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This was really when people started figuring out how bad fallout from thermonuclear bombs could be. General Fields described it most lucidly: "If Bravo had bee

This was really when people started figuring out how bad fallout from thermonuclear bombs could be. General Fields described it most lucidly: "If Bravo had been detonated in Washington, D.C., instead of Bikini, Fields illustrated with a diagram, that lifetime dose in the Washington-Baltimore area would have been 5,000 roentgens; in Philadelphia, more than 1,000 roentgens; in New York City, more than 500, or enough to result in death for half the population if fully exposed to all the radiation delivered. This diagram was classified secret and received very little distribution beyond the Commissioners." [1] Image reproduced here [2]. Thermonuclear bombs are really terrifying. If one goes off and you're in the fallout zone do not go outside for at least 2 weeks. If you survive the initial blast you have about 10 minutes to get inside where you must stay. If you're still outside and it's 'snowing' ash you're already dead. More tips and tricks in [3]. Though these days, they say it's likely that a single individual or small group can have even worse impact from a basement bioterror lab. [1] Hewlett and Holl - Atoms for Peace and War around pg 181 (free pdf history book) https://www.energy.gov/management/downloads/hewlett-and-holl-atoms-peace-and-war https://www.energy.gov/management/downloads/hewlett-and-holl... [2] https://whatisnuclear.com/img/castle-bravo-if-on-dc.png https://whatisnuclear.com/img/castle-bravo-if-on-dc.png [3] Nuclear War Survival Skills (free pdf book) https://www.oism.org/nwss/ https://www.oism.org/nwss/

