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Post by Barry Brook on Nov 1, 2013 17:23:30 GMT 9.5
During November 2013, a 3-part series on nuclear waste will be progressively published on BNC, authored by Geoff Russell. Part 1: bravenewclimate.com/stayin-alive-gene-pool-p1Part 2: bravenewclimate.com/stayin-alive-gene-pool-p2Part 3: bravenewclimate.com/stayin-alive-gene-pool-p3In this comprehensive and fascinating review, you will be taught to distinguish science fact from science fiction on the many vexed issues surrounding radiation, including cancer risks, genetic and physical mutations, and the biological legacy of exposure to acute or chronic ionising radiation. Read on (and tell us what you think). You may well be surprised with what you discover. This BNC Discussion Forum thread is for the comments related to all 3 of the posts in this series.
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Post by Colin Megson on Nov 1, 2013 21:34:06 GMT 9.5
I'm hoping the series will get us bang up to date with the latest in genetics and the effects of radiation. I'm also hoping to pick out the most pertinent facts to present as memorable sound-bites, for man-in-the-street consumption on my blog, on the premiss that they might be regurgitated down the pub. See: prismsuk.blogspot.co.uk/2013/06/radiophobia-and-health-effects-straight.html
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retired nuclear tour guide
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Post by retired nuclear tour guide on Nov 1, 2013 23:48:52 GMT 9.5
Great stuff! It's what we have been saying years ago on tours at Chalk River Laboratories - it all comes down to our extremely efficient DNA repair systems. Now I make pottery and recently had an exhibit on cups - "Cups for the 45%" - the percentage of people worldwide that support nuclear energy. They are in the shape of nuclear cooling towers with various slogans on them like "100% carbon free", "split don't emit", "safer than sex", etc. Now I can add "safer than jogging" to my repertoire! Looking forward to the next installment. If anyone is interested in pictures of the cups - below is the link to my Flickr account - www.flickr.com/photos/18590247@N03/
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Post by lightco2 on Nov 2, 2013 1:36:23 GMT 9.5
Right on Colin! Sound bites are what's needed to convince people -FAST- before eyes glaze over. Been trying to sort out these terms for a bit now (EEEEEEk!). Can they be related to some ordinary term, say, HZ? How?
When we can describe when ionizing radiation occurs in 140 characters, or at least with a catchy pop lyric, this public confusion will be licked. KISS,KISS,KISS
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Post by David McLane on Nov 2, 2013 3:45:03 GMT 9.5
I don't think the Tweeters need to be addressed. I think we should be focused on the U.K. to make sure the GE/Hitachi IFR project is accepted.
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Post by Dave Rossin on Nov 2, 2013 6:32:07 GMT 9.5
Very well written. This certainly should help interested people understand radiation better. It is to be respected but not feared, and fear should not be a basis for regulations.
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Post by Ed Leaver on Nov 2, 2013 8:47:51 GMT 9.5
Good article Geoff, but perhaps of utility somewhat more limited than it might. There are several points about which I think you might be more clear, or at least to which citations might be provided. The first is direct radiation injuries and deaths from the Hiroshima bomb. Your reference of about 0.2 Gy at 2.5km from hypocenter does not agree with other sources, Radiation Exposure Examples estimates 4 Gy at 1 km or 0.64 Gy at 2.5 km (intensity falls as square of distance). Although note-taking was forbidden for reasons of national security (natch), some members of the Medical Section of the Manhattan Engineer District did eventually describe their observations of what we now term Acute Radiation Syndrome (ARS), which would imply they saw victims exposed to something higher than even 0.64 Gy (more like 2 to 5 Gy, and thus probably closer to 1 km): see Hiroshima and Nagasaki Death Toll as just one example. In addition, to the some 70,000–80,000 people, or some 30% of the population of Hiroshima, that were killed by the blast and resultant firestorm (and another 70,000 injured), some 1,900 fatal cancers have since been attributed to exposures at those two "events": see Atomic bombings of Hiroshima and Nagasaki. I'm not completely certain your seemingly --though no doubt unintentionally-- superficial mention of atomic bombings is in complete accord with your earlier citation of Joe Romm's admonition about The difficulty of debunking a myth. Either way, I somehow doubt unintended minimization of the tragedies there and at Nagasaki will win much support in today's Japan, where it remains most needed. Your subsequent assertion "There are some slam-dunk winning reasons to avoid nuclear war but concerns about radiation aren’t among them" might raise the odd eyebrow as well. You might at least be asked to address concerns raised in Above-Ground Nuclear Blasts, and references therein. I realise these involve a lot of hard work, and as with all your articles, I do look forward to the remainder of this series. Sincerely, Ed
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Post by Leslie Corrice on Nov 2, 2013 9:05:40 GMT 9.5
Excellent job. It seems you suffer the same naïve, albeit well-meaning criticisms as I. We face a powerful "it MUST be dangerous" paradigm relative to radiation exposure. It is our cross to bear, at this point in history. But, 35 years of not giving up has shown me one thing...persistence in promoting the truth cannot be defeated.
