Mud in Fukushima

Dear Reader,

It has come to my attention that mud at the bottom of swimming pools at Fukushima has been found to contain cesium. A film has appeared on another blog which claims to be a reading of the work of a Masakazu Honda. In this film and the text it points out that the mud at the bottom contains lots of cesium while the film suggests that nothing was noted when the water was tested.

This is perfectly reasonable in terms of chemistry, I have been saying since the accident occurred that the cesium will stick to soil minerals. I would say that it is important to consider both the water in the pools and the mud at the bottom. I think that the best thing might be to use a swimming pool vacuum cleaner to suck out the mud. The mud will then have to be sent away as radioactive waste. It may be best to condition the mud with cement (plus put it into plastic drums) before sending it away as these actions will make a release of radioactive muck less likely during transport.

The cement will not bind the cesium, but it will hold the radioactive soil particles in a solid which will not form mobile dust. The best thing may be to put the waste into a waste store. If this is left for 300 years then the cesium will decay away and the drums will be giant paperweights.

Be careful of two groups of people, one lot to watch out for are the professional doomsayers. They seem to be unable or unwilling to find a real and useful job and then they make their money by scaring the wits out of people. They will tell you that the Fukushima accident has extinguished all hope and that there is nothing which we can do to protect ourselves or clean up our environment. The second lot are those who claim that there is absolutely nothing to worry about and that you should ignore the results of the Fukushima accident. My advice is do not trust either of these “friends”, they are false friends who will lead you into different but equally bad places.

The health condition of the Fukushima Children in Ginza, Tokyo .

Dear Reader,

I saw this film recently, it makes some claims that the Fukushima reactor accident is making children sick. I think that this film raises some interesting points.

Appeal concerning the health condition of the Fukushima Children in Ginza, Tokyo ..

There is a problem, if the above average level of radiation in Japan is able to make children ill then why is Ramsar in Iran not famous for ill children ? In this place in one year the background radiation dose is normally more than 100 mSv.

In Japan it has been decided that if the dose rate is greater than 20 mSv that people will be relocated, so the people in Ramsar should be more ill than the general public in Japan near the Fukushima reactor accident site.

One of the people in the film had to go for a CT scan, I would like to know if anyone has considered how this is likely to have involved quite a large X-ray dose. While people get concerned about an exposure from a reactor accident, many people do not seem to be as concerned about medical exposure (due mostly to X-ray radiography). This is something which I can never understand.

Also if the children of Fukushima were being exposed to so much radiation that they feel ill as a result (chronic radiation syndrome ?) then I imagine that their blood counts would be rather abnormal. If for argument’s sake they were so strongly exposed then blood samples from them would show signs of radiation exposure.

For a large dose, I would expect cell counts to be abnormal. At lower doses I would expect a much higher number of chromosomal abnormalities per litre of blood. If someone can bring us this type of evidence then I will believe that the children of Fukushima have been exposed to a lot of radiation, but until I am presented with such evidence I will remain very suspicious of the claims of these radiation related illnesses. The thing is that to induce the non cancer effects which appear shortly after a radiation exposure a very large dose is required, and the dose must be above a threshold. Below the threshold the effects can never be seen.

It is a bit like alcohol, humans and drunkenness. To get a person drunk requires alcohol, the more alcohol you feed them the worse the drunkenness becomes. Below the threshold dose it is impossible to get the effect of drunkenness, for example if 200 people take communion at a church and have a tiny sip of wine then non of them will come out of the church as crazed drunks (Unless they were drunks before the service). I hold the view that as a result of Fukushima that no member of the general public has had a radiation dose which is able to cause one of the deterministic effects which appear shortly after the radiation dose is delivered to a human.

Even after the much worse Chernobyl accident no members of the public were stricken with the deterministic effects of radiation (radiation sickness), so I would suggest that my readers take care when they here of claims from Japan about the radiation making children feel ill. We need to have a respect for the truth, part of a respect for the truth is to resist telling lies or making exaggerations even if you think (or know) that the thing you want to warn people against is very bad. One of my roles at Chalmers has been to help supervise research on serious nuclear accidents, I can tell you that serious nuclear accidents are thankfully rare but they can be horrible even without inventing new effects or exaggerating the effects.

