Skip to comments.Japan: Original plan to cool Fukushima nuclear reactor to be scrapped
Posted on 05/15/2011 6:56:11 AM PDT by TigerLikesRooster
Original plan to cool Fukushima nuclear reactor to be scrapped
TOKYO (Kyodo) -- An adviser to Prime Minister Naoto Kan indicated Sunday that a plan to flood and cool the No. 1 reactor's containment vessel at the crippled Fukushima Daiichi nuclear plant with water will be abandoned as holes have been created by melted nuclear fuel at the bottom of the pressure vessel.
Goshi Hosono, tasked with handling the nuclear crisis, told TV programs, however, that the government will keep intact the "road map" devised by plant operator Tokyo Electric Power Co. to bring the Nos. 1 to 3 reactors under control within six to nine months.
On the original plan to completely submerge the 4-meter-tall fuel rods by filling the vessel with water, Hosono said, ''We should not cause the (radioactive) water to flow into the sea by taking such a measure.''
(Excerpt) Read more at mdn.mainichi.jp ...
Interesting to see the leap the reporter makes from original words like “may” “suggesting” “suspected” to “holes have been created”;
“Hosono made the remarks after TEPCO found a pool of water over 4 meters deep, which could be highly contaminated and total 3,000 tons, in the basement of the No. 1 reactor building, suggesting water poured into the reactor core may be seeping through holes created by melted fuel. The water is then suspected to have leaked from the containment vessel or suppression pools, which form the vessel, into piping.”
“holes have been created by melted nuclear fuel at the bottom of the pressure vessel”
Based on the temperature of the reactor vessel surface temperature, the company said the fuel apparently has cooled.
This tells me that they have attained sufficient heat removal capacity to manage the remaining decay heat, which after this time is a relatively small fraction of the initial amount (solve the Way-Wigner equations yourself, as I have done, to verify this).
As far as how to move forward, we can learn from our experience at TMI. After decon of the area around the vessel, they'll have to approach the problem of removing the vessel head to inspect the extent of the fuel damage. That will require a crane to lift the vessel head, and a lay-down area to place it, cleared of debris and decontaminated. Assuming there is congealed material at the bottom of the vessel, the next step will be to clear that out, exactly as we did with TMI-2. Then they can make a decision on either SAFSTOR or repair. But that is speculative at this point until they can get a look at the inside of the PV.
“They buried OBL out to sea right after Japan released radioactive water into the ocean. This has the makings of an awesome monster movie.”
—a friend at Pixar
Osama bin Godzilla? A 100-ft tall Arab monster trashing New York City?
At a news conference April 1, Shunichi Tanaka, a former vice chairman of the Japan Atomic Energy Commission, said all the fuel rods in the No. 1 reactor had melted, raising the possibility of damage to the pressure container.
TEPCO’s latest measurements found the temperature of the pressure container was about 100 degrees. If the fuel rods had been exposed because of the low water level, the temperature should have been much higher. The only explanation is that the fuel rods melted, accumulated at the bottom of the pressure container and the melted fuel was cooled by the small volume of water at the bottom.
Note that this actually likely happened at about the 16 hour mark into this disaster BEFORE it was vented and BEFORE the explosion.
The cooling plan is halted. Why? Because of nonexistent holes??????????????????????????????????????????????????????????????????????????????????????????????????????????????????
Okay..so there ARE holes ..as admitted by TEPCO..but not to fear..they are only SMALL holes...IF you believe TEPCO
And they now admit the water level sensors in #2 and #3 are also probably malfunctioning. On the same day they admitted complete meltdown occurred in #1 within hours of the Tsunami wave hitting. So #1 core has been completed melted now for two months. One would hope the temp has finally cooled a little.
You are mistaken. There is no evidence at this time that there has been significant release of fuel. The decay time between the shutdown and onset of melting (as best can be determined at this time, about 16 hrs., last I heard) reduced the heat load significantly, below the melting temperature of the uranium oxide. Go ahead and run the numbers yourself. The equations are the Way-Wigner relationships that predict decay heat following fission shutdown. Let us know what you come up with. Do your own work, not a link to somebody else's article.
Coolant leakage can occur in any number of ways. Most likely is a breach of the pressure boundary, which is different than the pressure vessel. If it is a pressure boundary breach at any significant elevation, melted core materials are unlikely to reach it. Rather, as at TMI-2, where there was no PV breach, there is likely slumping of melted materials, things like cladding and support pins, to the bottom of the vessel, maybe with some fuel pellets mixed in that have fallen out of the damaged rods.