gambiting 5y ago
>>If you're still outside and it's 'snowing' ash you're already dead. Are you sure? Even from this article - Pacific Islanders came out and even licked the "snow" curious what it is, yet only a single death is attributed to it. Shouldn't they all have died if it's as bad as you say?
- acidburnNSA 5y ago
  Fine. Correction: You *may be already dead, within 2 weeks from acute radiation syndrome. It does depend how close or far to the detonation site you are. If you're catching the first snow in the nearby vicinity of the detonation, then that's where you're in a fatal dose range, by my understanding. There may very well be snow far away that is less fatal.
- bastawhiz 5y ago
  Castle Bravo was the first weapon of its kind. But moreover, many of those people likely died due to complications down the road. The US government has done a poor job of accurately tracking the deaths of even US service members years after their exposure to radiation. You might not die right then, but you'll live a significantly abridged life.
  - fifilura 5y ago
    >> you're already dead > many of those people likely died due to complications down the road Nitpick - with that interpretation of "already dead" I was "already dead" from the day I was born.
    - JohnJamesRambo 5y ago
      “If you wish to make an apple pie from scratch, you must first invent the universe.” -Carl Sagan
    - nkrisc 5y ago
      The implied difference is that the radioactive fallout is an unnatural event that will directly lead to your untimely demise, while being “dead” the moment you’re born is not useful to any discussion. I thought it was pretty clear what they meant. Your interpretation is not useful for anything, so I have to assume that’s not what they meant.
      - fifilura 5y ago
        I think it is relevant to understand whether "being outside in ash cloud" leads to more or less instant death (1 day - 4 weeks as is typical with acute radiation syndrome) as my interpretation of the original post implied. Or cancer 10 years down the road (unless you die of a car accident before that, or are treated with modern transplant/chemo therapies)
        nkrisc 5y ago
        Yes it’s not very precise language, but I believe the implication is death very shortly after, based on how I’ve heard similar language used in the past.
- mads 5y ago
  During ABC (nuclear, biological, chemical) survival training in the army we were taught to dust off the snowflakes off each other as often as possible to maximize survival until the radiation zone could be left. I got the impression it was survivable for some amount of time.
  - kodah 5y ago
    We got taught the same thing in the Marines. Dawn your mask (if you have it, and the right canister -- which, probably not), lay prone with your kevlar facing the impact area (if cover cannot be found), wait for the explosion to wash over you, and begin your trek away from the blast as quickly as possible.
    - corty 5y ago
      The right canister is any of them, most of the isotopes will be bound to dust, and anything you can do to reduce the dust you breathe in helps. Gaseous isotopes like iodine aren't that easy to filter, you are better off taking iodine tablets for that.
- rob74 5y ago
  The one recorded death was a Japanese citizen, which caused a diplomatic crisis. The Marshall Islands were occupied by the US and very remote, so it was probably easier to sweep any deaths that may have occurred in the local population under the rug...
  - hef19898 5y ago
    Nobody really wanted to count deaths and long time effects on people from Chernobyl neither. Because, IMHO, people knew. Accurately counting would have meant knowing, an nobody really wanted that.
    - acidburnNSA 5y ago
      On the contrary, UNSCEAR has painstakingly tracked the long-term effects at Chernobyl specifically because they wanted to know. [1] https://www.unscear.org/unscear/en/chernobyl.html https://www.unscear.org/unscear/en/chernobyl.html
      - hef19898 5y ago
        The immediate impact, yes. Liquidators and residents, no. Not even Soviet authorities really tracked how many were there or what happened to them after. Long term effects were not properly recorded. Everything done since is basically meta statistics on cancer rates and types.
        potatoman22 5y ago
        It seems like it's all tracked by that organization... plus, determining causality for diseases 30 years later is really hard.
- deleted 5y ago
  [deleted]
- LorenPechtel 5y ago
  Yeah, that doesn't make sense. LD50 for prompt exposure is 4-5 sieverts. 1 sievert of exposure translates to about a 1% lifetime cancer risk. Now, if you're inhaling the ash that's another matter. At that point you're probably dead.
nabla9 5y ago
In nuclear war, practically all detonations would be airbursts. They don't cause similar fallout. Castle Bravo had huge fallout for two reasons 1) It had natural uranium tamper that had very dirty reaction. Huge amount of radionuclides. Modern weapons use beryllium reflectors and gold. 2) It was ground burst in water. That white "snow" was coral. Neutron activaton of sodium in seawater makes things even worse. Hydrogen bomb can be made cleaner than fission bomb. In fact bigger bomb, less fallout.
- corty 5y ago
