Japan’s nuclear crisis may take nine months to resolve, according to the first timetable released by Tokyo Electric Power, operator of the crippled Fukushima atomic plant.
Tepco on Sunday unveiled a plan – its first since Japan’s March 11 tsunami critically damaged the power station – to stop permanently the radiation leaks that have contaminated the surrounding air and sea and forced tens of thousands of residents from their homes.
The company, which has faced harsh criticism for its handling of the crisis, said it would take three months to create a stable water circulation system to cool three overheated reactors and four spent-fuel pools.
Another three to six months would be needed to achieve a “cold shutdown”, it added. That would reduce the temperature inside every reactor below 100°C at atmospheric pressure – meaning that the radioactive fuel will not heat up again.
Tepco has faced intense pressure to explain how, and when, it will end the crisis. On Sunday, Tsunehisa Katsumata, Tepco’s chairman, suggested that top executives would resign over the accident.
“I feel responsibility……and so does our president,” he said, referring to Masataka Shimizu, the executive who is nominally in control of Tepco’s day-to-day operations but who has been ill during much of the crisis.
Government officials said evacuees would have to wait at least until the “cold shutdown” to return to their homes, though experts say it could be years before residents of the worst contaminated areas can do so.
To meet the timetable, Tepco engineers must cool down radioactive uranium fuel and deal with thousands of tonnes of contaminated coolant water that has collected under the site.
The two tasks are to some extent in conflict. Cooling requires large injections of water, but damage caused by hydrogen explosions means that the more water engineers pump in, the more will leak down into service tunnels and other low- lying areas – from where it could escape into the sea.
One possible new approach is to flood the reactors’ containment chambers with enough water to immerse the steel pressure vessels that hold the fuel. So far, Tepco has been pumping water directly into the pressure vessels – the usual procedure for cooling a reactor – but adding coolant to the normally dry area around them could help bring their temperatures down faster.
Before it can do so, however, engineers must find and seal leaks. The plan also calls for the blown-out reactor buildings to be covered to keep in air.
Once a “cold shutdown” has been achieved, the long decommissioning effort can begin. The whole process is expected to take at least a decade.
（Source:FTchinese.com By Jonathan Soble in Tokyo）