- Date published:
10:11 am, March 14th, 2011 - 72 comments
Categories: disaster, International, sustainability - Tags: japan, nuclear energy, nuclear free, sendai earthquake
Here’s the kind of headline you really really don’t want to wake up to:
Japan on brink of nuclear meltdown
Desperate attempts are being made to cool a Japanese nuclear power plant crippled by the country’s huge earthquake and tsunami – but indications are that one of its uranium reactors has at least partially melted.
And last night, a top Government official warned that a meltdown in the third of the plant’s three reactors was “highly possible”.
You can follow events as they happen on the inevitable Guardian Blog.
On top of the quake and tsunami aftermath, Japan is already dealing with evacuations and the effects of the radiation leaked so far. If the last ditch efforts (using sea water for cooling) fail then:
If the temperature inside the reactor continues to rise and reaches roughly 2200C, the uranium fuel pellets will start to melt. From there, melted fuel will eat through the bottom of the reactor vessel, then the floor of the damaged containment building. At that point, the uranium and radioactive byproducts of the nuclear reactions will start escaping into the environment.
At some point, the walls of the reactor vessel will melt into a lava-like pile, slump into any remaining water on the floor, and could cause an explosion much bigger than the one caused by the hydrogen, enhancing the spread of radioactive contaminants. …
In Auckland, Dr Krofcheck said that if the Fukushima Daiichi accident became a meltdown and released large amounts of radiation, “I’m sure it would not be a major problem for New Zealand. Most of it would be confined to the Northern Hemisphere, and most certainly, Japan itself.”
We’re looking at a second Chernobyl.
This event ends whatever remote possibility that ever existed of NZ heading down the nuclear power path. Coming as it does on the heels of the Christchurch earthquake, it is all too easy to imagine the same scenario playing out here. What price our agricultural exports, tourism industry, and “clean green” image then? NZ would be finished.
So now, even the Nats can stop their “gone by lunchtime” dithering and insincere commitments. New Zealand must remain nuclear free forever. Combined with the coming oil shock, that makes energy conservation and renewable energy sources an overwhelming priority for research, development and deployment. Any party heading in to the next election preaching business as usual deserves to be laughed out of politics. We need a plan for a nuclear free and oil constrained future, and we need it now.
All of my posts for March will finish with this note. While life goes on as usual outside Christchurch, let our thoughts be with those who are coping with the aftermath, with the sorrow of so many who were lost, and with the challenges ahead.
I cannot believe Japan would go nuclear after what happened to them in the war.
I also spotted this news, which really scared me…
‘Wellington plans for worst-case quake
The Basin Reserve could become a welfare centre, supplies would be flown in by Defence Force helicopters, and Parliament could make an emergency move to Auckland if the big one struck Wellington.
We don’t want NACTMU in Auckland. They can stay in the capitalist Babylon they are creating. We’ll just have the parties and independents that don’t adhere to the American Larry Kudlow capitalist thinking:
“CNBC’s Larry Kudlow expressed his relief in terms that seemed to appall even his fellow cheerleaders for capitalism: “The human toll here,” he declared, “looks to be much worse than the economic toll and we can be grateful for that.”
Wonder what Mill would have thought of that re the Harm Principle?
And to think my opinion of America and so many of its feral (Michael Laws-like) inhabitants couldn’t get any lower…
Never say never. The modern nuclear industry was driven by military needs for reactors not energy, in an era of cheap oil we did not need nuclear power! So the designs, the types, even the choice of fuel all had dual purpose. I think its naive to ignore how much radiation is shipped around the world, into NZ also, medically. Japan’s earthquake says nothing more about Nuclear as a viable energy than a tailing dam bursting built as part of a military build up. Thorium maybe a future nuclear fuel. Would we choose coal if we had known the dire problems of mining in the early coal era. Nuclear will adapt, will become safer, and will be coming to NZ. And we will never be building the type of reactor that has just gone into meltdown even if we were nuclear slap happy tomorrow.
“Nuclear will adapt, will become safer, and will be coming to NZ. ”
I hope you’re wrong about the last part – and I am nearly 100% certain you’re wrong about the first part. Adapt and become safer – how, by magic?
They had an interview with a professor of nuclear physics from a british university on 9 to Noon this morning. He was saying that from what he’s seen on TV and read about the situation, the major danger period has passed and that there is unlikely to be a release of radiation into the atmosphere.