Americium

While the general public get both excited and concerned about plutonium, some of the other actinides are equally important. Americium because of its higher stability of the +3 oxidation state has chemistry which is very different to plutonium.

I have seen predictions which suggest that the americium-241 either released from Chernobyl or formed in the environment as a result of the beta decay of the plutonium-241 released by the accident will become the radionuclide of greatest importance near Chernobyl after the cesium-137 has decayed away.

Fukushima will be a different matter as far less of the americium or plutonium in the fuel was released during the accident.

Cesium chemistry in Japanese soils

Dear Reader,

After having spent much of sunday in a fruitless search for a storage box for my garden tools, I get the chance to write to my beloved readers another blog entry. Now all along I had been making the prediction that the cesium would stick like glue to the soil and stay in the top layer. Some workers have examined soil samples and in a paper (Takeshi Fujiwara, Takumi Saito, Yusa Muroya, Hiroyuki Sawahata, Yuji Yamashita, Shinya Nagasaki, Koji Okamoto, Hiroyuki Takahashi, Mitsuru Uesaka, Yosuke Katsumura and Satoru Tanaka, Journal of Environmental Radioactivity, 2012, 113, 37-44) an examination of soil samples from the Fukushima area has been reported. In this paper it has been shown that the cesium is concentrated in the top layer of the soil.

Circa 70 % of the cesium is in the top 2 cm in the soil, while the iodine was more mobile. The good news is that the cesium will not enter ground water, further good news is that plants with deep root systems are unlikely to absorb much cesium. The bad news is that the cesium will be in the right part of the soil to enter grass via its shallow roots and the fact that the cesium is in the upper layers of the soil will increase the external threat due to gamma photons.

It is interesting to note that the Japanese may not worked out a sensible way to store the contaminated soil which is removed during the clean up of land. It has been reported that people are being required to store contaminated soil from cleaning up their own gardens on their own land. I think it would be better if industrial estates were used as places to store the contaminated soil while the government find a place to store the soil for the next 300 years.

I have spoken to my legal advisor about human rights, and my advisor told me that the right to have a safe environment could override the right to object to a waste store in a given town. I hold the view that if the waste stores are sited well away from homes and other places where the general public spend a lot of time, then it is OK to raise the dose rate in the waste store. The waste store should be designed to avoid releasing cesium into the environment and the construction of the waste store should be done in such a way that it does not increase the dose rate at the edge of the site. I think that the reference dose rate for the latter point should be the dose rate at the edge of the site before the clean up is done.

If the dose rate at the edge of the site is 2 microSv per hour, then this will give a person a dose per year of 17.5 mSv which is a big dose for the general public. But if the dose rate at the same spot was 2 microSv per hour before the clean up which generated the waste which will go into the store is conducted then the clean up will have a neutral effect at the edge of the waste store but will have a good effect on the majority of the land.

I may do some calculations on the subject if I get time in the near future.

Muons and Fukushima

Dear Reader,

One of the great problems right now is working out where the fuel in the damaged cores and the ponds is, and in what condition the fuel is in. We can take for granted that the fuel which was in units 1, 2 and 3 has been damaged by overheating. But the state of the fuel in the ponds was a bit more of a mystery to us.

After clearing the rubbish out of the pond at unit three it has been possible to inspect the pond, the pond is frankly in a bit of a mess. But the fuel seems to have escaped serious damage. Photographs have been taken of the fuel racks in the pond and it does not look like there has been been any dire melting or explosions in the pond.

I have seen that some samples have been taken from the pond at unit four to allow them to be examined (these were samples of unused fuel which were being stored in the pond at the time of the accident). The work so far suggests that the fuel in the pond is in good condition. This suggests strongly that no nuclear explosion occurred in the pond.

The other great question is the state of the reactors. I saw something interesting recently, it is a sensing system based on cosmic rays (muons). This looks to me like a good method for finding the fuel inside the damaged reactors without having to get up close and personal with the stricken reactors.

Another thing which needs to be done is for society to recover from the accident, I have seen some advice from the IAEA on the subject of remediation of the contaminated land (outside the nuclear reactor park). This document might be of interest to some of my readers. It includes a discussion of the cleaning of different types of areas which include farmland. As I predicted it does include the question of deep ploughing the land.

