Hot particles

Dear Reader,

I have been thinking about hot particles, these were the irksome little specs of radioactive stuff which were released by theChernobylaccident. When one of my readers (My brother) asked me if the ruthenium would enter the metabolism of humans it made me think.

I have come to the conclusion that some of the particles may be hard to digest, as a result it may well be hard to liberate the ruthenium from the particles. Now if you are getting very happy and complacent thinking that if the particles can not be digested then the radioactivity does not pose a threat to the public then think again.

With non radioactive toxic metals if they are in insoluble forms then they tend to be less toxic, this is because the dust will not dissolve in your lungs and thus poison you. Instead you hope that the dust will be slowly lost out of the lungs by the mini-oars which sweep dust out of your lungs.

The dust then passes up into your mouth and then is swallowed together with the mucus; it then passes into the digestive system. If the dust is insoluble in the gastric juices (I assume that if it survives the gastric juices then it will survive the more alkaline environment in the gut) then it will then pass out the other end of you in the poo.

A more soluble metal containing dust such as cadmium oxide or aerosol such as droplets of chromate will either dissolve in the lungs or the digestive system thus giving you a dose of metals.

It is important to note that cigarette smoke contains cadmium oxide particles, if I recall correctly metal foundry workers who are exposed to cadmium fumes tend to suffer from more lung cancer than the general population. This cadmium in cigarette smoke is yet another reason to either not smoke in the first place or to give up the vile habit.

But I guess you did not come here to be reminded of the evils of smoking so back to the topic of interest.

In the case of radioactive particles (and asbestos) the dust is able to exert a malign influence on your lungs without needing to dissolve. The radioactive hot particles emit radiation which damages the lung tissue as long as the particles are in the lungs, if the particles are soluble then they tend to dissolve. The soluble radioactive metals then enter the rest of the body; with some luck the body will then excrete the metals in either urine or poo. So the body is more able to dispose of the metals.

In the case of the insoluble dusts if they are of the wrong particle size then they can be very hard to clear out of the lungs, as a result they can stay in the lungs for years still exerting their malign influence. The worst offender would be an insoluble actinide oxide such as plutonium dioxide; this could sit in the lungs and carry on delivering alpha particles to your cells for many years.

Uranium is likely not to be quite so troublesome, when a DU bullet is used to shoot a tank it tends to ignite on impact which forms uranium oxides. I have been told that one of the signs to look for when trying to tell if a tank was taken out by a DU bullet is a yellow stain around the bullet hole. Many uranium(VI) compounds are yellow or orange in colour.

If uranium metal is burnt in air, I think it is likely to form U₃O₈ this can be regarded as a mixed U(IV)/U(VI) oxide. A crude way of thinking of it is as UO₃.UO₃.UO₂, it so happens that uranium(VI) oxide dissolves very well in water which contains carbonates. As it so happens that the human body generates carbon dioxide (which forms carbonates when it dissolves in water) then it is likely that uranium(VI) will be soluble in many body fluids as the anionic carbonate complex [UO₂(CO₃)₃]^4-, as a result I suspect that small uranium oxide particles will slowly dissolve if they enter a human. While the plutonium dioxide particles will be likely to never dissolve.

It is also important to bear in mind that the surface of uranium dioxide reacts with the oxygen of the air to form uranium trioxide; this process should help speed up the dissolving of uranium oxide if it is left out in the rain.

If you want to read more about radioactive particles then see F.J. Sandalls, M.G. Segal and N. Victorova, Journal of Environmental Radioactivity, 1993, volume 18, pages 5-22.

Role of ruthenium in humans

Dear Reader,

One of my readers asked the question of will ruthenium-103/106 which is released from a reactor accident enter the human metabolism ?

I understand the term metabolism to mean the sum total of all the chemical reactions which are occurring inside an organism. Thus metabolism includes lots and lots of different reactions. I will need to consider the question further and do some reading before I can answer this question with anything more than at best an educated guess and at worst the random ranting of Mark Foreman.