Meltdown is not a technical term, all it means is that the nuclear fuel has melted. They have detected caesium isotopes in the steam that they let off (part of the reason for letting the steam off) which indicates that some of the fuel rods have at least partially melted.
As long as the pressurised containment vessel stays intact, the radiation will not reach the atmosphere. Pumping seawater in is designed to cool the vessel, thus releasing pressure (high school chemistry/physics) and preventing an explosion. Once you put seawater into a reactor, it effectively can never be used to generate power again as it is too corrosive (putting aside the fact that no one can go into the reactor to clean up the mess).
What happened in Chernobyl is that the reaction continued in an uncontrolled fashion and the containment vessel exploded, releasing radiation and isotopes into the atmosphere. The nuclear reactions in these Japanese reactors ended on Friday when the automatic systems put the carbon dampening rods into the cores, the problem was the systems to continue pumping the water broke down so even though the reactions were stopped, the temperature could still build up to explosive levels. As they are now pumping seawater in (because it’s plentiful and readily available) to cool them down, it is highly unlikely that there will be any explosions.
So no, we are not looking at another Chernobyl.
Finally, modern nuclear reactors are much smaller, safer and cheaper than these old ones (built in the 60’s) that Japan is using. Any reactors commissioned in NZ would obviously be of the new design, and therefore much less at risk of being dangerous. This disaster will probably propel Japan forwards into further designing and building of newer reactors, as they’ll need to replace the base load power that these plants provided.
Japan’s US envoy on Saturday acknowledged there had been a “partial melt” of a fuel rod at the quake-hit plant. Another expert has said that an explosion like the one from unit 1 could only happen if the vessel itself explodes. I don’t trust Tepco to tell us the truth. After the Japanese prime minister said there was no problems with any nuclear reactors after the quake when there clearly was, I don’t trust the Japanese government to tell us the truth either.
Just in case you didn’t know already Lanthanide, there has been an explosion and radioactive material has been released into the environment. One worker has been killed and several more highly contaminated. Some people in the surrounding area have also been contaminated. That professor is obviously an idiot as pressure is still rising in unit 3, which is a much larger reactor than unit 1. This could potentially be worse than Chernobyl because the ocean is likely to get highly contaminated as well.
The explosion was not of the reactor vessel, but the concrete containment building around it.
The only release of radioactive material into the environment has been their deliberate release of steam, to help reduce pressure as well as monitor the state inside the reactor (as I mentioned in my comment).
As for the professor being “an idiot”, yeah, I guess he doesn’t know anything, he just does this stuff for a living.
“Tokyo Electric Power Co has successfully lowered pressure inside the containment vessel of unit 3 at its Fukushima Daiichi nuclear power plant, which was crippled by Friday’s earthquake, the company said Sunday.”
But hey, I guess that’s coming from the lying Japanese government, so we should just ignore everything they say and come up with our own doomsday scenarios because that’s more fun.
I am with you Lanthanide. I think that those who are opposed to nuclear energy are exaggerating the threat in Japan. (Wish they wouldn’t as it blocks any sensible discussion.)
Consider this. If the Japanese nuclear sites do not cause a Chernobyl type disaster, and there is no evidence at all so far that they will, then this would be very reassuring. There has been a 9 earthquake and huge tsunamis!
I would agree. So far the engineering seems to be holding out quite well. Looks like there have been some screwed up decisions, but the fallback options worked. The radiation threat to people outside the plant is minimal.
It does highlight another dependency. By dropping seawater into reactors they have destroyed those. It will be a messy cleanup. But also it will be sometime before power comes on to replace such a large power source. Could we afford to lose that much generating capability in one incident
There’s been talk of rolling blackouts, including for Tokyo. Whether these are just in the short-medium term (due to other undamaged reactors being taken offline) or long-term I don’t know.
The Japanese plants are 40 years old and technology around structures must have changed hugely since then, especially in regards to cooling. I guess that that much loss of power here would be devastating but fail safe could become a reality. Optimist you see.
Isn’t it ironic that the #1 reactor @ Fukushima was scheduled to be ‘switched off’ later this month. Was just extended another 10 years last month, guess someone didn’t get that memo.
lprent – iirc Huntly has a capacity just over 1400MW which put it on par with the plants planned for Fukushima I – 7 (& 8). Reduce the output of Huntly to ‘tick over’ levels or mothball – build a nice ABWR somewhere North of Auckland (Kaipara perhaps) and worst case, bring Huntly back online when needed. Currently, over summer Huntly is pretty much ‘wound down’ as river temperature output limits would be exceeded if they ran the plant at it’s rated capacity.
