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

Monday, March 28, 2011

Update, Monday evening (Eastern)

We've been hoping for some solid technical data today before making any kind of post, but precious little has yet appeared. Let's look at the plant-specific details (quite apart from the wide media coverage given the minute traces of plutonium found at the plant.)

TEPCO, NISA and the Japanese Government now clearly associate the volume of water in the trench at each plant with the core cooling water that has been injected; further, and probably more importantly now, they all also associate the volumetric flow rate of injection water to the reactor cores as being roughly directly transferable to the trenches.

What? What I'm saying is that X gallons injected to the reactor core will result in the short term in something less than X into the trench.... with buffers being the water getting through the reactor building, and/or turbine building.

Let's make something clear: Two breaches are in progress for this to happen. First, the water should not be getting out of primary system piping, and if it is it shouldn't be getting out of the reactor building -- that's what the ocntainment function of the reactor building is all about (and if you haven't seen my previous post on the subject of containment, please do so.) Next, the water is also, once in the turbine building, then getting out of the turbine building into the trench, somehow.

It's TWO places it shouldn't be.

Because of this direct relationship, TEPCO reduced the flow rate of water to the core of No. 2 plant and -- as we might guess -- has experienced a reported 20C increase in core temperature. Chief Cabinet Secretary Edano has stated publicly that when consideration is made, the priority is core cooling and water injection will be adjusted to ensure core cooling and not to prevent overflow of the trench. TEPCO has buried the trench drains.

It's now totally clear, in the very short term, that continued reactor integrity is going to be based on the ability to inject water AS NEEDED for core cooling with no incentive on anyone's part to prevent further spread of contamination from the trenches. It may be time for another brutally simple but aggressive solution - you could bring in a very large barge into which to put the trench water and further discharge. That sounds difficult, perhaps, but it might not be. It's time for the solutions to get ahead of the problems and not simply keep up with them... keeping in mind Patton's advice that a good solution applied vigorously is better than a perfect solution applied too late.

9:20 PM Eastern Monday 3/28
ATOMIC POWER REVIEW

11 comments:

  1. Thanks for the update - yes, the pace of information release leaves something to be desired.

    So keeping the reactors cool means contaminating the entire site making further repairs difficult or impossible - catch 22. So sacrificing the site and adjacent ocean in order to prevent more widespread release of aerosols is the solution... Any idea what likely paths are (from reactor vessel to turbines/trenches) for the coolant water? Does this tell us any more about the prior progression of the accident (breaches from seawater corrosion? over pressure? core melt leading to compromised containment from burn-through?) Surely the fuel storage pools are leaking too. Have you posted a schematic of the reactor/turbine rooms and associated plumbing or do you know of one? (and how the trench system might connect?)

    Perhaps most of these are unanswerable and answers may not even be apparent yet even to those onsite....

    Suggestion - when you point readers to a previous post please use a hyperlink if possible.

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  2. Will, thanks for the update.

    The barge sounds like a possible solution. Edano kind of backtracked with the "balance" comment and then the "oops" followup, didn't he?

    I was wondering about the implications of the very strong radiation content of the water in 2? If you get it out of the trench, don't you have to keep it in some sort of enclosed storage?

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  3. I don't think sacrificing the site is the question; the site probably will not be used for nuclear power generation again, except for the remote possibility of restarting essentially undamaged reactors No. 5 and No. 6.

    There is as yet no solid data on what exactly all of the transmission paths are or might be other than what I've detailed over the days/weeks. It is probable that the people onsite have much better ideas than we're getting now and those will probably only come out to us when the chances of core damage and further release are over and things onsite go from accident mitigation and control to cleanup.

    Readers are advised to look through the long list of previous articles or use the onsite Google search for finding anything I've posted. Sometimes I link, sometimes I don't.. but those features are always there!

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  4. @maxedoutmama.. My theory was that pumping the water through a filter into a storage tank -- tank truck, maybe multiple trucks.. or barges.. would give you time to decide what to do with the water and get it "out of your hair" while you deal with the powerplant. You'd be relieved of any tendency to cut down water injection for fear of filling the trench later on. You could store (or bury, for that matter) the filters. Right now they need working solutions, not permanent ones for things like this.. and you can be sure they're examining just this kind of option and others.