When I am ready to answer the question I will post something on the subject.

Silver and tellurium at Fukushima

Dear Reader,

I have been a little quiet recently as I have had a bit of writers block. I was not sure quite what you wanted to read, life would be better if my loyal readers would write in and say what they want to read more about but today my thoughts wandered onto the subject of silver chemistry.

Those of you who have been paying close attention to the Fukushima event will recall that some radioactive silver has been released by the accident, but to date no ruthenium has been released by the accident.

The boiling point of silver is about 2200 ^oC, while ruthenium metal has a melting point of about 4200 ^oC. As a result of this difference in a reducing environment the silver will boil out of the reactor and form aerosol particles at a much lower temperature than the ruthenium. But under oxidizing conditions (if air gets to the hot fuel) the ruthenium metal will be converted to ruthenium tetroxide (RuO₄) which is very volatile. It will enter the air even at room temperature.

What the RuO₄ will do is to coat the surfaces of dust particles which are formed from things like steel to form ruthenium rich hot particles which will then escape from the plant. The silver can not form a volatile oxide, above about 300 ^oC silver oxide will decompose to oxygen and silver metal.

These facts which we have from the radioisotope signature suggest to me that the fuel was at least 2200 ^oC but it was not exposed to air while it was hot. If we look at page 18 of the following set of slides, then you will see an Ellingham diagram which explains how tellurium is more noble than uranium. The lower down the diagram the more able an element is to react with oxygen, if the line for an oxide is higher than the yellow line for uranium dioxide then the element is likely to be in the zero valent state (elemental form).

Tellurium dioxide has a boiling point of 1245 °C, while tellurium has a boiling point of 988 °C. If the tellurium is in the form of the element then it will be able to diffuse and boil out of the fuel at a relatively low temperature. A paper was written by S.G. Prussin, D.R. Olander, W.K. Lau  and L. Hansson, Journal of Nuclear Materials, 1988, volume 154, pages 25 to 37 which is all about how the tellurium, iodine and other fission products can diffuse out of hot fuel.

Gamma spectrum of Fukushima soil

Dear Reader,

In case you want to look at a gamma spectrum for the soil from about 20 km from the Fukushima site then I suggest you look at the paper published by Keiko Tagami, Shigeo Uchida, Yukio Uchihori, Nobuyoshi Ishii, Hisashi Kitamura and Yoshiyuki Shirakawa, Science of the Total Environment, 2011, volume 409, pages 4885 to 4888.

The paper concludes that the only isotopes released from the plant were noble gases and volatile elements such as I, Te and Cs. The isotopes detected in large amounts were I-131, Te-129m, Cs-134, Cs-136 and Cs-137. Very small traces of Nb-95, Ag-110m and La-140 were detected but these levels were too low for measurement.

No Zr-95, Ru-103 or Ru-106 was detected which suggests that it is very unlikely that a large scale release of plutonium has occurred. If anyone suggests to you that plutonium has been released in large amounts then bear in mind that Zr-95 is a good mimic for plutonium in nuclear fuel. It forms a dioxide and a Perovskite SrZrO3 both of which are very similar to the plutonium dioxide in their boiling points and water solubilities. If a large scale plutonium release was to occur from a nuclear power plant accident then I would expect zirconium-95 to be found in the same places as the plutonium. The zirconium-95 is much more easy to find as it is a strong gamma emitter while plutonium is only a weak gamma emitter.

Control rod chemistry

Dear Reader,

In the blogosphere I have noticed that one blogger claimed that the radioactive silver spread around by the Fukushima accident was due to the use of silver in control rods. While one paper I read suggested that the reactor one used boron carbide, I can not rule out that the reactors used silver control rods.

Control rods are used on almost all reactors to control the rate of reaction, the further out they are pulled from the core the faster the reaction occurs. You can think of the control rods as the accelerator pedal of the reactor.

Silver has a high cross section for neutrons and as a result would make a good control rod material, the ideal control rod would.

