Robot Squeezes Suspected Nuclear Fuel Debris in Fukushima Reactor (theverge.com) 94
A robot outfitted with remotely controlled pinchers poked at debris that's suspected to contain molten nuclear fuel at the bottom of one of Fukushima's nuclear reactors, World Nuclear News reports. From a report: The poking and prodding is part of the ongoing cleanup effort at Japan's Fukushima Daiichi power plant, the site of a major nuclear accident in 2011. The dextrous robot was dangled into the Unit 2 reactor on February 13th, according to a news release from the plant's operator, Tokyo Electric Power Company (TEPCO). Unit 2 is one of the reactors at the Fukushima Daiichi power plant that overheated after a massive earthquake and tsunami hit Japan in 2011, which caused the reactor core to melt. TEPCO suspects that radioactive fuel may have melted through the bottom of the reactor vessel to fall into the containment structure surrounding it. The company has to find the radioactive debris and figure out how to remove them, so TEPCO has been sending in a series of robots to scout out the reactors. It's a dangerous journey that some of the robots haven't survived.
Re: (Score:3, Informative)
Of course you can induce criticality that way. You can hit a small chunk of uranium with a hammer and reach criticality, at least for a moment. U-235 can reach criticality with a mass as small as 780 g [osti.gov] under the right circumstances. And the presence of water, potentially with some amount of uranium in solution, greatly raises the risk. Of course, it would only remain critical while com
Re: (Score:2)
Of course you can induce criticality that way. You can hit a small chunk of uranium with a hammer and reach criticality, at least for a moment. U-235 can reach criticality with a mass as small as 780 g [osti.gov] under the right circumstances. And the presence of water, potentially with some amount of uranium in solution, greatly raises the risk. Of course, it would only remain critical while compressed, and so such a small criticality event would likely be a risk only to the robots, because it would be small and self-contained.
Perhaps you meant that it cannot cause a nuclear explosion (which requires not just enough material and moderation to sustain a reaction, but also for it to increase exponentially and not burn itself out in a fraction of a second).
But since it was a 60's style LWR, there wouldn't be pure U-235 in the reactor. It would be LEU which is probably 4% U-235 and 96% U-238 or so as new fuel. Exactly what the isotopic distribution of this material is, I'm not exactly sure, but I'm 100% certain it doesn't contain more than a few percent of U-235. Since U-238 is a neutron poison, I seriously doubt that criticality could be induced accidentally. You probably couldn't induce criticality in this material without explosives (or lots of a modera
So this -still- hasn't been contained? (Score:1)
Scary.
Re: (Score:2)
It's not going anywhere unless someone moves it or they get another tsunami.
Re:So this -still- hasn't been contained? (Score:5, Insightful)
That's pretty much the problem, they can barely get to it, let alone remove it for burial. They are trying to avoid it becoming another huge Chernobyl-style concrete coffin because it would need to be protected from tsunami and constantly maintained (they have regular earthquakes) indefinitely.
Also "overheated" is a rather obvious attempt to avoid the word "meltdown".
Re: (Score:3)
I'm not claiming it's a great situation, just that it's not as if the stuff is blowing around in the wind somewhere.
It is worth noting that the meltdown can be attributed to TEPCOs unwillingness to pump sea water into the reactor vessel since that would once and for all have ended the chance of a re-start. Of course, we know now that a re-start is out of the question anyway, but basically the management was not at the time willing to admit that they gambled and lost big.
Re: (Score:2)
There's the problem of where the now-radioactive seawater would go after you pumped it in.
Re: (Score:2)
Into a tanker truck. The processing would cost, but it would have been cheaper than the current post meltdown cleanup.
Re: (Score:1)
The containment structure is made of concrete. Concrete isn't water-tight. You could not capture all of the water with a pump.
Re: (Score:2)
At that point, the reactor vessels weren't leaking.
Re: (Score:2)
I'm not claiming it's a great situation, just that it's not as if the stuff is blowing around in the wind somewhere.
It is leaking radionuclides into the ocean, which is arguably worse. All of the stuff that was blowing in the wind has/is settling on the west coast of the US via the jet stream. IIUC Seattle and Vancover got the worst of it.
Re: (Score:2)
It WAS leaking radionuclides into the ocean, but I don't think that's still happening. The west coast didn't actually get much radiation from Fukushima.