Bob and his nuclear “facts”

Dear Reader,

It has come to my attention that a person calling themselves Bob Nichols is publishing “news” on a web site. Being a person with some knowledge and understanding of nuclear matters I thought I would take a look.

Bob as we will call him is making the bold claim that nothing is being done to mitigate the accident or clean up the site. I think that this claim is totally false, I am well aware that waste water on site is being contained, treated and then reused to greatly reduce the amount of radioactivity which is released into the ground and the sea.

Bob has claimed that even industrial robots can not cope with the radiation levels on site, I think that this is deeply wrong. A friend of mine has been on the site and he only got a small dose. I would like to know what location he is talking about. In a normal nuclear plant there are some areas which are off limits to humans for radiation safety reasons during normal operation. After shut down it is possible to enter some of these areas within minutes. There are areas at the Fukushima site (inside the reactor pressure vessels and in some areas of the containments) which might be off limits for humans for many years but I suspect that the vast majority of the plant buildings can be entered by either humans or robots.

He suggests putting the reactor cores under water, this is being done but as some of the reactors have leaks it is not a simple matter. His text suggests that no work has been done to fix the reactors is misleading, while fixing these reactors is not a simple matter the work to fix the site has already started.

He writes about the “evils of uranium”, but I would like to point out that small uranium particles are unlikely to stay in the human body for long. Uranium oxides tend to dissolve in water when oxygen and carbon dioxide are present. The uranium will then be lost via the urine. If he wants to think about any radioisotopes then he should be thinking of the shorter lived beta/gamma fission products which were released back in march 2011.

He also fails to note that the amount of radioactivity in the reactor site is now far less than it was back in march 2011, radioactivity in a nuclear reactor’s fuel tends to decay away greatly after the plant is shut down. He also makes some rather far fetched claims about chernobyl claiming that 30 % of the core was released, trust me only about 3.5 % of the fuel at Chernobyl was able to leave the plant. If Bob had read either an undergraduate text book on nuclear chemistry (I can name two books which would tell him this) or even (dare I saw it) wikipedia then he would have found that the release of radioactivity from a damaged nuclear plant is controlled by the boiling point of the main form of the element.

While iodine, tellurium and cesium are mobile, the real nasties such as plutonium and strontium are much less mobile (thank goodness for small mercies). His suggestion of using atomic bombs to cause a landslide to make the reactor site fall into the sea is very silly. I sincerely hope that nobody ever tries to do this !

Different reports on the same subject

Dear Reader,

In recent times we have had the first serious nuclear accident of the internet age, I am not sure why it is the internet age. The ‘ages’ were named after the materials used to make typical tools.

Stone age : Stone axes

Bronze age : Bronze swords made of a Cu / Sn alloy

Iron age : Iron ploughs

Then later the industrial age came, then we had the atomic age, the space age and then the internet age. My big problem is that for the majority of tools which we use in our lives we do not use atomic (nuclear), space or internet tools to do things like open cans of dog food or dig our gardens. For opening pet food cans and tending the vegetable patch I still use tools based on iron (steel).

While a nuclear powered digging machine or a space satellite which zaps the weeds might make life a little more easy (assuming you can afford to buy it) I think we will be sticking with steel spades and can openers for the forseeable future.

But I think that we do need to move onto something else. Recently a series of different reports have been published about the Fukushima event in Japan. Greenpeace have published a report as have the Japanese government and also Jon. M. Schwantes et. al. in the journal Environmental Science and Technology (DOI: 10.1021/es300556m) have published a paper in which they use the isotope signature of the accident to probe the event. In common with many things it is not always possible to make a direct measurement from samples which can be taken by hand, instead other measurements were used.

Now before we get going I will saw that it is impossible to have a single report which deals with a complex event in perfect detail. The problem is that if we examine one aspect of an event in great detail (using a state of the art study which includes as many details as possible) then this report is likely to become very large and close to impossible to read. If we then couple together a series of sections with a similar level of detail on all the different aspects of the event then we will end up with a wall of words which is impossible to comprehend.

Greenpeace have written about a recent Japanese report that

“The lethally high levels of radiation still present in the damaged reactors have prevented committee members from conducting a full analysis. They should be given all the time they need to complete their investigation.”