My primary objection to nuclear plants in NZ has always been what to do with the high level waste rather than the plants themselves. Although the plant sizes are also pretty damn risky as well.
One thing that became clear to me when I studied the geology of NZ is that there is nowhere to store long life waste here because it is far too unstable. There is nowhere in NZ that you could reliably place waste and not expect it to enter the water systems within a few hundred years or sooner.
The Japanese have the same problem, and chose to export the waste at a very very high risk to everyone else over the oceans. But they have far fewer choices than we do because of their population levels. We should not try to emulate their example.
NZ could dump it’s waste in Aussie. Yes, risky ocean journey, but most logical place for it.
I would like to see the insurance rate to completely cover for liability for that journey. I would expect it would make the power generated by a nuclear plant here to be the most expensive form of power available to NZ.
Another explosion at Fukushima reactor #3.
Nuclear power in NZ would be absurd and uneconomical. There are obvious problems of waste and back up if the plant went off line. There must be great potential for furthur development of solar-wind, sun and tidal. Clean burning coal plants may be a reasonable possibility. But the real problem in NZ seems to be old, inefficient and inadequate transmission systems and wires for transporting the power, nb from the south were much of it is produced to the cities and industry north of taupo. I am certain we could easily and affordably produce far more power without any contemplation of nuclear.
Much of the advocacy of nuclear is from act like ideologues who see nuclear as the future and potential easy power source of some future idyllic utopia for mankind. Obviously they also see trade advantages of becoming part of the nuclear community. But I view it all a bad idea- and not much different from communist utopian thinking. The pro nuke and act people often are people who would have been communists in the past.
And how much do we want a population of ten million based on heavy massively power using industry. In the 1960s we all thought people would work less and have much more leisure and pleasure. Less work would probably mean much less waste and power use. Seems like an excellent idea.
At the core of the thing I don’t think there’s a future for more nuclear plants in the west in its preseent form and I think the Americans and the Atomic energy commissions and authority are absolutely daft to encourage the spread of nuclear power. Why and earth would it be desireable to spread nuclear technolgy to the likes of Iraq and Iran. They have pleny of other power sources.
I also judge the idea of many of the US military authorities that the atomic and hydrogen bombs deter war and that if Iran had the nuke bomb it would be more secure, confident its regime would survive and less likely to throw one. I judge it entirely undesirable for the present Iranian and North Korean regime to survive.
There are good reasons to suppose Iran might throw one at Isreal and that nuclear war between India and Pakistan is quite possible, ( it is for that reason that the yanks have done everything to get the Pakistan nuclear bombs safely stored and at a lower level of rediness. The real point is that Stalin and Kruschev were deterred by the threat and disaster of conventional world war just as much as the destruction of the nuclear threat. Fundamentally the possiblity of another destructive global conventional war with even mass conventional hits by B-52s , B-47 etc was a greater deterrent in itself.
The real popularity of nuclear deterence was with the second line powers of Europe. Kennedy and mcNammara actually wanted to fight conventionally in Europe for up to three months and stocked their forces accordingly. It was the Germans, French and British would wanted the war to be nuclear immediately. JFK was always incensed that De Gaulle and Ardenau would not stock their forces for more than 1 or 2 days of conventional fighting.
Cruise missiles were what Schmidt the Germans and Italians wanted they were not the idea of Carter of Reagan. It was the French and Germans would wanted nucleear and were among the strongest opponents of nuke free NZ. But from today this will change-and maybe it is the Camerons and blairs who were among the most determined to reactivate nuclear building who will be in the most difficult situattion and a thorn for anti nuke NZ.
Nuclear plants remain steam age, heavy industrial stalinist style projects. Essentially modified big coal powered steam generating plants. Its essentially the same idea of heating water and driving steam turbines. Recent attempts to reactive nuclear building in the US and Finland have proved massively costly, delayed and troublesome. I think if nuclear comes again it will be in a completly different form several hundred years down the track. It is true that breeder reactors are more efficient and reduce the waste problem- but the proliferation problem is too dangerous to allow them. There are too many Islamics and fundamentalists who believe in the dictatorship of the ordinary people, guaranteeing war and trouble.
