Radioactive woodpellets from eastern Europe, new thread with the continued story...

[Stovensen]

[quote author="pdf27" date="1330865186"][quote author="Stovensen" date="1330831053"][quote author="pdf27" date="1330827235"]I'm a vacuum engineer working on a nuclear fusion reactor.[/quote]

pdf27, please read this:

https://www.hearth.com/talk/threads/38966/

Perhaps you have the knowledge to enlighten some worried minds over here.

The pellets I've burnt for the last four seasons are all made in eastern Europe. Right now I'm burning some pellets from Poland ( Barlinek). In fact these Barlinek pellets have the highest heat output and lowest ash I've experienced so far. But, if they contain even the smallest amount of Caesium 137, then I certainly WILL change to some of the pellets made here in DK ( more expensive, though ).[/quote]
The original article's long since expired, so I can't get any quantitative numbers to go on. A couple of things I can say though:

1) As isotopes go, it's relatively nasty - the salts are water-soluble and in the UK at least notification to the appropriate government agency is required for relatively small quantities (~3ng)
2) The actual concentration in Polish soil and in the pellets is likely to be massively below the legal limit*.
3) Any Caesium in the pellets (and I guarantee you that any pellets you buy WILL contain some Caesium, if in extremely low quantities) will be concentrated in the ash, with next to nothing going up the chimney.

Personally, I wouldn't worry about it at all - your ionising radiation dose rate from medical X-rays and cosmic rays when flying will dwarf any dose rate you get from a wood stove unless you're buying pellets made in Chernobyl. However, if you're worried there are two things you can do that will reduce your dose rate from incredibly insignificant to too small to measure:

1) Don't eat the ash
2) Don't spread the ash on any part of the garden you're growing things you intend to eat in.

In reality, Brazil Nuts are a far greater radiation risk than your wood pellets are likely to be (no joke - we've had a discussion at work recently where we decided that by the rules we work to if you've been eating Brazil Nuts and use a toilet, then technically you can't flush it without permission from Health Physics. We're thinking of waiting until the 1st of April to try explaining that one to them )


* The legal limit is almost certainly many times below the safe limit. Legal limits are set by taking cancer rates in those whose exposure rate is known - in reality almost exclusively atom bomb survivors - and assuming that cancer rates drop off linearly with dose. We're almost certain that this isn't true and that human beings can cope quite well with low radiation doses - witness the fact that cancer rates in areas with high natural radiation levels are much the same as those with low levels - but it's a sensible precaution. This suspected safe level is divided by ~10 to give dose rates for registered radiation workers (whose health is followed for the rest of their lives - when I signed up for my current job I had to let them have full access to my medical records for the rest of my life). The radiation worker dose rate is divided by 20 in the UK to arrive at the permitted dose rate to the public.[/quote]

pdf27, first of all thanks for taking the time to answer the questions above. However, in order not to disturb this fine thread: "What is/was your occupation?" :zip: , I've made this new thread :coolsmile:

Did a little home work on this topic today, but nuclear physics is an exact science, so new questions pop up all the time... it's like diving into a very deep ocean of information :ahhh:

Let us try to focus then: How do I measure/monitor the amount of Becquerels/g in the ash produced by my Whitfield stove? A professional high precision Geiger-Müller counter is way too expensive for me, but in my search it turned out that perhaps less can do...
I searched on the name of the unit of radioactivity: Becquerel, named after the french physicist Henri Becquerel. In 1903, Becquerel shared the Nobel Prize in Physics with Pierre and Marie Curie "in recognition of the extraordinary services he has rendered by his discovery of spontaneous radioactivity".

As often happens in science, radioactivity came close to being discovered NEARLY FOUR DECADES EARLIER when the french photographer Abel Niepce de Saint-Victor observed that uranium salts exposed to light emitted penetrating radiation able to darken photographic emulsions. Like Becquerel, Niepce de Saint-Victor believed he was observing a kind of phosphorescence, but unlike Becquerel he never gave up that belief, nor did he succeed in persuading other scientists that the effect was important enough to warrant thorough investigation.

Bottomline: It was the invention of photography that led to the discovery of radioactivity. Without this "photo eye" that could sense and record the rays from a hitherto mysterious hidden world, mankind would most likely never have entered the atom age as we know it today.

So, if radioactivity could be discovered by means of photography, then it also must be possible to monitor the radiation level of my pellet ash by a simple dosimeter made of some black and white negativestrips put in a small opaque plastic box.

On the developed negative, the alpha particles leave some traces that are clearly visible in a microscope. It should be possible to count them, thus getting a rather exact information of the radiation level. However, some sort of calibration, based on a known source of radiation, is needed. The faculty of physics on a nearby university may be helpful in this matter.