Re: (Score:2)
It WAS leaking radionuclides into the ocean, but I don't think that's still happening. The west coast didn't actually get much radiation from Fukushima.
It *is* leaking 400 tons of radionuclide contaminated water into the Pacific ocean everyday.
Re: So this -still- hasn't been contained? (Score:1)
Umm it may be âoeleakingâ thousands of gallons a day but any radioactive material is heavily diluted by said amount of water. Itâ(TM)s not leaking gallons of raidioactive materials but leaking tiny residue in thousands of gallons. Huge difference.
Also those thousands of gallons are further diluted by zillions of gallons of the ocean.
By conservation of matter the amount of any TRACE amounts that reach the shores of the west coast are going to be totally insignificant to human health.
Re: (Score:2)
It *is* leaking 400 tons of radionuclide contaminated water into the Pacific ocean everyday.
That's the mass of the water, tell me how much mass of actual radioisotopes are leaking into the ocean.
Now, tell me what are the actual isotopes. This is important because different isotopes pose different hazards, and some isotopes pose no hazard at all. Is it uranium? There's naturally uranium in the seawater already, Japan has been experimenting for a very long time on how to "mine" the sea for their uranium needs. Adding a bit more won't hurt anything. It is tritium? Also naturally occurring. Iod
Re: (Score:3)
The Chernobyl New Safe Confinement structure which was moved over the original concrete "sarcophagus" is not made of concrete.
Re: (Score:2)
Because as rad-hardened teleoperators improve, there will be a point at which we will want our robots to be able to take the corium out in small chunks to feed breeder/burnup reactors.
Re: (Score:2)
Also "overheated" is a rather obvious attempt to avoid the word "meltdown".
No, it's not. Overheating nuclear fuel is just that; hot material. Meltdown is nuclear fuel that has actually transitioned from solid to liquid form.
3 Mile Island is a good example of an overheating core that started to melt. Chernobyl and Fukushima are good examples of total meltdowns. Meltdowns breach containment vessels. Overheating cores just get SCRAM'd to capture neutrons and halted.
See also: Chernobyl Elephant's Foot.
Fukushima was not a total meltdown.
"Summary: Major fuel melting occurred early on in all three units, though the fuel remains essentially contained except for some volatile fission products vented early on, or released from unit 2 in mid-March, and some soluble ones which were leaking with the water, especially from unit 2, where the containment is evidently breached. Cooling is provided from external sources, using treated recycled water, with a stable heat removal path from the actual reactors to extern
Re: (Score:2)
As long as you don't expose it to any water that then seeps into the ground.
Which is probably unlikely on an island, right?
Re: (Score:2)
The water would have to get to it first.
Re: (Score:2)
I'm sure with a damaged building that there's no possible path to get water to it.
That's why they tried to freeze all the groundwater in the area. Because there's no possible path for water to get to it. :eyeroll:
Re: (Score:2)
Yep, it's all just blowing around in a field somewhere while small children make necklaces out of it.
This is the origin of (Score:4, Funny)
Poke-e-mon.
Re: (Score:1)
Gozilla is the word you're looking for.
Re: This is the origin of (Score:1)
No, it's Gojira.
Re: (Score:2)
I should hope they're trying to clean this mess up.
Well, first they've got to find the mess, which has taken years and which will probably take many more years. It's all well and good to say "clean the site up", but if you just had at it you'd probably cause more harm than good.
For the moment the situation appears stable-ish, but since we don't really know what's going on it makes sense to find out rather than trusting our luck.
I'll take "Sentences I Never Thought I Would Hear" (Score:3)
....for 1000, Alex.
Please don't squeeze the Charmin (Score:4, Insightful)
Re: (Score:2)
This was exactly the comment for which I came here looking. Thank youâ"you have just made my day.
Re: (Score:2)
He's got Adam Savage working on it.
Re: (Score:2)
No wonder it's taking so long (Score:5, Funny)
The dextrous robot was dangled into the Unit 2 reactor
Maybe if they didn't make their robots out of sugar they would last longer under the heat.
Re: (Score:3)
The dextrous robot was dangled into the Unit 2 reactor
Maybe if they didn't make their robots out of sugar they would last longer under the heat.
"Dextrous" just means it's a right-handed robot. If it were left-handed it would be "sinister". Any medical professional should be able to confirm this.
