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Japan Science

Nuclear Risk Expert: Fukushima Fuel May Be Leaking 500

Posted by timothy
from the so-step-lively dept.
An anonymous reader writes "Three weeks after the nuclear crisis began at Japan's Fukushima Dai-1 power plant, there's still a real danger of melted nuclear fuel escaping the reactor buildings and releasing a large dose of radiation. So says Theo Theofanous, an engineer who spent 15 years studying the risks of nuclear reactors. Theofanous believes that melted nuclear fuel has already leaked through the reactor vessels and accumulated at the bottoms of the primary containment structures. All attempts to keep the reactor buildings cool may not be enough to prevent the overheated fuel from eating through the concrete floors, he says."
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Nuclear Risk Expert: Fukushima Fuel May Be Leaking

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  • Some actual facts: (Score:5, Informative)

    by John Hasler (414242) on Friday April 01, 2011 @08:46PM (#35691608) Homepage
  • by Ponder (3878) on Friday April 01, 2011 @09:12PM (#35691696) Homepage

    No one at Fukushima has received a radiation dose that require treatment for radiation sickness let alone received a fatal dose. Two workers received a dose that exceeded their yearly dose limit and were removed from the site. Perhaps you are getting this situation confused with Chernobyl.

  • by Anonymous Coward on Friday April 01, 2011 @09:22PM (#35691722)

    From TFA:

    But the drywell's concrete floor is probably 5 to 10 meters thick, so Theofanous says there's not an immediate risk of a release of radioactive materials via this route. "A lot of melting has to take place before you get through 5 meters of concrete," he says.

    And:

    "We don't really know where the fuel is," he says

    .
    Also:

    Theofanous found that as long as there was a typical amount of water in the drywell--about half a meter--and that water was continuously cycled through to prevent it from heating up and boiling away, the nuclear fuel would not immediately make its way out into the environment. "We showed that if there's a severe accident, you must make sure there's water in the drywell," says Theofanous.

    So, yeah... Article is hype but the summary is outright lying.

    See... these are the moments when I wish that I was religious.
    So that I could find some modicum of relief believing that there is a special hell for people who are hyping up these stories just so they'd get more fucking clicks and page-views.
    You know... Trying their best to make a cent or two from their fellowman's suffering. Cunts.

  • Re:8 hour backup (Score:5, Informative)

    by Orne (144925) on Friday April 01, 2011 @09:38PM (#35691778) Homepage

    The information I have is that they did bring mobile generators to the site.
    * Fukushima Dai-ichi units 1, 2 & 3 successfully shut down when the plant lost off-site power during the earthquake. Units 4, 5 & 6 were already offline for maintenance.
    * On-site diesel backups successfully engaged to continue the cooling process, but the diesels were knocked offline when seawater from the tsunami flooded the fuel tanks. They got about an hour of cooling before these diesels were ruined.
    * At that point, an backup battery supply engaged, and ran for about 8 hours before it was depleted. This is 2x the average capacity of the battery backup system at an American nuclear power plant.
    * Meanwhile, they did get mobile diesels brought in, but the were only able to generate enough power to stabilize units 2 & 3. Unit 1 lost cooling water, and in 4 hours they were forced to vent the built up hydrogen gas.
    * I found some discussion that the coolant pumps require 5 MW to power, which a generator at 100,000 lbs is above what even a US chopper could airlift. This is why the helicopters were focusing on transporting coolant (seawater).
    * The issue then was they were physically leaking coolant water, and the rods were exposed at units 1 & 4. The exposed rods resulted in hydrogen explosions (which is what all the videos show).
    * The transco's goal was to get off-site power restored, which was basically rebuilding the transmission line to a neighboring plant. It took 6 days to get it restrung.
    Yes, it was that cut off.

    This appears to be a very informative article. I did not know that the batteries were actually the 4th backup system:
    http://www.backsidesmack.com/2011/03/explaining-the-fukushima-1-incident/ [backsidesmack.com]

  • by Kjella (173770) on Friday April 01, 2011 @09:49PM (#35691828) Homepage

    That's correct Russia did not exist when Chernobyl happened. The U.S.S.R. existed.

    Not the point, Chernobyl is in Ukraine. You wouldn't say that something that happened in London while it was part of the Roman empire happened in Italy, would you? They're not even originally a part of Russia, Ukraine was one of the states in the Soviet Union.

