FUKUSHIMA earthquake and tsunami thread and aftermath

[interestrateripoff]

IF…The situation at the reactors ARE far worse than we’re being told..and the cesium sure indicates it may be..what is the point of making a major panic at this point? It isn’t like the EU or the U.S. over there. Where can the people go? Swim? I’d say they are saying just enough now to get everyone who can, moving south . Panic would just give them one more Biblical disaster to handle on top of everything else. I’m thinking about population and density in Japan. Ouch

What happens if large portions of Japan become uninhabitable? Are there any UN protocols about what happens if a nation becomes uninhabitable? I'm sure it won't come to that but I'm just curious if any arrangements have been made.

[interestrateripoff]

Got to admire all those working there to try and contain it.

The full extent of damage to people from the Chernobyl contaminated rains hardly ever seems to be discussed. I know people from Northern Greece for instance where they have levels of thyroid cancer and inactive thyroid that can only be explained by exposure to radiation from Chernobyl.

Yes brave people working there if it has all gone pear shaped they face certain death.

Not surprised the effects of Chernobyl have never fully been discussed the conclusion might be nuclear is too dangerous then what for our power needs.

[Scott Sando]

What happens if large portions of Japan become uninhabitable? Are there any UN protocols about what happens if a nation becomes uninhabitable? I'm sure it won't come to that but I'm just curious if any arrangements have been made.

I don't think you'd be aloud to move people who were radioactive. I think you'd be left there with aid coming from outside,

[Tankus]

What happens if large portions of Japan become uninhabitable? Are there any UN protocols about what happens if a nation becomes uninhabitable? I'm sure it won't come to that but I'm just curious if any arrangements have been made.

The wealthy will leave , and the poor will have to accept shorter life spans ,higher birth mortality and disability ,and more expensive life insurance

allowable minimal safe exposure levels will be increased

who says its uninhabitable ?

Edited March 12, 2011 by Tankus

[Scott Sando]

Yes brave people working there if it has all gone pear shaped they face certain death.

Not surprised the effects of Chernobyl have never fully been discussed the conclusion might be nuclear is too dangerous then what for our power needs.

Your not going to here this on the MSM, but here go's

Chernobyl Radiation Killed Nearly One Million People: New Book

NEW YORK, New York, April 26, 2010 (ENS) - Nearly one million people around the world died from exposure to radiation released by the 1986 nuclear disaster at the Chernobyl reactor, finds a new book from the New York Academy of Sciences published today on the 24th anniversary of the meltdown at the Soviet facility.

The book, "Chernobyl: Consequences of the Catastrophe for People and the Environment," was compiled by authors Alexey Yablokov of the Center for Russian Environmental Policy in Moscow, and Vassily Nesterenko and Alexey Nesterenko of the Institute of Radiation Safety, in Minsk, Belarus.

The authors examined more than 5,000 published articles and studies, most written in Slavic languages and never before available in English.

The authors said, "For the past 23 years, it has been clear that there is a danger greater than nuclear weapons concealed within nuclear power. Emissions from this one reactor exceeded a hundred-fold the radioactive contamination of the bombs dropped on Hiroshima and Nagasaki."

"No citizen of any country can be assured that he or she can be protected from radioactive contamination. One nuclear reactor can pollute half the globe," they said. "Chernobyl fallout covers the entire Northern Hemisphere."

The Chernobyl nuclear reactor was destroyed by an explosion and fire April 26, 1986. (Photo issued by Soviet authorities)

Their findings are in contrast to estimates by the World Health Organization and the International Atomic Energy Agency that initially said only 31 people had died among the "liquidators," those approximately 830,000 people who were in charge of extinguishing the fire at the Chernobyl reactor and deactivation and cleanup of the site.

The book finds that by 2005, between 112,000 and 125,000 liquidators had died.

"On this 24th anniversary of the Chernobyl disaster, we now realize that the consequences were far worse than many researchers had believed," says Janette Sherman, MD, the physician and toxicologist who edited the book.

Drawing upon extensive data, the authors estimate the number of deaths worldwide due to Chernobyl fallout from 1986 through 2004 was 985,000, a number that has since increased.

By contrast, WHO and the IAEA estimated 9,000 deaths and some 200,000 people sickened in 2005.

On April 26, 1986, two explosions occured at reactor number four at the Chernobyl plant which tore the top from the reactor and its building and exposed the reactor core. The resulting fire sent a plume of radioactive fallout into the atmosphere and over large parts of the western Soviet Union, Europe and across the Northern Hemisphere. Large areas in Ukraine, Belarus, and Russia had to be evacuated.