Re: (Score:2)
Like we should have stopped building railroads after the first fatal accident and stopped building airplanes after the first crash killed someone and stopped the space program after the Apollo 1 fire and stopped production of all monoclonal antibodies after the first patient died from side effects?
We learn from each accident and improve. You are including accidents from the relative infancy of nuclear power. For example, at the time of the accident, Chernobyl was an ancient plant of ancient design with idio
Re: (Score:2)
... idiot operators.
Have we solved this problem yet?
Re: (Score:2)
... idiot operators.
Have we solved this problem yet?
Somehow I don't think anyone will ever be that stupid again. Basically, they simulated a meltdown by shutting off all the safety and power systems to see if the momentum of the spinning turbines could keep the cooling system going. Well, they couldn't so then they turned up the reactor to full power to keep them going which caused the reactor to get too hot and then try tried backing off the reactor but it was already out of control. And since all the safety systems were already disabled and couldn't qui
Re:whare are all the nuclear apologists? (Score:5, Insightful)
about 20 years ramping up from 0 to 2000 TWh/yr, plus 30 years at about 2200 TWh/yr = (20*2000/2) + (30*2200) = 86000
Cost of the above two cleanups divided by the amount of energy generated by nuclear power: $432 billion / 86000 billion kWh = $0.005 per kWh = 0.5 cents per kWh
I can live with paying an extra half cent per kWh to cover cleaning up after the occasional disaster every 25 years, in exchange for using a completely carbon-neutral power source which boasts the fewest deaths per amount of power generated [nextbigfuture.com]. Why exactly are you opposed to it?
Re: (Score:3)
Also, there are not only costs for disaster clean-ups, but currently completely unknown costs for the safe storage of the nuclear waste produced. The Asse II mine [wikipedia.org] alone, which was attempted to be used for nuclear waste storage during 11 years, has cost ~9 billion Euro as of today, with no end of additional costs in sight. And that was just one small site.
Re: (Score:3)
but currently completely unknown costs for the safe storage of the nuclear waste produced
1. Hyperbole claiming something we've been doing for 40 years is unknown. X.
2. Pointing to a single case to make a general claim rather than a study of industry practice. X.
3. Ignoring that the issue is mostly of political nature and that many better options for waste exist. X
4. Not reading the original links posted and making a claim that something is unknown. X
BINGO! Hey everyone, I got NIMBY Nuclear Bullshit Bingo!
Re: (Score:2, Informative)
I can live with paying an extra half cent per kWh to cover cleaning up after the occasional disaster every 25 years, in exchange for using a completely carbon-neutral power source which boasts the fewest deaths per amount of power generated [nextbigfuture.com]. Why exactly are you opposed to it?
The first is that information related to this subject is heavily censored. The information you have provided is from organizations who are restricted in what they are allowed to publish.
Money isn't the main consideration. The impact of a single disaster is. Fukushima was four disasters at once and considering the amount of spent fuel rods stored on the site had the potential to be an extinction level event. It still does as the removal process has stalled [phys.org] with 566 rods remaining in a precarious posit [tepco.co.jp]
Re: (Score:1)
Please excuse my ignorance, but how do you figure that Fukushima had the potential to be an extinction level event?
Not had, *has*. Fukushima *has* the potential to be an extinction level event.
I know I will probably get a lot of criticism for sharing this viewpoint and I don't care, this is a serious matter relevant to us all. The Fukushima disaster is still not controlled almost 10 years later. It's not over.
Even if every gram of radioactive substance on site detonated in a sustained criticality, my understanding is we'd be left with a big crater and a hot, ugly mess that could potentially increase cancer rates by a small amount.
There is a reason that spent fuel rods are kept in a pool with a constant supply of cool water. That is because the water not only cools them, it moderates the neutrons. When the water is absent the fuel rod
Re: whare are all the nuclear apologists? (Score:2)
That's an incredibly long way of saying "I have absolutely nothing to support my ridiculous assertion".
Gratitude to the Fukushima workers and engineers (Score:2)
I said "There is a reason that spent fuel rods are kept in a pool with a constant supply of cool water" that is the context. The fuel rods are MOX so we agree that they contain plutonium.
References: (Score:2)
A report called Nuclear Power Plant Security and Vulnerabilities [google.com.au] explored vulnerabilities at nuclear power plants.