Those who think the emergence of nuclear energy in war and peace in l945 changed everything are simply wrong in my opinion.
The meltdown in Japan will change the direction of the world, but it will take 20-25 years for this to be realy apparent.
So the answer to our growing power needs is to work less…. Well yes i guess a recession could help in that aspect.
But serioulsy, nuclear power is something that will arrive in NZ. Its only a matter of time.
The wikicable leaks have shown us that NZ has both under the labour and national goverments worked with the US to reconsider our no-nukes policy…
The Aussie goverment went to the elections with a pro-nuclear policy in 2007, how long do you think it’ll be before NZ changes its no-nuke policy if aussies build nuclear reactors?
Not to mention i suspect given how quickly our power needs grow, it’ll be less then 20 years before we are forced to either take a hard long look at nuke power.
Burning coal is something the greenies hate, and honestly its not very healthy. And with the ETS and kyoto treaty, its going to be hard to use coal for power.
We can’t get any damns built without years of litigation from the natives, or if there aren’t any natives, the rest of nz since its a wild stream..
Not to mention we can’t just keep damning our rivers, that’ll only buy us a few decades at best.
Nucular power is by far the greenest, cheapest power we have to mankind. NZ isn’t a terrorist nation, so as long as don’t import weapons grade urainum we’ll be fine.
Australlia is both a great source of raw uranium and storage space, if they were willing to commit, we’d have most of the logistics cleared.
NZ will have nuclear power, its just a matter of time.
“Consider this. If the Japanese nuclear sites do not cause a Chernobyl type disaster, and there is no evidence at all so far that they will, then this would be very reassuring. There has been a 9 earthquake and huge tsunamis!”
Yes, I fully agree. At the same time however, we’ve seen how bad a medium-sized earthquake can be when it’s in the wrong place with CHCH. How would these plants have fared if there had been a 7M+ quake within 30-40km of them, instead of hundreds of km out to sea?
Apparently the explosion happened because pressure was building up inside the vessel and was quickly pumped into the containment building. With a partial meltdown confirmed, that pressurized release explosion will have contained radiation.
Radiation exceeded the legal allowable limit after the radioactive steam release and before the explosion.
Tepco successfully lowered pressure inside the containment vessel of unit 3 by releasing more radioactive “steam” into the atmosphere. Unit three still has the potential to have a full meltdown scenario. A similar scenario has happened at Onagawa nuclear power plant (It was the most quickly constructed nuclear power plant in the world) where reports are that radiation levels have returned to normal. The Onagawa-3 unit is the most modern reactor in all of Japan so there goes all those theories that it is only old reactors that are having problems. Unit two at Fukushima is also having cooling problems bringing the total of dangerous reactors up to five.
At the Tokai No. 2 nuclear power plant, which is only 120km north of Tokyo, the cooling pump stopped working, while at the Onagawa nuclear power plant, in the Miyagi Prefecture, a state of emergency was declared because of excessive radiation levels.
Pumping seawater into a reactor is seen as a last-ditch effort to stop a meltdown because although the water acts as an effective coolant, the corrosive properties of the water mean that the reactor will never function again.
I wonder where all that radioactive sea water is going? The radioactive “steam” release is obviously not the only contamination.
Your link to an article by platts is hardly the confirmation we require that the danger has subsided. But hey, nuclear power is safe eh! We should all have a reactor under our houses so that we can stay warm and toasty till the cows come home.
So did the Japanese prime minister lie or not Lanthanide?
I don’t know for sure why the explosion happened, but yes I’d say it’s possible that if it is a result of pressure being let off from the core itself, that the explosion could have contained radioactive particles.
“A similar scenario has happened at Onagawa nuclear power plant (It was the most quickly constructed nuclear power plant in the world) where reports are that radiation levels have returned to normal. The Onagawa-3 unit is the most modern reactor in all of Japan so there goes all those theories that it is only old reactors that are having problems.”
As I understand it, the Onagawa-3 unit is not actually in any trouble at the moment and was successfully shut down following the quake. So yes, I would say it is good evidence that newer reactors are safer.
“I wonder where all that radioactive sea water is going?”
I bet they’re just pumping it back into the ocean. It’s the obvious thing to do with it.
“So did the Japanese prime minister lie or not Lanthanide?”