You also have to allow for not only heat load reduction by decay, but also heat removal mechanisms. They haven't been passive about adding coolant to this unit. Every time coolant is added, you get a reduction in heat load. Especially by evaporation, where the heat removal is aided by latent heat and also that the effective heat sink temperature is the wet-bulb temperature. I challenge you to run the heat transfer equations yourself. You'll see how effective that kind of cooling can be.
The contaminated water can come from a variety of things. If there was damage to the pressure boundary, you're going to have primary system blowdown and subsequent condensation of the blowdown steam. We know there is fuel damage. If there was damage to the pressure boundary, reflooding of the vessel likely flushed particulate debris and perhaps loose pieces out of the pressure boundary leak point. My guess it is the main steam lines, but there are also other points in the pressure boundary that could have been damaged. PV damage is the least likely since it is the strongest feature of the pressure boundary. It is like comparing a garden hose to a steel pipe. Where, in such a system, do you think a leak is most likely to occur if there is an overpressure situation?
Before you play whack-a-link with me, let me acknowledge that I am aware of the one ORNL (I think) study that noted the vulnerability of instrument tubes welds in the pressure vessel. But these are relatively small, even if relatively numerous. You are not likely to have significant debris extrusion through them. Coolant, yes, and this may be the source of some of the contamination in the building sumps, because coolant leakage can carry dissolved fission products (iodine, cesium) out through the opening, as well as small particulates. But when you're talking about cladding or support structure melt, you are not talking about a non-viscous liquid like water or soup broth, you're talking about a semi-congealed, lumpy mixture more like a thick stew or semi-cooled grits. Something like that does not flow readily through a small opening. In fact, it tends to clog it up.
You know there is fuel damage ? What an understatement. We have three reactors where their entire cores have melted down into a corium mass. Now tell me where have we studied the physical and chemical properties of freshly created corium ? Give it up. You know nothing.
How do you know that?
Right. Just enough nothing to get a Ph.D. and have 31+ years experience in the business. What degree in nuclear do you have? How much experience? I'd say very little. You won't even try to solve the Way-Wigner equations. Do you even know what they are, aside from what is in Wikipedia?
"Corium" is a boogeyman used to scare ignorant people. We have damaged fuel and some internal components, nothing more, nothing less. We (I) know the composition and properties of that, because we (I) know the nature of the constituents. We (I) know exactly what's in it because I was part of a team at INL that examined the damaged fuel from TMI-2, included the congealed pieces as well as the damaged cladding and partially intact fuel assemblies. Have you done likewise? If you haven't, then I'd say you are the one who knows nothing. The fact that you ask such a snarky question in the first place shows you have no knowledge or understanding of what you are talking about. If you did, you would know that Argonne National Lab did quite extensive studies of "corium" cooling capabilities using UO2 and other materials, which is part of the Large-Scale Reactor Materials Test Facility.
And there you go again, making this about me and you. This is about an entire planet now.
You examined corium that had cooled off. Not freshly created corium. Entirely different situation. Now please provide a link to the corium study you cited ? Or is that asking too much ?
Perhaps someone is enjoying the PR side of this, but anyone with any knowledge knew within an hour of them failing to restore core cooling that there would be core damage -- (in Jane Fonda terms, a meltdown).
What the extent of that damage is will not be known for years until they can lift the lids on those vessels and have a look inside. (exactly what happened at TMI -- it took five or six years before they saw the extent of the damage inside)
To declare that the "Entire Core" at three plants has melted is pure speculation, regardless of what the MSM people say. The damage is severe for sure, but it will be years before we know to what extent.
And no -- the China Syndrome is still just a movie. Even as bad as this is, it ain't going to burn through the center of the earth. It's all over now but the nasty job of clean-up.
Met some dumb PhD's for sure -- when they were out of their field. But the stupidest people I ever met were the totally arrogant fools who thought they knew more about a subject than the PhDs who spent their lives studying that subject.
Reminds me of a woman I got in a discussion with once who claimed x instead of y. I worked the math with her to show she was mistaken. She admitted the math was correct but then came back with the classic leftist line;
Well, I just don't feel that way"
Now how can you reason with that?
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