The claims come two weeks after The Independent revealed that checks at the company's Sellafield plant in Cumbria had been falsified. At the time, BNFL insisted that the falsification involved only fuel under production in the UK - not the consignment due to dock in Japan today.
However, an investigation into that fuel, earmarked for the Takahama 4 reactor in Fukui prefecture, has shown that one rogue set of tests might have allowed imperfect mixed plutonium and uranium oxide (MOX) pellets through the safety net. Information supplied by BNFL to the Kansai Electric Power Company, which runs Takahama 4, also shows the British company knew that data had been falsified as early as 20 August, but did not tell Mitsubishi, Kansai's contractor, until 9 September. The Independent had been making inquiries around this date and challenged BNFL on the 10th. Kansai was not told until the 13th, the day before the news broke.
Suggestions that one batch of pellets on board the Pacific Pintail, which is carrying the BNFL MOX, might be suspect follow an examination of data by Professor Hidiyuki Koyama, of Osaka Prefectural University, on behalf of anti-nuclear campaigners. It relates to tests on a batch of 200 pellets, numbered P824, in which 68 bore exactly the same microscopic measurements as their corresponding numbers in the previous batch. The suspicion is that the results were simply copied to save time.
BNFL said Kansai and the Agency of National Resources and Energy in Japan accepted its figures and were happy that the fuel on board Pintail had not been subjected to falsified tests.