Second explosion rocks Japanese nuke plant The first Japanese nuclear complex that reported problems following Friday afternoon's megaquake now has another problem with which to deal: a hydrogen explosion at its No. 3 reactor. At 11:01am on Monday morning, according to Kyodo News (2am on Monday in the UK, 10pm Sunday in New York), "A hydrogen explosion occurred ... at …
The hydrogen is created within the reactor vessel when the fuel rods are above the water line. It was vented in to the containment chamber to reduce pressure in the reactor vessel but in so doing the pressure in the containment chamber increased. To deal with this the containment chamber had to be vented releasing hydrogen into the reactor building where under normal circumstances ventilation systems would have exhausted it to atmosphere before the concentration became explosive. Those ventilations systems are out of action which is why it was known in advance that the explosions were likely.
No, it isn't.
But the Fukushima 1 plant *is* a BWR (Boiling Water Reactor) design (a mixture of BWR-3, BWR-4, BWR-5 and ABWR depending on which of the 6 reactors you are talking about), with de-mineralised water used for heat-transmission at a pressure of 75atm (about 1000psi). Only reactors 1-3 were/are in operation; 4-6 were down for maintenance at the time of the earthquake.
Reactor 1, which uses the older BWR-3 design, was not being cooled sufficiently and thus pressure and temperature started to rise. If the reactor is not cooling properly, some of the coolant water (or water in contact with any of the super-hot pipes) will degrade via that old formula 2H2O -> 2H2 + O2.
And eventually the loose hydrogen finds an ignition source...
The same thing seems to have happened with Reactor 3 (and less-old BWR-4 type). Considering the amount of sea-water being pumped around the plant in an attempt to cool down the cores, I'm surprised Reactor 2's building is still intact.
He's quite correct water doesn't break down appreciably even at 2000 C. Even then it's in equilibrium with only a small percentage of free hydrogen/oxygen.
The only way of generating sig. free hydrogen is to react the water with some material such as zirconium as others have mentioned
The zirconium encapsulation of the fuel rods reacting with water when they reach a certain temperature. One of the reasons, apart from the yellow flame rather than blue, that I doubt reactor 3's explosion was hydrogen again is that reactor 3 is (or was) using mixed oxide fuel, loaded in 2010, unlike the other three which are using zirconium encapsulated uranium oxide. It's possible the MOX uses the same carriers, though.
That didn't look like a hydrogen explosion to me. You'll note the blue "halo" right at the start of reactor 1's blowout, entirely consistent with a hydrogen blast, which was replaced by a yellow/orange flame and grey smoke of reactor 3's. I'm reserving judgment on this one. I don't think we're getting the entire truth.
Japan's wonderful "safety record" is in fact complete bollocks. They have had more serious nuclear incidents than any other western/non ex-soviet bloc nation.
Does nobody remember the incident a few years back when Plutonium/Uranium was spilt/dropped/mixed inappropriately in a processing facility ? The footage iirc was from a helicopter and we were able to see a view peeking through an entrance in to the facility.
The flickering lights were like a strobe, apparently at the range the chopper was at they were not allowed to fly directly past the open door (gamma radiation at lethal levels).
Japanese Nuke people said there was nothing to worry about and it was just a minor spillage. Minor enough to form a critical mass !!!!!
Daiichi 1 : Hydrogen Blast ? Yes I buy that, it looked like a gaseous explosion
Daiichi 3 : Hydrogen Blast ? My sainted airse !!! Sorry but 'shroom clouds form when internal temp's are in the mega hot region. And they are being maintained there by continuing combustion.
"But hydrogen burns" you say... Aye it does, bloody quickly. I refer you to Daiichi 1, what we seen was "combustible material" burning at bit more than gas mark 6 !
So what was in that build that was combustible ? Several kilos of assorted actinides springs to mind here !!! Oh and you need further proof of the heat in that cloud ? watch it again and look for the roof falling off the top of the cloud, then look how high it is when it falls.
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It's from the steam that formed when the water level dropped - as it's super heated, it reacts with the zirconium casing, creating hydrogen. as I'm sure you know, hydrogen atoms are impossible to contain, as they are so small they get through even the smallest gap, so they escaped naturally from the reactor itself, into the concrete building.
The question is, why wasn't it ignited the instant it got out of the reactor - there are supposed to be systems for burning it off - miniature versions of the idea of burning excess natural gas on oil rigs...
(I apologise for the title, it's late...)