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  5. all they have to do now is add a cooler to the water in the trench and feed it back into the reactor. It might even be easier to do that than work in the radioactive turbine hall 2. Number 4 reactor was shut down. It might have all the parts clean and ready to go. One operating system might handle all 3 reactors.

    (hard to comment on this board for some reason)

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  6. Really, what Will say's This needs to be done now. It's easy to let it go to the sea, well inevitable, do what can be done and do it YESTERDAY already.

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  7. Pump the same shit coming out back in and get er done. Remove heat,clalories, hobonaros, not fission "products". Keep the shit for oh, never mind...

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  8. Generally I think it'd be a good idea using a barge. I was thinking the same before, when in the first days of the accident cooling was mostly out of function: a barge with large generators and pumps could have been used to prevent cooling failures.
    But maybe there's some problem with the plants harbour, we don't know about: maybe there are some vessels or other debris sunken, the quay inaccassible or like this.
    The danger of a further tsunami or storm to happen also threatens solutions like this.
    I think it would need a bigger ship able to resist heavy sea anchoring there.

    This might be a solution of the problem having not enough capacity storing the used cooling water.

    Off course: after being used the ship is lost through the contamination, Also its crew is in danger. And recruiting a crew for this task may be impossible.

    Tepco doesn't seem to like the idea of spending money for having a solution in Fukushima: its a dead horse and a company going to earn money shouldn't put money into a dead horse, but just cover it for outside views. Thats what they are doing and I understand its rationale.
    Its just up to the government to do more. Maybe they begin to realize this - still very late.

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  9. Will, are you completely confident that the flow rate into the No. 2 trench is almost as great as the core cooling injection water? If true that seems to confirm major

    A couple of days ago KBMAN offered a hypothesis to explain the mechanism of the leaks. He is a guy who worked at the Oyster Creek NPP. Like the Fukushima plants, Oyster Creek is a GE BWR-I with a Mark I containment. I take him to be credible -- see what you think:

    https://seekerblog.com/2011/03/28/theory-of-corrosion-and-backflow-through-feedwater-lines-to-explain-fukushima-radiactive-water-leaks/

    KBMAN's theory does not acount for "output = almost as large as input" unless there is a large total cross section of holes between primary and secondary. How large does that need to be to account for the observed flow?

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  10. The latest IAEA presentation shows Unit 2 "Core and Fuel Integrity" has jumped to "Severe damage" today March 29. Yesterday was same as units 1,2 = "Damaged".

    The RPV pressure reports are unit 1 = "Slightly increasing" (due to restricting core cooling water); units 2,3 = "Stable". Looking for confirmation of Will Davis' thesis, I've examined the reactor status reports for evidence of RPV pressure drop on unit 2. I don't see it - TEPCO continues to operate unit 2 below one atmosphere - about 0.074 MPa, or 3/4 atmosphere absolute. I read unit 3 as stable around 1.3 atmospheres = 0.135 MPa. But if unit 2 is being operated below one atmosphere, why can't most of the flow leak out of the RPV + primary into the secondary circuit?

    Is stable 3/4 atmosphere RPV pressure consistent with most of the core coolant injection volume leaking into the trench? As I reported earlier regarding unit 3 leak concerns, nuclear chemist Cheryl Rofer observes that the pressure history indicates...

    (...) If there is a leak, it is not a big one.

    It’s not a big one, because reactor #3 has been pressurized. If you try to blow up a balloon with a big leak, nothing happens. You can blow up a balloon with a pinhole leak, though. The steel reactor containment vessel is equipped with pressure gauges to measure the pressure. With a big enough leak, the pressure wouldn’t rise, but it has been rising as water is pumped in and turns to steam.

    So where is the radioactive water coming from?

    (...)

    But unit 2 is a different case if RPV is at relative negative pressure, right?

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  11. At a guess a 1-3" diameter hole would enable all of the electrically pumped 120l per minute water entering the reactor to exit while keeping the reactor pressure constant at one atmosphere. And even if you turn off the pump the heating - without cold water addition -would continue to keep the pressure high while the water leaked out.

    But i thought these low temperature reactors directly drove the turbines with no heat exchangers or steam generators so that the primary coolant would normallly leave the reactor and enter the turbine hall?

    Is there a secondary system?

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