  • Re:This is absurd (Score:5, Informative)

    by borrrden (2014802) on Friday April 01, 2011 @10:03PM (#35691870)
    Burn it off with a controlled burn? How do you suggest that they do that? Light a match next to where it is coming out? It's not like they had a lot of options for the hydrogen gas with no power whatsoever on site. Also I don't know what you mean by "build the reactors along the fault line" You do realize that the fault line is in the ocean right? Not directly under Fukushima. By that reasoning, Tokai and Onagawa should not have been built either. "far lower than the historic tsunami wave-heights" where did you get this information? I can't find any data on historic wave heights of Fukushima. Don't just say "Oh there was such and such a high wave in Hokkaido" either, because the geography of the sea floor and the coast makes a big difference. They had a wall ready for a 5.5 meter tsunami, which is still a huge wave. The earthquake sunk the Japanese coast by about 1 meter AND it was hit by a 14 meter tsunami. This is documented in NOVA's documentary on the subject: http://www.pbs.org/wgbh/nova/earth/japan-killer-quake.html [pbs.org] . Salvage the reactors? They wrote off the reactors the minute they injected them with seawater. They have publicly said that reactors 1 - 4 will never run again. There is a good deal of information out there if you speak Japanese. Otherwise, you have to wait for someone to translate it which doesn't always happen. If you don't speak Japanese then you are in no position to comment on the amount of information that is or is not coming out.
  • by nido (102070) <nido56&yahoo,com> on Friday April 01, 2011 @10:07PM (#35691884) Homepage

    "Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence." -John Adams [quotationspage.com]

    Nuclear power has one thing going for it:

    • * High Energy Density

    Nuclear power also has several strikes:

    • * High maintenance - everything has to work all the time so that your plant doesn't explode and make hundreds of square miles uninhabitable
    • * High initial cost
    • * High shutdown costs
    • * stuck with billion-dollar boiling water reactors [wikipedia.org] and pressurized water reactors [wikipedia.org]

    Even if a superior reactor design comes along, there's an incredible financial incentive to stick with the technology that was first developed and deployed (see the Wired story on thorium [wired.com]).

    The best argument in favor of nuclear power is that "it may have problems, but it's all we've got". Nuclear advocates rightly point out that, compared to coal, oil, natural gas, and even hydropower (complicated), perhaps nuclear isn't so bad. Coal is abundant but dirty, oil is expensive and dirty, natural gas is cleaner but still poisons the ocean with CO2, and hydropower has it's own challenges.

    But the one "black swan" that never gets talked about is "disruptive technology" that changes the entire energy equation.

    One example: I've mentioned Global Resource Corporation's Microwave here before. This device uses specific microwave frequencies to release gaseous and liquid hydrocarbons from solids, such as coal (diesel, propane, butane). The company had a prototype that worked on tires, but they fell apart before they could get commercial versions of their technology to market. Luckily archive.org has a copy of their website: http://waybackmachine.org/*/http://www.GlobalResourceCorp.com [waybackmachine.org]. I remember reading about a cool patent that used Magnetic Resonance to figure out what specific microwaves a given sample of "trash" would need to be broken down...

    GRC's site talked about applying the technology to tar sands, to coal mining, breaking down hundreds of millions of used tires piled everywhere... How would the energy equation change if harvesting coal and tar sands didn't require massive amounts of energy?

    Here's something else: according to an old story on money.cnn.com [cnn.com], the largest single use of electricity in southern California is pumping water. And very large amount of water is used to generate electricity.

    So, with these twin issues... What if Raphial Morgado [angellabsllc.com]'s MYT (Mighty) pump [youtube.com] really is as good as he says it is? Suppose you could get 25% more water pumped for the same amount of electricity, or generate 25% more electricity with the same amount of steam?

    Whereas Global Resource Corp's special microwaves haven't reached market because it was torpedo'd by mismanagement (or maybe there's a technical problem - I'm pretty certain that the science is sound), Morgado's pump is in limbo because he hasn't yet found anyone who'd lend him $4-million or $10-million to build a factory. He has plenty of offers to buy the technology outright, but he has the audacity to presume that he should be the one to profit from his invention.

    Imagine if the demand for energy suddenly plunged by more than 25%. Oil is only going for $100/barell because demand roughly matches supply. If supply exceeds demand by a significant percentage, we'd be back to $1/gallon gas in a heartbeat.