Yablokov and his co-authors find that radioactive emissions from the stricken reactor, once believed to be 50 million curies, may have been as great as 10 billion curies, or 200 times greater than the initial estimate, and hundreds of times larger than the fallout from the atomic bombs dropped on Hiroshima and Nagasaki.

Nations outside the former Soviet Union received high doses of radioactive fallout, most notably Norway, Sweden, Finland, Yugoslavia, Bulgaria, Austria, Romania, Greece, and parts of the United Kingdom and Germany.

Disabled children from Belarus visiting the UK during Easter 2010 sponsored by the charity Medicine Chernobyl Belarus Special Aid Group. (Photo by Matthew and Heather)

About 550 million Europeans, and 150 to 230 million others in the Northern Hemisphere received notable contamination. Fallout reached the United States and Canada nine days after the disaster.

The proportion of children considered healthy born to irradiated parents in Belarus, the Ukraine, and European Russia considered healthy fell from about 80 percent to less than 20 percent since 1986.

Numerous reports reviewed for this book document elevated disease rates in the Chernobyl area. These include increased fetal and infant deaths, birth defects, and diseases of the respiratory, digestive, musculoskeletal, nervous, endocrine, reproductive, hematological, urological, cardiovascular, genetic, immune, and other systems, as well as cancers and non-cancerous tumors.

In addition to adverse effects in humans, numerous other species have been contaminated, based upon studies of livestock, voles, birds, fish, plants, trees, bacteria, viruses, and other species.

Foods produced in highly contaminated areas in the former Soviet Union were shipped, and consumed worldwide, affecting persons in many other nations. Some, but not all, contamination was detected and contaminated foods not shipped.

The authors warn that the soil, foliage, and water in highly contaminated areas still contain substantial levels of radioactive chemicals, and will continue to harm humans for decades to come.

The book explores effects of Chernobyl fallout that arrived above the United States nine days after the disaster. Fallout entered the U.S. environment and food chain through rainfall. Levels of iodine-131 in milk, for example, were seven to 28 times above normal in May and June 1986. The authors found that the highest U.S. radiation levels were recorded in the Pacific Northwest.

Americans also consumed contaminated food imported from nations affected by the disaster. Four years later, 25 percent of imported food was found to be still contaminated.

Little research on Chernobyl health effects in the United States has been conducted, the authors found, but one study by the Radiation and Public Health Project found that in the early 1990s, a few years after the meltdown, thyroid cancer in Connecticut children had nearly doubled.

This occurred at the same time that childhood thyroid cancer rates in the former Soviet Union were surging, as the thyroid gland is highly sensitive to radioactive iodine exposures.

The world now has 435 nuclear reactors and of these, 104 are in the United States.

The authors of the study say not enough attention has been paid to Eastern European research studies on the effects of Chernobyl at a time when corporations in several nations, including the United States, are attempting to build more nuclear reactors and to extend the years of operation of aging reactors.

The authors said in a statement, "Official discussions from the International Atomic Energy Agency and associated United Nations' agencies (e.g. the Chernobyl Forum reports) have largely downplayed or ignored many of the findings reported in the Eastern European scientific literature and consequently have erred by not including these assessments."

To obtain the book from the New York Academy of Sciences, click here.

[Pent Up]

Yes brave people working there if it has all gone pear shaped they face certain death.

Not surprised the effects of Chernobyl have never fully been discussed the conclusion might be nuclear is too dangerous then what for our power needs.

Wasn't there a team of divers sent on a suicide mission into the water storage tanks under chenobyl to drain it before the core meting through and causing a much much worse disaster. They were brave. Knowing you have got just minutes down there before to open the vents before you die.

[Tankus]

Wasn't there a team of divers sent on a suicide mission into the water storage tanks under chenobyl to drain it before the core meting through and causing a much much worse disaster. They were brave. Knowing you have got just minutes down there before to open the vents before you die.

Bet there will be no shortage if they ask for volunteers

[interestrateripoff]

http://www.guardian.co.uk/world/2011/mar/12/japan-earthquake-tsunami-aftermath-live

7.10pm: In this story my colleagues Jonathan Watt and Justin McCurry who are in Japan, and science editor Robin McKie, look at the situation surrounding the fears of possible nuclear meltdown at the Fukushima Daiichi atomic power plant.