To my knowledge it's not, but it can be created during an accident.
One of the explosions at Three Mile Island was hydrogen, created when the exposed core's fuel rod cladding reacted with the steam in the reactor. The yielded zirconium dioxide and hydrogen in an exothermic reaction.
By all accounts, the hydrogen is not normally present, but is due to low coolant in this incident as well.
According to MIT's Charles Forsberg:
"There's zirconium in the fuel rods. When you overheat the reactor core, the first thing that happens is that the zirconium begins to react with steam or water and forms zirconium oxide and hydrogen," he says. "You get a mixture of steam and hydrogen. When you release steam into a secondary building [to decrease pressure in the core], the steam condenses and leaves behind just the hydrogen. Then all you need is an ignition source and you can get a hydrogen burn. That's what happened at Three Mile Island. I don't know if that's what happened in Japan, but it's likely to be the source of that explosion."
Source: Boingboing
On the one hand, it is a bit worrying when nuclear reactor buildings begin to pop off one after another and I can imagine many an anti-nuke green activists rubbing their hands at the thought of such a propaganda coup.
However, on the other hand, it is highly reassuring that after the largest quake on record and notwithstanding the huge explosions around them, the reactor pressure vessels are holding and no significant leakage and contamination is taking place.
People may say that the reactors are old and the technology is obsolete but what matters is that even this obsolete technology is capable of containing the cores in extreme circumstances.
Looking at the videos, these explosions were at least equivalent to a large conventional bomb each (minus the kinetic impact) so the fact that anything remains intact in the affected building is worthy of respect.
Given everything else these "old" design reactors have survived, I suggest that we ask the Japanese to design and build the new reactors the UK is going to have to build(*) in the not so distant future.
(*) when the politicos run out of options and realise that renewables can only make a dent in the UK's growing energy needs (unless of course you want to rely on Vladmir Puttin's gas and government of the week mid-east LPG)
Japan is possibly the most technologically advanced country in the world.
It is certainly the most prepared for earthquakes and the Japanese are famously fastidious.
And still we get two explosions at nuclear plants with possibly more on the way.
NUCLEAR POWER IS JUST NOT WORTH IT.
but not alot else. Whats your point? A big scary bang isn't the end of the world, despite what the news would try to make you believe.
The worst thing about this is ill informed news reporters desperately trying to make this all sound like something awfuls happening when in reality compared to whats going on in the rest of Japan its really a non event.
These things are built to withstand a bomb strike, they have to be, you wouldn't want to go to war and your enemy just drops a few bombs on your power plants and irradiates the entire country.
Headline: Explosion in power generation didn't kill anyone. Wow - big news. How many people each year are killed in explosions in coal mines? 2,631 in 2009 in China alone, and that was by far their best year for the decade. The gulf oil rig fire killed 11 men.
OIL AND COAL IS JUST NOT WORTH IT.
Don't let the facts get in the way of being a Mail reading moron though.
In a disaster that exceeded the worst predicted scale possible, some reactors that were at the end of their service life were vented to release small quantities of radioactive material into the environment in spite of pretty much all of their supporting infrastructure being badly damaged in some way while aftershocks continued to hamper the plant operators abilities to deal with the issues.
It will be interesting to see (once Japan has an opportunity to recover from the massive damage inflicted by the earthquakes/tidal waves) just how much radioactive material was released and whether nuclear plants are viable.
If Japan does decide to phase out nuclear plants, they need to find >46GW of alternative power from somewhere - most likely oil or gas due to a lack of natural resources, which will increase their carbon output and global oil/gas prices.
So, is nuclear power really not worth it?
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For not reporting on this story in the same hysterical "mushroom cloud" way that the mainstream media has. All I've heard from them is "Aaaa, nuclear, it's gonna kill everyone, radiation!" They keep shoving the death toll and the nuclear accident together in the same sentence, as if they were related, and it's completely irresponsible.
At some stage BBC was talking about the first reactor building explosion while showing what obviously was some port oil terminal fire - a column of black smoke, red flames, crushed storage tanks, bent pipes, all inundated with water - the whole shebang, in other words... Very dramatic. And totally misleading.
You constantly absorb background radiation from your environment, just by standing on the face of the Earth. This is all perfectly normal and natural. What they're saying is that the radiation exposure from the minor plant leak is equivalent to 9 months worth of natural background radiation.
So a higher dose than you'd normally get, but small enough that it's not likely to seriously hurt you. Which is good!
