Saturday 17 December 2011

Cold Shutdown

The Prime Minister today announced that Step 2 of the roadmap has been achieved and Fukushima Daiichi has reached cold shutdown ahead of schedule. The temperature at the bottom of the pressure vessels in all 3 reactors is stable at well below 100'C ( 2,000'C at the time of the accident), there is a cover on Reactor No.1 and the emission of radioactive materials is slight: one of the standards was to get it down to 1mSv/hr around the plant. A cooling system is working for all four fuel pools. Actually there's nothing new to report since I posted Update on 31 October but the government is hailing this as a milestone, the 'end of the accident' (jiko no shusoku 事故の収束).

We're glad things are under control and emissions are down. The workers at the plant have done a great job. A few weeks ago Yoshida, the man who's been in charge since the disaster, was taken to hospital for health reasons. He's something of a hero in these parts (at the time of the explosion he famously disobeyed an order from head office and continued to inject seawater into the plant) and he's worked selflessly and tirelessly ever since. We were worried that he might have got radiation sickness. It turns out to be (by his own admission) cancer of the oesophagus so is probably not connected with the accident. We wish him a speedy recovery.

Although it may be the end of the accident phase there are still many unknowns. First, the temperature at the bottom of the pressure vessels may be under 100'C but the fuel has melted through  and is sitting on the concrete floor of the containment vessel. Temperatures there are not known. Only when the reactors are opened up will they know for sure and since levels inside the reactors are high and there is so much debris this won't happen for a long time. Secondly, there have been worrying announcements in the last few weeks: that fuel in Reactor No.1 has burnt through the 2 m concrete floor of the containment vessel leaving a rim of only 37 cm., that there are leakages of water etc.

It may be the end of the accident but for us this is the start. Or as Hosono, Minister for the Nuclear Accident, put it, 'korekara ga honban' (これからが本番). Time to get on with the Clean Up and get back to normal. The big question is when can the 160,000 evacuees go home? Can they go home? They've been in limbo for nine months but they may be getting answers soon. The government today announced guidelines which it is going to discuss with local leaders over the weekend. Areas with external radiation of under 20 mSv/yr are to be cleaned up so the evacuation order can be lifted. Areas above 20 mSv/yr will have some restrictions. People will not be able to return to areas showing over 50 mSv/yr. These are huge areas: all of Futaba-machi and Namie-machi and part of Iitate-mura.

Step 2 may be over but it's going to take 40 years to fully close the plant. Hosono, the Minister in charge, said he was committed to seeing it through: either getting people back or seeing they get proper compensation. He's 40 so with a bit of luck he might see it through - but it's not going to be done in my lifetime.

Meanwhile, the governor has announced that Fukushima is to be a no-nuclear prefecture. The four reactors at Fukushima Daiichi are to be closed but there are two more, 5 and 6, and then four more at Fukushima Daini. These are currently closed for safety tests but could be re-opened. It's a brave decision as the nuclear power plants provide jobs and generous government grants. But his stance reflects the wishes of the majority. So new energy companies, please flock to Fukushima!
Bye for now

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