There is also a new story from McKie which says that the Japanese government has ignored previous warnings from seismologist Ishibashi Katsuhiko that an accident was likely and that the nuclear plants have a 'fundamental vulnerability' to major earthquakes.

Really I mean who'd have thought that!

[Scott Sando]

Wasn't there a team of divers sent on a suicide mission into the water storage tanks under chenobyl to drain it before the core meting through and causing a much much worse disaster. They were brave. Knowing you have got just minutes down there before to open the vents before you die.

True hero's.

[Scott Sando]

Bet there will be no shortage if they ask for volunteers

seems like the right place to find a kamikaze truck driver.

[interestrateripoff]

who says its uninhabitable ?

I'm just talking hypothetically, surely the worse case scenario is a radioactive leak that would lay waste to huge areas.

[Alan B'Stard MP]

Wasn't there a team of divers sent on a suicide mission into the water storage tanks under chenobyl to drain it before the core meting through and causing a much much worse disaster. They were brave. Knowing you have got just minutes down there before to open the vents before you die.

Valves might be opened to drain the water, but this could only be done by divers. Soviet soldiers were offered special inducements to undertake the deadly dive into the radioactive water. If they succeeded in opening the valves their families would be given cars, dachas, apartments, and special benefits.

http://www.efilmgroup.com/News/The-Heroes-and-Villains-of-the-Chernobyl-Disaster.html

[bogbrush]

The wealthy will leave , and the poor will have to accept shorter life spans ,higher birth mortality and disability ,and more expensive life insurance

allowable minimal safe exposure levels will be increased

who says its uninhabitable ?

You forgot to mention this was all started by bankers.

Edited March 12, 2011 by bogbrush

[Scott Sando]

You forgot to mention this was all started by bankers.

Oi, step away from the tin foil hat, I'll have that for my collection. And by the way its islamic aligned earthquakes.

Edited March 12, 2011 by Scott Sando

[interestrateripoff]

Wasn't there a team of divers sent on a suicide mission into the water storage tanks under chenobyl to drain it before the core meting through and causing a much much worse disaster. They were brave. Knowing you have got just minutes down there before to open the vents before you die.

http://www.efilmgroup.com/News/The-Heroes-and-Villains-of-the-Chernobyl-Disaster.html

Apparently, the fire fighters did not understand the radiation hazard present. They did not have appropriate protective clothing. One by one they began to experience pressure in the chest, severe coughing, nausea, vomiting, and fainting. At first they thought it was from the smoke and heat of the fire.

They were unaware that they had been walking on radioactive material that was emitting 20,000 roentgens per hour. Doctors found the fire fighters extremely agitated and nervous- suffering from "nuclear frenzy of the nervous system." They had extinguished the fires, but they were burned, many fatally, by the invisible flame of gamma and neutron radiation.

.......

But the fire in Reactor 4 continued to defy all attempts at extinguishment. Military helicopters were brought in to fly over the reactor and drop sand on it. Working to the point of exhaustion and being zapped by radiation on every overflight, the pilots flew up to 300 sorties a day, dropping some 5000 Tons of friable material on the reactor. Still the fire burned.

Valves might be opened to drain the water, but this could only be done by divers. Soviet soldiers were offered special inducements to undertake the deadly dive into the radioactive water. If they succeeded in opening the valves their families would be given cars, dachas, apartments, and special benefits. A number volunteered. Miners were put to work tunnelling underneath the compartments. Cement workers poured cement on the radioactive debris.

Mentioned here but it doesn't say if the plan actually happened.

[okaycuckoo]

http://www.guardian....-aftermath-live

Really I mean who'd have thought that!

Well, they seem to have coped very well with the earthquake, but not with the flooding.

Denninger has alot to say about this (and everything!) - it's on the technical side, no doubt he'll have more on the financial side:

Latest reports are that they are now attempting to flood the containment building with borated seawater. This is a last-ditch attempt to get temperatures under control, and should work. Doing so economically destroys the plant, and it appears they were attempting to avoid that outcome up until this point.

http://market-ticker.org/akcs-www?post=182139#discuss

I hope he's right.