Is it that, if you sat at that level of radiation for a year, you'd get 1 year's normal dose + 9 month's extra? That is, the rate is at 175% of normal?
Because it's definately not a case of "you go near it and get insta-blasted with 9 month's radiation at once", because that would be dumb, and isn't how physics works.
Actually the article says that "hourly radiation levels around the plant have settled back to 75 per cent of normal yearly exposure" so you get your extra 9 months' worth in one hour. Which is not "insta-blast" level but is not great, especially if you are there for significantly longer than that.
"But the US military, which has been helping the relief effort, said it had moved its ships and aircraft away from the area after one of its aircraft carriers detected low-level radiation about 100 miles (160km) offshore."
http://www.bbc.co.uk/news/world-asia-pacific-12729138
The Japanese or perhaps the Nuclear Industry is playing this down significantly. You would think Nuclear was totally safe!
Seems the USA Navy does not think so.
No matter how inconsequential the radiation levels are, if they're above normal - even by the tiniest fraction - and you're able to move out of the way, why would you stay there?
Or do you stand right behind smokers, inhaling deeply, when you could move a couple of feet away?
"Seems the USA Navy does not think so."
The US Navy (and the DoD) are probably more interested in avioding ambulance chasing lawyers than in minor details like facts and genuine precautions.
example of US litigation mentality, Air France airbus lost for reasons unknown in the south atlantic, only 3% of the aircraft recovered and no clues as to what happened. 50 US citizens now suing. (US litigation is based largely on oportunism)
First, read the reports. The radioactive material (Cesium and Iodine) that actually did get released from the steam venting (which venting incidentally caused the hydrogen explosion), was carried out into the Pacific, away from the populated land mass. This is why the radiation was deemed "safe," since it would have time to decay whilst blowing to and fro over the (usually) uninhabited ocean. Now, if you stick a few military ships directly in the windfall, of course you'll detect some of that radiation and it would be wise to relocate...
Thus, you AC are spouting FUD.
if it's low level sensors were going off due to external source, then it probably has to move to another area , otherwise it won't be able to tell if the issue was local.
One of the 'good things' is that the gases are going offshore rather than towards populated areas.
You know you are having a bad day when two nearly identical reactor buildings blow up within hours because of the same problem.
Surely they must have realised after *1 blew that hydrogen build-up was a problem.
I'd be more worried that the larger explosion could have done more damage than they first thought, buildings don't normally just disintegrate like that without a pretty big shock wave heading in all directions.
About the worst possible scenario is that the continuing hydrogen build-up within the core ignites, blasting cooling water out of the base and the entire pressure vessel into the air like a rocket because the core supports have been weakened by the previous blast.
Needless to say at that point there won't be any coolant left so "Bad Stuff!" will happen.
AC, because the lack of it caused this problem in the first place.
It seems like good design to me. You would want a flimsy outer shell so any energy from blasts is released rather than contained and causing damage to your reactor.
What seems apparent is despite one of the largest recorded earthquakes and a tsunami these reactors have yet to be breached and there has been no significant release of radiation.
There shouldn't be any danger of hydrogen within the core exploding as there is no free oxygen (the reaction that will have created the hydrogen was caused when the oxygen reacted with the metal of the fuel cladding). It's only when the hydrogen comes into contact with oxygen that there is the danger of an explosion (and then in a confined space).
Note that in Chernboyl there were a couple of explosions - the first was a steam one that was caused because of a runaway reaction. That exposed the core as its containment was relatively weak. Then a later, much more powerful explosion a few second later may well have been a hydrogen one, and that, and the subsequent graphite fire spread huge amounts of radioactive material into the atmosphere.
In the case of these reactor buildings what appears to have blown off is the buildings cladding which is essentially there to keep the weather out. It's not part of the reactor containment.
Radiolysis of the steam would split it, adding oxygen and yet more hydrogen to the system. Joseph Hendrie of the NRC hypothesized such a situation during TMI and they flew in a recombiner to lower the elemental hydrogen levels in the reactor. At these high temperatures, oxygen levels of around 5% will explode the hydrogen if there's an ignition source and 11% will cause the gas to autoignite.
The engineers have certainly lost any meaningful control of these reactors.
The bloody things withstood a force 9 quake! What the hell is wrong with you people?
When the quake hit, they lost primary power, so they dropped to diesel generators. Unfortunately, there was this rather inconvenient tsunami (you may have heard of it) that swamped them and took out the generators. They weren't just ignoring the buildup, you tit - they couldn't do a damn thing about it until backup arrived.
