judging by just the few reports cited below, I would say that Lord Flasheart is a lot less ignorant than "stungun".....

In the company where I work, we use nuclear reactors to produce radiopharmaceuticals for hospitals around the world (including the US), which are far more radioactive than Pu-238. And of course we do it safely.

http://www.space.com/spacenews/businessmonday_050117.html

stungun wrote:

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Please don't confuse inhalation of pu-239 for weapons with pu-238. The pu-238 is 275 times more radioactive, and that much more tissue and genetic destruction occurs with pu-238 exposure.

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Thanks for reminding me that  Pu-238 is 275 times more radioactive than Pu-239 -- I didn't realise that I was confusing it with Pu-239.

It would have been nice if you had added why that is so :  because the radioactive half-life of Pu-238 is 275 times shorter than that of Pu-239 (24,400 years versus 86 years).

Well guess what -- the half-life of typical radiopharmaceuticals is about 36 million times shorter than Pu-239, making them that much more radioactive (there is a biological effectiveness factor that also enters into the calculation, due to the different kinds of radiation, but this is generally not more than a factor of ten).

Similarly for some of the naturally occurring radioactive materials (NORMs), like for example Polonium-210, which is 64,500 times more radioactive than Pu-239, and 227 times more radioactive than Pu-238 (and same kind of radiation too - alphas - in this case).

If you want to talk about the "Big Picture," consider the following.

Typically, the first top meter of a 15 by 25-metre house lot contains, on average, three kilograms of uranium and ten kilograms of thorium.  One of the elements borne from the decay of uranium is a gas called radon. Radon escapes continuously to the air from the surface of the earth. On average, every square meter of land releases about 10 thousand atoms of radon every second, that is, a source of 10,000 Becquerels. Radon, which is also radioactive, decays into a series of radioactive atoms, one of them being Polonium 210. Rain, fog, snow, and dust bring polonium 210 back to the ground, where it accumulates. Since the source of radon never stops, the quantity, and the activity (quantity) of polonium on the ground remains constant at about 10,000 Becquerels per square meter. The International Commission on Radiological Protection calculates that polonium-210 is five to ten times more harmful than plutonium 239, on a per-radioactive quantity basis (i.e. on top of the 64,500 factor for half-life applied on the per-unit-mass basis) . Therefore, in terms of theoretical risk of cancer due to radioactivity, 10,000 Becquerels of polonium 210 are equivalent 50,000 to 100,000 Becquerels of plutonium 239. If one converts the quantity of polonium 210 on the ground into a mass of plutonium that presents the same theoretical danger to health, there is the equivalent of 0.044 mg of plutonium per square meter of land. This does not look like much, but for the Province of Quebec alone – an area of 1.5 million square kilometers - this is equivalent to some 60 tons of plutonium 239 -- or 220 kg (480 pounds) of Pu-238. This is the normal natural radioactive "fallout" -- way more than a remote chance of a spacecraft like Cassini crashing its load of 70 pounds of Pu-239 somewhere into the deep ocean.

As regards Radon, a very good paper is "Test of the linear-no threshold theory" by Bernard L. Cohen, in the February 1995 issue of Heath Physics.posted at http://www.phyast.pitt.edu/~blc/LNT-1995.PDF (8.8 MB PDF)

http://lifestyle.scotsman.com/families/columnist_specific.cfm?articleid=2823&columnist=FC1

Kath Gourlay, The Scotsman Tuesday, 6th March 2001

Eric Voice shows not the slightest emotion as he describes himself as "the most radioactive man on the planet". He speaks as precisely as he dresses; the pronouncement is not meant to shock or scare. Said by someone else, it could perhaps be taken for some kind of joke.

But Voice is not the sort of man for lighthearted distractions. For over a decade the retired nuclear scientist has voluntarily taken part in human experiments on the effect of plutonium to prove his belief that it has no harmful effect whatsoever on his health.

He has willingly allowed his body to be filled with plutonium - often described as the most dangerous substance known to man - first by injection and then through direct inhalation. Going to such lengths publicly to re-affirm his faith in its safety may horrify some but Voice stands by his convictions, believing that what he does is for the good of mankind.