1. Last forever
2. Cost nothing to make
3. Not become radioactive while in service
4. Behave nicely even during a horrible accident

The first issue is an interesting one, designs for control rods vary from reactor to reactor. One common choice is to use boron; this is because one of the isotopes of boron has a very large cross section for neutrons.

The cross section for neutrons is expressed in barns; this is an old unit of measurement which dates back to the Manhattan project. The idea was that if everyone expressed the cross section areas in barns rather than square meters then if a spy saw a cross section then it would be just a meaningless number. I suspect that the term barn relates to barn door.

The choice of boron has a sting in the tale which can come back to bite you on the arse. The problem is that any isotope with a very high cross section for neutrons will not be needed in large atom numbers. Each time it catches a neutron then one less atom will be present, so this can cause a change in the effectiveness of the control rod. This idea is known as burning out the neutron poison.

While the slow weakening of a control rod’s effect is an undesirable effect, this effect can be used in a beneficial way. Some fuels which have very high fissile contents have a little boron blended in. The idea is that as the fissile atoms are used up the boron is also burnt up by the neutron bombardment. The overall idea is that the fuel keeps the same reactivity level throughout its whole life inside the reactor.

The reaction by which the boron works is

n + ¹⁰B –> ⁴He + ⁷Li

This reaction generates helium gas; one Russian design for a control rod uses a boron steel alloy. The problem with this design is that the life of the control rod is limited because the helium starts to form bubbles in the steel. These bubbles then harm the properties of the rod.

A common western design is to use boron carbide (B₄C), the rods are made of a steel and have holes into which are place pellets of boron carbide. As the steel is separated from the boron we do not have the helium bubble problem, but if the rod is overheated then a reaction can occur between the stainless steel and the boron carbide. This is an exothermic reaction which forms metal borides and some carbon. For example

B₄C + 4Fe –> 4FeB + C

One other disadvantage of boron carbide is that during an accident it can form methane; the methane can lead to the formation of methyl iodide during an accident.

An alternative is to use a cadmium-silver alloy; the nice thing about cadmium is that it is very selective. It has a very large cross section for slow thermal neutrons while for fast neutrons is has next to no cross section. As the thermal neutrons are more able to cause fission then the cadmium has the nice effect of selectively mopping up these neutrons thus altering the energy spectrum of the neutrons in the core.

As a result of the fact that cadmium is selective for slow neutrons, I think that a control rod based on only cadmium would be a poor choice for a fast reactor such as a sodium cooled fast breeder, for such a reactor I would be inclined to use boron as it has a simple broad graph of absorption cross section as a function of neutron energy.

Cadmium is a metal which has a series of non radioactive isotopes, so when the cadmium-113  (the isotope with the largest thermal cross section) swallows up a neutron it forms cadmium-114 which is non radioactive and has a small capture cross section for neutrons. In this way many of the cadmium atoms can swallow up a series of neutrons without forming much radioactivity. Also the radioactive isotopes of cadmium are mostly well behaved short lived isotopes.

¹⁰⁶Cd, 1.25 %

¹⁰⁷Cd, half life of 6.5 hours decays to ¹⁰⁷Ag

¹⁰⁸Cd, 0.89 %

¹⁰⁹Cd, half life of 463 days decays to ¹⁰⁹Ag

¹¹⁰Cd, 12.49 %

¹¹¹Cd, 12.80 %

¹¹²Cd, 24.13 %

¹¹³Cd, 12.22 %, very long half life (7.7 x 10¹⁵ years or 7.700000000000000 years)

¹¹⁴Cd, 28.73 %

¹¹⁵Cd, half life of 53.46 hours decays to ¹¹⁵In

¹¹⁶Cd, 7.49 %

¹¹⁷Cd half life of 2.49 hours decays to ¹¹⁷In

On the other hand silver has two stable isotopes, both of which form radioisotopes when they swallow up a neutron. This means that silver control rods will make more long (half life > 1 day) radioactivity per million neutrons which they absorb than a cadmium control rod will.