    These are just the two technologies that

  • by Fnkmaster (89084) on Friday April 01, 2011 @10:16PM (#35691908)

    I am sick of the idiots saying "seal it". What the fuck do you think that means? The core material has most likely melted through the inner steel vessels and probably in places through the concrete containment (at least that seems likely) - as a result, highly radioactive water is leeching out into the drainage tunnels and out to the Pacific Ocean.

    How exactly can you "seal" that? Furthermore, even if you could, what makes you think that sealing it before you've cooled down the corium material is a good idea? I mean, if it's been hot and radioactive enough to melt through concrete, how exactly do you "seal" it?

    The whole point is it needs to be cooled down enough and stabilized so that it's not melting through anything on an ongoing basis, and only then do the existing leaks need to be sealed up as best as possible, or at least mitigated so that whatever has escaped stays relatively localized.

    As for "shut it down", it was shut down within seconds of the original earthquake. It's just that it needs ongoing cooling even after shutdown for quite some time - and once the fuel rods have melted down, it needs even more cooling.

  • Re:Mine it. (Score:5, Informative)

    by Anonymous Coward on Friday April 01, 2011 @10:33PM (#35691944)

    After fission, there's a whole lot more in there than uranium in there, and uranium is the least of the concerns from a radioactivity point of view.

    The stuff will be a molten mix of uranium, zirconium, ceramic, steel and all sorts of other stuff, mostly the materials with high boiling temperatures. The molten core material would have the gross composition of a mix of metal and silicate rock. It's very dense and very difficult to cut up, if the melted products in the bottom of Three Mile Island are any indication. For leaching to be effective it would have to be crushed up (in order to increase the surface area and let the water percolate through) and you'd have to use a leaching solution that removes all the elements of interest. I'm not sure such a chemical solution exists. Furthermore, you have to do it at high temperatures without the introduced solution reacting with the concrete. Given how chemically reactive concrete is compared to typical metal or silicate rock, I can't think of a solution that would promptly dissolve the latter two without probably dissolving the former. Even if you were successful at selectively removing the dangerous stuff into solution, then you've got a solution full of the dangerous stuff -- a solution that can leak and escape lot easier. Worse, if it is boiling off it might even end up concentrating the radioactive solids as it evaporates and eventually could increase the nuclear reaction where the solids are concentrated.

    This is not the same rock that they mine uranium from. It's a different material. This is a bad idea even if there was any chance of it actually working, which seems doubtful.

  • by Technician (215283) on Friday April 01, 2011 @11:03PM (#35692036)

    Often glazed over in reporting is the amount of heat that was in there in the residual heat. The core was producing residual heat of about 7% of the power level it was running before shutdown.

    If a unit was running at 700 Megawatts, the core would then be running at 49 Megawatts, but with no output outside the shell. When the cooling quit for a couple of days, it did not take long to boil the kettle dry.

    In the US a partial meltdown of a small sodium reactor happened before 3 Mile Island. Google it. They could not add cooling water due to the flammable Sodium.

    All the experts that have covered reporting current situation has not said a word about flammable Zirconium. Zirconium is highly flammable in water just like Sodium. The only difference is one is flammable at room temperature and the other catches fire at much higher temperature. When the core was exposed and overheated one of the experts said the cladding oxidized.

    If you heat a chunk of Zirconium with a torch and get it dull red, it will catch fire. If you then throw it in water, it will burn using Oxygen from decomposing water and leaving Hydrogen as a byproduct, just like burning Sodium the reaction is exothermic. Zirconium melts at 1852 C. It catches fire at a lower pressure than it melts. To simply say it melted is false.

    When they had fluctuating core pressure and a large Hydrogen release, I knew a large amount of Zirconium burned. This includes reactors 1-3 and fuel rod pool in #4, and possibly the fuel ponds in 1-3. This Hydrogen confined in the outer containment combined with air went boom. The boom most likely happened when the rods in the cooling ponds boiled dry and got hot enough to be an ignition source.

    When the experts say they don't expect any more hydrogen explosions, it is because there is no Zirconium left.

    The high radiation levels in the water is because the Uranium Oxide was subjected to both the residual heat and the cladding fire.

    Speaking of cladding fire, remember a couple of rod storage areas with some fires?

    Overheated graphic seals is no surprise if the cladding burnt off and the ceramic uranium oxide overheated.

  • by Anthony Mouse (1927662) on Friday April 01, 2011 @11:17PM (#35692062)

    The energy content in one ton of uranium using 1960s reactors is roughly equivalent to 16,000 tons of coal. Using newer reactors that consume U-238 as well as U-235, a ton of uranium will produce more energy than a million tons of coal.

