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We now have details of the size of the cobalt-60 source stolen and then found in Mexico, it was 3000 Ci according to the IAEA. I was wondering why such a source should be allowed to be driven around without either a police or military escort. I think that if two policemen were to escort the truck with the source then the chances of it being stolen would be greatly reduced, but hindsight is a great thing. With hindsight everything is so clear, with hindsight I am sure that we would allow have more success in life. Just think you would be more able to get your dream job, have success in your love life and avoid doing stupid and embarrassing things. But sadly like the rest of you I can not change the past or rewrite history !
But back to cobalt sources.
I recall in my youth under the supervision of Barry E. Tyler (genius physics teacher) doing the Searle’s bar experiment which is a simple system where heat flows along a thermally isolated bar.
If we have a solid bar with a thermal conductivity of k (W / m K) which has a cross sectional area of A (square meters) and a length of L (meters). Then if a difference of x kelvin (ΔT) exists between the two ends then the thermal power (rate of heat energy transfer through the bar) will be given by
P = k ΔT A / L
The temperature gradient along the bar will be linear.
If on the other hand we were to have a sphere of a solid with a spherical void in the middle containing a heat source then the maths will be a bit more complex.
The surface area of a sphere is given by
A = 4πr2
So it should be clear that the area over which the heat is being transmitted is a function of the distance from the centre of the sphere.
We can say for Searle’s bar that the thermal power is given by
P = A k (dT/dx)
(dT/dx) is the temperature gradient along the bar.
So we can apply our equation to the sphere (x is the distance from the centre of the sphere)
P = 4πx2 k (dT/dx)
Rearrange to get
P / 4πx2 k = (dT/dx)
It is important to note that at the centre of a perfect sphere we could have an infinite thermal gradient, so we should be careful to make sure that the heat source at the centre has a non zero radius.
Things will get more complex in a real shield around a cobalt-60 source as the gamma photons will travel some distance into the lead before their give up their energy to the lead.
If we make a lead shield which is a sphere which has a spherical void which has a radius of 2 cm in the centre and is 12 cm in radius, then we can do some calculations. If we assume that all the radiation is absorbed inside the source at the centre of the sphere and that the thermal output of the source is 250 W then we can make a graph of the temperature of the sphere as a function of the distance from the centre of the sphere.
This was easy but the more complex case of the photons traveling some distance into the lead does seem more fun, now the decay energy of cobalt-60 is 2.824 MeV, of this 96 keV on average is the energy of the beta particles. So we know that 3.4 % of the energy has to be released in the source. If we choose to use the first approximation for gamma rays that they obey the Beer-Lambert rule and that the linear attenuation coefficient in lead is 0.6 cm-1 then we can make a new calculation.
250 W of power from the decay of cobalt-60 in a sphere of lead with a 2 cm radius cavity in the middle
It has come to my attention that a truck containing a radioactive cargo from a hospital (A used cancer treatment unit) was stolen recently in Mexico. You will be glad to know that the radioactive cargo has been found. A short comment on the case (made at an early time) by the IAEA can be seen here.
Currently it is unknown why the truck and the radioactive cargo was stolen. I do not know if it was a simple truck theft where they wanted the truck, a scrap metal theft or something more sinister such the theft of radioactivity by someone with the intention of causing harm with it (dirty bombers ?).
I hope when I get some time soon to be able to comment further on this case and on cobalt-60 in general. One report claims that circa 3000 curies of cobalt-60 was inside the machine when it was stolen. From my own personal experience I can tell you that this is a large amount of radioactivity, I would expect that the outside of the shielding could feel warm if that amount of radioactivity is inside. The warmth is due to heat being created in the shielding by the absorption of the beta and gamma rays from the cobalt-60, this heat production (decay heat) is perfectly normal.
We can do some fun calculations with decay heat, but I want to save those for later.
The problem with radioactivity units is that two units for activity exist, the old one (curie) was defined as the amount of radioactivity which is equal in terms of decays per unit time as one gram of radium-226. This is a very large amount of radioactivity, one curie is 37,000,000,000 radioactive decay events per second. Or as I would write it 37 x 109 events per second. On the other hand the modern (SI) unit for radioactivity is the Becquerel which is named after the discoverer of radioactivity. This is defined as one radioactive event per second.
The problem with the Becquerel is that it is very small and for most applications, event things like expressing how much natural radioactivity is in a person, a kilo of earth from my garden [As far as I know there has never been a radioactive soil contamination problem in the town where I live in Sweden] or a packet of coffee) you need to write a large number.