But it's good to know that Captain Hindsight is alive and well, spouting ill-informed bullshit everywhere it's needed. I just love your signoff. Never mind the thousands of nuclear specialists in Japan - you know best.
It does occur to me that a mixture of the 5th largest earthquake ever recorded, a huge consequent tsunami and just about the highest concentration of nuclear facilities in the world built on a tsunami-prone coastline and with 40+ year old technology is coming close to a worst case scenario. If there is no major loss of life then I would argue this goes some way to showing that nuclear facilities can be built safely.
However, it does occur to me that placement of facilities such as this on such a vulnerable coastline is debatable (and it's not as if they didn't known - tsunami is, after all, a Japanese word). I realise that nuclear power stations need copious supplies of cooling water, and that a coastal location is very convenient, but surely it would be possible to build these stations out of the reach of this scale of tsunami. Yes, it would be more expensive, but a few tens of meters above sea level would do it. Perhaps plate areas could be created in the hills near the coastline so the vulnerable elements could be kept out of reach of the tsunami, which is what appeared to have damaged the auxilliary power generators.
I'm no expert, but they probably don't have much choice in siting the reactors; if they build them on higher ground, then they are probably more vulnerable to damage by the earthquake (higher ground will be on top of geological structures that transmit the earthquake energy better, hence the relative higher danger of earthquakes in mountainous regions). Building the plants on relatively shock-absorbing squidgy flood plain was probably seen as an advantage. The tsunami is a bit of a hindsight thing and I guess the first thing that they do after this is build tsunami proof backup generators.
As others have pointed out, this is almost a "worst case scenario" and the danger to people from radiation is still "fuck all"; 10,000 people have been killed by sea-water but no-one's suggesting that you avoid the beach this summer! As usual, arts graduates see the words "nuclear" and "explosion" and can't seem to grasp that the two can occur in the same location without massive loss of life.
BTW, while this terrible natural disaster is distracting the world's news agenciesand so-called "leaders", WTF is happening in Libya? I expect that Gadaffy Duck will be quietly committing genocide while we're all debating how much nuclear contamination is equivalent to ten minutes on a sun-bed!
...just put the reactor buildings underwater to start with? The US has nuclear submarines, and a power station doesn't have to be mobile, so you would think it would be a matter of building the reactor off-shore and then sinking the building.
Tsunami? Who cares, it's already submerged. Radiation leak? Where's it going to go? The 60 feet of water above or the quarter mile of water between it and shore? Full on explosion? Sink the station further before it goes to minimize catastrophic effects.
Job done.
When it does go boom/release radiation/other, you have these wonderful little water currents carrying all your radioactive material all over the place, in addition to a few three-eyed fish.
Plus what do you think the logistics of moving staff/material to/from, as well as connecting the thing up to the power grid, would be like?
The reactors were shut down automatically and the main chain reaction process did stop. However, there is still residual heat in the core, as it's rather hot. However, more importantly, the fuel elements are highly radioactive with a lot of isotopes that continue to give off heat. It's small compared to the main fission chain reaction, but it's plenty hot enough to boil off water or, indeed, melt the fuel rods if they are not kept cooled. You see this with spent fuel - for a few years after removal these are cooled in pools which have to be refreshed with cooling water. Eventually this radioactivity dies away as the more energetic isotopes decay and, therefore, so does the heat. At this point the rods can be removed for reprocessing and any remaining radioactive waste can, after several decades, be vitrified and put into containers for deep disposal.
What is happening here is that that these partly used fuel rods are still generating heat within the reactor vessel so they must be kept under water or there is a danger of fuel rods melting into a pool, and if the worst happens, breaching the containment vessel which would be rather nasty (albeit still nothing likje Chernobyl as there is no graphite fire to spread the isotopes and the molten fuel would end up in a concete basement).
From elsewhere on the net: (im not so sure about the figures but the principle is correct)
When the reactor is shut down, all the fissioning stops, but the decay heat of the fission products continues as they decay. At shut down, that fission product energy is ~7% of the total reactor power. That decays quite rapidly. After ~100 seconds it is down about half, after 2,000 seconds it is down by half again. We are now at ~1.5 x 10^5 seconds so the power is now down to about 0.5%. That means if it was a 1,000 MW power plant, it is about 3,000 MW thermal and would now be putting out 15 MW of heat. That is still a lot of heat, it is enough to vaporize 23 tonnes of water per hour. If you want to cool it without vaporizing any water you need ~10x more flow.