[Tankus]

I'm just talking hypothetically, surely the worse case scenario is a radioactive leak that would lay waste to huge areas.

yeah I get it , but who decides what is waste and what is not .?.. There will be a political decision on final dosage levels , not a wholly medical one , If enough area gets contaminated .... The genetic defects and cancers down the line will be a future politician's problem , not the current ones !

may even be roadblocks

[bogbrush]

yeah I get it , but who decides what is waste and what is not .?.. There will be a political decision on final dosage levels , not a wholly medical one , If enough area gets contaminated .... The genetic defects and cancers down the line will be a future politician's problem , not the current ones !

may even be roadblocks

How will you know you're wrong?

[interestrateripoff]

yeah I get it , but who decides what is waste and what is not .?.. There will be a political decision on final dosage levels , not a wholly medical one , If enough area gets contaminated .... The genetic defects and cancers down the line will be a future politician's problem , not the current ones !

may even be roadblocks

That's what today's politicians are experts at, making it someone else's problem.

http://www.physorg.com/news6858.html

Ten years after the Chernobyl disaster, journalist Mary Mycio made her first trip to the Chernobyl region. Equipped with dosimeter [describe what this is used for] and protective gear, Mycio set out to explore the world's only radioactive wilderness environment and the defiant local residents who remained behind to survive and make their lives in the Zone."

She discovered a wilderness teeming with large animals, more than before the nuclear disaster and many of them members of rare and endangered species. Like the forests, fields, and swamps of this unexpectedly inviting habitat, both the people and animals are radioactive. Cesium-137 is packed in their muscles and strontium-90 in their bones. But, quite astonishingly, they are also thriving.

Chernobyl's flourishing new ecosystem is "one of the first examples of how, in the absence of human intervention, nature in the zone could recover its balance," writes Mycio—even in the face of radioactive "ghost towns and villages [that] stand in tragic testimony to the devastating effects of technology gone awry.

A vivid blend of reportage, popular science, and illuminating encounters that explode the myths of Chernobyl with facts that are at once beautiful and horrible, Wormwood Forest brings a remarkable land—and its people and animals—to life to tell a unique story of science, surprise, and suspense.

Although it might not all be as bad as feared.

[Kilham]

sendai has a population of 1 million and downwind of the reactors , what do you do if your the government , and have just gone through an 8.9,,,, dunno

Nice find chris

So the heat exchanger (torus at the base) was furthest away from the explosion

, bet they have lost the suppression pool

This was posted on another forum where this is being discussed:

http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf

It might provide a bit more information, apparently this is the mark 1 configuration.

[Tankus]

How will you know you're wrong?

when I don't die of cancer ......dunno

that's what the Italians did with their pigs

[ImA20SomethingGetMeOutOfHere]

Right then. Who wants to know what actually happened?

First a couple of basics about how nuclear power actually works. Nuclear power stations produce energy from the fission of an isotope called uranium-235. U-235 is unstable and when it splits in two it produces two small atomic nuclei plus 2 or 3 neutrons. If one of those neutrons hits another U-235 atom it causes it to split apart releasing energy and more neutrons which hit more U-235 atoms and so on. If uncontrolled, this chain reaction results in a nuclear explosion. If harnessed correctly it can be used as a source of energy.

Here's a simplified schematic of a boiling water reactor (BWR) - the same type of reactor as the one in Japan.

The way it works is this. Fuel rods containing low enriched uranium (typically less than 10% U-235 with the rest being made up of U-238, a more stable, non-fissile isotope of uranium) are inserted into the reactor. Only a small percentage of the fuel rods are made up of U-235. This is partly because uranium contains naturally less than 1% U-235 and separating it out from natural uranium (uranium enrichment) is expensive and time consuming. Also when U-238 absorbs neutrons produced by fission of U-235, it turns into plutonium which can be extracted and used to make atom bombs.

Because of the low U-235 content, the core will not attain criticallity (i.e. a self sustaining chain reaction) by itself. Most neutrons produced by U-235 fission have to much energy to be easily absorbed by other U-235 atoms and with the low level of enrichment in nuclear fuel the reaction will never start. To attain criticallity it is necessary to introduce a moderator to slow down the neutrons inside the reactor making them more likely to go on and cause fission in other atoms. Without the moderator, you get no chain reaction.

In a BWR the coolant water circulating through the reactor also acts as a moderator. This is a safety feature inherent in the design in that if there is a total loss of coolant to the core, the reaction will slow and stop by itself, albeit with considerable damage to the core as a result of excess heat produced.