The great problem I see with the curie and the Becquerel is that both units are very different to each other in size, the Becquerel can be thought of being like expressing the weight of a car in grams while the curie can be thought of as like expressing the weight of my dog in terms of equivalents of blue whales.
I saw with interest an article in the Local about how the Swedes are so opposed to cannabis, I would like to share something with you. Trust me it is not a joint, my idea of a nice joint is a cut of meat from a good butcher.
I think that the hard line of the Swedes on drug abuse is a good thing, from what I know the end goal of the Swedish government policy on drug abuse is a Sweden with no drug abuse. This is a noble aim, I am not sure if it will be possible to get to this point but it is a good target assuming that the state does not go mad. In some parts of the US school system some of the zero tolerance (zero common sense !) people have banned children from carrying an asthma inhaler, it is very hard (or maybe even impossible) to get high on salbutamol inhalers. Salbutamol is an indole (amphetamine) like drug in which the general CNS simulant effect has been designed out, the early days before salbutamol more people with the condition needed to use adrenaline as a treatment. This is a drug which can get you high and cause adverse cardiac effects.
The problem with weed, cannabis (marijuana) is that it is a drug which is associated with a serious mental illness, it can unlock a latent disease in some people. The worry is that a sizeable minority of people are predisposed towards psychosis, many of these people could live out their lives without experiencing any symptoms (staying asymptomatic) but exposure to cannabis can unlock the disease according to one paper. A meta study (P.Y. Le Bac et.al., Encephale-Revue de Psychiatrie Clinique Biologique et Therapeutique, 2009, 35(4), 377-385 ) found that in the majority of decent investigations of the link between cannabis smoking and psychosis, schizophrenia and psychotic symptoms.
The great problem with psychosis / schizophrenia is that it is condition which fouls up people’s lives and can transform healthy and productive people into people who can not work and need expensive long term care. For moral reasons we should provide medical and other care for the disabled, even for those disabled people who become disabled as a result of their own silly, reckless or stupid choices. For instance we should still offer lung cancer care to smokers, even while has been known since the 1930s that smoking causes lung cancer and a drunk driver who hits a tree should not be left to die of his wounds by the paramedics if they have a intense dislike of drunken drivers (I guess that clearing up the mess at a few horrible alcohol related RTAs will give anyone a hatred of drunk drivers).
But even if we ignore the moral argument for banning the recreational use of cannabis or the argument that it is harmful to the user, we have a strong argument for banning the drug to protect society as a whole from the unreasonable and avoidable burden caused by the long term harmful effects of the drug.
While all activities might carry some risk, for example I might fall out of bed and break something, or I might laugh myself to death if someone tells me a very funny joke (in the late 1980s a German man died as a result of laughing too much at a comedy film, it sounds like a wonderful way to leave this moral existence) while I could get injured while putting out a fire or dealing with a sea monster which has invaded the teaching lab (Trust me I found it hard to keep a straight face while typing the last one). All these varied activities have a key benefit to society.
To stay healthy I need to sleep, a good joke has great cultural value, as a “traditional” chemist I do not run in terror from fire (I stop think and decide if I will retreat or take the bull by the horns, the question of do I run or stand and fight it is not simple) I will fight a fire to protect humans and/or property and if a sea monster emerges from the sink in the teaching lab I think that as an associate prof I should subdue it to keep my students safe (I doubt if I will ever have to do that !).
But on the other hand smoking weed to get as high as a kite brings no reward to society, if I was to smoke “drugs” and fall down dead or go out of my mind then it would be a disgusting and pointless waste of human life. On the other hand if I was to fight valiantly against a sea monster which was attacking the students but sadly die during the battle at least the manner of my demise might motivate and inspire the students to strive to become better scientists and people. Maybe someone would name a teaching lab or a lecture room after me !
It has come to my attention that something deeply wrong has occurred according to a law suit in the USA. People who know me well will know that I am not the most exactly the most antiradiation person in the world, but I do hold the view that the reckless exposure of people to radiation is wrong and should be punished by criminal law.
For example the East German authorities years ago are strongly suspected of having used radiation for a series of nefarious purposes, such as inducing cancer in political prisoners. Those responsible should go to jail for murder or GBH.
In the USA according to the lawsuit the police in one area are accused of making unreasonable searches of people and subjecting them to X-ray examinations which include the high dose CT scans. The most perverted part of it is that bills are being sent to the victims of this police misconduct for these examinations. It reminds me of an ancient jewish folk tale about Sodom and Gomorrah, some of the oldest jewish texts on the subject of these two cities state that their crimes are not sexual in nature. Instead it was the cruelty and vile crimes against strangers which were the reason why these two cities had to go. Lot and Abraham left before a prehistoric version of a naplam airstrike occured.