  > In nuclear war, practically all detonations would be airbursts. They don't cause similar fallout. No, definitely not. It really depends strongly on who your opponent is and what their strategy might be. And on whether they stick to their pre-anounced strategy. And how many exchanges (first, second, third strike) you might get to. Generally, there are two strategies that are usually distinguished in US literature for leading a strategic (i.e. big, as opposed to small, tactical) nuclear war: counter-force and counter-value. Counter-value means that your nukes target what values the enemy has by destroying enemy cities and the population and goods/industry/infrastructure in those cities. Destroying a large, non-reinforced, "soft" target like a city with humans in it is more efficiently done by airburst, because the overpressure/temperature effect is weaker but spread over a far larger area. Weapons also don't need to be that accurate, if you miss downtown Manhattan by a kilometer, it won't matter much. Most smaller nuclear powers, those with a no-first-use doctrine and those without accurate fast delivery systems (i.e. modern ICBMs or SLBMs) do rely on a counter-value strategy. The goal there is usually something akin to France: They aim to be able to kill more of the enemy population than there are French to kill. Counter-force means that your nukes target the enemy military infrastructure, most prominently ICBM silos and command infrastructure. Usually this strategy calls for a preventative first strike with very accurate weapons that can destroy heavily reinforced underground structures surrounded by possible anti-missile systems. Meaning you have to hit the target with multiple ground bursts, quickly and as accurately as possible. Since you have only one try at this, some of your warheads might be shot down and some might miss by a few hundred meters, causing the crater to not destroy that ICBM bunker enough, there will be quite a few warheads on the way to each single silo. Meaning that this supposedly "humane" strategy will produce enough fallout to still kill a lot of the enemies population. One example would be https://www.nukestrat.com/china/Book-173-196.pdf https://www.nukestrat.com/china/Book-173-196.pdf p184, where a US counter-force strike against a Chinese missile silo site out in the sticks would kill between 5 and 20 million Chinese just from fallout. And of course, if your counter-force strategy includes command bunkers near capital cities (ground burst), nuclear submarine bases near other harbors (ground/sea burst) or larger military airports (air burst), you are bombing much closer population centers, also with mostly ground bursts. Most prominent in claiming a counter-force strategy is the US. So most probably, if your opponent is the US, GB or Russia, you'll receive a large number of ground bursts in the first strike. Only if there still were an exchange after that, would there be any significant number of air bursts.
baybal2 5y ago
> If Bravo had been detonated in Washington, D.C., instead of Bikini, Fields illustrated with a diagram, that lifetime dose in the Washington-Baltimore area would have been 5,000 roentgens; in Philadelphia, more than 1,000 roentgens; in New York City, more than 500, or enough to result in death for half the population if fully exposed to all the radiation delivered. If it were to, half of Washington-Baltimore would've been blown to pieces, and burnt to the ground first.
- fennecfoxen 5y ago
  > If it were to, half of Washington-Baltimore would've been blown to pieces, and burnt to the ground first. No way. Looking at NUKEMAP right now, a 15 megaton surface burst like Bravo, in the center of Washington, wouldn't even deal "heavy blast damage" much past the National Cathedral. Beyond that, you're looking at "moderate" blast damage sufficient to destroy wooden homes afflicting the rest of the District proper; once you're out past Laurel or so (a decent halfway point between Washington and Baltimore) you're not even breaking windows anymore. https://nuclearsecrecy.com/nukemap/?&kt=15000&lat=38.895&lng=-77.0366&airburst=0&hob_ft=0&ff=68&psi=20,5,1&zm=11 https://nuclearsecrecy.com/nukemap/?&kt=15000&lat=38.895&lng... This is why they made films to teach kids to duck and cover. The bombs weren't survivable at ground zero, but most kids wouldn't be at ground zero.
Andrew_nenakhov 5y ago
Hm. That's strange, because USSR's 57 Megaton Tzar-bomb had a negligible amount of radiation: "Radioactive contamination of the experimental field with a radius of 2–3 km (1.2–1.9 mi) in the epicenter area was no more than 1 milliroentgen / hour, the testers appeared at the explosion site 2 hours later, radioactive contamination posed practically no danger to the test participants" [1]. [1]: https://en.wikipedia.org/wiki/Tsar_Bomba#Test_results https://en.wikipedia.org/wiki/Tsar_Bomba#Test_results
- gambiting 5y ago
  Most modern bombs can be tuned for the size of the explosion + the amount of fallout produced. Also the fallout heavily depends on how high up the bomb is detonated - detonate it close to the ground, then all the soil and debris gets irradiated and thrown into the air. Detonate it high up and you still get the destructive heat blast and shock wave, but not a whole lot of fallout.
- Teknoman117 5y ago