If you’re referring to “After the Japanese prime minister said there was no problems with any nuclear reactors after the quake when there clearly was, I don’t trust the Japanese government to tell us the truth either.”
Because that statement is so vague, I’m assuming you’re talking about something he said on Friday or early Saturday. Note that the reactors all did automatically shut themselves down, the problem is the water cooling systems that broke down. So I don’t think he was “lying” at all, but just explaining the situation with the information he had on hand at the time – that all reactors had automatically and safely shut down. The fact that problems started to occur after this doesn’t mean he lied. Or, he could have been informed of the water system failures (questionable – he’s the PM, he has many other things to deal with) but was assured at the time that they expected to fix the problem quickly, so saw no reason to mention it in his statement.
There’s a big difference between “deliberately lying about information that is on hand” and “conveying the important information that is on hand”.
I believe he made the statement soon after visiting Fukushima 1. Clearly the reactors had not safely shut down because they were not being cooled. I believe this would have been apparent at the time. In my mind a safe shutdown includes infrastructure to maintain that shut down process. But then they always minimize the effects of such “accidents” just to try and make us believe nuclear power is safe.
Initially, the backup diesel generators did cut in And when they failed, the battery back-up to the backup cut in. Problem was that the batteries lasted only a few hours, and it takes days to cool a shut down nuclear reactor to a safe temperature level.
I’m not sure of the exact chronology, but its’s possible he made that statement at the time one or other of the backup sysytems were running and that he had been advised everything was okay.
Then again, given the history of disinformation during the Three Mile Island and Chernobyl nuclear accidents, there’s also a high likelihood he was lying.
So where did the caesium-137 that has been detected around the plant come from? Sure, the steam release (although not the hydrogen explosion) was deliberate, but I can’t see how caesium-137 could get into the steam unless there had already been damage to the fuel rods themselves.
Yes some damage to the fuel rods (could have been minor) and also some damage of the primary reactor coolant system which then allowed the free caesium into the secondary coolant system or outer containment area, where it escaped with the pressure venting of excess steam.
Coming as it does on the heels of the Christchurch earthquake, it is all too easy to imagine the same scenario playing out here.
The same scenario? I suspect that if the Christchurch earthquake had caused a 10-metre tsunami, whether or not there was a nuclear power plant in the region would be the least of your worries.
There was someone else on the radio this morning, saying they were in the city of Sendai. Everything there didn’t seem too bad from the tsunami – they even had power restored. But as he went out into the countryside, the damage was much worse.
This makes sense of course – a tsunami wave that meets substantial resistance in the form of buildings in a city won’t actually damage much of the city itself before it loses strength, whereas when it has a clear run of space such as a rural area with farmland, it can go much further inland and easily destroy the few buildings or small towns it comes across without losing significant strength.
As an aside, the media haven’t been clearly distinguishing the damage from the earthquake to that from the tsunami. The earthquake damage itself has not been terribly significant, as the quake struck off-shore and was much deeper than those we’ve seen in NZ recently. This means the shaking is of much longer wavelengths, more of a ‘rolling’ motion than a sharp shaking motion, and is generally easier for buildings to withstand. Similarly Japan’s building code is one of the strongest in the world for dealing with earthquake damage (and historically they used very light building materials such as paper and plywood) and so withstood it fairly well. Most of the loss of life and structural damage has come from the tsunami itself and as such is concentrated on the coast.
I saw satellite photos of some of those towns hit by the tsunami. In Christchurch you can see where the remains of the buildings have fallen. In Japan, entire suburbs have been washed away outright, leaving mud, and foundation debris. Truly scary.
A broken nuclear plant would be at the forefront of everyone’s worries and an earthquake like the last one would most likely break it.
Would it? The 40-year-old Japanese ones came through their quake without a problem – apparently they were rated to stand up to an 8.2 quake. It was the tsunami taking out multiple backup generator systems that has caused their problems (which isn’t actually likely to cause a Chernobyl-like explosion – that’s just wishful thinking by anti-nuclear activists).
You mentioned the Chch earthquake which, as you may have noticed, didn’t have a tsunami but did do a hell of a lot of structural damage – they type of damage that you do not want at a nuclear plant.
But we aren’t Nuclear free today. Refer: GNS National Isotope Centre, all sorts of lovely ‘glow in the dark’ products in-use & stored there.
“Nuclear free” refers to power generation and weapons, as in actual nuclear reactions taking place on a large scale. Not the simple use of radioactive isotopes or emissions such as gamma rays.