In a BWR the heat absorbed by the cooling water turns it to steam at the top of the reactor. This steam is then fed directly into a turbine which turns a generator to produce electricity. Because this water passes through the core it is slightly radioactive. Under normal circumstances the coolant water is separated from the fuel rods and so will not be tainted with radioactive isotopes from the fuel. It does however absorb neutrons from the core which can produce short lived radioactive isotopes. The principle isotope produced is nitrogen-16 from the oxygen in the water. This has a very short half life as the N-16 decays back to oxygen and so the risk from the coolant water is low.

One final element in the design of the reactor is the control rods. These are made of a neutron absorbing material. In the event of an emergency, these are inserted into the reactor and cause all fission to cease by absorbing the neutrons required to sustain a chain reaction.

At Fukushima, as soon as the earthquake was detected, all the reactors at the site were scrammed - that is they had all their control rods fully inserted to halt the fission reaction. This is a standard safety precaution and is done to cater for the unlikely event that a quake could damage the reactor.

Inside the reactor core, although the fission of U-235 had stopped, the core carried on producing some heat. The reason for this is that as well as the uranium, the core contains a large amount of fission products - that is radioactive atoms that were produced from the fissioning or U-235 atoms. The heat produced by these fission products is considerable - up to several percent of the total power output of the reactor. Because these fission products are subject to the laws of radioactive decay, the heat produced by them decays exponentially over time but for the first few days of a reactor shutdown, the core still needs to be cooled as left alone, the heat from these fission products could cause significant damage to the core.

At Fukushima, with the reactor shut down, the plant was dependent on the national grid for power to keep the pumps supplying coolant water to the core turning. There were also diesel generators on site to provide emergency power should this fail and these were in turn backed up by batteries. what appears to have happened is that all these systems with the possible exception of the batteries were damaged or destroyed by the tsunami which hit the site subsequent to the earthquake leaving the reactor with no source of power to supply coolant to the core.

To understand what happened next, we need to look at the design of the reactor itself. I have been unable to find a decent diagram of the actual reactor at Fukushima, but here is a similar reactor, taken from the United States Nuclear Regulatory Comission's Reactor Concepts Manual.

Notice the extremely thick concrete wall surrounding the reactor itself. This is a mandatory element of all reactors in the West and is designed to contain a catastrophic explosion of the core itself (more on that later).

Now with all power to the coolant pumps lost, there is still an emergency system functioning. Underneath the reactor there is a torus (that's a fancy name for a doughnut shaped thing) which is usually about half full of water. As the reactor begins to overheat, steam from the top of the reactor is fed through pipes into the cold water in the torus. If you do this, the steam rapidly cools and condenses to water when it comes into contact with the cold water in the torus. This creates a powerful suction effect which draws steam down into the torus and this current of steam can be used to drive a turbine with sufficient power to pass water from the torus up into the reactor, cooling it down. This is however a measure of last resort and while it prevents the core from melting, it is insufficient to prevent a buildup of steam pressure inside the reactor. This has the potential to burst pipes inside the reactor or even to cause a catastrophic explosion, so normal procedure is to vent this steam into the atmosphere. Under normal circumstances this is the same steam that gets fed through the plant's main turbine to generate electricity. Provided the core is not damaged, it should not contain any fission byproducts and the only major source of radioactivity is nitrogen-16 produced from neutron irradiation in the core. As I said previously this decays very quickly and is not especially hazardous but it will lead to increased radiation levels at the site.

This appears to be what was happening at Fukushima I, the reactor in question, and at the other reactors on the site which were said to be venting radioactive material. The important thing to remember is that the radioactivity is low level and very short lived.

So what about this explosion then?

To understand what happened, we need to look at the schematic above and at this picture, taken earlier today at the site:

First of all, let's compare the level of destruction with that at Chernobyl, a situation where a reactor actually exploded.

If you look at the picture of the Japanese reactor, the first thing to notice is that the metal structure underneath the concrete which has come off appears to still be intact. At Chernobyl, the steam or hydrogen explosion which destroyed the reactor was big enough to blow the roof off of the reactor (indicated with the red arrow in the picture) and leave it lying on its side. This is a slab of concrete weighing hundreds of tons. It has also destroyed a large part of the building itself. If the explosion at Fukushima was an explosion in the core, or even in the containment structure around the core, it needed to be big enough to rupture the concrete and steel containment vessels (note, plural) around the reactor which were far stronger than their equivalents in the Chernobyl plant. The fundamental design of the two reactors is markedly different as well. The RBMK reactor at Chernobyl uses water as a neutron absorber not a moderator. Thus if the coolant water in the reactor boils off, the chain reaction actually speeds up producing more heat and boiling more coolant producing more heat and so on. The BWR design uses water as a moderator and so with a total loss of coolant, the chain reaction will stop and any subsequent core damage will be contained by the multiple containment layers around the reactor. Should some freak accident somehow still lead to a sufficiently powerful explosion to destroy the core and rupture the containment around the reactor, it would have to be of such a size that to leave a flimsy steel structure standing seems highly unlikely. Such an explosion would also release a vast amount of radioactive material from the reactor core and to cover up such a leak would be utterly impossible.