While the Japanese writers of the big government report stated that their mandate was

1. To investigate the direct and indirect causes of the Tokyo Electric Power Company Fukushima nuclear power plant accident that occurred on March 11, 2011 in conjunction with the Great East Japan Earthquake.

2. To investigate the direct and indirect causes of the damage sustained from the above accident.

3. To investigate and verify the emergency response to both the accident and the consequential damage; to verify the sequence of events and actions taken; to assess the effectiveness of the emergency response.

4. To investigate the history of decisions and approval processes regarding existing nuclear policies and other related matters.

5. To recommend measures to prevent nuclear accidents and any consequential damage based on the findings of the above investigations. The recommendations shall include assessments of essential nuclear policies and the structure of related administrative organizations.

6. To conduct the necessary administrative functions necessary for carrying out the above activities.

I have highlighted in bold the part which interests me most as a chemist, the Japanese panel  also stated that they would not undertake a series of actions which included.

“investigations that would require on-site visits to reactors with dangerous levels of radioactivity.“

My understanding is that they have chosen quite wisely to avoid either waiting for a full examination of the reactor sites (which will take decades) or rushing into a dangerous area to gather data. My view is that samples collected from outside the reactor buildings, eye witnesses from the site, data from those sensors inside the plant which continued to work together with details which can be obtained from undamaged BWR plants. I see the problem of the clash of two cultures.

The scientific and engineering communities are seeking to get the best quality report which is correct, the speed of publication of the report is a secondary factor. In these communities it is better to delay the publication of a report if the delay will allow the quality to be improved. Also the answer has to be traceable, the computational methods used, the persons who did the work, the devices used and the samples used all have to be documented clearly in this type of work.

On the other hand the newspapers and many of the green NGOs (like Greenpeace) are aiming for speed of publication as their highest priority. In these reports the things which were used to produce the final answer are often not as traceable. What is interesting is when both the rapid publication of people like Greenpeace agrees with the slower and more thorough investigation which goes into the official reports. I would say that it is important to avoid being caught by statements by “The findings of both these reports match closely with the Lessons
from Fukushima report released by Greenpeace in February” in a trap where you think that both reports are the same.

The Greenpeace report has some similarities with and some differences from the Japanese government report, but I would say that neither report deals at length with the containment chemistry and the radiochemistry of the accident. I am unsure of what Greenpeace would be hoping for in an extended report which might be written in 20 years time when the insides of the containments have been fully explored. I think that a main part of the final purpose of the examination of the reactor buildings will be to determine what chemical and physical effects occurred during and after the accident.

The Greenpeace report is more dominated by photographs which relate loosely to the event, I am unsure why it is important in a report of 52 pages to include devote ten pages to photographs of things like wrecked buildings with very little explanation of what is going on in the photograph. For example on page 28 a whole page is devoted to a person holding a pair of radiation meters in a field. There are a series of important questions which are not answered in the text such as “what level of radioactivity has the person found in the field”, “what is the testing protocol” and “what is the date of the measurement”. I hold the view that the report should be written in a way to make these things clear rather than forcing the reader to dig deeply in a series of documents for the answers.

The Japanese government report is much more text and far fewer pictures in the main body of the text than the Greenpeace report, towards the end a lot of data is presented in appendix in the form of graphs. These graphs include things like the fraction of the public who were aware at a given time of some key events. While graphs might be less eye catching than photographs, I hold the view that a well labeled graph is a better way to communicate an idea to another person than a photograph which has little if any commentary in the caption.

The problem I see is that if I show 100 people a photograph with very little writing in the caption then a danger exists that each of the 100 people will interpret it in a different way, while in recent years there has been a backlash against science made by people like the postmodernists. Some people value their “feelings” above everything else and express the view that a series of different interpretations of the same evidence are equally valid, I have to disagree. Firstly there is no such thing as an impartial observer (Read the section of the Alan Chalmers book “Whats this thing called science” on induction for more details).

Secondly some interpretations of evidence are deeply wrong, for example if I was photographed by an alien (who has no knowledge of pet ownership) while walking my dog in the forest the aliens might think (based on the photograph) that I am some sort of cruel person who enslaves small white animals and chains them up. While this interpretation might fit the evidence in the photograph it is deeply flawed.