  One of the main differences is what the tamper is made out of (the casing). You need a material that is reflective to the X-rays used to compress the fusion fuel. In Castle Bravo, this was made out of uranium-238, in the Tsar bomb, it was made from lead. Using uranium boosted the power output by about 2x, at the expense of making the bombs far, far dirtier. The extreme heat and the high neutron radiation from the primary (a fission device) detonating would cause the uranium to decay into more unstable isotopes (U-235, Pu-239, etc.) which would then fission themselves. The ideology at the time was that a larger blast was more important, since at the time nuclear weapons were still to be dropped by bombers (No ICBMs for another decade). You wanted the bomb to take out the target even if you couldn't quite reach it. The Soviets estimated that using the same technique would have produced a yield of 100 Mt, but for testing, lead was used to limit the fallout to something they deemed manageable.
  - corty 5y ago
    There are multiple effects, tamper material is only one of them. Ground bursts also increase the overall amount and concentration of fallout: First, with the explosion closer to ground, more neutrons can reach the ground and activate material there, producing radioactive isotopes from previously harmless earth. The "fireball" is a shell of expanding lower-density plasma which doesn't dampen neutrons as much as gas (especially water vapour) in non-plasma air. So that fireball touching ground produces more activated elements increasing overall fallout. Second, all newly created active elements and more fusion/fission products get bound to ground particles like dust, coral or water droplets if the explosion stirs up more of that. Those particles are larger and heavier, producing a more concentrated fallout closer to ground zero, whereas unbound products would be dispersed higher in the atmosphere without producing too much of a distinctive fallout pattern.
tomxor 5y ago
Being fairly ignorant of this stuff, your comment made me check the location of bikini atoll. I had just assumed it was reasonably close to the USA but it might as well be south east asia's back yard compared to the distance across the pacific to the US. History and international nuclear testing rules aside, imagine the reaction from nations like China, Japan or Australia today if the US set off a 15 megaton thermonuclear reaction that close to them! 1954 was a different world.
- thefounder 5y ago
  >> if the US set off a 15 megaton thermonuclear reaction over there right now! 1954 was a different world. Ok..how different? What would Australia do?
  - corty 5y ago
    Look stupid. The British tested their smaller nukes in the Australian desert, Maralinga.
  - caf 5y ago
    The first political action I ever participated in was a country-wide walkout of high school students protesting Chirac's France resuming testing weapons in the Pacific. It was a pretty big deal at the time - boycotts etc.
- lumost 5y ago
  The US detonated a bomb in space over Honolulu. The timing was broadcast and tourists/locals gathered to watch the blast like a fireworks show. It was a very different time.
  - monkeybutton 5y ago
    https://www.pbs.org/wgbh/americanexperience/features/atomic-tourism-nevada/ https://www.pbs.org/wgbh/americanexperience/features/atomic-... >The Las Vegas Chamber of Commerce issued a calendar for tourists, listing the scheduled times of the bomb detonations and the best places to view them. The Sky Room at the Desert Inn, offering a panoramic view of the Nevada horizon, was a favorite watch spot of tourists, as was nearby Mount Charleston. Many tourists packed "atomic box lunches" and had picnics as close to ground zero as the government restrictions would allow. On the eve of detonations, many Las Vegas businesses held "Dawn Bomb Parties." Beginning at midnight, guests would drink and sing until the flash of the bomb lit up the night sky. >For twelve years, an average of one bomb every three weeks was detonated, at a total of 235 bombs. Flashes from the explosions were so powerful that they could reportedly be seen from as far away as Montana. Not going to, I would've gone to see it.
deleted 5y ago
[deleted]
dredmorbius 5y ago
Should you ever find yourself in a situation where this information is useful, there's the seven-ten rule of fallout radiation decay: A book by Cresson H. Kearny presents data showing that for the first few days after the explosion, the radiation dose rate is reduced by a factor of ten for every seven-fold increase in the number of hours since the explosion. He presents data showing that "it takes about seven times as long for the dose rate to decay from 1000 roentgens per hour (1000 R/hr) to 10 R/hr (48 hours) as to decay from 1000 R/hr to 100 R/hr (7 hours)."[41] This is a rule of thumb based on observed data, not a precise relation. https://en.wikipedia.org/wiki/Nuclear_fallout#The_seven-ten_rule https://en.wikipedia.org/wiki/Nuclear_fallout#The_seven-ten_... The 7x intervals are: - 7^1 (7) hours: 1/10 initial radiation - 7^2 (49) hours, about 2 days: 1/100 - 7^3 (343) hours, about 2 weeks: 1/1,000 - 7^4 (2401) hours, about 2 months: 1/10,000 - 7^5 (16,807) hours, about 2 years: 1/100,000 7^6 is about 15 years, 7^7 is about a century. The empirical data is based on values to 7^4 (two months). See: https://physics.stackexchange.com/questions/336049/can-the-7-10-rule-of-thumb-for-radiation-be-understood-theoretically#351180 https://physics.stackexchange.com/questions/336049/can-the-7...