Simple really, contrary to common beleif, nuclear power plants take power in off the grid as well as pump it out. This incoming power is used to light peoples office and make cups of tea etc and most importantly to pump the coolant around the reactor.
The incoming power was lost due to the earthquake, the backup diesel generators failed due to being flooded by the tsunami, so there was no power to pump the coolant around with.
If your coolant (water generally) doesn't move around it just gets hotter and hotter.
Yes the control rods slow the reaction down, thus reducing the heat output of the reactor. But if the heat has nowhere to go because the coolant isn't moving, then the heat will just build up. This is why they were pumping sea water into the other reactors.
The reactors have failed safe. So far. The control rods were inserted and the nuclear reactions have stopped. However neutrons and alpha particles are still being emitted from the fuel rods. This generates heat. Which needs to be taken away from the reactor core by some sort of cooling system. If the (shut down) reactor' s fuel rods get too warm, hydrogen is released from the water that the Japanese reactors use for primary cooling. That hydrogen can go bang rather easily.
Fail-safe is a relative term here. The nuclear reactions have been shut down. But if the fuel rods don't get cooled, Bad Things will happen. The cooling systems and their backups for the Japanese reactors haven't failed safe, admittedly because the tsunami has created a scenario that was probably hard to anticipate: the multiple-redundant cooling systems can't get power from on-site diesels or from the grid to keep the pumps running.
> Don't these gizmos have control rods that descend to quench the chain reaction, and thus stop the production of heat?
The purpose of the control rods is to stop the neutron chain reaction only. All the heat already generated has to go somewhere else. Not to mention the heat decay.
The rods are like disc brake pads, but leave behind a glowing red hot steel disc.
Just the decay of fissile stuff (eg Uranium and Plutonium) in a 1200 megawatts PWR for instance, generates 11 MW of heat, for at least 2 days. That's still a lot.
Actually, they calculate the theoretical time that would take for a PWR to boil after control rod shutdown with no cooling pumps (which is fail safe condition with the lid closed). It is estimated in 30 minutes after 2 days it was shutdown, so immense is the decay heat.
In other words, if it was shutdown, and you had cooling pumps working fine 2 days straight, then lost them, the reactor would still boil in 30 minutes, if you opened it. Literally, not cool. The reactor is like a giant pressure cooking pan, after all. But this is PWR.
Logically, it varies with each reactor, and these japanese reactors are not PWR, they are BWRs so some variables change, but the outcome is the same: even after control rods dropped, a lot of heat is still generated.
Which is the next phase of concern: How long can they keep the generators (and hence cooling pumps) running in the reactors that were cut off the main grid. Once you have a closed heat exchange system and pumps to force water through it, you are safe.
Oh, and it DID fail safe. Last ditch effort, you lose the reactor (as it becomes a molten lump of fissile stuff in the bottom of the pressure vessel), and must keep cooling it forever. Three Mile Island reached that stage.
If it was built like Chernobyl, you could erase (name city where reactor is) off the map.
Please correct me on any details or concept, please. But the main idea is that decay heat is still going.
The control rods just stop the chain reaction. The residual nuclear waste still produces heat through decay that must be dissipated. When pumps fail (as happened) this becomes a major problem. Hence the partial core meltdown that apparently now has happened at block 2 as the fuel rods became exposed.
And, btw, much as the resident pro-nuke faction might disagree, nuclear technology cannot be made safe. No technology can be made entirely safe. It's a question of whether we think the risk being acceptable, including the as-yet-unknown risks. Personally, I much rather use "green" energy (water, solar, wind) than nuclear, although I accept that nuclear is probably "cleaner" than fossil energy.
Yesterday, somebdoy posted a very useful URL:
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html
What you can see in the 3D-diagram is the reactor and the building around it. The brown "pill" vertically in the center is the reactor vessel containing many bundles of fuel "pipes". In each pipe, there are many fuel "pills", where the fission reaction takes place. The fuel pipes are cooled by water, which doubles as a moderator to slow down the neutrons so that fission is possible.
https://secure.wikimedia.org/wikipedia/en/wiki/Nuclear_reactor_technology
The problem is when the cooling water flow ceases, the water heats and at one point begins to boil. This builds up pressure, which must be vented to protect the reactor vessel at some point. Heat is even generated, even when the control rods (neutron absorbers) are fully pushed into the reactor. This is because fission creates a chain of after-products which are not stable atom kernels, but after some time emit radioactive particles and/or break into even smaller nuclei. This process will continue for weeks and generate between 300MW (immediately after shutdown) down to 1MW(weeks after) of power.