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Post by geoffrussell on Nov 2, 2013 22:13:44 GMT 9.5
Good article Geoff, but perhaps of utility somewhat more limited than it might. There are several points about which I think you might be more clear, or at least to which citations might be provided. The first is direct radiation injuries and deaths from the Hiroshima bomb. Your reference of about 0.2 Gy at 2.5km from hypocenter does not agree with other sources, Radiation Exposure Examples estimates 4 Gy at 1 km or 0.64 Gy at 2.5 km (intensity falls as square of distance). [snip] Your subsequent assertion "There are some slam-dunk winning reasons to avoid nuclear war but concerns about radiation aren’t among them" might raise the odd eyebrow as well. You might at least be asked to address concerns raised in Above-Ground Nuclear Blasts, and references therein. I realise these involve a lot of hard work, and as with all your articles, I do look forward to the remainder of this series. Sincerely, Ed Hi Ed. The 0.2 Gray figure comes from RERF www.rerf.jp/radefx/late_e/cancrisk.html As for the "slam dunk" line. Compared to the non-radiation impacts of an atomic bomb, the radiation impacts are small. By which I mean the number and degree of injuries. There'll be more on that later in the series. I cycle and worry quite a bit about being hit by a car or truck. I could also worry about the extra pollution I'm breathing in, but that seems a relatively minor matter. We have a limited capacity for worry and should focus on the big risks. Over a million children will die this year because of diarrhea ... that's what I call a BIG problem.
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Post by Ed Leaver on Nov 3, 2013 2:28:15 GMT 9.5
Good article Geoff, but perhaps of utility somewhat more limited than it might. There are several points about which I think you might be more clear, or at least to which citations might be provided. The first is direct radiation injuries and deaths from the Hiroshima bomb. Your reference of about 0.2 Gy at 2.5km from hypocenter does not agree with other sources, Radiation Exposure Examples estimates 4 Gy at 1 km or 0.64 Gy at 2.5 km (intensity falls as square of distance). [snip] Your subsequent assertion "There are some slam-dunk winning reasons to avoid nuclear war but concerns about radiation aren’t among them" might raise the odd eyebrow as well. You might at least be asked to address concerns raised in Above-Ground Nuclear Blasts, and references therein. I realise these involve a lot of hard work, and as with all your articles, I do look forward to the remainder of this series. Sincerely, Ed Hi Ed. The 0.2 Gray figure comes from RERF www.rerf.jp/radefx/late_e/cancrisk.html As for the "slam dunk" line. Compared to the non-radiation impacts of an atomic bomb, the radiation impacts are small. By which I mean the number and degree of injuries. There'll be more on that later in the series. I cycle and worry quite a bit about being hit by a car or truck. I could also worry about the extra pollution I'm breathing in, but that seems a relatively minor matter. We have a limited capacity for worry and should focus on the big risks. Over a million children will die this year because of diarrhea ... that's what I call a BIG problem. Hi Geoff. I happen to agree. But in fact I did see your RERF reference in your helpful Technical Appendix and was curious as to that particular choice, as the article is relatively recent and its authors explicitly contend their results support the Linear Non-Threshold hypothesis and include a possibly ambiguous table of values and figure as evidence. You, on the other hand, as a central thesis of your present article contend LNT remains at best unproven, and is in fact in all likelihood quite wrong. And again I happen to agree. Nonetheless, LNT is embraced as revealed truth by the no-nukes community. Presumably, you (and I) wish to demonstrate to them that it is nothing of the sort. But citing what gives the appearance of being a recent medical article that says otherwise does not lend obvious support to your case. Particularly when all you were after was a non-critical exposure value readily obtained elsewhere.