Did you know that common smoke alarms use radioactive isotopes in them?
Yep – well aware of that. And let’s not forget all the lovely X Ray machines, MRI machines etc that our health service relies on – these all emit radiation well above back ground noise levels.
Hey you’ve missed out the Coromandel massif. All of that lovely granite that emit radiation well above back ground noise levels
Just pointing out that your statement was on being made by an idiot. Background radiation levels under a house in granite country can be hundreds of times higher than those in the open air over a silt flood plain for instance. Quantify what you’ve talking about if you want it to be taken seriously…
Not a specific reply to Lynn here (I’m sure he knows it), but in the US they can have fairly big problems with building cities and towns on granite.
In the US because it gets so cold in a lot of places, they build basements. Basements are effectively for insulation purposes, providing a pocket of air that is warmer than the surrounding ground, over which the house is built. They’re also useful places to put furnaces etc. In areas where they’re building into granite, the radioactive decay of the granite can result in radon seeping into the houses. Radon is a noble gas (like helium and neon) but it is also radioactive. Because basements tend not to get much airflow, houses can end up with basements full of radioactive gas that kill the occupants. They now have radon detectors in basements to monitor the levels and warn when it getting unsafe.
maybe this explains all them there teabaggers blogging from their basements in their pajamas slowly evolving into something eldritch.
I think the NZ legislation prohibits nuclear power only on sea vessels (along with nuclear weapons). There’s no law against land-based nuclear power generation.
That’s a totally different thing:
– the quantities are much, much smaller: milligrams and grams, not kilograms and tonnes.
– the isotopes are generated with a particle accelerator which stops when you switch the power off
– the amount of heat produced by the small quantity of isotopes (both during and after production) is negligible, so they can be safely stored in a sealed container without active cooling
Theres another nasty scenario that lurks throughout the Iraq area. Its the atomised detritus of radiation from depleted uranium projectiles used during both Gulf wars. We have seen campaigns against land mines. They can at least be cleaned up, the radiation in that area will cause genetic damage for centuries. The Vietnam vets came down with Agent Orange damage, Gulf war vets are displaying symptoms such as thyroid cancers and deformed offspring.
It would be nice to know if our armed forces use depleted uranium weaponry.
Yeah, I think calling them “depleted uranium” is sort of a white-washing PR move. So anyone that objects to them can just be fobbed off with “it’s *depleted*”, not that that actually means they’re safe.
Radioactive waste security
A secure, medium-term storage facility for radioactive wastes, including depleted uranium, is maintained under surveillance.
Is it actually stored in CHCH or is that just their offices?
I’ve also heard rumours that a university in Auckland has a small-scale operating reactor for scientific research, know anything about that?
I have also heard there was a “little accident” at Victoria University in the 1960s or 1970s that involved some radiation leakage.
The urban myth goes that the material was eventually buried under Ian Galloway Park.
If a meltdown involves a 2200 degrees lava-like pile of uranium melting through whatever it comes into contact with, then where does this idea come from that it simply sloshes on the ground and explodes on cantact with water?
Not saying that isn’t one consequence….or a part of the consequence. But doesn’t it continue melting through whatever is beneath it? And when and how would it stop melting whatever it came into contact with?
Admission. I’m an 80’s kid. And I remember the fear of a meltdown was the prospect of a hole descending down to the magma beneath the earth’s crust.( Three Mile Island presented such a fear. So did Chernobyl. From memory, neither of these accidents were reported at the time as having resulted in a meltdown.)
So would somebody mind telling me whether that fear was based on nothing more than a social myth or if the consequences of a meltdown are beng down played? Or if the term ‘meltdown’ is being used to apply to different scenarios and confusing matters?
I can’t answer most of your specific scientific queries, but I can say that you would need an absolutely huge (or very very hot) ball of anything in order to melt all the way to the center of the earth. Or even just several kilometres to get down to a magma pocket. Melting rock, eg turning it into liquid, involves the transfer of heat from your hot object to your rock. This in turn cools the hot object down (much like adding cold water to a hot cup of coffee cools the coffee down).
So fears of something burning through to the centre of the earth, or even a significant depth, is pretty unfounded.