    Assuming coal mining kills 5000 people a year and uranium mining kills as many people per ton, to produce the same amount of electricity you're looking at less than one mining death every 3 years for 1960s plants and one death every 200 years with newer plants.

  • Re:Mine it. (Score:3, Informative)

    by Whillowhim (1408725) on Friday April 01, 2011 @11:18PM (#35692064)

    http://mitnse.com/2011/03/16/what-is-decay-heat/ [mitnse.com]

    There is no more uranium fission, that was stopped within seconds of the earthquake hitting. The problem is the decay products of the reaction, which are unstable and thus radioactive. The power given off by the reactor at this point is just a percent or so of its original power, and all of that is coming from unstable isotopes splitting on their own. There is no real point to separating the fuel, the byproducts will continue to fission without any neutrons hitting them. Removing them to make them easier to cool is pointless, since by the time they could set something up, they could've set up a real cooling system and solved the problem on site.

  • by antifoidulus (807088) on Friday April 01, 2011 @11:40PM (#35692112) Homepage Journal
    Except for the fact that the Japanese government rubber stamped a proposal to extend the life of the plant by at least 5 years in February. Had it really been planned to be shut down in 15 days I doubt it would have been running at the capacity it was when the quake struck.
  • by ChatHuant (801522) on Friday April 01, 2011 @11:46PM (#35692126)

    Oh japan.org? ... fake rads map ... fear mongering anti-nuke crap ... Good call.

    Instead of a brain-dead attack on the messenger, why not try finding out the truth for yourself? It takes all of 10 seconds to go to the IAEA site here [iaea.org] and see the numbers quoted by the OP are correct:

    The average total deposition determined at these locations for iodine-131 range from 0.2 to 25 Megabecquerel per square metre and for cesium-137 from 0.02-3.7 Megabecquerel per square metre. The highest values were found in a relatively small area in the Northwest from the Fukushima Nuclear Power Plant. First assessment indicates that one of the IAEA operational criteria for evacuation is exceeded in Iitate village. We advised the counterpart to carefully assess the situation.

  • by DrJimbo (594231) on Friday April 01, 2011 @11:47PM (#35692132)
    I've been getting my news about Fukushima from the English translation of NHK World. They have generally been much less sensational than the foreign press. The term the Japanese officials and nuclear experts have all been using day in and day out is "highly radioactive water". I may be an idiot but I will trust their terminology over the rant of an anonymous coward on Slashdot.

    The level of radioactivity at the surface of the water near reactor #2 is over one sievert per hour. This will give a worker their lifetime dose in 10 to 15 minutes. It will kill anyone who is next to the water for 8 hours. All work on reactor #2 was halted when the highly radioactive water was discovered about a week ago and it hasn't started up again. The analysis TEPCO did on some of the less highly contaminated water showed a significant fraction of the radiation coming from Cesium-137 which has a half-life of 30 years. Sure, all radioactive materials have a half-life, and the shorter lived materials emit more radiation per unit time. But that doesn't mean that all levels of radiation are benign, nor does it mean that all highly radioactive substances will soon become safe. Perhaps it is a judgment call but AFAIAC, water that is radioactive enough to hamstring efforts to fix the leaking reactor for a week and is radioactive enough to kill anyone who is near it for 8 hours is some pretty damned highly radioactive water.

    My point was that containment at Fukushima has been seriously breached and the full extent of the breach is unknown. Fukushima made headlines in the US before it was known the containment was breached releasing significant amounts of radiation into the environment. Now that the breach has been discovered, the US press isn't covering the situation nearly so much. I believe this has led people here on Slashdot to make completely erroneous claims that the containment has not been breached and the situation is evolving according to plan. These posts were modded +5 informative. I'm trying to correct the record with information coming directly from Japanese officials as reported on NKH World.

  • by DrJimbo (594231) on Saturday April 02, 2011 @12:23AM (#35692214)
    From Japan.org [japan.org]

    The world's largest concrete pump, deployed at the construction site of the U.S. government's $4.86 billion mixed oxide fuel plant at Savannah River Site, is being moved to Japan in a series of emergency measures to help stabilize the Fukushima reactors.

    ... Initially, the pump from Savannah River Site, and another 70-meter Putzmeister now at a construction site in California, will be used to pump water -- and later will be used to move concrete.

