TEPCO Readies Plan To Bring Reactor Under Control

Kyusaku Natsume writes "TEPCO has released details of their plan to bring Unit 1 of Fukushima Daiichi under control, to improve the working conditions inside the reactor building of this unit and install a new cooling system. From the success of this operation maybe we will know how they will address the emergency in the remaining damaged nuclear reactors."

Comments

Reasonable first steps

[Animats]

That's just the very beginning - hook up an air filtration system so humans can briefly enter the containment. Then try to hook up a water level gauge for the reactor pressure vessel, so they can actually tell how much of the core is uncovered. Then they can think about what to do next.

All this work is taking place in partially collapsed buildings where explosions have destroyed the structure. Ordinarily, one would bring in big cranes with grabs and start removing debris. But they can't do that.

The situation remains dangerous as long as there are still many red blocks on the JAIF's status chart. Note that reactors 1,2, and 3 still have not reached cold shutdown, where the reactor core is below the boiling point of water, all steam has condensed to water, and pressure in the reactor vessel is down to one atmosphere. All the ad-hoc cooling measures aren't enough to get the core temperature down. Normal time to cold shutdown for a GE Mark I reactor is about a day. Even at Three Mile Island, it took only about two days to reach cold shutdown.

Re:Reasonable first steps

[Anonymous Coward]

Humans are not entering the "containment". They are entering the reactor building. Reactor building was damaged - especially the top floods. It was not damaged at the bottom, where the cooling equipment is.

Reactor 1 is being tried first because the building as the least amount of radiation. The robot that went in measured about 40-50mSv/h. This is reasonably low and can be brought down further.

The reactors are not in cold shutdown because there is no water cooling. They *could* achieve cold shutdown quickly by water in faster, but it would not help the situation. They need to repair the recirculation pumps and find the leaks and plug them. They also need to find out if there is any hydrogen in the reactor vessels and to deal with that. These 2 reasons is why cold shutdown mode is very BAD right now - they had to slow down water pumping to prevent pressure from dropping as that could cause air to be sucked into the reactor and hydrogen could burn (explode), if there is any hydrogen there.

Don't second guess them now. They are doing things very carefully.

TEPCO failed at not having prepared for the scenario when the plant suffers complete blackout, including all backups being flooded. That's all. Had they had prepared for this scenario, this would not have happened. Period. Now they are dealing with consequences and I'm certain that plans will now be in place that no nuclear reactor will melt even if they lose all cooling - ie. external emergency cooling will be setup before coping batteries die.

Re:Reasonable first steps

[DerekLyons]

Even at Three Mile Island, it took only about two days to reach cold shutdown.

No, TMI-2 didn't reach cold shutdown until 27 April - nearly a month after the accident.

Re:Reasonable first steps

[Anonymous Coward]

Don't second guess them now. They are doing things very carefully.

How dare you try to stop me from being an overly critical armchair nuclear physicist! Who are you to curtail my freedom of speech? Some hoity-toity reactor expert I'd suppose?? Why don't u take off ur white coat and roll up your sleeves like the rest of us? .. oh, not willing to get ur hands radioactive I suppose?

I thought this was a democracy? I'd suppose ur one of them neo-fascist high-folutin Republican extremists? Harry S Truman would've sorted u out good proper like!

Re:Reasonable first steps

[Idou]

That's all? So TEPCO did not falsify safety inspection records, cover-up a defective reactor, use the yakuza to get expendable workers, continue on with a foreign journalist QA session even without the foreign journalists, or make numerous blunders immediately after the tsunami to put us into the current situation ?

What a relief . . . here I was thinking TEPCO would become the poster child of the part of Japanese society that remains corrupt, arrogant, and incompetent. Good thing they have apologists like yourself . . .

Re:Just Unit 1?

[antifoidulus]

Well, we have the dummy plug, and SEELE is sending us the 5th children so I think everything is going to be A OK!