‘meltdown’ is really just the term for when uranium goes from being a in controlled state – eg rods coated in zircaloy, to being in a form where it isn’t controlled, eg through melting. Under controlled states, scientists know enough about how it behaves to be sure that it is safe. Under uncontrolled conditions, it could explode, potentially spreading radioactive isotopes into the environment.
I get your analogy and understand about heat transfer resulting in cooling. But the heat is coming from, or being replenished by a nuclear reaction within the material that is doing the melting, no? So…that means the heat doesn’t dissipate into the surrounding environment in the manner it would with an object containing a given and unreplenishable amount of kilo joules.
Good point. I’d have to pass on that question, although I think the mass involved would still need to be much larger than is contained in the average power station, since only a small amount of uranium is required to be in the core to generate power.
The ‘china syndrome’ was always pretty much of a myth. Reactors by their very nature rely on concentration and control. Quite simply if something got that hot (which is extremely unlikely), it’d melt everything around it which would cause immediate dilution. It would also have continuous explosions as volatiles heated, spitting lumps of radioactive material everywhere and diluting the neutron emitting mass. It would be hot and radioactive as hell, extremely dangerous to be downwind of, and would not melt more than 10’s of meters at best.
Has anyone tried to build a reactor which simply utilised decay heat from fuel rods but could never go critical? It seems that those fuel rods in themselves pour out heat without needing to go critical.
Thermal energy generation relies on heat differential. The bigger the heat differential the more energy that can be extracted, making it more efficient.
I suspect that the heat generation from a fuel rod isn’t sufficient, by itself, to make it commercially feasible. Especially if you can take that same fuel rod and use it in a different process and get 1,000x the energy from it.
This seems vaguely relevant.
I read that the Hiroshima bomb it could have been considered a technical failure since less than 2% of the uranium underwent a fissile reaction. The rest of it was just blown apart and vapourised before the chain reaction could reach it.
Yeah, most atomic bombs don’t come anywhere near 100% fission.
Neither do atomic energy plants – that’s why there’s the big palava over making more advanced reactors (thorium?) that can process the existing “nuclear waste” that is actually still a viable fuel for the right design of reactor.
yep – we’re so lucky that Edmund Teller made the the world more efficient.
The problem I have with regards to the safety of nuclear power plants is that their safety systems are still based on redundancy. Something goes wrong and another system comes in to take over.. essentially, and if that goes wrong there’s another redundant system to take over from that one etc etc. But if they all go wrong, you’re basically fucked.
I’d be against building a reactor here until reactors with passive safety measures, ones that shut down without the need for any intervention when something goes wrong (like pebble-bed reactors), become the norm. Reactors like this are still in the testing phase though. As far as I’m aware there’s only one full sized pebble-bed reactor, a prototype in China.
Of course the other issue is waste, burying it for the next 10,000 years isn’t such a great solution.
Although I would add that with the Gen III+ reactors they’ve gone out of their way to reduce the number of systems and parts as well, so there is much less which can go wrong. Using gravity and natural convection to drive coolant is an improvement for instance – you don’t need electricity or steam supply to the plant to keep pumps working.
But yeah, its the waste aspect which really gazumps the whole thing.
I fail to see how you can cool a hot thing (whether a reactor or a car engine) with a gravity fed coolant supply (unless you built it under a waterfall). Eventually you’ll have an empty header tank and a reservoir of warm coolant, surely.
Equally, I’m not convinced how convection cooling could work unless the reactor was in a large tank relative to its energy output (research reactors that produce a few kilowatts of energy work like this).
All the third generation designs I could find referenced just rely on multiple redundant systems, they aren’t intrinsically safe.
Maybe they use the coffee percolator principle?
Coolant drips from header into reactor, boils, and is carried up tube by bubbles to header tank, where it is cooled. Don’t ocean archeologists use vacuum hoseson the seasbed to clean silt offsites by bubbling compressed air up the tube and the bubles add motion to the water?
New reactor designs do use passive safety systems which are effectively fail safe.
Even the older systems could be contained in the event of a serious accident. Despite the sinking and breaking up of two US nuclear submarines there are no signs that the reactor containment has failed after many years underwater.
One of the disadvantages of the older reactors (and much US technology pre 1990) was the propensity to solve safety problems by adding more systems. Leading to the type of chain of cascading failures they have in Japan and earlier in 3 mile Island.
Engineers have learn’t from mistakes made and recent designs use simple passive safety systems.
Things like coolant that is part of the reaction path, so if it drains away the reaction stops, for instance.
