Tuesday, March 22, 2011

Why nuclear power stations are not safe, whether it be in Japan or elsewhere.


To some extent, the authorities may have stabilised things as not much has changed recently .... but it could just suddenly go bang L unexpectedly. 
What’s happened?
Amid the chaos and disaster caused by the earthquake and tsunami in Japan, something disturbing has happened to its nuclear plants. Several such plants, notably at Fukushima, have been shaken by the earthquake and (presumably) washed over by the tsunami. One after another, the reactors at these plants have begun to show sinister symptoms.

Many socialists have long warned about the dangers of nuclear power, although some would argue that it cannot be avoided given the overwhelming demand for power today. However I always felt that we must replace fossil fuel energy with renewables and go for an international strategy, under worker’s control, for economy and replacement of gas-guzzling processes with efficient, communal solutions, instead of nuclear power.

This warning about nuclear power have suddenly been given light by the massive disaster now unfolding; indeed what I have written keeps going out of date, given the speed of developments. We should use the following Q and A as a guide when discussing it with our colleagues, comrades and friends, but update it as we find out more.

How do they work?
All nuclear reactors rely on fission. This is when very large atomic nuclei such as Uranium 235 and Plutonium 239 break apart. When this happens, smaller nuclei are formed, typically Caesium, Strontium and Iodine, in radioactive form. Each breaking nucleus also shoots out neutrons. These sub-atomic particles can hit other similar nuclei, causing them to  break apart in the same way. In this way, a chain reaction occurs when the neutrons, flying around within the material of the nuclear core, trigger more and more successive breakups. If the material is sufficiently concentrated, a cataclysmic explosion results. This is the principle behind the fission (atom) bombs that destroyed Hiroshima and Nagasaki. However, in more diluted form, the heat produced can be used to make steam and drive generators.  

The fission also produces another kind of dangerous radiation, gamma rays, which are highly penetrative (like exceptionally powerful x-rays) and require thick containment to stop them from escaping.

What is in them?
There are two nuclear fuels in common use, Uranium 235, and Plutonium 239. According to the BBC, Fukushima 1, the oldest and the one which exploded first, contains just U235; Fukushima 3, newer, contains both. Both are highly toxic. These are not used in pure form, but are mixed with other chemicals to moderate the intensity of the reaction to the point where it can be controlled.

Both Uranium and Plutonium are radioactive in their own right. Uranium “decays” by ejecting an Alpha particle. Plutonium decays much faster, also emitting alpha particles.

How are they controlled?
Each reactor consists of fuel rods, which contain a mix of chemicals including the fissile material. The reactor is designed to have holes into which rods of a material that absorbs neutrons can be inserted. These are called Control Rods. Inserting and withdrawing these rods controls the intensity of the reaction and the heat produced. Dropping the control rods fully into the reactor reduces fission to a very low level and essentially the reaction stops.

How is heat produced from them?
The Japanese reactors are boiling water reactors. The water circulates through the reactor using more holes, and boils and produces steam (there are other designs, but I won’t go into these here).

What are the reactors contained in?
The immediate container seems to be a very strong steel box called a Reactor Pressure Vessel. The operators are claiming that these remain intact. There is an outer containment building, designed to stop any radiation from escaping into the atmosphere, which is what seems to have blown apart in the explosion in Fukushima 1.

What is dangerous about them?
This sounds a silly question, but it’s worth understanding the risks in more detail.

The Uranium and Plutonium contained in these plants are themselves highly radioactive and (less well known) exceedingly toxic. The fission products  are various radioactive versions (the technical word is Isotopes) of elements like Caesium, Strontium and Iodine. These are known to accumulate in the bodies of people, especially children, and animals and food-stuffs, because they behave chemically like common chemicals that make up bones and bodily organs like the thyroid gland. In time, these can cause cancer and other genetic diseases, as the radioactivity damages the genome.

The direct radiation (mostly gamma rays) from an exposed fission reaction can also cause potentially deadly radiation burns and genetic damage in people and other living matter. This is what happened to the workers at Chernobyl, and caused the death of vegetation around that reactor.

Why is Plutonium more dangerous?
It’s more radioactive,  chemically active and is particularly toxic. It is also more energetic when involved in nuclear fission.

What happened during the quake?
There is some guesswork here, but essentially, the operators will have dropped all the control rods into the reactors to stop the fission, and they tried to flood them with coolant (water) to cool them down. The quake itself may have damaged the reactors and loss of power seems to have stopped the coolant pumps. They were probably wrecked internally by the shaking of the earthquake and also the tsunami (while probably not damaging the reactors themselves), seems to have damaged the pumps that circulate the coolant.

