Thursday, May 5, 2011

#Fukushima I Nuke Plant: Human Workers Entered Reactor 1 Building, Installed Air Filter Pipes

(UPDATE: The maximum radiation that the workers received by braving the Reactor 1 reactor building exceeded 3 millisieverts. It was 3.16 millisieverts, as announced by TEPCO in the morning press conference on May 6.)

For the first time since the Reactor 1 blew up on March 12, human workers entered the reactor building to install pipes for the air filtering system that they are building outside the reactor building. TEPCO hopes to lower the radiation level using this system to the level low enough for more human workers to work in the reactor building long enough to set up an external cooling system for the reactor.

Points from Asahi Shinbun (in Japanese; 5/5/2011):

2 TEPCO employees entered the reactor building at 11:32AM on May 5 to measure the radiation level.

13 workers installed pipes for the air-filtering system by 3:08PM.

The workers were equipped with air tanks so that they wouldn't breathe in radioactive materials. The work was scheduled so that each worker would not receive more than 3 millisieverts. The maximum radiation exposure was 2.8 millisieverts (provisional number).

TEPCO will run the air-filtering system for 24 hours. The air inside the reactor building goes through the pipes, through the air filters to reduce the amount of radioactive materials and circulate back into the reactor building.

If the radiation level is lowered according to the plan, they will start assembling the external cooling system in the reactor building on May 8.

The article is a bit puzzling because it talks about the cooling system using water. But the talk was to build an external cooling system with air, as Yomiuri reported (in Japanese).

That aside, if the max exposure limit was 3 millisieverts per worker and the radiation level inside the Reactor 1 reactor building was between 10 and 1,120 millisieverts per hour, the time a worker could have spent inside the reactor building was anything from 9.6 seconds (1,120 millisieverts/hr location) to 18 minutes (10 millisievert/hr location).

How can the air-filtering system filter out radioactive materials from the air inside the reactor building, when there is practically unlimited source of radioactive materials - i.e. reactor core which has been melted, at least partially if you believe TEPCO and the Japanese government, completely if you believe Mr. Ishikawa of the Japan Nuclear Technology Institute?


Majia's Blog said...

The whole story does not make sense. 8 days Bloomberg reported record radiation coming from unit 1. As you note, workers would only be able to spend second in there under those conditions.

Unless, of course, they were completely expendable.

And you do a good job pointing out there is "practically unlimited source of radiation"...

What is coming from unit #4? Is it smoke or steam?

What a mess...
"Radiation readings at Japan’s Fukushima Dai-Ichi station rose to the highest since an earthquake and tsunami knocked out cooling systems, impeding efforts to contain the worst nuclear crisis since Chernobyl.

"Two robots sent into the reactor No. 1 building at the plant yesterday took readings as high as 1,120 millisierverts of radiation per hour, Junichi Matsumoto, a general manager at Tokyo Electric Power Co., said today. That’s more than four times the annual dose permitted to nuclear workers at the stricken plant...."

netudiant said...

It is not an impossible task, but it surely is close to it. The hope is that with aggressive air filtering the area will be safe enough for work crews to rapidly connect new nitrogen and water lines along with additional sensors, to allow the cooling water for this reactor to be recirculated. The shifts will need exceptional preparation and luck to do this without lifetime radiation doses.
It is still incomprehensible to me that this crisis, which threatens the heart of Japan, is such a peripheral issue in the Japanese media and that there is no sign of a national resolve to get this fixed. Instead, there are absurd comments such as the recent one that TEPCO would pay compensation> With what? That firm cannot even cope financially or managerially with the immediate disaster at their plant, much less with anything in the surroundings.
Must the Emperor stand up to say that Japan is in danger and needs to be defended, because no one else has the status to say so?

arevamirpal::laprimavera said...

@netudiant, it is mind-boggling how Japanese media and government manage to drive the Fukushima disaster, and for that matter, recovery from earthquake and tsunami, out of the minds of the residents there. They are eagerly debating how to raise more taxes to pay for every pet projects they have (which they present as "recovery" projects). Recover from what?

There are so many people still living in school gyms partitioned by cardboards, with no shower and very little food even though the food and water are spilling out of the government depots. No shower yet on site for fukushima plant workers either.

@Majia, they must be considered expendables, by the way they've been treated. How else would the government allow them to go on for weeks and weeks without proper air filter, without even mattresses, shower, hot meals, clean underwear and socks? The government has said it is TEPCO's problem.

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