So what did happen?

Let's have another look at that reactor schematic. More specifically, look at the upper floor above the reactor. This area is used to insert fuel rods into the reactor and to lift spent fuel out of it. There are pools of water up there to hold spent fuel rods while they cool down enough so that they can be removed for reprocessing and not a lot else. Obviously the area needs to be inside to protect it from the elements and to contain any radioactive material but because it is outside the reactor confinement area itself it is much more flimsily constructed.

All power plants, fossil fuel ones included, are vulnerable to the buildup of hydrogen gas. See http://science-hamza.blogspot.com/2010/12/hydrogen-explosion-accident-at-us.html for an example of a hydrogen explosion at a coal fired power station. Hydrogen is used to cool the generators in the turbine hall and in some circumstances can be produced by the breakdown of hot steam catalyzed by various metals. With a loss of power, the hydrogen containment for the generators may well have failed. Hydrogen produced from steam is possible but this would have to have happened inside the reactor and it is unclear how it could have leaked out of the pressure tight reactor containment.

However it was formed, because hydrogen is lighter than air, it rises and will collect at the top of a building. All it needs then is an ignition source and power plants are full of those. The building housing the reactor was designed with this in mind and in the event of a buildup of hydrogen gas and subsequent explosion, the top floors of the building were designed with blowout panels. These are meant to be easily blown away so that the explosion can vent out through them and not damage the rest of the building. This is what has happened at Fukushima I. Obviously, this is bad and shouldn't happen and the owners of the plant need to examine their emergency procedures for venting hydrogen gas from the turbine hall, but it is not, repeat not a core breach or a meltdown or any other apocalyptic word we can think of.

So, before we start panicing, let's bear a few points in mind. This plant has withstood an earthquake, a tsunami and a hydrogen explosion and the core is still basically intact. There has been very little radiation released and the situation is being brought under control. If anything, this to my mind suggests rather encouraging things about nuclear safety.

[Scott Sando]

That's what today's politicians are experts at, making it someone else's problem.

http://www.physorg.com/news6858.html

Although it might not all be as bad as feared.

Do you recon I can get anyone to post me a radioactive spider from fukushima

[Tankus]

This was posted on another forum where this is being discussed:

http://www.nrc.gov/r...teachers/03.pdf

It might provide a bit more information, apparently this is the mark 1 configuration.

Its just struck me that the explosion would have destroyed the control rod assembly and possibly the storage pool, got to hope all the rods are in , The have no containment to open the core to drop on in any way !

Doing so economically destroys the plant, and it appears they were attempting to avoid that outcome up until this point

.

its the only option left if they cannot now access the core

tis the salt , when the core got damaged its probably totalled anyway

Edited March 12, 2011 by Tankus

[interestrateripoff]

http://www.travelblog.org/Europe/Ukraine/Kiev/Chernobyl/blog-420728.html

When they finally had created a cover over the reactor radioactive materials could no longer escape right into the air. But that was by no means the end of the disaster. Instead they had an even worse situation building up under the “lid”. When the fire fighters put out the initial fire they used water. This water ended up in a large pool underneath the reactor. The boron they had mixed with the sand had slowed down the chain reaction. But the core was still very hot. Heat was also building up in the core faster than before since they had put on a “lid” that prevented the heat from dissipating. It is like when you are running on a warm day and you get hot. If you put on a cap, warm trousers and a thick jacket and keep running heat builds up faster and you get hotter than before.

When they realised that they might face a massive explosion underneath the reactor, an explosion that would spread thousands of tons of highly radioactive material over large parts of Europe, they started to make plans for stopping this. Three divers were sent down in the pool to open a valve to drain the pool. They managed to do this but all three died in the pool. They probably knew before they went down that they were scarifying their lives on this mission. If they didn’t drown when the water in the pool started to rush out they would die from exposure to radiation.

I had no idea someone had to do this. I wonder what went through there minds when they went into the water.