As a result I think that a report which is dominated by photographs which do not have a clear set of captions explaining what is going on is not a good report. But a report which uses the same amount of space for graphs and figures which bear captions which explain all the key points does communicate in a better way with the reader.

The comment that Greenpeace made of “The lethally high levels of radiation still present in the damaged reactors have prevented committee members from conducting a full analysis. They should be given all the time they need to complete their investigation.” suggests to me that Greenpeace want the Japanese government report to be a comprehensive report which deals with all aspects of the event. It might even be understood as Greenpeace suggesting that their report is more comprehensive.

I have read both reports and I can say that some rather important things are missing from both reports. Neither report mentions the transfer of cesium from soil to plants and then to humans via the food supply. I hold a view that this is an important issue, depending on the soil chemistry, the biology of the food production system and what countermeasures are taken the cesium in the diet is either going to be a small issue or a large issue. Also neither report gives a detailed list of the radionuclides released from the reactors and the amounts which were in the cores during the accident.

One of the best reports on this issue is the paper by J.M. Schwantes et. al., this paper uses the relative amounts of the different radionuclides in soil samples taken from Japan to work out what happened inside the cores of the damaged units.

This paper concludes

1. Volatility dictated by temperature and reduction potential dictated the fraction of the radioisotopes which were released.

2. All coolant was likely to have evaporated by the time the containments were vented.

3. The damage to the fuel was extensive.

4. The vast majority of the less volatile elements such as plutonium, niobium and strontium were contained within the reactors.

In the paper it has been calculated that the ratio of released cesium to plutonium from the Fukushima event was 100000 : 3 which suggests that the Fukushima event was far closer to a pure cesium / iodine release than the Chernobyl event was. The cesium to plutonium ratio for Chernboyl was about 10 : 1. I had from an early time made this prediction as the Chernobyl and Fukushima events were very different types of accident. One was a power surge while the other was overheating.

The most interesting thing in this paper is the graph of soil activity / reactor inventory against the oxygen potential of the dominate oxide form. This graph suggests that the more thermodynamically stable the oxide is then the less of the element will be emitted. The good news from this graph is that worst elements (plutonium) will not be emitted. The only problem is that the graph has some points which are a long way from the trend line.

More barium was released than this graph suggests while less ruthenium and silver was released than this simple model suggests. I think that I can explain why less ruthenium was released, the most easy ways to release ruthenium are either as fuel particles (which did not happen at Fukushima) or as ruthenium tetoxide which would not form as the reactors stayed under reducing conditions during the accident.

The purpose of nuclear reactors and something about plutonium

Dear Reader,

It has come to my attention that the myth that the civil nuclear power industry is part of the military nuclear sector has shown itself again. I would like to point out the folly of this idea. One blogger has repeated this claim recently, so that I can not be accused of quoting him out of context. I am going to make a length quotation of his text. He claimed recently that

“If fission technology did not have military application, if the fission of uranium did not produce plutonium for use in nuclear weapons, there would be very few nuclear reactors on the planet.

The production of boiling water due to waste heat from isotope creation in nuclear reactors is not the reason for their existence.

The very first nuclear reactors were built in order to produce the bomb which killed Nagasaki.

Every reactor in the world is dual use. The primary use is military.”

Now I think what is happening is that Paul is mixing a small amount of truth (yes the first reactors were part of the US nuclear bomb project) with a lot of his personal opinion. Then he is posting it in a way which makes it look like a series of facts. It is important to distinguish between fact and opinion.

Many reactors are needed for isotope production for medical and industrial purposes. A world without reactors would mean that radiotherapy would become much more expensive in some parts of the world. Thus if we get rid of reactors we will make this life saving treatment less available to the poor, frankly the idea of the rich getting medical treatment while the poor suffer and die of curable things is as morally offensive as it gets.

Next while the idea of wicked nuclear plant companies supplying plutonium to an equally wicked bunch of bomb makers might be something which troubles many people. I can tell you that there is very little to worry about as the problem has been solved.

I have been inside a range of civil nuclear sites in different parts of Europe, I can tell you that a lot of security features exist in these sites which prevent the illicit movement of nuclear materials. One of the safeguards are cameras which are watching you, I never quite know when I am being filmed in a such a place so I make a policy not to have a silly look on my face. Frankly I do not want some bunch of UN inspectors to end up looking at pictures of me with a silly face on my face.