One story was that Eliezer, Abraham’s servant went to visit Lot. He got into a dispute with one of the local men who hit him with a stone making him bleed. He was then told he would have to pay his attacker for the service of making him bleed (doctors at this time would do bloodletting), then one of the judges of the city (whose job it was to pervert the law) agreed that he would have to pay his attacker. What happened next was that Eliezer hit the judge in the head and told him to settle both debts by paying his original attacker.
Here in the US case I see a similar attempt to force a victim of a crime to pay for the “service” of the criminal.
While some people might consider it immoral let us for argument’s sake consider how much a human life is worth in terms of money. One 1977 paper from the UK considers the value of a life, the lower estimate was £50 while the upper estimate was £20000000. The lower value is from a view of the value of a unborn child, which I think is too low a value while the higher value is from a study of building codes (Ronan point).
Now using US data on inflation this £ 20000000 would now be worth 77.28 million UK pounds.
Now the dose from a CT scan of the lower torso gives you a dose of 10 mSv, which is half my yearly limit as a radiation worker.
If we use the normal 5 % chance of cancer as a result of 1 Sv of radiation then the court ordered CAT scan will have a small chance of killing the person (1 in 2000). If we assume that all cancers are fatal then we can make the next step.
If we multiply the chance of killing the person with 77.28 million pounds we get a number of £ 38640, which according to the current exchange rate (1.61 US$ per UK£) gives a sum of 62210.4 US$.
I think in this case that the RICO act can apply which allows triple damages to be awarded which brings the radiological aspect to $ 186631.2. Now I think that compared with the other aspects of the unreasonable search that this amount of money is a small amount. But the criminal law side of the event could (and should) get very nasty for the police.
While I think that members of the public who might be exposed as a result of radiological accidents should enjoy the protection of criminal law. But in the case of an accidental exposure the mens rea (guilty mind or intent) to deliberately perform an act which exposes another person to radiation is not present. While a person might be careless or lazy and thus expose the public to radiation, due to the lack of intent to expose others to radiation the person should be pubished more lightly than a person who chooses to expose others. It is similar to my mind to the distinction between murder and manslaughter.
In this case the mens rea falls short of the extreme level of depraved indifference to human life which would be needed in a professional radiation worker who chooses to spike a child’s breakfast with large amounts (mCi amounts of calcium-45) of radioactivity. Trust me experiments with radioactive breakfasts have been done but with about far less radioactivity (microCi range doses of calcium-45, one mCi = 1000 microCi).
I think that a suitable rod for these policemen’s backs could be radiation law. This is because the X-ray examination is clearly not in the best medical interests of the person, and as they have not freely agreed to undergo this exposure then the law should regard is as compelled radiation work.
Having a knowledge of radiation work I would say that if we declare the motorist to be an involuntary radiation worker then I suspect that a vast litany of violations of radiation law have occurred. For example no preexposure medical assessment has been made of the person’s fitness to be a radiation worker has occurred. I reason that both the police and the hospital should be considered as possible targets for prosecution.
I also think that if the medical staff of the hospital were aware that the person was being scanned against their will (no free consent) then they should be struck off from their professional bodies and thus no longer be allowed to practise their profession. This might seem harsh but I hold the view that a strong argument exists for using extreme punishments to discourage radiological assaults.
I would like to take the time to explain some of the basic ideas in corrosion to you, now corrosion is a funny thing where it is not wanted it is called corrosion and it is a destroyer of valuable objects much where it is wanted it is called leaching or dissolution and there it is the beneficial liberation of metals and other materials from solids.
One of the things which we need to be aware of is the problem of stress corrosion cracking, now this does not sound as exciting as “metal fatigue” but in many ways SCC is a bigger monster which can cause things to fail.
SCC has two main parts, firstly an object must be under tensile stress for it to occur and secondly a chemically corrosive environment must be present.
The mechanical stress can take many forms, it can be residual stresses in an object which are left behind after it is made or it can be an imposed stress. For example one of the most eye watering and shocking SCC cases was the failure of the stainless steel members holding up a false celling at a Swiss swimming pool (http://www.corrosion-doctors.org/Forms-SCC/swimming.htm). Here the weight of the concrete kept the rods loaded under tension. The corrosive fumes and spray from the swimming pool caused one member to corrode and finally snap. This then imposed a new larger load on other stainless steel members, the overloaded members snapped and a cascading failure then brought the celling falling down.
To my mind a bombardment of concrete from above is about as horrible as someone putting a sea monster in the kid’s pool !