It is what it is. But one thing "Solid cancer risks among atomic-bomb survivors" is not, is dated. Nor are authors listed. Which makes it cumbersome to even cite in a fashion that ensures your readers actually know to what you are referring. You might as well say "In a recent (but undated) article "Solid cancer risks among atomic-bomb survivors" researchers at the Radiation Effects Research Foundation have suggested the direct radiation dose received by any survivors 2.5 km distant from the Hiroshima hypocenter was about 0.2 Gy. We accept this estimate for the purpose of present discussion. However, we do not accept those authors' assertion "The dose-response relationship appears to be linear, without any apparent threshold below which (malignancy) effects may not occur" as necessarily correct, and suggest those appearances may be deceiving. In fact, as we shall demonstrate in subsequent sections of the present series, they most likely are."
You might then (later, in next week's exciting episode) continue with something along the lines "For example, in a more recent article Feinendegen et al. conclude
(Ref: Ludwig E. Feinendegen, Myron Pollycove, and Ronald D. Neumann Hormesis by Low Dose Radiation Effects: Low-Dose Cancer Risk Modeling Must Recognize Up-Regulation of Protection Therapeutic Nuclear Medicine Springer 2012 ISBN 978-3-540-36718-5). Closer to home might be RERF’s Views on Residual Radiation, which also apparently does not support increased cancer risk beneath cumulative ~100 mSv (nor do the authors reject the possibility).
Or something. It does get cumbersome. And controversial.
Ed, thanking David Benson for the aforementioned "Low Dose Radiation Effects" link.
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Post by geoffrussell on Nov 3, 2013 7:40:18 GMT 9.5
Ed, I'm trying to avoid the hormesis debate in these articles. The doses to a-bomb victims will have an average, regardless of the distribution. I picked the RERF number of 200 mSv because they are a respected authority and it's also the number that Robert Gale picks in his recent book on Radiation. He's an expert's expert, I'm not. But this isn't a number that is amenable to exact measurement, nor does its precise value matter for the purposes of making good decisions. In my view, whether LNT is true or false won't effect the outcome of rational decision making on nuclear power. We desperately need a massive nuclear roll out and that conclusion wouldn't be altered by LNT being true. That said, I changed my view on LNT after reading Wade Alison's book in which he argues that modern radiotherapy treatment schedules are predicated on LNT being false. If it were true, you'd just have one treatment, there'd be no reason for a spaced out series of doses. But perhaps I'm wrong, perhaps the key to changing public perception will be to get LNT officially dumped. If that's true, it will be experts who make this happen, not me.
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Post by Mike in Brisbane on Nov 3, 2013 10:10:48 GMT 9.5
Geoff is correct : no evident genetic effects on offspring except a predisposition to higher cancer incidence
Radiat Prot Dosimetry. 2012 Oct;151(4):671-3. Epub 2012 Aug 19.
Long-term epidemiological studies of atomic bomb survivors in Hiroshima and Nagasaki: study populations, dosimetry and summary of health effects.
Okubo T.
Source
Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan.
Abstract
The Radiation Effects Research Foundation succeeded 28 years' worth of activities of the Atomic Bomb Casualty Commission on long-term epidemiological studies in Hiroshima and Nagasaki. It has three major cohorts of atomic bomb survivors, i.e. the Life Span Study (LSS) of 120,000 people, the In Utero Cohort of 3600 and the Second Generation Study (F(1)) of 77,000. The LSS and F(1) studies include a periodic health examination for each sub-cohort, i.e. the Adult Health Study and the F(1) Clinical Study, respectively. An extensive individual dose estimation was conducted and the system was published as the Dosimetry System established in 2002 (DS02). As results of these studies, increases of cancers in relation to dose were clearly shown. Increases of other mortality causes were also observed, including heart and respiratory diseases. There has been no evidence of genetic effects in the survivors' children, including cancer and other multi-factorial diseases. The increase in the expected mortality number in the next 10 y would allow the analyses of further details of the observed effects related to atomic bomb exposures.