The UN make sure that nobody sneaks plutonium or used fuel from the civil sector into the military sector.

I have also had my workplace inspected by the UN, unlike some rogue states I was cooperative. A few polite but firm men from the UN visited my lab, they wanted to know what I was doing. I told them (truthfully) that there was close to no radioactivity in the lab, but they still collected a gamma spectrum in my lab. I think that they were using a BGO detector and they found nothing interesting in the spectrum. I imagine that if I had been cooking some illegal nuclear brew in the corner that the inspection would have been rather disagreeable for me.

For many decades the civil nuclear sector has been quite rightly very separated from the small islands of the military nuclear sector.

Also the plutonium which is made in the civil sector is frankly no good for the bomb markers, if anything plutonium has been crossing from the military sector into the civil sector. I have seen reports explaining how Soviet made bomb grade plutonium is to be converted into MOX and then sold to civilian nuclear power companies. Now to my mind that is a great example of beating swords into ploughs and converting spears into pruning hocks. This is because when the plutonium comes out of the civil power reactors it will no longer bomb grade, as far as bomb makers are concerned it will be a rather disagreeable grade. The great redeeming feature of this used plutonium will be the plutonium-240.

Now in the interests of world peace I am not going to give out any details which have misuse potential but I feel that I can tell you that to build an atom bomb which works the device must do the following three things.

1. Change from sub critical to super-prompt critical
2. Make change 1 in less time than the typical time between the random appearance of neutrons in the fissile material
3. Inject a pulse of neutrons into the fissile material at the right moment to power up the bomb

Now requirement three in a plutonium based bomb is already quite hard to do, but there are ways to do it. I think that the main barrier against would be wicked nuclear hooligans is requirement two.

The spontaneous fission of plutonium-240 is the key to stopping bomb makers. If we consider for a moment the plutonium signature in the fuel of unit 2 at Fukushima then we will see that the fuel has the following isotope signature (all in atom %). I got the data from Z.D. Thome et. al. in Nuclear Engineering and Design, 2012, volume 247, pages 123-127. 

0.69 % Pu-238, 65 % Pu-239, 21 % Pu-240, 11 % Pu-241 and 2.5 % Pu-242.

Now this 21 % Pu-240 will be a major head ache for a bomb designer, it will raise the spontaneous fission rate for the plutonium by a factor of 27 from the grade of plutonium which was used for the first atomic bomb test.

It is also important to bear in mind that even for fast neutrons the fission to activation ratio is worse for Pu-240 than it is for Pu-239. As a result the addition of a large amount of Pu-240 to the fissile material in a bomb would require the mass of plutonium to be made larger. In general the more plutonium in the bomb the higher the rate of spontaneous fission.

This will mean that the bomb designer working in his den will need to design something which works more than 27 times faster than the first American design had to. Now while technology may have improved, but I am sure that given the choice a bomb maker would far rather use a bomb grade plutonium with far less Pu-240.

Now imagine some evil gremlin of a bomb maker has built a nefarious bomb and I imagine that the gremlin wants to threaten the world and hold it to ransom with the threat of an A-bomb detonation somewhere. I imagine the wicked gremlin wants his long and dire reign of evil, and he knows that he needs a bomb which can be left on the shelf for a long time and still be trusted to function. As soon as his bomb has gone past its “best before date” the gremlin will lose his means to threaten the international community.

The plutonium-241 will shorten the shelf life of the bomb, this isotope of plutonium undergoes a beta decay to form americium-241 which has a far higher decay heat and emits gamma rays. As a result the bomb will be plagued by an increasingly intense heat source at its core which also is becoming a bigger and bigger radiation threat to the gremlin each time it tries to service the bomb. I have done some calculations (using A-level physics) and I have been able to confirm that the Fukushima grade of plutonium will emit much more heat than a bomb grade plutonium. The heat output will skyrocket as more and more americium-241 forms.

Now some of my readers will agree with me, that is fine with me but some of my readers may not agree with me. If you do not agree with me then feel free to comment and we will discuss the matter like adults.