How to make a simple dosimeter:

(broken link removed to http://www.instructables.com/id/Quick-and-Dirty-Film-Badge-Dosimeter/)

Is the radiation from Caesium 137 only particle radiation, or is it also gamma radiation? and is the negative based dosimeter capable of sensing/recording gamma rays as well? I don't know.

BTW, interesting info about the brazil nuts. I've ate a lot of these through the years. Now I'm sceptic... I've just read that the radiation level of brazil nuts is about 1000 times higher than that of normal food :ahhh:

 

[pdf27]

Yeah, a film badge should be fine to monitor it - calibrating it is rather harder though.

Caesium-137 decays by Beta emission (it basically spits out an electron). That will go through maybe a centimetre of plastic before being absorbed, and a film badge will show that up nicely (I have to wear one at work all the time).
Caesium-137 upon decaying becomes Barium-137, which pretty much immediately spits out a Gamma ray and become stable. Gamma rays should also show up on a film badge, and while in nuclear applications they use various filters to separate out the Gamma from the Alpha and Beta doses, for your purposes that shouldn't matter.

Most radioactive foods such as Bananas have the radiation coming from Potassium. Since 0.0117% of all Potassium on earth is the radioactive isotope, and your body regulates the content quite well, consuming them has no effect on your total radiation dose though. A handful of foods (with Brazil nuts being the most extreme I'm aware of) concentrate other isotopes though. In the case of Brazil nuts it's Radium, however, which isn't an isotope you'll normally be exposed to so any dose will be additive. It also has a long biological half-life (20-30 years) as opposed to Caesium-137 at around 70 days. Radium is also an Alpha emitter, which is much more biologically dangerous than the Beta & Gamma of Caesium.

 

[Fsappo]

What the hell are all these big words about?

Do these pellets grow you a third arm or not?

 

[pdf27]

There are four types of radiation (if something is radioactive that means it gives off radiation):
- Alpha particles. There consist of two Protons and two Neutrons (which essentially makes it a Helium atom with the electrons stripped off. These can typically be stopped by something as simple as a single sheet of paper, so in most cases aren’t a problem, but if you get them inside you then being big and heavy they do a lot of damage. Think of them like an old black-powder musket – lots of damage at close range, but if you’re more than 50 yards away from the person with it you’re pretty much safe.
- Beta particles. These are just an electron, and normally need a bit more to stop them than an Alpha particle – ¼ to ½†of plastic would typically do it. Being massively lighter they do much less damage. Think of them like an air rifle – reasonable accuracy and range, but doesn’t do much when it hits something.
- Gamma rays. These are just another type of electromagnetic radiation like radio, light or X-ray, although they’re more powerful than most types and hence penetrate more/do more damage. Stopping them takes big thick lumps of lead or concrete. This goes both ways though – they’re quite likely to go straight through you without actually doing any damage. With the gun analogy, they’re something like a .22 rimfire.
- Neutrons. It’s rare to encounter these outside a nuclear reactor, but when you do they’re very bad news – in atomic terms they’re rather large and can be extremely powerful and penetrating. Stopping them is typically done with thick bits of concrete, water or plastic to slow them down, interspersed with Boron to absorb them. Think of them like a .30 calibre rifle – long range and do a lot of damage when they hit.

Radioactive atoms will randomly decay, and once they’ve decayed to another substance typically don’t emit any more radiation (although they will sometimes go through three or four substances before they become stable). This means that the amount of radiation they give off will go down over time. The way of measuring this is called the Half-Life, which is the amount of time it takes for half of the substance to decay into something else. Very short half lives (e.g. a few seconds) mean the substance is giving of a hell of a lot of radiation but isn’t a problem for long, while very long half lives mean it’s giving off virtually no radiation and will continue to do so for a long time, often millions of years. That’s one of the reasons I get upset when environmentalists talk about nuclear waste being dangerous for “millions of yearsâ€. They’re taking the half-life of some of the less radioactive substances like Uranium or Plutonium, and assuming it’ll be dangerous for all that time. The reality is if something has a half-life that long it’ll be a minor nuisance for a long time, while the really radioactive stuff has a short half life and is a major headache for a few hundred years.