Some time ago I visited a disused nuclear power plant in Sweden; it was a small heavy water plant which produced only 10 MW of electric power and heat for district heating. In the reactor containment I saw the area where the used fuel used to be stored (the fuel had been taken away long ago) but the control rods remained locked inside the storage area. They were being left there to decay while everyone is waiting to decommission the reactor building. The thing about decommissioning is that the longer you wait the lower the levels of many irksome isotopes. For example the ⁶⁰Co which forms as a result of the cobalt impurities in stainless steel will become half as strong every five years, thus by waiting for 50 years this radiation source will become one thousand times weaker.

Due to the fact that the control rods are exposed to such high neutron fluxes when in use, and as they are intended to absorb neutrons they can become very active.

When an accident occurs and a core melt occurs, it is likely that silver containing control rods will melt and start to form fine silver rich particles. This is likely to be a good thing as iodine has a strong affinity for the silver; this aerosol of silver may help to trap out radioactive iodine inside the plant. On the other hand if the silver particles are of the “wrong size” then maybe they will assist the escape of the radioactive iodine. One of the key features of the Chernobyl accident was that ruthenium tetroxide (RuO₄) was formed; this is a very volatile and strongly
oxidizing metal oxide. The RuO₄  enabled the ¹⁰³Ru and ¹⁰⁶Ru to form a coating on steel surfaces. These steel surfaces included both parts of the plant and also fine steel particles which were then able to escape from the plant. This is likely to be the reason why ruthenium rich hot particles were observed after the Chernobyl accident.

Ruthenium is a nice metal which I have a deep love of; I picked up this liking for it when I worked for Tony Hill. He joked that he had a special attraction to [RuHCl(CO)(PPh₃)₃] which is a complex formed by heating ruthenium chloride in methoxyethanol with triphenyl phosphine. I think I can see why Tony likes this complex; it is a useful starting material for a series of other things. It is also possible to make an osmium version of this complex but I will save my views on osmium for another day. The formation of this rather interesting looking compound is related to the work of Vaska. Vaska is a chemist from Eastern Europe who is something of a genius, he did a lot of nice chemistry with elements such as iridium. But lets get back to control rods.

So sometimes formation of solids or particles are a good thing and sometimes a bad thing.

One alternative to boron carbide, boron steel and indium-silver-cadmium alloys is to use hafnium. This is an interesting element; while zirconium has a very low cross section for neutrons (it is close to transparent to neutrons) hafnium is a very strong absorber of neutrons. As the elements are so similar in chemistry hafnium is commonly found in zirconium minerals, the zirconium used for nuclear reactor applications is normally a special low hafnium grade.

The hafnium is used in the form of hafnium hydride in control rods; these control rods are unlikely to react violently during a reactor accident or to form troublesome gases.

More isotope data from Japan

Dear Reader,

As promised I am going to share with you some of the isotope data which I have obtained from the NISA and the JAIF in Japan. I have looked at the data and I have come to some conclusions.

1. The uranium level in the soil close to the reactor is about the right range for a normal soil, and the isotope signature matches natural uranium. I think that if the majority of the uranium in the soil was from the nuclear fuel at the plant then the isotope signature would be different.

2. The transuranium actinides (Plutonium and curium) need to be considered. The level of the actinides (when the activities are normalised to make the Cs-137 levels the same) is much lower, this suggests to me that the level of damage to the nuclear fuel is much less in the Japanese accident than it was at Chernobyl. At the Chernobyl accident a nasty big steam explosion smashed the fuel into small fragments which were flung out of the reactor building. The Nb-95 : Cs-137 ratio at Fukuashima also suggests that the level of damage to the fuel is lower. The Zr-95 and Nb-95 isotopes are very important, this is because ZrO2 has very similar solid state chemistry to plutonium.

3. The lack of Mo-99, Tc-99m and Ru-106 in the release from Japan suggest to me that the fuel has been subject to less mechanical violence and heating in an oxygen rich environment. The Mo could form volatile MoO3 if it is heated in air, while the Ru can form RuO4 when it is heated in air.

