Mitsuhiko Tanaka, a former Japanese reactor engineer says that he assisted in covering up critical design flaws, known to him and others, when working on the nuclear plants in Fukushima, in 1974. Many engineers were aware that reactor No 1’s diesel powered back up power generators had sustained over 33 stress cracks leaving them vilnerable to rain and seawater. Despite this the regulators granted an extension to the operational lifespan of the reactors shortly before the earthquake last month. When the quake hit, the power to cool reactor No 1 and the other reactors was lost in hours. Tanaka said that all of the reactors should have been shut down or replaced long ago. If the pipes and machinery had worked, the radiation leaks probably would not have been as significant. Tanaka originally brought his allegations before the Ministry of Economy, Trade and Industry in 1988. Tanaka says the reactor pressure inside No 4 was damaged at a Babcock-Hitachi foundry in Kure Hiroshima during the last step in the manufacturing process.