The truth about the purpose of nuclear reactors and something about plutonium

Dear Reader,

It has come to my attention that the myth that the civil nuclear power industry is part of the military nuclear sector has shown itself again. I would like to point out the folly of this idea. One blogger has repeated this claim recently, so that I can not be accused of quoting him out of context. I am going to make a length quotation of his text. He claimed recently that

“If fission technology did not have military application, if the fission of uranium did not produce plutonium for use in nuclear weapons, there would be very few nuclear reactors on the planet.

The production of boiling water due to waste heat from isotope creation in nuclear reactors is not the reason for their existence.

The very first nuclear reactors were built in order to produce the bomb which killed Nagasaki.

Every reactor in the world is dual use. The primary use is military.”

I hold the view that this blogger is mixing a small amount of truth (Yes the first nuclear reactors were there to support the USA’s nuclear bomb program) with his own opinions which have been dressed up as facts.

Many reactors are needed for isotope production for medical and industrial purposes. A world without reactors would mean that radiotherapy would become much more expensive in some parts of the world. Thus if we get rid of reactors we will make this life saving treatment less available to the poor, frankly the idea of the rich getting medical treatment while the poor suffer and die of curable things is as morally offensive as it gets.

Next while the idea of wicked nuclear plant companies supplying plutonium to an equally wicked bunch of bomb makers might be something which troubles many people. I can tell you that there is very little to worry about. The problem has already been solved.

I have been inside a range of civil nuclear sites in different parts of Europe, I can tell you that a lot of security features exist in these sites which prevent the illicit movement of nuclear materials. One of the safeguards are cameras which are watching you, I never quite know when I am being filmed in a place like CLAB so I make a policy not to have a silly look on my face. Frankly I do not want some bunch of UN inspectors to end up looking at a picture of me with a silly face on me.

Also the UN do make inspections at short notice of any site where they think nuclear activities either do occur, or might be going on.

I have also had my workplace inspected by the UN, unlike some rogue states I was cooperative. A few polite but firm men from the UN visited my lab, they wanted to know what I was doing. I told them (truthfully) that there was close to no radioactivity in the lab, but they still collected a gamma spectrum in my lab. I think that they were using a BGO detector and they found nothing interesting in the spectrum. I imagine that if I had been cooking some illegal nuclear brew in the corner that the inspection would have been rather disagreeable for me. To my mind the fact that the UN can catch the bad guys with inspections is another thing which reduces the chance of people being able to bad stuff.

For many decades the civil nuclear sector has been very separated from the small islands of the military nuclear sector. The degree of separation is quite rightly strict.

Also the plutonium which is made in the civil sector is frankly no good for the bomb markers, if anything plutonium has been crossing from the military sector into the civil sector. I have seen reports explaining how Soviet made bomb grade plutonium should be converted into MOX and then sold to civilian nuclear power companies. Now to my mind that is a great example of beating swords into ploughs and converting spears into pruning hocks. This is because when the plutonium comes out of the civil power reactors it will no longer bomb grade, as far as bomb makers are concerned it will be a rather disagreeable grade. The great redeeming feature of this used plutonium will be the plutonium-240.

Now in the interests of world peace I am not going to give out any details which have misuse potential but I feel that I can tell you that to build an atom bomb which works the device must do the following three things.

1. Change from sub critical to super-prompt critical
2. Make change 1 in less time than the typical time between the random appearance of neutrons in the fissile material
3. Inject a pulse of neutrons into the fissile material at the right moment to power up the bomb

Now requirement three in a plutonium based bomb is already quite hard to do, but there are ways to do it. I think that the main barrier against would be wicked nuclear hooligans is requirement two.

The spontaneous fission of plutonium-240 is the key to stopping bomb makers. If we consider for a moment the plutonium signature in the fuel of unit 2 at Fukushima then we will see that the fuel has the following isotope signature (all in atom %). I got this data from Z.D. Thome et. al. in Nuclear Engineering and Design (2012, volume 247, pages 123 to 127)

0.69 % Pu-238, 65 % Pu-239, 21 % Pu-240, 11 % Pu-241 and 2.5 % Pu-242.

