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Fukushima Stabilization Plan

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Overview of major countermeasuresOn Sunday TEPCO released a rather ambitious plan for stabilization of the three reactors and the #4 spent fuel pit. The presentation by the utility is quite dense so let’s take a detailed look at it. The immediate plans involve shoring up the existing temporary reactor cooling systems and gaining control of the radioactive wastewater situation, particularly in Unit 2 where the containment is damaged and leaking water.

Intermediate term plans include the water entombment of Units 1 & 3 (filling the containment building with water up to the level of the fuel.) and attempting to grout the leak in Unit 2. Other plans include the installation of a water treatment plant to desalinate and decontaminate the water that is being pumped from the turbine buildings and Unit 2.

Longer term plans include building a containment structure over each reactor building, similar in concept to the sarcophagus erected over Chernobyl (but hopefully of higher quality.) The utility hasn’t stated as much but the illustration (above) seems to show a girder structure covered with some sort of tough fabric, perhaps something like they put on domed stadiums in the intermediate term, followed by concrete and steel buildings later.

TEPCO announced today that the French firm Areva has been given a contract to construct the on-site water processing facility. (This should be an American company but alas, our politicians chose to walk away from the nuclear option many years ago. Lots of good jobs gone bye-bye.)

The TEPCO documents detailing the plan are here, here, here and here.

Roadmap for immediate actionsSpecifics

Short Term (three months)

Mid-Term (3-6 months)

Longer-Term

iRobot Entry

irobotA US-supplied robot has been used for the past several days to peer around and take measurements inside the reactor building air locks. The radiation measurements don’t look promising. Levels around 7R/hr were measured just inside the Unit 3 and slightly lower values in Unit 1. These levels are, of course, too high to allow any significant amount of work to be done. Unless they use a lot of “jumpers”, that is. (A jumper is a person without significant previous radiation exposure that is used to do short term work in a high radiation field. He uses up his annual exposure limit and then he is transfered out or laid off.)

Inside the air locks the radiation levels were 27R/hr in the Number One reactor, 1.2R/hr in Number 2, and 10R/hr in Number 3. This indicates that something quite hot is on the other side of the air locks. There is a pump adjacent to the air lock that handles reactor water so that may be the source.

110419 1f 3Or as can be seen in this photograph taken by the robot, the control rod drives are just inside the door (shiny tubes to the left under the white drape. These are also connected directly to the reactor and so may contain highly contaminated water. In any event, not much work is going to go on in that environment.

Since some of the utility’s plans as described above involve working in the reactor building, I don’t have a lot of hope for them achieving the time schedule they’ve specified.

Other Stuff

In this section I’m going to throw up some photos of the plant that show the damage done by the tsunami. As with all the photos on this page, these came from TEPCO

110422 2f tsunami 7Before photo of the rear of the plant

 

 

 

 

 

110412 2f tsunami 6“During” photo of the same area.

 

 

 

 

 

110412 2f tsunami 5High water mark.

 

 

 

 

 

110411 2f tsunami 2Photo showing damage to a high security door and the MCCs (motor control centers) behind them. This is probably at the seawater intake system area. This photo shows just how much damage the tsunami did to vital systems. This is why TEPCO has decided to build an external reactor cooling system instead of trying to recover the in-plant system.

 

 

110411 1f tsunami 1Seawater intake area. The damage is unbelievable.

 

 

 

 

 

110411 1f tsunami 2Another view of the seawater intake area.

 

 

 

 

 

110411 1f tsunami 4Ocean side of a support building.

 

 

 

 

 

110412 1f tsunami 5Another support building. If you look very closely you can see the high water mark.

 

 

 

 

 

 

 

Posted by neonjohn on April 19th, 2011 under Energy, Nuclear


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