Another mechanical stress can be a thermal stress, if a system is heated up (or cooled down) then the expansion of different parts can set up mechanical stresses in it. For instance in a long pipe line it is common to have a half loop to reduce the impact of the expansion and contraction, but in service it is possible for this half loop to have some parts which are under tension. If the object is under compression then SCC will not occur.
The core of SCC is that metals are ductile while corrosion films tend to be brittle. A crack appears in the corrosion film, this crack will locally raise the stress level and the crack will tend to grow. When the crack reaches the ductile metal it tends to stop, but it will have exposed a new metal surface. If this metal surface then undergoes corrosion and is converted into a brittle corrosion film then the crack will grow again. This process will go on and on until something fails.
It can either be regarded as a mechanically assisted corrosion or as a chemically assisted cracking process. I will get onto another type of corrosion another day soon.
It has come to my attention that TEPCO are planning to remove the fuel from the pond at unit 4 of the Fukushima reactor site. If you want to see more details then visit this site.
A great question will exist of how well will this fuel age with time, the chloride concentration in the ponds at Fukushima was higher than they should be. If you want to read about the corrosion of zircaloy under accident conditions then please see the paper by O. Lavigne et. al, Journal of Nuclear Materials, 2012, 426, pages 120-125. To cut a long story short the addition of chloride (3000 ppm) does increase the ease by which the surface of zircaloy undergoes corrosion.
But it is interesting that nitrate and hydrogen peroxide formed by the action of radiation on the water do inhibit the pitting corrosion caused by chloride on the zircaloy. If you want to read more then I would suggest you look at G. Bellanger, Journal of Materials Science, 2000, 35, 1759 to 1771. I hope some times soon on this blog to explain a few things about corrosion. But it is getting late in the evening and I need to go to bed soon !
In recent times the Russians have decided that the Greenpeace 30 are hooligans rather than pirates, now Greenpeace and their supporters are calling for the release of the Greenpeace 30 and are saying how harsh the Russians are. But we should bear in mind that the ship did enter a restricted area near an oil / gas platform without permission. Two Greenpeace protestors did climb onto the platform. I think that they were lucky not to have been shot doing that. I would never dream of trying to force my way into an industrial or nuclear site, I tend to find that presenting myself at the front gate and talking politely to the guards (on a day they are expecting me) works well for me.
Now it is clear to me that Greenpeace sincerely hold the view that they are doing something noble, they think that they are helping to save the world. But I would like us to think is a sincerely held belief (a wrong one) an excuse for anything. For example if I think that the postal worker driving up to my house is about to stick a bomb in my postbox and that I should use violence to prevent this act of terrorism. Am I being reasonable or would I just have an overactive imagination or be going paranoid ? I think that the latter would be true.
Now lets consider a group of people who have a very different view of the world to the typical person, these are people in psychotic states. But I want to make one thing very clear first. It is a little known fact that the majority of mentally ill people are harmless (including psychoics), if anything most of them are more of a threat to themselves (with their chaotic lifestyles and self harm) than they are a threat to random members of the public.
But sadly there are some who are a danger to others, one of the classic groups which are a danger to the general public are those psychotic people who are experiencing the “positive” symptoms of schizophrenia. Some times their delusions, disordered thoughts and hallucinations can make them sincerely believe that they are under attack from other people.
These people who they think are attacking them appear to be randomly selected, but I suspect that public figures tend to be the subject of more of these delusions than the average person.
A quick yahoo search using the terms “paranoid schizophrenic stabbed” reveals a great number of news paper articles such as this one from Reading, Erith, Bristol and Brimingham. Now I hope that I have not given any of you nightmares but if you read these four randomly chosen cases you will see that in general society tends to keep those who have carried out serious acts of violence while in psychotic states in secure hospitals (or prisons sometimes) until they are no longer thought to be a threat to the public.
While I feel sorry for people who have experienced the terror of persecutory delusions I understand that some of these people need to be isolated from society while others need to be kept away from some things.
For example should we allow a person who is prone to intense persecutory delusions to work as a gunsmith with free and easy access to firearms ? I think not, in the same way as a person who has a serious alcohol problem (drunk on a regular basis before lunch time) should not be allowed to work as an air traffic controller (until they have cleaned up their alcohol problem) the gunsmith with these delusions should not be allowed to work alone in a room with 1000 assault rifles until he/she has been shown to be cured or at least not be a threat to himself or others.
A less harmful behaviour which could come from a delusion that the toy shop staff are torturing a child which has metamorphosed into a barbapapa soft toy. A deluded person might then steal the barbapapas from the toy shop, while it is less harmful than a violent act I still think that the soft toys should be returned to the toy shop and the liberator of the barbapapas should not be viewed as a hero. While the person might have has a sincere belief that a justification existed for taking the soft toy I still think that while the person might be found “not guilty by reason of insanity” their stealing of the barbapapas is not a commendable act.