"This fuss about plutonium is largely media hype," he says. "The truth of the matter is that it’s a well-known chemical element and there is nothing sinister about it."

Voice, 75, is a wiry man with steely blue eyes. He looks years younger than his age. It is hard to believe that half a century ago, he was one of the founder members of the CND movement with Bertrand Russell . He says he realised from an early age that making protests from outside achieved very little and felt more influence could be brought to bear working from within the industry.

His convictions go back 56 years to when he heard the news that an atomic bomb had been dropped on Hiroshima. "I was so appalled. The most momentous discovery and what had man done? He’d used it for aggressive purposes and sealed its fate for generations. I swore that from then on I’d work towards utilising this wonderful source of energy for the benefit of mankind."

Voice spent 15 years in biochemical research and 28 years in the nuclear industry, many as a chemist at Dounreay. One of the first scientists on the Dounreay site, he worked out of a Nissen hut while the complex was constructed, and still lives in the coastal town of Thurso.

Two years ago, Voice caused a stir by stating: "People still do not understand plutonium and there is such a lot of nonsense talked about it.

"There is no evidence that any human on Earth has suffered in health from plutonium and I have no adverse effects."

He remains convinced that nuclear power is our only hope for the future in the fight against global warming. The lengths to which he has gone to justify these beliefs are extraordinary.

His neighbours are used to the regular visits of an armoured van to pick up his bodily waste, for example. "The practicalities can be a bit irksome but I’m used to it. When I arrive at people’s houses with a carrier bag of bottles, people assume I’ve brought them a gift," he smiles. "When I explain I can’t use their facilities their expressions are extremely comical." Quite. Which invites the next question. He’s not in his first flush of youth, so what will happen to his body when he dies? His reply - "It has all been responsibly taken care of" - politely prohibits further discussion.

So what does he hope to prove by doing the experiments? "It is the duty of those involved in the industry to ensure strict safety limits for workers worldwide," he says. "That was always one of my aims and I feel I’ve done something useful and practical towards that end."

Voice, who is married, is fiercely protective of his family and refuses to discuss his wife or her reaction to what he is doing. "I have dedicated my life to improving standards in the nuclear industry," he says, "and I have no intention of letting myself or my family be a subject of tabloid interest." A more measured, precise and emotionally continent individual would be hard to find. He presents calmly reasoned arguments for everything he does or believes in.

Voice is one of two volunteers who have recently taken the experiments a stage further. Several times a year, he would travel to Harwell. There, in a sealed room, he would breathe in plutonium through an inhaler-type device straight into his lungs. "We have learned a lot about what plutonium does in the bloodstream," he says. "The vital link being made now is how it gets into the bloodstream in the first place."

Voice inhaled a mixture of two isotopes, plutonium 244 and plutonium 239, the type found in nuclear reactors. They are both alpha-emitters, the most dangerous type of plutonium for causing biological damage. Voice says he is not afraid of causing fatal damage to his body. Even if he has, he says he will be dead before he feels the effects. "Plutonium 244 has an enormous half-life - something like 80 million years - so it’s a very slow emitter. I don’t think I need worry too much about what could happen in the rest of my lifetime." The results of the latest trials, which are still being analysed, will provide information on absorption levels in the lungs, and the speed at which plutonium travels to the gut.

What it’s doing in there is not something Eric Voice dwells on. He doesn’t have time. He is now acting as a consultant in a UK project on the use of what he describes as "safe reactors" (which are gas-cooled) for future production of electricity. He also gives lectures and acts a climate expert for the Highland Council.

"We’ve been given this amazing resource for the good of mankind, not for destruction," he says.

As he flies between venues, it is doubtful he will be able to resist informing fellow passengers of their close proximity to 20 kilos of depleted uranium. "Why don’t people think about why it’s referred to as ‘depleted’? Because they prefer to listen to media hype, that’s why." The radioactive element has been removed, he says. Less than 0.7 per cent remains - less than in naturally occurring uranium.

"It’s really useful because its mass-to-volume ratio means it provides weight without taking up space. It’s used for rudder balance in aircraft. It’s used in the keel of yachts too and nobody bats an eyelid."

stungun wrote

> The Cassini is cited in these articles. As I have already stated, the Cassini, deep in their own documents, risked contaminating 2/3's of the world with a pu-238 burnup if they missed the sling shot acceleration manuever.