gambiting 5y ago

>>If you're still outside and it's 'snowing' ash you're already dead. Are you sure? Even from this article - Pacific Islanders came out and even licked the "snow" curious what it is, yet only a single death is attributed to it. Shouldn't they all have died if it's as bad as you say?

acidburnNSA 5y ago
Fine. Correction: You *may be already dead, within 2 weeks from acute radiation syndrome. It does depend how close or far to the detonation site you are. If you're catching the first snow in the nearby vicinity of the detonation, then that's where you're in a fatal dose range, by my understanding. There may very well be snow far away that is less fatal.
bastawhiz 5y ago
Castle Bravo was the first weapon of its kind. But moreover, many of those people likely died due to complications down the road. The US government has done a poor job of accurately tracking the deaths of even US service members years after their exposure to radiation. You might not die right then, but you'll live a significantly abridged life.
- fifilura 5y ago
  >> you're already dead > many of those people likely died due to complications down the road Nitpick - with that interpretation of "already dead" I was "already dead" from the day I was born.
  - JohnJamesRambo 5y ago
    “If you wish to make an apple pie from scratch, you must first invent the universe.” -Carl Sagan
  - nkrisc 5y ago
    The implied difference is that the radioactive fallout is an unnatural event that will directly lead to your untimely demise, while being “dead” the moment you’re born is not useful to any discussion. I thought it was pretty clear what they meant. Your interpretation is not useful for anything, so I have to assume that’s not what they meant.
    - fifilura 5y ago
      I think it is relevant to understand whether "being outside in ash cloud" leads to more or less instant death (1 day - 4 weeks as is typical with acute radiation syndrome) as my interpretation of the original post implied. Or cancer 10 years down the road (unless you die of a car accident before that, or are treated with modern transplant/chemo therapies)
      - nkrisc 5y ago
        Yes it’s not very precise language, but I believe the implication is death very shortly after, based on how I’ve heard similar language used in the past.
mads 5y ago
During ABC (nuclear, biological, chemical) survival training in the army we were taught to dust off the snowflakes off each other as often as possible to maximize survival until the radiation zone could be left. I got the impression it was survivable for some amount of time.
- kodah 5y ago
  We got taught the same thing in the Marines. Dawn your mask (if you have it, and the right canister -- which, probably not), lay prone with your kevlar facing the impact area (if cover cannot be found), wait for the explosion to wash over you, and begin your trek away from the blast as quickly as possible.
  - corty 5y ago
    The right canister is any of them, most of the isotopes will be bound to dust, and anything you can do to reduce the dust you breathe in helps. Gaseous isotopes like iodine aren't that easy to filter, you are better off taking iodine tablets for that.
rob74 5y ago
The one recorded death was a Japanese citizen, which caused a diplomatic crisis. The Marshall Islands were occupied by the US and very remote, so it was probably easier to sweep any deaths that may have occurred in the local population under the rug...
- hef19898 5y ago
  Nobody really wanted to count deaths and long time effects on people from Chernobyl neither. Because, IMHO, people knew. Accurately counting would have meant knowing, an nobody really wanted that.
  - acidburnNSA 5y ago
    On the contrary, UNSCEAR has painstakingly tracked the long-term effects at Chernobyl specifically because they wanted to know. [1] https://www.unscear.org/unscear/en/chernobyl.html https://www.unscear.org/unscear/en/chernobyl.html
    - hef19898 5y ago
      The immediate impact, yes. Liquidators and residents, no. Not even Soviet authorities really tracked how many were there or what happened to them after. Long term effects were not properly recorded. Everything done since is basically meta statistics on cancer rates and types.
      - potatoman22 5y ago
        It seems like it's all tracked by that organization... plus, determining causality for diseases 30 years later is really hard.
deleted 5y ago
[deleted]
LorenPechtel 5y ago
Yeah, that doesn't make sense. LD50 for prompt exposure is 4-5 sieverts. 1 sievert of exposure translates to about a 1% lifetime cancer risk. Now, if you're inhaling the ash that's another matter. At that point you're probably dead.

nabla9 5y ago

In nuclear war, practically all detonations would be airbursts. They don't cause similar fallout. Castle Bravo had huge fallout for two reasons 1) It had natural uranium tamper that had very dirty reaction. Huge amount of radionuclides. Modern weapons use beryllium reflectors and gold. 2) It was ground burst in water. That white "snow" was coral. Neutron activaton of sodium in seawater makes things even worse. Hydrogen bomb can be made cleaner than fission bomb. In fact bigger bomb, less fallout.

