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

Saturday, April 16, 2011

Saturday morning update

Unfortunately, your author suddenly became quite ill yesterday and hasn't been on his feet since. However, he's back vertical temporarily and here are the most important updates since the last post.

TEPCO continues to try to stop any and all leakage of contaminated water into the ocean by the use of further plates outside the plant seawater inlet screens, and the use of zeolite in large bags to trap radioactive particles in the water. While the vast majority of the coverage on Japanese television stations and other media there is focusing now on the problems being suffered by the evacuees, there continues to be a major focus outside Japan on the effect that spread of radioactive contamination will have in the Pacific fishing business. This cannot be denied, but it shows the focus of those not living in the disaster area.

The dewatering problem at the Fukushima Daiichi plants continues to slowly get more ponderous as water being deposited into the very complicated universe of buildings, pipe tunnel connections, drain pipes and drain sumps, various cracks in the outside and the substrate material continues to grow in volume; yet, it is necessary to clear the turbine buildings of this water in order to stop the supply. Apparently new reviews by NISA and TEPCO indicate that only half the theoretical maximum volume in the plant main condensers can now be used for water storage, since with the weight involved at a higher level they're not guaranteed safe in another earthquake. This loses TEPCO about 3750 tons of water storage capacity it would like to have used.

Further work continues on-site but not right in the plants to clear the area of rubble using the aforementioned remotely-controlled construction equipment, and more spraying of polymer to fix the radioactive debris and dust to the ground has been accomplished.

Electrical distribution gear for the core supply pumps at Fukushima Daiichi have been moved up to a nearby hill, as part of the overall action (being taken at every nuclear plant in Japan, to some extent, too) to prepare for any further earthquakes and tsunamis.

Temperatures at No. 1 plant continue to lower, while pressures remain steady. None of the plants is rising in temperature or pressure at this time.

The most interesting news of the day is the still developing story that TEPCO has ordered a large number of special heat exchangers, planned for a new external cooling system that it will construct for each reactor plant. This is a novel approach, and probably the best idea TEPCO has had yet. According to the Kyodo story, TEPCO will use several heat exchangers for each plant, and will connect them to the existing external emergency connections that it's been using prior to this for core injection. Apparently TEPCO will use electric pumps, and two core connections to establish recirculating cooling flow and then use hoses to bring in and return seawater, if we understand the plan correctly. No timeline is given on this plan -- but given the mounting complications of the water in the buildings and in the ground, I would have to say that this plan should be given top priority.

9:20 AM Eastern Saturday 4/16


  1. My best wishes for recovery.

    How they establish recirculating flows if the PV are leaking ? Or is it because the leaks are considered to be "vapor only" and therefore very small once the recirculating water is below boiling temperature ?

  2. @freeandsustainable: Thank you! I am not entirely sure, as is practically no one else, where all the outlets for primary coolant flow are on these plants. Not only are all the plants different, but the physical condition due to derangement might be very different. Surely TEPCO has a much better idea, hence this newly released plan. I am very interested with this possibility and will be watching for any and all further details on it, which I will report on the blog.

  3. Thanks Will. Get well soon.

    On recirculating flow; I'd say it doesn't have to be perfect (ie. leak-free) to be a lot better than they presently have. And once they have set it up, it can presumably be incrementally improved.

  4. It would seem to me that if they can find the parts of the reactor building or turbine building where the leaked water drains to first before spreading that they could collect it there and feed it back into the loop, obviously, there would still be some losses from evaporation, and any leaks that are either not located or are too small to try and collect, but that would creat a mostly closed loop system.

    not perfect, but it beats flooded basements....

    Im somewhat suprised that they haventalready been recirculating the water from the basements as it is to avoid overflowing...

  5. Thank you all for your well wishes, and for your comments! I think probably the main reason not to recirculate the basement water is that it's not only probably mostly salt water, but is very likely contaminated with all sorts of other things... like probably lubricating oil from the turbine generators, and maybe the diesels.

  6. I have been wondering why, with all this water draining into the ocean, they coud not use this water as the source for what is being sprayed onto the reactors and SFPs? (Rather than using a continuous supply of freshwater).

    Sort of an ad hoc recirculating loop that would reduce net discharge as opposed to washing down the site with uncontaminated water, at least until new closed loops can be established.

  7. I forgot about the diesels(and fuel) in the basement...

    in light of that, putting water with flamable liquids in it back in the hot cores wouldnt be a good idea...

    it will be interestuing to see how much of the basement water came from the tsunami, and how much from the cooling..

  8. Getting well should be your job 1.
    This situation is not going to go away quickly anyways, so there will be ample opportunity for adding more insight.
    Be well and all the best!

  9. Hope you get over your illness Will. You're doing a great service (We pray you don't have the dreaded man flu http://manflu.info/)

  10. @oldman: Manflu ... that site is hilarious! Thanks for giving me the first laugh of the day!

  11. Thanks Will. My speculation is TEPCO will try to flood and recirculate the PCV including drywell and wetwell. Does that make any sense to you?

    TEPCO's chairman just announced their rough schedule as this:

    -- three months to achieve stable cooling of R1, R2, R3 and all spent fuel pools

    -- six to nine months to achieve ''cold shutdown''