    "Our understanding is, they are preparing to go to next phase and it will require a lot of concrete," Ashmore said, noting that the 70-meter pump can move 210 cubic yards of concrete per hour.

    Putzmeister equipment was also used in the 1980s, when massive amounts of concrete were used to entomb the melted core of the reactor at Chernobyl.

    ... Ashmore said officials have already notified Shaw AREVA MOX Services, which is building the MOX plant for the U.S. Department of Energy's National Nuclear Security Administration, that the pump was being moved and will not be returned because it will become contaminated by radiation.

    "It will be too hot to come back," Ashmore said.

  • by thegarbz (1787294) on Saturday April 02, 2011 @01:07AM (#35692278)
    Irrelevant. In the metric of deaths per TWh for which nuclear has 0.04 and coal has 161. If capacity increases this death RATE should remain constant. You get more energy out of uranium so you need less of it.
  • by Anonymous Coward on Saturday April 02, 2011 @01:43AM (#35692356)

    The battery backup in commmercial nuclear plants does NOT run the large scale cooling equipment, that is what the multiple independent channels of diesel backup power (which failed along with offsite power) are for.

    The battery backup is for instrumentation and control only, including computer monitoring systems, process control computers, some valves, etc. At a typical GE BWR (like fukushima, I was an operator at a newer GE BWR myself) the entire basement of the control/auxialiary building is filled with lead acid batteries (multiple THOUSANDS of car battery sized cells) and large UPS's (27 of them at the plant I worked at) for backup power to intrumentation and control only.

    The RHR (recirc heat removal pumps, used for both emergency and normal shutdown cooling) are huge beasts, batteries could not possibly keep them running. They are 4160v multiple 1000 horsepower motors (can't remember exact size), no way lead acid batteries can do that (let alone the UPS's), simply no way. One easy way to vouch for this fact is that the UPS's only produced 270VAC power!

    There is the HPCI and RCIC systems driven by decay heat steam from the reactor itself (via small to mid sized steam turbines), and in the fukushima situation these likely functioned until control power was lost (assuming piping to these stayed intact). After control power is lost, these systems shutdown or break, or overspeed, can't remember, probably varies with the individual plant. Either way, no control power, no HPCI or RCIC

    The spent fuel pool is another matter entirely. It has a separate electric motor driven pumped cooling system, but once again, batteries do do not drive these, these pumps are something like multiple 100Hp 480v pumps, once again outside the range of what even a ton of lead acid batteries can manage for any significant length of time. (see paragraph about heat sink below too)

    The loss of offsite power, followed by the loss of the diesel backup power is really the root failure, and you need BIG diesels (or gas turbines even) to manage this load. At the plant I worked at, there were 4-4+ MW diesels onsite for a single reactor. 2 at a minumum were needed to keep things cool if offsite power was lost (assuming no other failures). We had fuel for approximately 2 weeks of run time of each diesel within the control building (about 200000 gallons, with another million available in a non safety rated tank outside the buidling). 4Mw locomotive or marine sized diesels cannot be simply trucked or helicoptered in, these are BIG machines, not to mention replacement fuel (they're thirsty!). In my plant's case, each diesel was a 5000Hp, 16 cylinder twin turbocharged monster that was originally designed for use in diesel electric cargo ships!

    Perhaps if they parked an aircraft carrier right on the coast and somehow ran cables that could have made up for the loss of power, or maybe a dozen or so diesel electric locomotives, a few large diesel electric container ships, etc. but nothing smaller than that could have handled this load (original design Nimitz class aircraft carriers have about 20Mw electrical generating capacity INCLUDING their 4 emergency diesel generators at 4160v 60Hz, and remember they need some of that to keep their own engine room and other ship functions operating in this sort of scenario). But even then you would need some hellish power cables and functioning switchgear and control power in the plant itself BEFORE you could consider turning on a big cooling pump

    Oh yeah, you would also need a functioning "service water" system (part of the normal seawater cooling system for the plant, not the emergency seawater cooling that is being used, provides cooling water and makeup water to cooling towers at some plants), those pumps (assuming control power AND intact piping again), needs another megwatt or so to operate. If you don't have service water, you don't have a heat sink even if you get the cooling systems inside the plant building operating.

    Most people have no idea of the scope of the pow

  • by Mindcontrolled (1388007) on Saturday April 02, 2011 @03:52AM (#35692620)
    For added irony, Putzmeister is a german business, located in just that state that saw a landslide victory of the Green Party over the issue of atomic power last weekend...

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