What happened in Japan is that the cooling system (for yet unexplained reasons) failed and the water essentially cooked off. This means dozens of MWs are now at work melting the fuel pipes (aka "fuel rods"). At this extreme temperatures (up to 2500K), water and the metal present generates Hydrogen. When the reactor vessel is vented for protection, this hydrogen gets into the top part of the building (which is structually not more than a tent), where a nice big hydrogen explosion occurs. This blows off this weak structure, but the reactor vessel and the protective Concrete-Steel Containment around the reactor vessel stay intact !
This is what we saw - not a Czernobyl-type explosion/graphite burn of the reactor itself. Czernobyl didn't have a Concrete-Steel Containment at all ! The USSR was too busy building weapons for their Panzer Troops in Germany to afford that.
Bottom line: All the Nasty Stuff is contained, as in Harrisburg. Cooling of the Containment and Reactor Vessel by Sea water is performed. Expected Effects: As in Harrisburg, no significant health effects expected.
What utter pish and balderdash.
In the north of my country there is a nuke facility with a rather, shall we say dubious safety record.
Leaks, fires, cover ups etc. But I am not going to try explain any of that to you.
But how is this for "no significant health effects expected" ?
The radiation "leaks" into the sea and gets into the food chain. The seabirds eat the fish and then shit all over the nearby shore. Now we have collections of radioactive guano in the north of scotland that according to the Environment Agencies and the Nuke agencies doesn't exist and even if it could be proven to exist ? "no significant health effects expected"
Pish and Balderdash ? allow me to amend that to hosreshit my good fellow !
You are mostly correct in your post. Obviously nuclear is well thought out and mostly safe. which is why no-one even considered arranging for the hydrogen to be vented outside the building
You say the cooling system failed for unexplained reasons. I don't care what the reasons were - terrorists shooting out the pipes between the reactor and the generator building, jellyfish blocking the cooling intakes, earthquakes cracking pipes, tsunamis taking out the backup generators whatever. It seems that until they build reactors that can cope with a cooling loss at any time safely then they are simply not even approaching safe.
When I studied Nuclear Engineering as a major part of my degree I was told, upon pointing out the problems with cooling loss, that these things could never happen. They've happened at least 5 times to my knowledge since then and they still say its safe.
There's a lot of money for a lot of people in nuclear but I doubt it will ever be truly cost effective without massive public input.
I wish renewable would get 1/10th the investment into research that nuclear gets in PR - in a normal non-disatser period.
The reactors didn't and won't go boom, but the reactors are stuffed and probably can be salvaged at unwielding costs. but...
How can one replace over 1000MW of energy, (I bet all 3 plants generate more than that together) over night?
Fossil fueled generators then? I want to see Greenpeace try to veto this.
I hope a better solution than FFs presents itself.
"The incoming power was lost due to the earthquake, the backup diesel generators failed due to being flooded by the tsunami, so there was no power to pump the coolant around with..."
I am not a scientist (engineer in fact) and am puzzled. Surely large tsunamis often follow large earthquakes. Once the earthquake has occurred power supplies will be disrupted. Then the tsunami will rush in and inondate an area several kilometres inland. This is not rocket science.
But it seems the safety measures to cool down the reactors in the event of this happening were pumps which did not work as no electricity locally following the earthquake, pity about that) and the back up diesel generators were swamped by the tsunami as the reactors were on the coast, pity about that too. Is this really state of the art disaster planning?
I can understand no one ever getting round to planning for this sort of scenario in the UK, but in Japan? Where they have had generations to plan for the "big one"?
As the posts on this thread make clear, there is an inherent difficulty with nuclear power. It can never be a closed system, owing it would appear, to nuclear physics and the laws of thermodynamics.
This presents designers with intractable problems that cannot be solved economically if at all. Need cooling water and protection from earthquakes, site it near the coast near sea level. Need to protect it from tsunamis, site it in an elevated site (chose one). External inputs are always required, they require fine control and their absence from whatever cause very quickly results in cascading (and apparently unpredictable) problems, The result is the risk of radio-active contamination and the need to evacuate people for miles around which is a non-trivial problem regardless of whether people die immediately or not.
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