We are hearing as I write that another reactor near Fukushima, Onagawa, is also possibly in trouble as radiation has been detected outside the plant. There have also been problems with a coolant at another plant at Tokai.

What went wrong afterwards?
Again, more guesswork, but several things could have happened. Damage to the reactors in the quake could have caused the control rods to jam part way in or not work at all, allowing the reaction to continue (the Japanese authorities and power company seem to be denying this). The BBC says also that the pumps that circulate the water also failed, so that cooling would have stopped. Either way, either through residual heat or continuing reaction, the reactors appeared to continue to heat up.

So what seems to have happened next?
The reactors could have reached a temperature where the nuclear material and other components would melt – a Meltdown.  Things clearly started to go more seriously wrong as radiation has been detected in the atmosphere, and the authorities started a mass evacuation. It now seems likely that all three of the reactors have melted at least partially.

What are the operators doing to try and stop this?
They are pumping sea water into the reactors to try and cool things down until the reaction slows of its own accord. This could take a long time – possibly months or years, during which time the reactors will be too dangerous to approach. They are also venting steam (which has been irradiated and is probably radioactive itself) to reduce the pressure inside the reactor.

There is a problem with using water though. The water molecules act as a moderator. This sounds good, but actually what is happening is that the neutrons flying around inside the core of the reactor are being slowed down, which makes them MORE likely to meet up with a Uranium/Plutonium nucleus. This could have restarted the fission process. Nuclear advisors say that Boron should be added as well, but this may not be happening as the operators frantically try to cool things down. However, the latest statement from the operators is that Boric Acid is being added as well.

What caused the explosions?
This isn’t entirely clear. It could be a steam explosion caused by water coming into something very hot. But it’s more likely that hydrogen was involved. What the experts seem to think is that,  in the intense heat of the reaction, components of the reactor such as Zirconium, will have reacted with water producing Hydrogen. Inside the containment building, this mixed with oxygen and sooner or later with a spark or other source of ignition, it exploded violently.

This is a big problem because it is almost certain that some radioactive material will have been blown into the atmosphere by this. Furthermore, it may have impacted the reactor itself by damaging the pressure containment vessel, but currently the operators seem to be saying that it hasn’t.

What could happen next?
We are in the realms of speculation here because we don’t really know to what extent the reactions have been stopped, or what the damage really is. In the worst scenario, a meltdown could eventually melt its way through the containment and get into the ground. Gigantic steam explosions could happen if the hot material comes into contact with ground water. Without the containment, these would throw large quantities of radioactive materials (see above) into the environment. Aquifers, rivers and the sea could also be contaminated. Some of the radioactive material could get into the atmosphere and be carried around the world as happened at Chernobyl. This is called Fallout and consists mostly of tiny radioactive fragments of nuclear fuel,  fission products and possibly highly irradiated bits of the reactor structure itself, as well as some radioactive gas.

At the time of writing, Fukushima 3 has now exploded. It looks to have been far more violent. 2 is now in trouble, and the rods have been fully exposed to the air several times. My guess is that it may explode as well. The explosion of F3  is particularly worrying because of the Plutonium.

I should hasten to add that this worst case scenario may not happen.  However, the Japanese authorities are warning their people of the likelihood of more explosions and other unpleasant events. The opinion of most experts is that the reactors were better designed than Chernobyl and the scale of this accident should be smaller. But this may be over-optimism or downright misinformation.

What about the consequences?
Immediately, as the news is telling us, the Japanese authorities are moving hundreds of thousands of people away from the plant. If significant radiation escapes in the form of fallout, this may mean that, like with Chernobyl, people in Japan and neighbouring countries like Korea, Russia and China may be told to avoid rain (which carries fallout out of the atmosphere) and stay indoors as much as possible. More long-term effects are to agriculture as fallout can get into crops and be eaten by farm animals and fish, and general effects on the environment such as  wildlife being damaged. Right now, the BBC reports that radioactive Caesium has been detected in the atmosphere. If true, this is bad news, because it means that the reactor core itself has come into contact with the atmosphere, and the containment hasn’t been 100%.

One area where the authorities seem to be less than candid is what is happening to the seawater being pumped through the reactors now. It has certainly been in contact with the fuel rods and must therefore have dissolved some of the fuel and fission products. It must then be going into the environment but it is not clear then what is being done with it. I suspect it is either going back into the sea or into the ground. The contamination would then be extensive. In a country with little agricultural land and reliant on fishing for a lot of its food, this is serious.

At the time of writing, US warships have been moved away from the area because, 160km out to sea, they have detected radiation. It must be much worse close to the plant.

Japan has started imposing rolling power cuts on the population. This may be partly because of the general destruction to the infrastructure of power transmission and generation, but is almost certainly due to loss of nuclear power. Japan generates about 30-40% of its power through nuclear energy as it has almost no fossil fuel reserves of its own. I heard on a news item (not confirmed) that Japan has started importing power through an interconnector cable from Russia.