Note that true to form, after going around the solar system a few times and moving almost faste than anything else man-made before, they hit within 4  miles of their mark over the south Pacific. Please don't bring in that tired discredited anti-nuke hysteria from the past. I never heard any response from any of the protestors about whether a launch accident or even missing the mark on the interplanetary trajectory could possibly cause the complete vaporization of all the Pu in the RTG (especially the irrational hysteria over a possible launch accident). It seems to be taken for granted that it's packaged in the space probes in the perfectly ideal way to make a "Dirty Bomb".

> So basically these rocket scientists are willing to risk most of the world's environment and developing children for their project. That is unacceptable to me and most of the people on earth, who's health you appear willing to gamble with. We have plenty of science we can do, and new energy breakthroughs can be achieved that do NOT risk this assinine gamble.

Yes, can't trust those "Rocket Scientists". Evil geniuses all, who never had any motherly love and grew up to be misanthropic recluses who sit in their labs dreaming up horrendous things to threaten the world's good and decent people with.

BTW, give it a rest.

> How much pu-238 do doctors recommend for pregnant women? The answer is zero because of the radiosensitivity in the womb.

How about something truly refreshing: some constructive criticism and useful ideas about specifically how things could be made safer and cleaner. I stand second to none in my distaste and revulsion for making every great discovery in human history into a weapon first. Nobody outspeaks me in my mistrust for the military/industrial complex and it's distortion of science and politics and society throughout history -for oil!-, but I refuse to accept that all such technology is inherently evil and without any redeeming features whatsoever. I recall the late Dr. Theodore Taylor as reported by George Dyson: "When we first open the pandora's box which is nuclear energy, all these horrible things immediately evident on the surface pop out, and we turn away and must say 'no, no, we cannot do these things.' But if we dig a little deeper, we find the really important content of the box, down near the bottom, which is hope."

 I'll debate at great length and in detail about the imperative as I see it to consider Nuclear Pulse rockets, even including good old-fashioned dirty inefficient Atom-Bomb powered "Bang-Bang" Orion.

 You mentioned DS 1 & Rosetta as examples of how we can go into deep space without nuclear power. Anything about how we can go out into deep space in a direction away from the Sun? Important distinction there. I don't doubt that we could innovate ways to use solar energy in space probes built and launched with today's boosters out past a couple of AU, but why never any recommendations of departments or projects that deserve a lot more money to R&D these things for use within the timeline of today's engineer's lifetimes. Always gripes about Nukes, mentions of a few 1 AU or so probes, and urgings to cut the space program either partially or in toto.

Please continue here and give us more reasonable arguments about our contention of the basic need for nuclear power in space. As Freeman Dyson said about Orion, there's just nothing in our human toolbox which is adequate to the true scale of the solar system.

   Hi there,

     I wanted to ask, just how serious is Plutonium to humans, and pregnant women in particular? My understanding was that it was an alpha emitter (as stated a couple of times), and that alpha emitters are locally dangerous to tissue, as alpha radiation is comprised of basically a stripped down hydrogen atom sans electron. But it does not effectively penetrate tissue very far.

     So if it were a health concern to pregnant women, it would presumably have to be small enough to move through the blood stream and into the placenta in order to be detrimental to a fetus. This would require a certain partial size to be (I hate to use the word in this case) "efficient" at moving from the lungs (as that would be the presumed point of entry) and into the bloodstream. Obviously, if it were too large, it would be unable to effectively move into the bloodstream and be either lodged in the lungs (a plutonium version of silicosis) or passed out with the help of a cough and a lot of mucus.

    I understand that Pu-238 is used in RTG's (the whole purpose in making the stuff in the first place) and that large quantities produce heat, so naturally production would have to be in small unit sizes. But I was wondering what size chunks are produced? is there a real risk of this stuff naturally producing "dust" sized particles, and what are the inherent risks in refining and transporting refined Pu-238? Is the risks that stungun is stating about the concern of HEPA filters valid in the respect that producing Pu-238 lends itself to a serious health concern? Are the physical characteristics of Pu-238 metal such that it would pose a hazard in it's physical properties as it relates to production and refinement? Are industry standards for Pu-238 geared to addressing the health concerns in it's manufacture?