From that the issue of spent fuel pool vulnerabilities warranted further study in the now declassified report Safety and Security of Commercial Spent Nuclear Fuel Storage: Public Report [google.com] by the Committee on the Safety and Security of Commercial Spent Nuclear Fuel Storage within the National Research Council which details variation of the above scenario from a terrorist attack, as opposed to a
Re: whare are all the nuclear apologists? (Score:2)
Fukushima was four disasters at once and considering the amount of spent fuel rods stored on the site had the potential to be an extinction level event.
This is by far the stupidest thing I have read so far in 2019. You have another 10 months to try and top it, but I doubt that's possible.
Re: (Score:1)
Fukushima was four disasters at once and considering the amount of spent fuel rods stored on the site had the potential to be an extinction level event.
This is by far the stupidest thing I have read so far in 2019. You have another 10 months to try and top it, but I doubt that's possible.
Your comment suggests this information is so far out of your capacity to process you have to use ridicule to mask your fear, knowing that the truth is far from your capacity to comprehend. Your discomfit is evident in your inability to ask questions which exposes ignorance that Mr AC had the social skills to ask to be excused for.
It seems from the way you communicate, c6gunner, that you carry the consequences of some serious trauma. From your pseudonym you are presumably a serviceman or woman, probably
Re: whare are all the nuclear apologists? (Score:2)
Sorry, all I read was "blah blah blah, I'm a dirty tramp".
Re: (Score:2)
You can't point at the cleanup costs, any more than you can point out how cheap it is for a dude to dig coal out of the ground and burn it or someone who just randomly put a wind turbine on his house and now claims to get free electricity.
The best method we have is levelised cost of energy [wikipedia.org]. I don't know if LCOE for nuclear includes cleanup costs - I would guess not as it's rare that they need to deal with it, but as you note it might not be that much anyway.
The most interesting thing though is the LCOE of r
Re: (Score:2)
You pay this in addition to other costs for nuclear which are already so high that nobody really invests in nuclear anymore. Also the deaths per TWh you refer to from a random source on the internet is not plausible as it obviously ignores excess deaths from radiation which is hard to estimate but also can't be ignored completely.
Re: (Score:3)
I can live with paying an extra half cent per kWh to cover cleaning up
Something you wouldn't need to do if our reactors weren't 40+ years old and if the greenies hadn't handcuffed development of safer nuclear technologies for the past 50 years.
Re: (Score:2)
That's a vast under-estimate for the cost of the Fukushima clean up. Are you including all the compensation and knock-on costs like delayed tsunami damage repair and having to build new communities because the old ones have dissipated over the years?
Also, calculating the per kWh cost based on global production is ridiculous. Only Japanese people are paying that cost, and for them it's vastly higher.
Of course, this is a pretty horrific example of externalizing your costs. Even if you accept the monetary cost
Re: (Score:3)
I'm not a nuclear apologist by any means, but it's an empty argument to say Fukushima means nuclear is impossible. Nobody would build a plant remotely like this one, or situate a modern plant anywhere like there.
I'm a huge proponent of upgrade the electric grid. This would enable renewable sources to power distant cities, but it could *coincidentally* give more flexibility in locating nuclear plants, should we decide to build more of them. And if we do we need to build what we've learned about organiza
Re: (Score:3, Insightful)
I'm not a nuclear apologist by any means, but it's an empty argument to say Fukushima means nuclear is impossible. Nobody would build a plant remotely like this one, or situate a modern plant anywhere like there.
Consider that there is approximately 80 of these types of reactors still in operation and that their service life is 40 years which has been extended to increase the return on investment.
The next thing to consider is that it is possible to make a reactor design that isn't an improvement over older designs. Currently the best one is EPR which...
And if we do we need to build what we've learned about organizations running nuclear plants (we can't rely on them doing the right thing) into the design.
incorporates some of the improvements the NRC commissioned the Nuclear industry to uncover. They came up with 30 improvements to Nuclear reactor design. The mos
Re: (Score:2)
Nobody would build a plant remotely like this one, or situate a modern plant anywhere like there.
And was this the last unsafe plant in operation, or are there more plants at risk ? If there are more, what are the plans for shutting them down ?
Re: (Score:2)
No. There are a number of plants *exactly like this one*, although few in such dangerous places.