4. The Sr : Cs ratios also suggest that at Fukuashima that the fuel has been damaged less, I think that the steam explosion at Chernobyl would have flung a lot of solid and less water soluble forms of strontium out of the reactor. This would have included the SrZrO3 phase which is present in used nuclear fuel. This SrZrO3 phase is the perovskite phase which is found in used uranium dioxide (and MOX) fuel.

Part of the isotope signatures of the Chernboyl and Fukuashima accidents

One of the things which I think should be done in Japan is that a sample of the soil with the radioactive contamination should be subjected to a series of chemical leaching.

Firstly the soil should be extracted with water, to extract the water soluble fission products which do not bind to soil minerals. Then the soil should be subject to a series of extractions, each extraction should be more harsh than the last. The idea of such an experiment is to get some idea of the chemical forms of the radioactive isotopes which are present in the fallout.

Rather than being a “waste of time experiment” the results of this experiment would help by giving clues on how the radioactvity will behave in the wide wide world. We need to know how easy it will be for the radioactivity to enter the food chain and thus endanger humans. The leaching rate of the solid particles of the fallout is very important, for example plutonium which is formed by neutron activation of uranium in an atom bomb is more soluble (and able to enter living things) than the plutonium in bomb fallout which was part of the plutonium used to build an atom bomb.

Isotope signatures from Japan

Dear Reader,

I have been able to track down details of the soil contamination which has occurred at the Tepco site in Japan, while soil contamination with radioisotopes is clearly not a good thing. The isotope signature does give us some thing to be glad about, I have made bar charts of the isotope signatures of the Chernobyl release and the soil contamination in a playground near to the stricken Japanese reactor. As the Chernobyl data was the total activity which escaped from the plant while the Japanese data was for the level of contamination (Bq per kilo of soil). Below is the bar chart, here I used data obtained by the Japanese Chemical Analysis Center.

Radioisotope signatures of the two accidents (Fission products)

I adjusted the Chernobyl data so both graphs have the same sized bar for Cs-137. The first thing to look at is the Sr to Cs ratio. The Fukushima accident has released far nicer Sr:Cs ratio than Chernobyl. While Cs-137 and Cs-134 are not good for you, Sr-90 is much worse. It has a longer biological half life, and it concentrates in a radiosensitive part of the anatomy (the bones). So the fact that less Sr-90 has got out is good news.

 

At Chernobyl Mo-99 and Ru-106 escaped from the reactor (Tc-99m is the daughter of Mo-99), this is likely to have occurred as a result of the Chernobyl fuel being heated in air by the fire. The Mo would have got oxidised to form MoO3 which is volatile, while the Ru was converted into RuO4 which is a gas. An alternative route out of the reactor at Chernobyl was the steam explosion which flung fuel out of the reactor, no such dire explosion occurred in Japan. Also neither of these isotopes were found in the soil in Japan then it is good news.

 

I will comment on the other data which is from the JAEA in the near future.

Reentry into unit two and other matters in Japan

Because of the high humidity inside the unit two building an attempt by a robot to enter the building did not work. The humidity (water vapour) clouded the robots vision and prevented it from going inside.

A team of four workers entered the building to check the radiation levels and other things inside. The team found that the radiation levels were between 10 and 50 mSv per hour. These dose rates are too low to cause “instant death”. To reach a 2 Gy dose of gamma rays a person would have to stay in the 50 mSv per hour part of the buildings for 40 hours, even at 2 Gy death would be unlikely as a misguided person who sat in the 50 mSv h-1 spot for almost two days would have access to good medical care when they finally emerge from the building.

TEPCO are trying to improve the cooling of the used fuel pond to reduce the humidity in the building and thus improve the conditions for workers who have to toil inside the building. It is important to understand that in a damaged nuclear plant not only is the radiation a threat to the wellbeing of the work force. During the Three Mile Islandcleanup some workers over heated inside their anticontamination suits. I imagine that being inside an anticontamination suit in a hot place would be like being the kipper in a boil in the bag kipper. (Neither healthy nor nice!)

