Japan’s nuclear crisis worsens with third explosion

Tokyo: Japan's nuclear crisis worsened with a third explosion rocking the crippled Fukushima nuclear park and officials acknowledging for the first time that radioactive fuel inside one of the damaged reactors was in jeopardy of melting down. In escalating the crisis, apart from natural factors such as an earthquake and a tsunami, human error too has begun to play a part as fumbling workers at the n-plant have made mistakes with grave ramifications.

Hedging his response, chief government spokesman and chief cabinet secretary, Yukio Edano, said at a news conference Tuesday that the Fukushima reactor, about 150 miles north of Tokyo, "…is not necessarily in a stable condition."

Prime minister Naoto Kan called the situation "worrisome."

Adding to Japan's perfect storm of woes, strong aftershocks have struck a wide area since Friday's quake and Japan's Meteorological Agency warned Saturday that there was a 70% probability of another powerful temblor in the coming three days.

Tokyo Electric Power Co (TEPCO), which owns the Fukushima plant, acknowledged that human error was responsible for fuel rods inside the plant's No 2 reactor being at least partially exposed to air for more than two hours. This exposure allowed them to heat up and cause a build-up of explosive hydrogen gas. The third explosion followed as a result.

Heated fuel rods react with water and produce hydrogen gas that vents from the reactor into the containment building. When enough hydrogen accumulates, it becomes explosive. It is this chain reaction that has been responsible for two explosions at containment domes around two other reactors at the Fukushima complex on Saturday and Monday.