Submarine reactors have to take design accelerations many times that in even the biggest quake or tsunami.
Safety is actually a good argument for nuclear power especially if you compare it with the safety record of coal mining and the resulting pollution.
Nuclear power should not be an option presently, in NZ, for the reasons that: we are lucky enough, and have a small enough population, to be able use conservation of energy and sustainable generation from other cheaper sources. And the big kicker. Waste disposal.
Other countries, like Japan, are in the unfortunate position of having to decide between contributing to global warming, acid rain and other downfalls of energy production, starving their people or using Nuclear power.
There may well be a case for nuclear power as being better and safer long term for them than the alternatives.
New technology in nuclear power may yet make it a good alternative energy supply. Fusion is still a possibility as well as reacting waste to make it less harmful.
The reactors have actually held up well considering the earthquake was 100’s of times bigger than their design criteria quake.
They wouldn’t tell people if there was radiation leaking from the numerous submarine accidents. It is only a matter of time till they do start leaking. I wonder what all those forty-gallon drums of nuclear waste they dumped into the ocean are doing about now?
I suppose one can argue that nuclear power is safer overall in that as far as we know, it has not killed as many people as coal, but the real question is about its potential to kill and the time it takes to decontaminate an area when an accident occurs.
Luckily it is not a choice between coal and nuclear power, there are many alternatives that are proven to be efficient and are vastly more suitable to New Zealands terrain and conditions.
In light of six Japanese reactors failing (with two probable meltdowns) after the 9M earthquake, including a recently built one using the newest technology around, I really don’t think that you can formulate an argument that nuclear reactors are safe KJT.
Greenpeace Response to Radioactivity Release from Fukushima Reactor
“Greenpeace is concerned about the lack of facts and transparency about the total amount of radiation that has already been released, the exact state of cooling in all the reactors, and about whether the spent fuel ponds are secured – they contain large amounts of radiation and are located outside of the containment – any damage to them would release contamination directly to the atmosphere, We request that Japan’s government share this information with the public immediately.“
Unit 3 at Fukushima Explodes
Japan’s chief cabinet secretary says a hydrogen explosion has occurred at Unit 3 of Japan’s stricken Fukushima Dai-ichi nuclear plant. The blast was similar to an earlier one at a different unit of the facility.
Campbell live devoted his half hour to credible earthquake information and a piece on the reactor and why the explosion is not a specific threat. A good session.(Note that TV1 is still linking the explosion with that of Chernobyl. Oh dear!)
First time I’ve gone back to watch Campbell since the Ring debacle, and this was a huge contrast – very pointfully but carefully pushing the “can’t predict specifics” line without mentioning the moon once.
Also for the first time I watched bits of Firstline this morning, quite repetitive (like all continuous news programs) and too “correspondent” focused but a huge improvement on the old style chat around the breakfast table.
Another Reactor Explosion/Meltdown
Reports are that Unit 2 at Fukushima has exploded this morning at 6:14 AM Japan time. The New York Times reported today that the explosion appeared to be more severe than the previous detonations at the other reactors.
“Gone by lunchtime”?
Speaking of which, thinking about lunch tomorrow, what foods do we import from Japan?
Will we be screening them? What are the NZ authorities going to tell us? Zzzz?
The Japanese plants have a third containment vessel that the Soviets never had that can (on paper at least) contain a melted core, they also vent the steam/hydrogen/cesium/iodine into area between the third containment and the outer building (which is what caused the explosion), at Chernobyl they vented this inside the containment area, so it seems unlikely that there will be a Chernobyl type event unless:
– One of the core melts, and
– One the third containments ruptured during the earthquake, tsunami or explosion (unlikely as they’re 3 – 6 feet thick and made of concrete and graphite)
Comparing the Chernobyl reactor to this one is like comparing a Lada to a Lexus…
yeah and Lexus’s still crash and people still die in them despite all the safety features. Especially if it’s a Lexus from the 1960s using an out-moded design.
Four reactors have experienced various failures, all of which supposedly wouldn’t happen. I hope disaster will be avoided but I wouldn’t be blase about it.
Power generation is inherently dangerous, 44 died in the last decade from wind generation compared to 7 from Nuclear… So if a Soviet nuclear plant is a Lada, a Japanese nuclear plant a Lexus, then wind generation is a Pinto…
I’m not blase just outlining the design specs…