J Radiat Res. 2006;47 Suppl B:B67-73.
Genetic effects of radiation in atomic-bomb survivors and their children: past, present and future.
Nakamura N.
Source
Department of Genetics, Radiation Effects Research Foundation, Hiroshima, Japan. Nori_Nakamura@rerf.or.jp
Abstract
Genetic studies in the offspring of atomic bomb survivors have been conducted since 1948 at the Atomic Bomb Casualty Commission and its successor, the Radiation Effects Research Foundation, in Hiroshima and Nagasaki. Past studies include analysis of birth defects (untoward pregnancy outcome; namely, malformation, stillbirth, and perinatal death), chromosome aberrations, alterations of plasma and erythrocyte proteins as well as epidemiologic study on mortality (any cause) and cancer incidence (the latter study is still ongoing). There is, thus far, no indication of genetic effects in the offspring of survivors. Recently, the development of molecular biological techniques and human genome sequence databases made it possible to analyze DNA from parents and their offspring (trio-analysis). In addition, a clinical program is underway to establish the frequency of adult-onset multi-factorial diseases (diabetes mellitus, high blood pressure, and cardiovascular disease etc) in the offspring. The complementary kinds of data that will emerge from this three-pronged approach (clinical, epidemiologic, and molecular aspects) promise to shed light on health effects in the offspring of radiation-exposed people.
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Post by jimbaerg on Nov 4, 2013 4:12:49 GMT 9.5
"Remember back to the cold war when various Governments were exploding large atomic bombs in the atmosphere? Some of these where thousands of times bigger than the Hiroshima bomb of World War II. And by how much did they raise background radiation levels? Not even once, let alone the 200,000 times you’d need to double our DSBs. They raised global radiation levels by less than 1/4 of one percent."
I had always thought there was some justification for opposing the atmospheric bomb tests while accepting the underground ones, but according to the post that isn't so.
So maybe once we've built enough nuclear power plants to provide all the energy we need, we can build <a href="http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)">Orion</a> or <a href="http://en.wikipedia.org/wiki/Nuclear_salt-water_rocket">the NSWR</a> to go into space & get all the platinum group elements we could want. If we launch those from the middle of the Pacific the radiation will be diluted to harmlessness before it gets to anyone.
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Post by Soylent on Nov 4, 2013 8:08:17 GMT 9.5
Your reference of about 0.2 Gy at 2.5km from hypocenter does not agree with other sources, Radiation Exposure Examples estimates 4 Gy at 1 km or 0.64 Gy at 2.5 km (intensity falls as square of distance). No, intensity does not fall of as the square of distance. An air column a little longer than 2.5 km air column is something like 3 tonnes per square meter of shielding, or about the same as putting a 1 meter thick granite wall between you and the radiation source, in excess of what you'd expect from inverse square law. That's not quite true either, though, because a nuclear bomb is not a point source at a fixed distance. Fast neutrons react with air by inelastic scattering(which emits secondary gammas) and react with nitrogen, which relaxes by emitting a gamma. And furthermore very short-lived isotopes in the rising fire ball emit gammas. These have the effect of limiting the effectiveness of shielding by air. With the DS86 model you get <10 mGy at 2.5 km distance. But that's not even what Barry said; he said the AVERAGE dose from people LESS than 2.5 km from the hypocenter was 200 mSv(for gammas 1 Gy = 1 Sv).