   I think ultimately, if I were in Stunguns position (that is, if someone decided to open a Pu-238 factory in my backyard) I would be justifiably concerned. But I was struck by one observation made in one of the posts on this thread about Radon. While Radon could (and probably does) produce a significant portion of the ambient radiation in our environment. Living in New England (where Radon is a serious issue) most people would not associate Radon with radiation at all. So while people may be concerned or annoyed if there was radon buildup in there basement. They may have a far greater reaction to a discussion of a Plutonium factory that could pose a potential for exposure to radiation that they are already getting when they go to check the oil levels to there furnace.

Hi Roland and Googlenaut,

    The questions are good Roland. While radon is an alpha emitter, and considered the second leading cause of lung cancer, the main difference is that radon is a gas, and the pu-238 escapes in dust size, sub-micron particulate. Even the tiniest particles , when inhaled, provide on ongoing point of perpetual radiation, because they have thousands of atoms, vs radon gas, which is one atom. The problem in radon houses is the trapping of the radon, providing multiple random alpha strikes.

     Internally, the pu-238 can be absorbed, and usually shows up in nearly all organs. It can even be mistaken for iron, and used for hemoglobin in blood cells.

   In the CDC historical dose at LANL, the pu showed up in elevated levels, in autopsies of citizens who never worked there. Opps, DOE likes to emphasize, that yes, you might exhale the pu-238 you inhale, or cough it out. Seems like plenty stuck around for an ongoing body burden...

    In the ongoing modern LANL pu-238 accidents, workers were exposed to greater than their 5,000 mrem annual limit. The legal public safety limit is 10 mrem, or about a chest x-ray's worth. But doctors in the ER don't give pregnant women x-rays, to protect the fetus, unless the mother's life is in danger.

   Googlenaut, you summized the HEPA issue well, but is there any documentation behind your conclusion that all is well, and the classic "some people will never be convinced" comment? I have consulted Dr Liu, as written, and have suggested the testing method to finally quantify how much pu-238 dust whispers through. DOE has refused to do these studies. I have shown the scant DOE documents proving the filters leak, so where is the science in your rebuking the concerns?

Hi Philipum,

You asked : are you against uses of plutonium for space applications, or are you for an improvement of the way it is managed?

    That's a fair question. I would say "Yes and yes!" 

     Specifically, I am pointing out the present, documented, flaws of pu-238 containment. I do this at official scoping hearings, calling for official acknowledgement of the problems, and scientific approaches to revealing how much pu-238 really escapes the filters.

    This has NOT been done by DOE. My impression is that it is presently physically impossible to contain the pu-238. So that would make me oppose pu-238 production, because "improvement of the way it is managed" is fruitless, if it is technically impossible. If the basics of containment are worked out, I am open to it's use, but I doubt that will happen.

    From reading the DOE worker accident reports, it seems that despite "triple safety measures", and plenty of brain power, the phrase "unforeseen circumstances" still keeps popping up in the next accident report.

    So knowing that, and having read the crash vulnerabilities of the final "contained" RTG, I presently oppose it for space exploration, and the "national security" applications. It is too large a risk, when we can do solar space exploration. We need to  work on cleaner energy forms, instead of going full speed down the present deadend road, wearing blinders...

Hi Jaro,

   You have articulated better than usual! It is nice you have a pro-nuke email discussion reference for your debate on a minor point of what I said. My reference would be the actual CDC study I referred to.  

     I noticed the guy downplayed the higher than background pu in autopsies of citizens who never worked there, and I didn't see your reference for how much plutonium you were recommending for pregnant women though

    If you  are wanting the exact CDC statement on excess pu in citizen autopsies around LANL. PLEASE see p 111 of 397 from this LANL CDC report from CDC website. Third paragraph...

The Los Alamos Historical Document Retrieval and Assessment (LAHDRA) Project is assembling pieces of Los Alamos National Laboratory's history to evaluate releases of materials that had the potential