APR: your source for nuclear news and analysis since April 16, 2010

Tuesday, April 5, 2011

Good overhead view of Fukushima Daiichi / update

TEPCO has done us two favors at once. First, it has revealed just exactly where the now-media-permeating "7.5 million times" sample was taken... inside the breakwater as we might have thought... and it did this along with a fabulous overhead diagram of the portion of the Fukushima Daiichi site that covers reactor plant complexes No. 1 through No. 4. I have colored the reactor buildings red and the turbine buildings gray (with service building spaces between the turbine buildings) to help those who get glazed eyes looking at line drawings. Note the green pipe trench / tunnel routing, and the accompanying purple cable tunnels.
Click to enlarge!

Note that I've marked NORTH on the drawing, and that when viewed as seen here the Pacific Ocean is off the top of the illustration. Many other features can be noted on this illustration and I expect we might use it again, perhaps marked differently, for later articles.

Briefly, TEPCO seems confident that the "liquid glass" or sodium silicate injection into the area below and around the tunnels is starting to have effects on the positive side in stemming the leakage rate into the sea. It appears that there is a gravel layer supporting and perhaps around some of the cable and pipe tunnels that are nearer the surface; TEPCO is filling the voids in this material by injecting the sodium silicate which expands and plugs it. More details to come.

9:45 AM Eastern Tuesday 4/5


  1. Couple of quick questions. You seem to think that the 7.5 million times above the legal limit measurement being within the breakwater as very reassuring. In particular you mention the measurements at the 15km line being within safe levels.

    I appreciate we don't have solid information on this but to be have an estimate of the volume of water discharged which was at the 5 million - 7.5 million times the legal limit? If the highly irradiated water only started to leak recently would traces of it have the time to reach the measurement point 15 km out? How many measurement points are there and has there been any modelling/thinking been done as to where the currents would take that discharge? Do we have confirmation of what the isotope mix of the discharged water is? Does it only contain the elevated levels of Iodine mentioned?

    Anyway, any water with that level of contamination outside the facility should be a serious cause for concern. Once you start dealing with discharge which needs to diluted into 7.5 million times its volume of water to be considered safe then any significant volume entering the environment is bound to have at least a local effect.

    In any case, once you have the volume discharged and information about what it contains surely it should be possible to generate at least some basic models of how it will spread and likely concentrations at various points.

  2. Ah, just saw the report stating caesium-134 was 2 million times above the levels permitted and caesium-137 was 1.3 million times above.

  3. @modular... The level isn't reassuring... it just isn't surprising, given the proximity to the plant at which it was detected. This of course is being left out of many media reports, and if they mention the location they seem to be giving themselves the letout that "dilution is uncertain."

    We don't seem to have solid data as to how long there has been monitoring at this particular point, right outside the water inlet screen and seawater pump pit. I have a feeling that highly contaminated water has been getting to sea one way or another, in greater or lesser amounts, depending on some variables, for some time now. (I won't speculate further.)

    Remember; the discharge of large volumes of water from the rad waste facility, central fuel storage facility, and turbine building drain pits of No. 5 and No. 6 plants is NOWHERE near the contamination level of the water in No. 2 plant's turbine building, pipe tunnels and cable tunnels. What does that mean? It means that the figure of 7.5M times the limit right outside the inlet at No. 2 plant is due solely to the leak rate, whatever that is, from No. 2 plant alone and not due to the total 11,500 tons of water contaminated to low levels that TEPCO is continuing to discharge offshore. It's important not to get these very different aspects (large amounts of low contamination, relatively small amount of very high contamination in terms of water masses) mixed up because their destinations are very different.

    In other words, finally, the 7.5M times the limit detection point is kind of like putting your nose right up to the exhaust pipe of a bus. Of course it's going to be very bad right there; you need more data on dispersion which we don't have yet (except that the current at the moment seems to be roughly S/SE.) But the important distinctions I've made in this comment response, and in the blog posts, are being (deliberately) left out of many big media reports.

  4. Hi...
    Fantastic blog of atomic power review and these diagram are very nice.Plugs and Tunnels