As part of the transition from a dire accident to a controlled careful cleanup a pair of special fork lift trucks with ten centimetres of steel plate as shielding, a 20 cm lead glass window and air filters to protect the operator will be delivered to the site. According to Yasufumi Ohsaki (Mitsubishi Heavy Industries) these machines will be used to clear rubble and thus hasten the normalisation of the situation at the reactor site. I think that clearing rubble from around the site is an important activity which will allow workers to deal more effectively with the reactors.

Another step in the right direction is the establishment of a special office of the Japanese health ministry. This office will watch over the radiological health of the workers who are toiling on the site.

TEPCO have explained how they are planning by June to start to reuse cooling water. The idea is that cooling water will be injected into the plant; the used water will be cleaned up using a zeolite column. I think that the idea is a reasonable idea which will help with the clean up.

I suspect that the use of a zeolite to clean the water will minimize the volume of radioactive waste water which needs to be processed off site. Also the zeolite will absorb much of the radioactivity. It will concentrate the radioactivity into a small volume which will be cheaper and safer to dispose of.

At the same time the fishing and farming cooperatives have started to bring civil claims against TEPCO. As I am not a combination of the judge and jury I will not try to usurp the court and say how much the compensation should be. I am sure that this accident will result in a series of court cases, but I have no idea of how they will turn out.

Already the farming community has been subject to special rules and now the government have banned the growing of rice in the 30 kilometre zone and in some areas where the radioactive cesium level is high. While farmers may not like being told that they can not grow rice, I think that the rice ban is in the interests of society.

I would like to pose the question of “what should TEPCO / MEXT do about the accident ?”

I hold the view that rather than paying farmers and fishermen to do nothing, that TEPCO / MEXT should strongly consider the creation of worthwhile alternative economic activities which will prevent unemployment within the fishing and farming communities. One problem which TEPCO have right now is that they are running low on money. TEPCO are selling off assets, the workers are being subjected to pay cuts and the executives are going to have no pay.

What ever people might think about the way which TEPCO have behaved I think it is important not to blame the rank and file members of the workforce. I suspect that the typical plant worker is a person who is trying hard to make the best of a very bad deal. The people who have been toiling at theFukushimasite should not get a pay cut, if anything they should be given a special bonus for their good work.

I think that either TEPCO needs to be kept afloat or some other body needs to take over the financial obligations of TEPCO. One option would be for other energy companies and utility companies could provide assistance to TEPCO to try to keep the company afloat so that it can continue to clean up the mess and compensate the victims. Another option is for the state to bail out TEPCO.

In the recent past in the UK a series of banks have collapsed or at least come close to collapse. The UK state bailed out the failing banks, I agree with the idea of the bail out but I hold the view that the bail out should come with strings. The bailed out bank should be subject (forever) to a set of rules which limit the bonuses of staff and prevent the bank doing irresponsible things which cause banking chaos.

In the same way if TEPCO is bailed out by the state then the state should get something in return, TEPCO should not be allowed to profit from this event or to get an easy ride at the expense of the tax payer. One option would be for TEPCO to issue shares which be sold to the government. So perhaps TEPCO may be nationalised by the Japanese government, the government would then become a major shareholder in TEPCO.

Now for a moment let us assume that TEPCO will stay afloat, now we need to consider what it should do.

One scenario would be for TEPCO to provide training to a team of farmers who would then be paid to perform dose reduction actions on farmland. I suspect that the farmers may already have some of the equipment needed for the work. For example deep ploughing and potassium fertilizers are method for reducing the transfer of cesium from grass to cows.

The Japanese have been reported to be considering flooding rice paddies with water, stirring them up and trying to flush away the radioactivity. I fear that this will not remove cesium from the soil. The stirring up might have the same effect as deeply ploughing a European field as if all the soil becomes a slurry then if the soil has come clay in it then the cesium will stick to the clay.

