Japan Nuclear: Cleaning up the reactor sites at Fukushima

Getting the water out is the first priority

Over at Atomic Insights blog my friend Rod Adams asks whether the radioactive water at the devastated Fukushima nuclear site in Japan is such a big deal. He writes, ? . . . a million gallons of water is a rather modest amount of water.?

The basis for this dialog is my blog post at the American Nuclear Society blog ANS Nuclear Cafe titled Decommissioning Fukushima which was published April 6th.

Worker safety

In his blog post April 8, Rod says that I?m overly concerned about risk of exposure to the radioactive water by plant workers. Considering that TEPCO initially sent some people on to the damaged site without dosimeters, I am concerned about their safety. That doesn?t mean I am seeking perfection. The Kyodo English news wire service for April 1 reports:

?The government's nuclear regulatory agency said Friday it had issued another warning to Tokyo Electric Power Co. over the management of workers' radiation exposure at the crippled Fukushima Daiichi nuclear power plant, after it was found that there were not enough dosimeters to cover all of the workers.?

Uncontrolled water at Fukushima

The difference at Fukushima is the radioactive water is not inside a reactor cooling circuit. A lot of it is in an uncontrolled state flowing down the sides of buildings into storm drains, into the sea, etc.

Rod says that as a former nuclear submariner, he understands water and that I, as a desert rat from Idaho's Arco lava beds, do not. I agree that Rod certainly has the edge understanding water in nuclear reactors. However, even in ?sun-dried Idaho,? when water shows up at a nuclear facilities in a place where it doesn?t belong, it sets off a cascade of communications.

The operator making inspection rounds notifies the shift supervisor who notifies the plant shift supervisor. Radcon is dispatched to survey the water for radioactivity. A system engineer is dispatched to evaluate the situation along with a spill response team.

That?s a summary of plant procedures at a fully staff, undamaged facility. The situation at Fukushima is anything but normal.

What to do about the water

I don?t know what TEPCO is doing about capturing radioactive waste water after fresh water is being sprayed on the spent fuel pool at Unit 4 and on Units 1-3. It seems to just about everyone that doing so would be a good idea.

The amount of fresh water being sprayed just on the spent fuel pool at Unit 4 is estimated to be in the range of 200 tons of water a day. A gallon of water weighs 8.35 pounds which yields [200 * 2000]/8.35 or about 48,000 gallons. Additional amounts of water are being sprayed on Fukushima Units 1-3.

So, there is a lot of water and it is not not controlled once it leaves the spray hose from the top of the pumper boom. (see image right ? the red ?stick is the pumper boom taking water to the damaged secondary containment area over spent fuel pool at Unit 4)

Here are some initial thoughts about where it is going after it hits the reactors.

There is evidence from photographs that there is some loss to evaporation based on steam plumes from Units 2 & 4.

A worst case is that the water cascades to the ground running into storm drains and on to work surfaces at ground level. Also, it may be entering pits, conduit trenches, and other underground spaces. Storm water drains probably discharge into the sea which would account for radioactivity found some distance from the shoreline.

With all of these pathways to the surface, from the spent fuel pool about four stories up in the secondary containment building, it might be difficult to figure out how to curtail the various pathways to pooling on site or flowing out to sea.

Logic would suggest that getting the installed cooling systems inside the reactors working again is the fastest way to stop the uncontrolled flow of radioactive water outside them and around the site. TEPCO will have to find a way to determine the condition of the pumps and piping in order to decide if this is a feasible solution.

There is an interesting news report in the NY Times for April 8 which notes hundreds of engineers from Toshiba / Westinghouse are working on the decommissioning issue. Also, Toshiba said in a Reuters news report it thinks it can complete decommissioning of the four reactors by 2020.

Access issues

Also, Rod says that people and supplies to respond to the damaged reactors can be brought to the site by sea. He?s right about that up to a point since the docks and pilings for the plant were also damaged by the same 15 meter high tsunami that swept over the sea wall.

In that blog post, I wrote that access to Fukushima by road or rail would be a problem due to earthquake damage. The Wall Street Journal for April 6 reports on how a Japanese civil engineering firm used its most experienced crews to clear the roads. Their work started March 16. Hopefully by now some of the debris has been removed from roads. Restoring rail access could taken longer. Rebuilding railroad lines from scratch, including signal equipment, is not easy or quick.

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