been using the controversy to try to persuade the British Government not to issue a licence for a pounds 300m plant in which BNFL plans to mass produce MOX. Until now, only small amounts have been made. Pete Roche, a Greenpeace nuclear campaigner, said: "After last week's revelations about faked safety checks at Sellafield, Tony Blair should alert the Japanese Prime Minister to the fact that Britain cannot guarantee the safety of this fuel in use."