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Monday, July 25, 2011

Nuclear Energy in Japan: July 25, 2011

FUKUSHIMA DAIICHI UPDATE

Conditions at the site are essentially as reported before, with some expected problems. Perhaps most notable is the slow increase in nagging small complications with the filtration / decontamination / desalination system that TEPCO has been using. At this time, NHK has reported that the system is not running and that TEPCO has resorted to direct fresh water injection (supplied remotely, and not from the system storage tanks) which of course again begins to increase the total amount of contaminated water on site. The very latest readings do not show any increase yet in accumulated water levels by direct measurement. A new supplemental system is being brought in (called SARRY for short, an acronym) and will be running by the end of next month if all goes well.

Meanwhile, reactor cooling has as a function not been hampered, as TEPCO constantly makes adjustments to the system to counteract clogging, and has made repairs to reduce air binding and head loss so that reactor core temperatures are actually coming down. In fact, No. 1 plant's lower head temperature has been below 100C for some time now.

Spent fuel pool cooling continues as before, with TEPCO still continuing to inject hydrazine for corrosion control as needed (the last injection was in fact today at No. 2 plant's spent fuel pool.)

Viewers of the live camera on site will see, as this is written (9:20 PM Eastern on Monday) three crane heads visible around No. 1 reactor building engaged in the work to construct the fabric type reactor building enclosure.

FUKUICHI LIVE CAMERA

Finally, nitrogen injection continues at all three reactors. Dry well pressure at No. 2 plant now essentially matches that at No. 1 plant, which is encouraging, while pressure at No. 3 plant is much lower. There are no reports of TEPCO or NISA being dissatisfied with the results of this operation, which as mentioned before will continue until defueling or dry well flooding, whichever comes first, it appears likely.

OTHER NUCLEAR NEWS FROM JAPAN

A recent poll reported by NHK shows a sharp rise in the number of persons who wish to have a non-nuclear future. However, what is not totally clear is to what extent the politicians can actually implement such a plan - and their devotion to such is not clear either. This was all sparked by Prime Minister Kan's statement about desiring a non-nuclear Japan, which he later backed away from by stating that it was a personal goal, not a political agenda. However, certain anti-nuclear groups have picked up on it and certainly the confused governmental actions now are making it seem as if the government is, itself, highly indecisive. This will not lead the public to believe it can make solid, rapid decisions about things that affect the public safety (such as nuclear energy) and will not help the pro-nuclear cause at all. Further, the new plan to remove NISA from the trade ministry comes at a time when Japan had been preparing to restart plants to avoid rolling summertime blackouts and then switched tracks to go with IAEA inspired "stress tests" on all its reactor plants, pushing off the restarts.

If the Japanese people are wondering who is in charge (NISA, the executive portion of the government, or the IAEA) and what whoever is in charge will end up doing, they surely have a right to be wondering because the Japanese government is sending out such a wide-ranging shotgun pattern of messages that no one at this moment could be one hundred percent certain which way the outcome will be. One certain thing is that when Japanese industry (primarily car makers, but also steel makers) gets deeply leveraged by lack of energy supply, the case for nuclear will become much more solid.

To bolster its plant protection at Hamaoka, Chubu Electric Power is building a new 18 meter wall and enhancing other protections, leading the way to a truly tsunami proof site.

One report in right now describes a piece by a Japanese professor which is calling into question the integrity of the pressure vessel at Genkai No. 1. This is a separate issue from anything we've been dealing with so far in Japan, and since it is also one of the kinds of things the AP piece of recent note called out and is one of the anti-nuclear crowd's favorite sticking points, I will give this topic a special post after checking up on Genkai-1 and looking at some reference materials on pressure vessels of that day and age.

9:40 PM Eastern Monday July 25, 2011
ATOMIC POWER REVIEW

1 comment:

  1. I had an idea for tsunami defence. It was inspired by the possibility that the ramp up from the shore at Fukushima Daiichi had to some degree worsened the inundation from the tsunami due to run-up - this may or may not have been true in this case but might happen in other cases. However, easy shore access from the plant is a useful part of the site design, that may well allow robust safe operations that a cliff (or solid high wall) would prohibit.

    Anyway, the concept is that (part of) the slope down to the shore is composed of pontoons that are able to swivel at their top (shore end), with large flotation chambers at the sea end. The pontoons could be about 10m wide x 20-30m long down the slope. The bottom end of each pontoon would fit into a flood chamber on the ground that could quickly fill with water. In the event of tsunami, the flood chambers would fill, floating the pontoons on the incoming water and allowing them to rise with the tsunami to contain the water, both by adding height and by reducing run-up. The barrier would not need to be perfect but ideally would allow flow through only a small percentage of its length, represented by small gaps.

    The anchoring of the pontoons would be key. They would need to resist the hammerblow of the tsunami rush and contain the high water level for as much as several minutes. Anchoring would need to be below the top of the rise with serious support. Movement of the pontoons should probably be limited (via shape) to about 30-40 degrees above horizontal.

    One challenge to my scheme would probably be maintenance. Flotation could be assured by keeping a slight overpressure of gas inside, movement could be tested occasionally be cranage but corrosion might be problematic.

    The cost might be large, and of course at any given site the chances of full use would be small - although the site might be in use longer than whichever particular infrastructure it was built to protect.

    Well, it may be full of problems, costs and challenges, but for what it's worth, I hereby release this concept sketch to the public domain.

    Oh yeah, here's an alternative offshore concept:
    http://www.noort-innovations.nl/Tsunami_index.htm

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