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Post by Soylent on Nov 4, 2013 8:33:44 GMT 9.5
Good article Geoff, but perhaps of utility somewhat more limited than it might. There are several points about which I think you might be more clear, or at least to which citations might be provided. The first is direct radiation injuries and deaths from the Hiroshima bomb. Your reference of about 0.2 Gy at 2.5km from hypocenter does not agree with other sources, Radiation Exposure Examples estimates 4 Gy at 1 km or 0.64 Gy at 2.5 km (intensity falls as square of distance). [snip] Your subsequent assertion "There are some slam-dunk winning reasons to avoid nuclear war but concerns about radiation aren’t among them" might raise the odd eyebrow as well. You might at least be asked to address concerns raised in Above-Ground Nuclear Blasts, and references therein. I realise these involve a lot of hard work, and as with all your articles, I do look forward to the remainder of this series. Sincerely, Ed Hi Ed. The 0.2 Gray figure comes from RERF www.rerf.jp/radefx/late_e/cancrisk.html As for the "slam dunk" line. Compared to the non-radiation impacts of an atomic bomb, the radiation impacts are small. By which I mean the number and degree of injuries. There'll be more on that later in the series. I cycle and worry quite a bit about being hit by a car or truck. I could also worry about the extra pollution I'm breathing in, but that seems a relatively minor matter. We have a limited capacity for worry and should focus on the big risks. Over a million children will die this year because of diarrhea ... that's what I call a BIG problem. This is true EVEN for ground bursts(which is the only way you are destroying a missile silo), which generate a lot of early fallout. These silos are located out in the middle of nowhere precisely for this reason. The thumb rule for nuclear fallout is that for every factor 7 increase in time since detonation, the activity drops by a factor of 10(note, this is not exponential, since it's a mix of isotopes with different half-lives). If you live just downwind of a ground-level blast, the radiation dose can peak in excess of 1000 R/hr at 1 hour; which is quite lethal and requires sheltering. Fallout is not a goo, or a gas. It's more like radioactive sand. Since it's a gamma emitter, radiation dose does not primarily come from a few specks of fallout that get on your clothes, it comes from a wide area. Normally a shielding factor of 5 or 10 is trivial to achieve by just choosing the right spot. E.g. cellar in the corner. And you can easily double that shielding factor by rearranging furniture and piling junk ontop(e.g. sturdy table with buckets of water, books etc. ontop, sofa on one side etc.). After 7 hours, it's down to 100 R/hr; you can go out on short errands, but still requires sheltering almost the entire day. After 2 days, 10 R/hr, you can stay out for a few hours each day. After 2 weeks 1 R/hr, which is approximately what's tolerable on an indefinite basis.
I've seen estimates from civil defence buffs that radiation sickness from early fallout would account for about 10% of the deaths; essentially all of that would be from ground bursts.
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Post by jimbaerg on Nov 4, 2013 11:43:21 GMT 9.5
Soylent: Can you direct me to some information on how much worse a ground burst is than an air burst for creating nuclear fallout?
A bit of quick googling didn't give me numbers on that. Judging by the hard to detect effects of the atmospheric nuclear tests of the cold war, ground bursts would have to create several orders of magnitude more radioactivity than airbursts for the fallout from a nuclear war to matter, especially compared to all the other disastrous effects of many nuclear explosions.
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Post by geoffrussell on Nov 4, 2013 19:16:41 GMT 9.5
Geoff is correct : no evident genetic effects on offspring except a predisposition to higher cancer incidence [snip ...] Mike, did you read what you wrote? The study abstract you pasted finds no genetic problems in offspring. It doesn't talk about their predisposition to cancer and certainly doesn't say they had a higher predisposition to cancer ... because they don't.
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Post by stevek9 on Nov 6, 2013 1:51:25 GMT 9.5
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Post by Barry Brook on Nov 7, 2013 16:31:45 GMT 9.5
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Post by edireland on Nov 8, 2013 1:34:40 GMT 9.5
Because I like to write science fiction as a hobby, I have done quite a lot of research on the source of gamma radiation from low yield nuclear explosions, in the hopes of determining a way to reduce the minimum range such weapons can be employed at on the battlefield to avoid friendly casualties.
Almost all of the gamma flux from the weapon is produced by secondary decays, since essentially all the primary gamma flux is absorbed by the bomb materials before it disintegrates. This being decays of fission products and nitrogen isotopes entrained in the blast cloud as it rises into the sky.
It is actually possible, against a large device detonation, to avoid a large fraction of the total gamma dose by taking cover immediately upon observing the flash, since it is primarily produced in such detonations by the fission product decay in the blast cloud.
Additionally you have to account for the attenuation of the atmosphere by the blast wave in these calculations as virtually all the gamma flux is released after the detonation has already occurred.