Now this 21 % Pu-240 will be a major head ache for a bomb designer, it will raise the spontaneous fission rate for the plutonium by a factor of 27 from the grade of plutonium which was used for the first atomic bomb test. A typical bomb grade plutonium contains less than 8 % of plutonium-240. While the trinity test used a very good quaility bomb grade (less than 1 % Pu-240) according to P.P. Parekh et. al. in Journal of Environmental Radioactivity, 2006, volume 85, pages 103-120.

If you look at the history of the American bomb project you will see that when the first atom bomb was being got ready for testing a great concern existed that it would fail due to the tiny trace of plutonium-240 in the fissile material. I suspect that a master bomb making team which have already built many designs of bombs that they could cope with 8 % Pu-240, but for a first timerI think that this level of Pu-240 would be a great barrier.

It is also important to bear in mind that even for fast neutrons the fission to activation ratio is worse for Pu-240 than it is for Pu-239. As a result the addition of a large amount of Pu-240 to the fissile material in a bomb would require the mass of plutonium to be made larger. In general the more plutonium in the bomb the higher the rate of spontaneous fission.

This will mean that the bomb designer working in his den will need to design something which works more than 27 times faster than the first American design had to. Now while technology may have improved, but I am sure that given the choice a bomb maker would far rather use a bomb grade plutonium with far less Pu-240.

Now imagine you are some evil gremlin of a bomb maker, you have built your nefarious bomb and I imagine that the gremlin wants to threaten the world and hold it to ransom with the threat of an A-bomb detonation somewhere. I imagine the wicked gremlin wants his long and dire reign of evil, and he knows that he needs a bomb which can be left on the shelf for a long time and still be trusted to function. As soon as his bomb has gone past its “best before date” the gremlin will lose his means to threaten the international community.

The plutonium-241 will shorten the shelf life of the bomb, this isotope of plutonium undergoes a beta decay to form americium-241 which has a far higher decay heat and emits gamma rays. As a result the bomb will be plagued by an increasingly intense heat source at its core which also is becoming a bigger and bigger radiation threat to the gremlin each time he tries to service his bomb. I have calculated the heat output of ten kilos of plutonium with the same isotope signature as the Fukushima plutonium, and the heat output of this reactor grade plutonium will be far higher than a bomb grade plutonium.

While some of my readers might agree with me, that is fine with me. However some of you might not agree with me, that is fine with me as long as you do not allow your disagreement to lead you to misbehave. If you do not agree with me then please leave a comment and we can discuss the matter like adults.

Pussy riot and the dose meters

Dear Reader,

The women who are alleged to be part of the punk band in Russia are still in trouble, I saw alleged because the punk band wear masks when then appear in public and at least one of the women who were arrested has claimed that she is not part of the band. I predict that this case will be an interesting one which we should keep an eye on.

A second thing which I have noticed is that a claim has been made that workers at the Fukushima site were told to tamper with their dosemeters to reduce the dose that they recorded. I do not want to sit in judgement on the matter as the full story has not been gathered. I think that guilt by accusation is deeply wrong.

Imagine a world where I could accuse TEPCO, Greenpeace or even you of being “in league with evil aliens from Mars who are planning to poison the school meals in Göteborg with mind distorting drugs” and then these companies or you are then punished based simply because I have made this accusation. Such a world would be a deeply wrong place, and I have to confess that I could not keep a straight face while typing that nonsense about aliens.

If you read the IAEA book (Lessons Learned from Accidents in Industrial Radiography) you will read about the dire actions of the small minority of bad industrial radiographic workers. One common bad behaviour is that some of the radiographic workers remove their dosemeters before they enter a high radiation area to do a source recovery operation, this is a behaviour which is calculated to hide an accident from the radiation protection authorities and also from their supervisor. I wholeheartedly condemn these attempts to sweep accidents under the rug, and I am displeased at the idea that the employers would encourage such a behaviour.

I hope that I am merely being “angry in the abstract” rather than being displeased by a real case of a employer trying to make false measurements.

I worry that in todays climate that some people will say or write anything to blacken the name of some unpopular person. I think that testilying is wrong. For example while Mark Brandon “Chopper” Read has done some rather unspeakable deeds, it would be wrong for me to make a false claim that he murdered ten policemen using a toothpick and a bag of dog treats. Just because someone like Al Capone has done many bad things it does not make dishonesty right.