corty 5y ago
> In nuclear war, practically all detonations would be airbursts. They don't cause similar fallout. No, definitely not. It really depends strongly on who your opponent is and what their strategy might be. And on whether they stick to their pre-anounced strategy. And how many exchanges (first, second, third strike) you might get to. Generally, there are two strategies that are usually distinguished in US literature for leading a strategic (i.e. big, as opposed to small, tactical) nuclear war: counter-force and counter-value. Counter-value means that your nukes target what values the enemy has by destroying enemy cities and the population and goods/industry/infrastructure in those cities. Destroying a large, non-reinforced, "soft" target like a city with humans in it is more efficiently done by airburst, because the overpressure/temperature effect is weaker but spread over a far larger area. Weapons also don't need to be that accurate, if you miss downtown Manhattan by a kilometer, it won't matter much. Most smaller nuclear powers, those with a no-first-use doctrine and those without accurate fast delivery systems (i.e. modern ICBMs or SLBMs) do rely on a counter-value strategy. The goal there is usually something akin to France: They aim to be able to kill more of the enemy population than there are French to kill. Counter-force means that your nukes target the enemy military infrastructure, most prominently ICBM silos and command infrastructure. Usually this strategy calls for a preventative first strike with very accurate weapons that can destroy heavily reinforced underground structures surrounded by possible anti-missile systems. Meaning you have to hit the target with multiple ground bursts, quickly and as accurately as possible. Since you have only one try at this, some of your warheads might be shot down and some might miss by a few hundred meters, causing the crater to not destroy that ICBM bunker enough, there will be quite a few warheads on the way to each single silo. Meaning that this supposedly "humane" strategy will produce enough fallout to still kill a lot of the enemies population. One example would be https://www.nukestrat.com/china/Book-173-196.pdf https://www.nukestrat.com/china/Book-173-196.pdf p184, where a US counter-force strike against a Chinese missile silo site out in the sticks would kill between 5 and 20 million Chinese just from fallout. And of course, if your counter-force strategy includes command bunkers near capital cities (ground burst), nuclear submarine bases near other harbors (ground/sea burst) or larger military airports (air burst), you are bombing much closer population centers, also with mostly ground bursts. Most prominent in claiming a counter-force strategy is the US. So most probably, if your opponent is the US, GB or Russia, you'll receive a large number of ground bursts in the first strike. Only if there still were an exchange after that, would there be any significant number of air bursts.

baybal2 5y ago

> If Bravo had been detonated in Washington, D.C., instead of Bikini, Fields illustrated with a diagram, that lifetime dose in the Washington-Baltimore area would have been 5,000 roentgens; in Philadelphia, more than 1,000 roentgens; in New York City, more than 500, or enough to result in death for half the population if fully exposed to all the radiation delivered. If it were to, half of Washington-Baltimore would've been blown to pieces, and burnt to the ground first.

fennecfoxen 5y ago
> If it were to, half of Washington-Baltimore would've been blown to pieces, and burnt to the ground first. No way. Looking at NUKEMAP right now, a 15 megaton surface burst like Bravo, in the center of Washington, wouldn't even deal "heavy blast damage" much past the National Cathedral. Beyond that, you're looking at "moderate" blast damage sufficient to destroy wooden homes afflicting the rest of the District proper; once you're out past Laurel or so (a decent halfway point between Washington and Baltimore) you're not even breaking windows anymore. https://nuclearsecrecy.com/nukemap/?&kt=15000&lat=38.895&lng=-77.0366&airburst=0&hob_ft=0&ff=68&psi=20,5,1&zm=11 https://nuclearsecrecy.com/nukemap/?&kt=15000&lat=38.895&lng... This is why they made films to teach kids to duck and cover. The bombs weren't survivable at ground zero, but most kids wouldn't be at ground zero.

Andrew_nenakhov 5y ago

Hm. That's strange, because USSR's 57 Megaton Tzar-bomb had a negligible amount of radiation: "Radioactive contamination of the experimental field with a radius of 2–3 km (1.2–1.9 mi) in the epicenter area was no more than 1 milliroentgen / hour, the testers appeared at the explosion site 2 hours later, radioactive contamination posed practically no danger to the test participants" [1]. [1]: https://en.wikipedia.org/wiki/Tsar_Bomba#Test_results https://en.wikipedia.org/wiki/Tsar_Bomba#Test_results

gambiting 5y ago
Most modern bombs can be tuned for the size of the explosion + the amount of fallout produced. Also the fallout heavily depends on how high up the bomb is detonated - detonate it close to the ground, then all the soil and debris gets irradiated and thrown into the air. Detonate it high up and you still get the destructive heat blast and shock wave, but not a whole lot of fallout.
Teknoman117 5y ago
One of the main differences is what the tamper is made out of (the casing). You need a material that is reflective to the X-rays used to compress the fusion fuel. In Castle Bravo, this was made out of uranium-238, in the Tsar bomb, it was made from lead. Using uranium boosted the power output by about 2x, at the expense of making the bombs far, far dirtier. The extreme heat and the high neutron radiation from the primary (a fission device) detonating would cause the uranium to decay into more unstable isotopes (U-235, Pu-239, etc.) which would then fission themselves. The ideology at the time was that a larger blast was more important, since at the time nuclear weapons were still to be dropped by bombers (No ICBMs for another decade). You wanted the bomb to take out the target even if you couldn't quite reach it. The Soviets estimated that using the same technique would have produced a yield of 100 Mt, but for testing, lead was used to limit the fallout to something they deemed manageable.
- corty 5y ago
  There are multiple effects, tamper material is only one of them. Ground bursts also increase the overall amount and concentration of fallout: First, with the explosion closer to ground, more neutrons can reach the ground and activate material there, producing radioactive isotopes from previously harmless earth. The "fireball" is a shell of expanding lower-density plasma which doesn't dampen neutrons as much as gas (especially water vapour) in non-plasma air. So that fireball touching ground produces more activated elements increasing overall fallout. Second, all newly created active elements and more fusion/fission products get bound to ground particles like dust, coral or water droplets if the explosion stirs up more of that. Those particles are larger and heavier, producing a more concentrated fallout closer to ground zero, whereas unbound products would be dispersed higher in the atmosphere without producing too much of a distinctive fallout pattern.