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Post by Roger Clifton on Nov 8, 2013 16:05:30 GMT 9.5
I think it may be too late to dodge on seeing the flash.
Fission creates two excited nuclei, with an energy preference to promptly emit gammas and neutrons. Often, a (slower) beta decay will create a daughter, similarly excited and neutron rich. However the delayed gammas would see(*) the same number of scatterers, solid or vaporised, as the prompt gammas.
The initial fireball would start off with x-ray temperatures, cooling rapidly as the x-rays escape only to absorb in nearby air, expanding the fireball and cooling it to ultraviolet temperatures. Air is transparent to ultraviolet, so UV would escape to dominate the flash at ground level, until the fireball cools below ultraviolet temperature sometime within the first second. In turn, visible light would fade, while infrared continues to radiate as the fireball reddens, drying combustibles to tinder. However the radiation injuries, mostly due to ultraviolet, would already have happened.
IMHO, our preoccupation with the minority of gamma injuries has more to do with its exotic nature than its contribution to the casualty list.
(*)PS: I was wrong there. In fact, the delayed gammas would see an increasing amount of "sky" (for escape) between the scatterers as they shrank into the distance. So Ed Ireland's idea that the dose from delayed gammas could be more than from prompt gammas, still stands.
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Post by Barry Brook on Nov 8, 2013 17:52:52 GMT 9.5
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Post by edireland on Nov 9, 2013 5:31:49 GMT 9.5
I think it may be too late to dodge on seeing the flash. Fission creates two excited nuclei, with an energy preference to promptly emit gammas and neutrons. Often, a (slower) beta decay will create a daughter, similarly excited and neutron rich. However the delayed gammas would see the same number of scatterers, solid or vaporised, as the prompt gammas. Only a very small fraction of the 'initial' gamma radiation is actually 'prompt' however. 'initial' is defined, at least in American Circles, to be the gamma flux from the instant of detonation to one minute post detonation. This is defined on the basis that the mushroom cloud will have carried the remaining highly active materials to a height sufficient to eliminate the remaining dose to people on the ground at that time. (Excluding some very low yield devices). The delayed gammas are relesaed primarily after the weapon has expanded into a cloud of tenuous plasma or gas, which means that unit mass that a gamma ray has to pass through on its way "out" of the burst cloud has been drastically reduced, drastically reducing the number of gamma rays absorbed. It is the same principle that you see in a "shadow shield" type device on nuclear powered spacecraft proposals. This is why, apparently, very few of the 'prompt' gammas escape the weapon since the weapon is still a very compact ball of material at that time. This is why proposals to wrap a thicker lead tamper around low yield tactical device fissile pits to reduce the gamma flux failed. Otherwise you could potentially use low yield nuclear weapons in 'danger close' situations which would have had a massive effect on Cold War strategy for the employment of battlefield nuclear weapons. The initial fireball would start off with x-ray temperatures, cooling rapidly as the x-rays escape only to absorb in nearby air, expanding the fireball. Air is transparent to ultraviolet, so UV would escape to dominate the flash until the fireball cools below ultraviolet temperature within the first second. Infrared would continue to radiate as the fireball reddens, drying combustibles to tinder. However the radiation injuries, mostly due to ultraviolet, would already have happened. IMHO, our preoccupation with minority of gamma injuries has more to do with its exotic nature than its contribution to the casualty list. This is the thing, its a misconception that the majority of the 'initial' radiation is produced by the detonation, even looking at the mushroom cloud that is forming in the seconds after detonation can give you a massive gamma-ray dose if you are too close to the hypocentre. This is because the cloud is full of incredibly short lived isotopes including massive amounts of 15N and the various fission product produced by the detonation. Additionally the problem with gamma-ray flux on the battlefield is that it is very difficult to take cover against. UV can be defeated by a foxhole or even a soldier's fatigues, provided you are not so close to the burst that you catch fire from the massive heat flux. You can be in a dugout protected by 24 inches of concrete and protected completely from the thermal effects of the burst but still suffer a fatal dose from the gamma flux.
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Post by Roger Clifton on Nov 10, 2013 17:18:19 GMT 9.5
It is an appealing idea that public announcements be made in units of "average background levels". The word "average" then reassures people who are liable to panic before they think.