Now imagine that I sincerely believe that the people in the wool shop are sewing a dragon together with magic wool which will come to life and breathe fire and lay waste Sweden (major environmental damage) then I hope my readers will understand that the fact my misguided act (stealing all the wool) was an attempt to protect the environment does not make it a noble act.
Now while stealing the wool might irk the local knitters, a crime which endangers people is a more serious matter. I was told recently by a seaman that the Russian gas platform may have had divers working in the water at the time of the Greenpeace protest. We will never know if the Russians were being truthful about the divers in the water at the time or not (or if they were posting the standard warnings that divers were at work), but this adds a new dimension to the event.
Lets assume that Greenpeace have a sincere belief that the use of oil and gas is harmful to the environment, they then choose to have a protest where they drive motorboats close to a platform. Now if these motorboats endanger divers working in the water then I hold the view that a crime has been committed by Greenpeace. Both the people doing it and the organisation as a whole would be even more guilty if some ill came to the workers on the platform or in the sea.
Ben the seaman told me that he would never go within three quarters of a mile of a ship which has divers in the water for safety reasons, now we need to understand that while it is important that we look after the environment it is more important that we protect human life. I would argue that the death of a single gas platform worker is more serious that a very large oil spill which fouls many birds.
I would also say that endangering or harming an oil / gas field worker is a perfect way for Greenpeace (and the environmental movement in general) to upset people and harm the interests of the environment. It does not matter how noble their aims and views are, it does not matter how sincerely they think that they are doing the right thing if they are putting workers in danger then it is wrong.
One of the best justifications for improving the environment is to improve the health of people, by improving the environment many diseases can be reduced or eliminated. For example in Japan after world war two a series of horrible pollution related diseases occurred (cadmium poisoning, mercury poisoning and air pollution related ill health), by keeping the environment clean the rate of these diseases can be reduced.
But if while protesting against the factory spewing mercury into the river where the locals catch the fish they feed themselves on we were to drive a car in a reckless manner and run over some of the local children then however successful we are at cleaning up the environment we have failed as instead of giving the children a cleaner environment to enjoy and live in we have snuffed out their lives.
Rather than doing something to make the world a better place we would have done the reverse. I would also argue that killing a man working for a living is also making the world a worse place for him, his family, his country and his coworkers. I also want to point something out, some years ago the Greenpeace ship (Rainbow Warrior) was bombed, it is said that the bombers never intended to kill anyone but they managed to kill a member of the crew.
Even if you believe the bombers claim that they never wanted to kill anyone, I would still stay that the reckless disregard for human life exhibited when they bombed the ship makes them guilty of murder. Now I am sure that all Greenpeace staff and members will agree with my view of the bombers guilt, we should apply the same logic to a group of Greenpeace protestors who endanger workers. We should think for a moment about the scandal which would occur if the Greenpeace protestors killed a diver the same way that Kirsty MacColl died.
Now we should consider what should be done about Greenpeace, what is it reasonable for the Russians to do ? Should they charge only the Captain (and the senior members of the ship’s crew), should they charge the junior members of the crew, should they charge only the people who climbed onto the platform and should they charge Greenpeace as a corporate body ?
Years ago at the University of Sussex a serious accident occurred in the chemistry department, some details can be seen here. After this accident the university as a corporate body was dragged to court and then punished. Should the same happen to Greenpeace ? It could be argued that the people at the HQ had no idea of exactly what the people on the ship were going to do, but on the other hand it can be argued that they should have considered what the people on the ship might do. It can be argued that the boss of the ship (Captain) had a duty to make sure the people under him worked safely and obeyed the law, and that the people who the captain answered to had a duty to supervise the captain. It can be argued that they should have made a point of knowing what their subordinates were doing and also to supervise them.
As I am not an expert on Russian law I can not say what will or should happen, but I want to ask you what should the Russians do ?
Please note that the views and ideas expressed within this blog are my own personal views and are not necessarily shared by my employer (Chalmers University of Technology), anyone else or by any other organisation.
Also please note that some activities, experiments and materials mentioned in this blog require specialist training and/or special facilities to perform or use safely. If you are in any doubt as to your competence to try out anything mentioned in the blog then please seek expert advice before attempting to do something. While all reasonable care is taken in the writing of this blog, I accept no responsibility for any death, injury, burn marks on the floor, boredom, social harm, property damage, feeling of self disgust or any other harm / loss caused as a result of an act, substance or process discussed in this blog.