tomxor 5y ago

Being fairly ignorant of this stuff, your comment made me check the location of bikini atoll. I had just assumed it was reasonably close to the USA but it might as well be south east asia's back yard compared to the distance across the pacific to the US. History and international nuclear testing rules aside, imagine the reaction from nations like China, Japan or Australia today if the US set off a 15 megaton thermonuclear reaction that close to them! 1954 was a different world.

thefounder 5y ago
>> if the US set off a 15 megaton thermonuclear reaction over there right now! 1954 was a different world. Ok..how different? What would Australia do?
- corty 5y ago
  Look stupid. The British tested their smaller nukes in the Australian desert, Maralinga.
- caf 5y ago
  The first political action I ever participated in was a country-wide walkout of high school students protesting Chirac's France resuming testing weapons in the Pacific. It was a pretty big deal at the time - boycotts etc.
lumost 5y ago
The US detonated a bomb in space over Honolulu. The timing was broadcast and tourists/locals gathered to watch the blast like a fireworks show. It was a very different time.
- monkeybutton 5y ago
  https://www.pbs.org/wgbh/americanexperience/features/atomic-tourism-nevada/ https://www.pbs.org/wgbh/americanexperience/features/atomic-... >The Las Vegas Chamber of Commerce issued a calendar for tourists, listing the scheduled times of the bomb detonations and the best places to view them. The Sky Room at the Desert Inn, offering a panoramic view of the Nevada horizon, was a favorite watch spot of tourists, as was nearby Mount Charleston. Many tourists packed "atomic box lunches" and had picnics as close to ground zero as the government restrictions would allow. On the eve of detonations, many Las Vegas businesses held "Dawn Bomb Parties." Beginning at midnight, guests would drink and sing until the flash of the bomb lit up the night sky. >For twelve years, an average of one bomb every three weeks was detonated, at a total of 235 bombs. Flashes from the explosions were so powerful that they could reportedly be seen from as far away as Montana. Not going to, I would've gone to see it.

deleted 5y ago

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dredmorbius 5y ago

Should you ever find yourself in a situation where this information is useful, there's the seven-ten rule of fallout radiation decay: A book by Cresson H. Kearny presents data showing that for the first few days after the explosion, the radiation dose rate is reduced by a factor of ten for every seven-fold increase in the number of hours since the explosion. He presents data showing that "it takes about seven times as long for the dose rate to decay from 1000 roentgens per hour (1000 R/hr) to 10 R/hr (48 hours) as to decay from 1000 R/hr to 100 R/hr (7 hours)."[41] This is a rule of thumb based on observed data, not a precise relation. https://en.wikipedia.org/wiki/Nuclear_fallout#The_seven-ten_rule https://en.wikipedia.org/wiki/Nuclear_fallout#The_seven-ten_... The 7x intervals are: - 7^1 (7) hours: 1/10 initial radiation - 7^2 (49) hours, about 2 days: 1/100 - 7^3 (343) hours, about 2 weeks: 1/1,000 - 7^4 (2401) hours, about 2 months: 1/10,000 - 7^5 (16,807) hours, about 2 years: 1/100,000 7^6 is about 15 years, 7^7 is about a century. The empirical data is based on values to 7^4 (two months). See: https://physics.stackexchange.com/questions/336049/can-the-7-10-rule-of-thumb-for-radiation-be-understood-theoretically#351180 https://physics.stackexchange.com/questions/336049/can-the-7...