There is a risk that axe-grinders would insert the word "normal" instead of "average", so that any man-made increase could then be posed as an "abnormal radiation level" to the horror of good-hearted folk. However, if we are talking about man-made increases, then we might be better put to talk about natural increases than natural averages.
This way, it might be more distortion-proof for an increase in radiation to be measured in terms of "normal variation in background". A critical reader who tracks down its definition link would presumably be directed to a measure of the standard deviation of background levels. Such a page by the IAEA probably already exists.
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Post by Roger Clifton on Nov 10, 2013 17:41:50 GMT 9.5
Geoff demonstrated the use of images to distort representations of reality to those who are primed to believe. One such case sticks in my mind, having first seen it in the Peace Museum at the Hiroshima epicentre forty-odd years ago. You are probably aware of a popular concept that people were "vaporized" by the flash. As far as I know, the most frequently referred basis for vaporization is in the following photograph, Fig 4 in: www.blex.org/research/apparitions.htmlTo my eye, it is an image of a wall of wooden planks, lightened (dehydrated) by a flash of heat, except where the shadows of a ladder and a human had shielded it. The imprint of his head is narrow, suggesting a sudden injury suffered by a person who had only time to move his head slightly during the peak of the flash, presumably as he ducked for cover. First aid is and would have been to apply copious cold water to a skin burn, an example of which is shown in the same website's Fig 3. We are not told what he did next or how he fared. Instead, with all the deaf assertion of a religious chant, the caption on this website echoes the standard interpretation: "Fig. 4: A shadow was all that remained of this individual vaporized by the atomic blast." It remains politically incorrect to suggest that no-one was vaporized at Hiroshima, but even the believers have forgotten why.
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Post by Roger Clifton on Nov 11, 2013 19:25:40 GMT 9.5
You can be in a dugout protected by 24 inches of concrete and protected completely from the thermal effects of the burst but still suffer a fatal dose from the gamma flux. Considering that gamma ray flux is halved when passing through 100 kg/m2, a 24 inch shield of concrete would represent about 1000 kg/m2, and thus a protection factor of 2^10, or 1000 fold reduction in gamma dose. Heck, if I was so close to the blast that the outside of my bunker received a thousand times a lethal dose of gamma rays, I suspect that I would have been taken out by 24 inches of flying concrete wall long before the radiation damage had time to make me sick.
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retired nuclear tour guide
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Post by retired nuclear tour guide on Nov 12, 2013 12:31:23 GMT 9.5
In the interests of simplicity for the lay person, perhaps all the facts could be put into table form - with headings such as event/location, dose received, population size affected,"natural" cancer rate/number of "natural" cancers and then extra cancers seen or expected from the radiation dose. It would be important to include areas where there is high natural radiation level, high natural radon levels etc. as well as rate and dose from atomic workers. Such a table could be a great summary and very useful for those that do not have time or want to read all the details. It would also be a great thing to have on hand when we need to present our pro-nuclear case.
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Post by edireland on Nov 12, 2013 13:45:31 GMT 9.5
You can be in a dugout protected by 24 inches of concrete and protected completely from the thermal effects of the burst but still suffer a fatal dose from the gamma flux. Considering that gamma ray flux is halved when passing through 100 kg/m2, a 24 inch shield of concrete would represent about 1000 kg/m2, and thus a protection factor of 2^10, or 1000 fold reduction in gamma dose. Heck, if I was so close to the blast that the outside of my bunker received a thousand times a lethal dose of gamma rays, I suspect that I would have been taken out by being hit by 24 inches of concrete wall long before the radiation damage had time to make me sick. Numerous military documents I have seen suggest that the 'Tenth Value Thickness' for concrete against the spectrum of fission products from a nuclear explosion is on order of eleven inches. Against Nitrogen decay gammas it is something like 16 inches. A 24 inch thick concrete shelter would produce a factor of protection of roughly 158x against the first type of radiation and only 31x against the latter. Being roughly 500 metres from a one kiloton burst will produce an unprotected tissue dose of something like ten thousand rads, giving us a protected dose of between 63 and 322 rads depending on which type of radiation is dominant. At that distance from the burst the blast overpressure will only be 20-30psi, which while large enough to collapse any unhardened structure with ease or cause near complete casualties to unprotected personnel is certainly feasible to protect against in a bunker type structure. Indeed military facilities have been proposed with two orders of magnitude more blast resistance than that. A concrete blockhouse with 24" reinforced concrete walls is capable of resisting an overpressure approaching 100psi. Although 63-322 rads is not going to cause all the soldiers to keel over, the situation gets worse if the soldiers are closer to the detonation, additionally soldiers on the nuclear battlefield could easily be exposed to multiple detonations over the course only a few hours or days, causing the cumulative dose to rapidly become problematic. And apparently the LD50 is only 400 rads over a relatively short time.....