Another idea is to use zeolite in drainage channels to extract the cesium inside a small volume of the mineral. This will make the waste processing more easy, if the government was to scrap 1 cm of the soil then a vast amount of contaminated soil would need to be disposed of as radioactive waste. I think that top soil removal should be reserved as a last resort method for dealing with stubborn radioactive stains on the land. A less dramatic method is to use pytoremediation of the land. This is a fancy term for “cleaning with green plants”.

A fast growing plant like rape or sunflowers can be used to clean the soil. To work well the plant needs to be easy to grow, fast growing and able to extract cesium from soil. Vast fields of sunflowers could absorb cesium from the soil. As long as the Japanese society has devised a disposal method for the fully grown sunflowers then this crop could be of some use to the farmers. I reason that a typical Japanese farmer will be unhappy about now being able to earn a living the way he used to.

Even if a farmer was given the same amount of money as he earned in a year from farming and was told to sit on his bottom then I think that many farmers would be unhappy. I think that being able to farm an alternative crop or to farm in an alternative way of farming would be good for the mental and social wellbeing of the farming community.

One idea which I have seen before is for the farmers to change from growing food crops to growing plants which can be harvested for oil. The oil from sunflowers or rape could be used in industry or for making fuel oil. According to one book which I have read on the topic, the part of the plant where the oil is harvested from has very little radioactivity while the other parts of the plant contain plenty of radioactivity.

Maybe a contaminated farm could be changed from a food farm into a vegetable oil farm; if the oil is not suitable for food use then it could be converted into biodiesel. The biodiesel could be used for cars, trucks and buses as a replacement for normal diesel. The more radioactive parts of the plants could then be disposed on in a special way to avoid returning the radioactivity to the top soil.

If you are interested in the way that vegetable oil is converted into diesel then I can tell you something about it. Normal vegetable oil has the wrong mechanical and physical properties for use in a diesel engine. Also it is very hard to use sunflower oil in an oil lamp; instead the very large molecules in the vegetable oil need to be shortened to make them suitable for use.

One classic method is to make the FAME type of diesel fuel; this is the Fatty Acid Methyl Ester type of diesel. In common with diesel fuel production the formation of the methyl esters is often done in chemical labs when we want to analyse cooking oil. For analytical purposes my normal method is to shake a hexane solution of the cooking oil with potassium hydroxide in methanol. Then after allowing it to stand for a moment, I remove the glycerol rich bottom layer with a pipette and then I wash the mixture with brine, remove the brine, dry the hexane layer with sodium sulphate. Then I dilute it and inject it into my divining stick (opps I mean GC machine)

For making biodiesel the easy way is to boil methanol with cooking oil with some sodium hydroxide added. After boiling it for an hour, I let it cool. I then remove the bottom layer, then I wash the upper layer with dilute acetic acid, then with water and then I tend to dry it with sodium sulphate. This reaction works in the following way, methoxide acts as a nucelophile on the glycerol trimester to form a methyl ester. This is a classic bit of organic chemistry.

The alternative method uses more modern chemistry, a fancy catalyst is used to hydrogenate the oil and also do a hydrodeoxygenation reaction, this forms a mixture of propane and long chain alkanes (parafins).

http://www.biodieselmagazine.com/articles/1505/heeding-hydrogenation/

Rather than the farmers having to work out their recovery plan on their own, I think that TEPCO and/or the Japanese government should provide guidance to the farmers, and financial and material assistance to help them change the way they earn a living from the land.

Ruthenium in Japan

Looking at the update on the accident in Japan it looks like some ruthenium has escaped from the plant, it is important to note that ruthenium has two radioisotopes (103 and 106) which have half lives which are long enough to allow these isotopes to escape from the plant.

One thing which can happen is that the ruthenium forms the tetraoxide (RuO4) which is mobile, it is able to deposit onto surfaces in the plant and also onto particles which could then escape from the plant. I currently have no idea what chemical form the ruthenium is in or how much ruthenium-103 and ruthenium-106 has escaped from the plant.

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1301056350P.pdf