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Friday, May 20, 2011

Fukushima Daiichi update; Friday evening 5/20

TEPCO has released photos taken at Fukushima Daiichi as the tsunami hit. I've assembled them into a slide show movie and the sequence is now available on the Atomic Power Review YouTube Channel. Link to new video below.

Tsunami Hits Fukushima Daiichi

In other news... TEPCO has further increased the rate of water injection to the reactor at No. 3 plant at the Fukushima Daiichi site. TEPCO is now injecting a total of 21 cubic meters per hour to the plant; 9 through the fire extinguishing line and 12 through the feed system. Prior to today, the rate had been 18 cubic meters per hour, 9 each system. This rate had existed since May 17th, when the feed line was increased from 6 to 9 cubic meters per hour. The feed line was added to the fire extinguishing line as a source on May 12th.

This continuous increase is of interest; also of interest is the injection of 180 kg of boric acid on May 15th from 14:33 through 17:00. Soon after this, there appears on the temperature tracking graphs released by TEPCO a sharp rise in a number of temperatures, particularly those at the top of the RPV but also at least one related to a downstream (tailpiece) temperature reading on a steam relief valve. There was also a drop in RPV indicated water level that this increasing of feed rate has corrected.. the drop in level occurring before the borated water was added. I'm both looking for more details on this and waiting for another TEPCO press release that might mention their thinking.. and their suspicions.

One further note released by TEPCO which is not particularly surprising is the discovery of about 12 feet or so of water in the reactor building basement at No. 1 plant. I say not surprising, because everyone knows by now that the water is going somewhere after injection.. and that string of "somewheres" starts in the reactor building.

Finally for now... TEPCO has a diagram showing what exactly it means when it says that it will apply grout to the suppression chamber ("toroid") at No. 2 plant. Essentially, TEPCO intends to fill the whole room with concrete, it appears, from the illustration below. This will seal the chamber and allow recovery vis a vis cooling of the core to go forward.


9:00 PM Eastern Friday 5/20
ATOMIC POWER REVIEW

2 comments:

  1. Do you have a concrete idea where the fuel/corium is located in any of the units? Is it still in the RPV or melted through?

    See also this comment:

    http://ex-skf.blogspot.com/2011/05/hiroaki-koide-of-kyoto-university-no.html

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  2. @ashen: I am of the belief that most or all of the fuel material is still in the pressure vessels of all three reactors, although it is also very possible, and .. given the numerous studies done on the subject both prior to the use of, and after the use of, complicated computer models .. that some amount may have exited the pressure vessels through some of the penetrations at the bottom end of the RPV's or through other failed piping connections. The high recurrence of this type of result in the studies is high enough we cannot rule it out until a much more thorough examination of the plants is possible.

    I would think, looking at that link, that right now the clue that corium is not eating its way down through the containment and below is the fact that TEPCO isn't reporting any massive gassing that you would expect to see with the corium-concrete reaction. I see that the person making those comments is well educated on the subject, but is decidedly anti-nuclear, so that his worst-case scenario diagnosis is not all that surprising to me. I would post immediately if I saw evidence that looked like this was occurring -- in fact, I was one of the very earliest reporters with experience in nuclear power to declare that Fukushima Daiichi was actually an accident with certain core damage. I just don't see right now the evidence that the cores have fully melted out of the pressure vessels... given the data we are able to read from TEPCO and other cognizant government agencies. (Which is a LOT more than I post on the blog, by the way, so as not to clutter it with huge colums of facts.)

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