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Post by geoffrussell on Nov 12, 2013 13:58:49 GMT 9.5
In the interests of simplicity for the lay person, perhaps all the facts could be put into table form - with headings such as event/location, dose received, population size affected,"natural" cancer rate/number of "natural" cancers and then extra cancers seen or expected from the radiation dose. It would be important to include areas where there is high natural radiation level, high natural radon levels etc. as well as rate and dose from atomic workers. Such a table could be a great summary and very useful for those that do not have time or want to read all the details. It would also be a great thing to have on hand when we need to present our pro-nuclear case. The problem is that natural cancer causes are highly contentious. The World Cancer Research Fund is similar in nature to the IPCC in that it summarises the state of research and produces big reports ... about once per decade in the case of the WCRF. In their latest report (2007) on "Food, Nutrition, Physical activity and the Prevention of Cancer" they announced that red and processed meats cause cancer. NB they didn't say "are linked to", "are associated with" or any of the other usual statements that such people normally use. They defined what they meant by "cause" and just said it, no caveats. There were very few things that they were so emphatic about. The full list is: red and processed meat, salted fish, alcohol, body fatness, arsenic in drinking water, beta-carotene supplements, aflatoxins, adult attained height ... and you might argue that 3 of these are contaminants rather than natural. I'll talk about "adult attained height" in Part III. Deciding on the relative level of these causes is incredibly difficult scientifically and politically impossible. Then come a modest list of "probable" causes which are even tougher. But you don't have to have highly accurate measures of things to form a reasonable picture of ranks and relative importance which how I work in Part III.
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Post by Roger Clifton on Nov 12, 2013 16:03:15 GMT 9.5
Thanks Geoff, for the link: "For the average radiation exposure of survivors within 2,500 meters (about 0.2 Gy), the increase is about 10% above normal age-specific rates." A subsequent table says more precisely that a dose of 100-200 mGy increases risk by 7.6%, without saying what the radiation is. The outer boundary of 2.5 km sounds clinically factual. Much more horrific is the concept of an inner boundary of the zone, wherever that was, where most of the people around each survivor were dead or dying. To observe that these people also received an additional dose of penetrating rays as well as suffering the sudden horrors of war seems indecent. They already had been burdened with scars to last forever. But were they gammas, as of accidental fallout or neutrons, irrelevant to fears of fallout ? Gamma emission (from fission products relaxing) is incidental to a nuclear explosion. Most of the fission energy is the 100 MeV of kinetic energy of each of the two FPs, with a few neutrons escaping (with mode of 0.7 MeV according to CyrilR ). The FP kinetic energy is quickly shared with adjacent material, which thus reaches 1 MeV at most. Material at temperatures below 1 Mev emits Xrays, not gammas and even the hottest of Xrays die off (are absorbed) with half-ranges of tens of metres in air. On the other hand, neutrons have a range limited mainly by water, contained in the gases from the surrounding HE and the air beyond that. In the 1980s a survey of recoil tracks in glass fragments upgraded the measure of neutrons reaching the survivors and subsequently downgraded our sensitivity to them. I dont know how the dose was originally measured, it may have been "total ionization" of 200 mGy in which case the casualties may well have been stopping more neutrons than gammas. (EdIreland, is your "10000 rads" from neutrons or gammas? - link please) But I am drifting away from Geoff's thesis. Despite the evidence that the correlation between cancer and dose is real but low, many people are still being persuaded to associate the word "nuclear" with horrors of war and fantasy.
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