Politically this event is highly significant.  Nuclear power has been seen increasingly as a non-global-warming way of producing power and governments (particularly ours) have been trying to get private capital to fund construction of new plants. This is bound to be hit by the Fukushima event, for two reasons. One is that NP will now seen to be less politically and socially acceptable, just as memories of Chernobyl, Three Mile Island and Windscale start to fade. Investors will look at schemes far more sceptically as a result, as will some governments. Costs, e.g. of stronger containment, propaganda etc will increase. The other is more subtle. All large projects like nuclear development, as well as things like bridges, tunnels, buildings etc are underwritten by insurance against risk, partly of repairing damage caused, but particularly what is known as Third Party Risk – that of harm to “the general public” and other “assets” such as agriculture, housing, industry and so-on. But if the insurers don’t like the look of something, they will either raise premiums hugely or will just walk away. This is a major factor that slowed nuclear development after previous accidents.

What other lessons could be drawn from this?
One thing is clear. Siting a nuclear power station on a tectonic plate boundary is shear madness, especially on the coast and vulnerable to tsunamis. Japan’s people are now faced with a double crisis, with the awful destruction caused by the earthquake and tsunami being compounded by the evacuation needed from the area of the power plants.

The smooth reassurances of the authorities about the power plants immediately after the quake are now replaced by barely concealed panic as the plant literally blew its top. The latest we have from a nuclear expert here is:

“A former adviser on radiation to the UK government, Dr Christopher Busby, has told the BBC the situation at the nuclear plants is extremely serious. "Particularly concerning is the [Fukushima] number three reactor which I understand is in trouble now, because... it runs on a different sort of fuel; it doesn't run on uranium, it runs on a mixed uranium plutonium fuel, and plutonium is an extremely serious hazard so if this stuff comes out then it's going to make what's happened so far, in terms of the tsunami damage, look a little bit like an entr√©e to the real course."
Given the size of the tsunami damage, that sounds pretty chilling! 

Busby also points out in an interview for the BBC Radio 4 Today programme that this accident could have happened anywhere and the process is intrinsically dangerous. He suggests that the releases are significant and agrees with me that the water pumped through the plant will be contaminating the environment. He also points out that the Geiger counters being used only measure the gamma radiation from the reactor. They don’t measure the short-range radiation (alpha particles) emitted by Uranium and Plutonium, or what is given off by the breakdown products, and they cannot judge the toxicity of these in the environment.

Why do we oppose nuclear power?
It’s important to understand what is different about it from other methods of power generation:
·         The fuel is highly concentrated and there are lots of fears, some justified, of it falling into the wrong hands. This means that the authorities set up a special repressive apparatus (special police, secret agents, military units etc) to guard the process. It also reduces the ability of the working class to grasp control of the process of power generation.
·         A by-product of the nuclear cycle can be to produce more fissile material for use in nuclear weapons. The way in which this is done is too complicated to explain here in detail and the internet is suspiciously silent about this. However, in principle, it is done by exposing the non-fissile isotope of Uranium, U238, to the neutrons from a reactor. This can make Plutonium, which is highly fissile and is relatively easy to make a bomb from.  ( I say relatively, because in reality making nuclear weapons is not easy without the huge resources of the state or the world’s largest corporations. We should debunk stories about terrorists making nuclear weapons).
·         The danger of accident, such as this one, although small,  is potentially devastating to the mass of the people and the environment.
·         Nuclear knowledge is overwhelmingly with huge corporations and governments.
·         The state has been notorious for hiding nuclear, plans, as well as knowledge and the true impact of disasters
·         Nuclear sites, for the reasons above, have often been imposed on the populace effectively by force, whether via subterfuge, judicial decision or direct imposition.
·         It is not renewable, although the fuel can be reprocessed to extract by-product Plutonium which can be used again (or be used to make bombs)
·         Disposal of nuclear waste is a huge, very long term and intractable problem, which would be passed to any future Socialist society, as well as imposing risks to the people and environment now, and huge financial costs which will be passed to the state if nuclear power is privatised. Attempts to set up reprocessing plants (such as Thorp) and find storage facilities have been notoriously unsuccessful.
·         Another by-product, Depleted Uranium (U238), is used in munitions such as anti-tank weapons and is both highly toxic and long-lived (millions of years) in the environment.

Politically, the workers movement and socialist organisations, apart from a few that represent nuclear workers, has always been against nuclear power and correctly makes the link between it and weapons. The history of lies about nuclear power, bribery and force being used to impose it is well known.

Useful links:

No comments:

Post a Comment