The biological half-life takes much the same concept, and extends it to the human body. The body is usually pretty good about flushing things out that aren’t supposed to be there. Tritium (radioactive hydrogen), which is a substance I work with, is a good example. It has a nasty habit of swapping places with stable hydrogen in water molecules, at which point it gets into the human body quite easily (e.g. when working with it we have to wear two pairs of gloves and change the outer pair every few minutes to stop it being absorbed through the skin). Tritium has a half life of about 13 years, so is actually quite radioactive – it’s used for things like the more expensive glow-in-the-dark watches – although fortunately as a Beta emitter it doesn’t do much damage. Since the body replaces it’s water content quite regularly, getting rid of it through urine, the biological half life (i.e. the time it takes for your body to flush out half of the dose) is only a week or two. Beer is in fact the standard treatment for excessive Tritium exposure – it accelerates the rate at which your body expels water, while providing replacement uncontaminated water.

Elements (the purest form of a chemical, such as pure Oxygen, Iron, Silicon, etc.) don’t have all their atoms weighing exactly the same. Instead, they will have varying numbers of neutrons in the nucleus (the bit in the centre of an atom where the Protons and Neutrons live), and hence different atomic weights. These different nucleus weights are known as isotopes. Most are stable, but a few are radioactive. The best known use of these is Radiocarbon dating, AKA carbon dating. This uses the fact that Carbon-14 (i.e. a form of carbon with 14 Protons and Neutrons in the nucleus) is formed when air in the upper atmosphere is formed by cosmic rays. While living, everything absorbs this radioactive Carbon at the same ratio to normal Carbon that you will find in the atmosphere. When you die, you stop absorbing this and it will gradually decay away. Measuring the ratio of Carbon-14 to normal Carbon will enable you to work out how long ago something died – the higher the fraction of Carbon-14, the more recently.

 

[DV]

I've always been intrigued by radiation. Its very interesting.

 

[stoveguy2esw]

" Beer is in fact the standard treatment for excessive Tritium exposure – it accelerates the rate at which your body expels water, while providing replacement uncontaminated water."

rubbing my watch face up and down my arm vigorously as i contimnue reading ;-P

 

[woodchip]

I'll add a little here to anyone who thinks they may have been exposed to any radiation, be it from cheap East European wood pellets, or even x rays at the dentist.

A type of soup made from brown seaweed and soy called miso (it's Japanese), is very good at flushing out heavy metals and radiation from the body. This was discovered after the bombs fell in 1945, and some survivors did not get radiation poisoning, and a study was done to find out why. It was found that several people who did survive were miso drinkers, and this information was passed on to the people at Chernoble after the accident there some time later. To me, this sounded like some quack remedy until I met someone who had radiation treatment for cancer, drank miso regularly, and they did not get the usual radiation side effects of bad sickness etc.

Sorry if that strayed a little of topic there, but it's a useful snip of knowledge that might come in handy......

 

[pdf27]

Mine has it in ( http://www.traserusa.com/html/h3_technology__tpl-h3_technology.html ), but it's pretty rare and expensive for what it does. I only got one because I was away with the army a lot at the time and it made life significantly easier to be able to read my watch in any light without worrying about being seen.

 

[pdf27]

I'll add a little here to anyone who thinks they may have been exposed to any radiation, be it from cheap East European wood pellets, or even x rays at the dentist.

A type of soup made from brown seaweed and soy called miso (it's Japanese), is very good at flushing out heavy metals and radiation from the body. This was discovered after the bombs fell in 1945, and some survivors did not get radiation poisoning, and a study was done to find out why. It was found that several people who did survive were miso drinkers, and this information was passed on to the people at Chernoble after the accident there some time later. To me, this sounded like some quack remedy until I met someone who had radiation treatment for cancer, drank miso regularly, and they did not get the usual radiation side effects of bad sickness etc.

Sorry if that strayed a little of topic there, but it's a useful snip of knowledge that might come in handy......

I can think of at least one reason it's almost certainly true, and that's Iodine-131. It's roughly 3% of the fission products from a nuclear bomb or reactor, has a short half-life and is preferentially absorbed by the thyroid gland. Taking stable iodine (whether as miso soup or as Potassium Iodide tablets) saturates the Thyroid gland so it can't take up any additional Iodine from the environment, and hence the Iodine-131 causes minimal damage. It's pretty standard practice to hand out Potassium Iodide tablets whenever there's a major reactor accident (IIRC in the UK they're held at police stations near to reactors).
So far as other side effects or other types of exposure go, I'm pretty sceptical. It will have some effect (it's comfort food to some extent so will have a psychological impact, and it's also easy to eat when you're feeling awful plus relatively nutritious), but most other vegetable-based soups will have pretty much the same effect, less the Iodine.

 

[nate379]

Huh, I didn't know Tritium was radioactive. The gun I carry has that for the sights.

 

[PA_Clinker]