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Author Topic: Hitting a Barn - can you help with a fission question?  (Read 2438 times)

Offline Colin2B

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I joined to look for an answer which I have been unable to find on the net. Hoping someone can confirm my thinking or point me to a reference.
I came across a site claiming that nuclear weapons cannot exist. As my learning of nuclear physics was some 35 yrs ago, and then part of an electronics course, I am a little rusty and looking for help.
A key argument of the 'conspiracists' runs: nuclear fission requires slow neutrons to split the nucleus. The fission produces fast neutrons so needs a moderator to slow them down. Putting a moderator into a bomb would make it much larger than we are told they are. Hence everything is faked.
From what I understand should be the true interpretation: uranium in a reactor is only a few % U235, in other words the nuclei are widely spaced, in order to increase the probability of fission the nuclear cross-section must be increased by slowing the neutrons down to thermal energies. Hence a moderator.
In a bomb they can't be slowed down so other means are used to increase the probability of fission. The fuel is highly enriched 90% U235 giving a greater density of nuclei, the mass is increased to the point where most neutrons will cause fission before leaving the mass.
Would anyone add anything to this?
Thanks

PS the writer of the site didn't really understand friction & gravity either!
« Last Edit: 03/02/2015 23:44:43 by Colin2B »


 

Offline alancalverd

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Re: Hitting a Barn - is this answer to a Conspiracy Theory?
« Reply #1 on: 03/02/2015 00:16:26 »
Faking the devastation of Hiroshima and Nagasaki, to such a realistic extent that the Imperial Japanese Armed Forces surrendered unconditionally, was pretty impressive. As was the idea of splashing around enough radioactive iodine, cesium and strontium to convince everyone else that there had indeed been a nuclear explosion, then topping up the fallout from time to time in the 1950s to kid the rest of us that "they" were testing bigger bombs. I wonder how "they" managed to vaporise Bikini Atoll with conventional explosives - or perhaps "they" just dug it up and moved it when nobody was looking.

Given the choice, I prefer to believe my old bosses whose CVs included exploding five atom bombs in ground tests and vaporising HMS Plym with an airdrop, with photographs.
 

Offline Colin2B

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Re: Hitting a Barn - is this answer to a Conspiracy Theory?
« Reply #2 on: 03/02/2015 10:32:34 »
Faking the devastation of Hiroshima and Nagasaki, to such a realistic extent that the Imperial Japanese Armed Forces surrendered unconditionally, was pretty impressive. As was the idea of splashing around enough radioactive iodine, cesium and strontium to convince everyone else that there had indeed been a nuclear explosion, then topping up the fallout from time to time in the 1950s to kid the rest of us that "they" were testing bigger bombs. I wonder how "they" managed to vaporise Bikini Atoll with conventional explosives - or perhaps "they" just dug it up and moved it when nobody was looking.

Given the choice, I prefer to believe my old bosses whose CVs included exploding five atom bombs in ground tests and vaporising HMS Plym with an airdrop, with photographs.

Thanks Alan,
You missed out faking burnt in shadows of people and objects and glazing concrete etc. I agree with your analysis, a common feature of conspiracy theories is the convoluted and complex sequence of events and resources needed to pull them off. I personally doubt most govenments have the ability to project manage such complex tasks, given their inability to manage more simple ones. But then they would deliberatly fail at the simple ones to fool us into thinking .........

Any thoughts on the atomic physics bit?

 

Offline JohnDuffield

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Re: Hitting a Barn - is this answer to a Conspiracy Theory?
« Reply #3 on: 03/02/2015 11:59:12 »
I just hate conspiracy theories like this.
 

Offline Ethos_

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Re: Hitting a Barn - is this answer to a Conspiracy Theory?
« Reply #4 on: 03/02/2015 15:06:33 »
I just hate conspiracy theories like this.
I frankly just chuckle out loud when I read such nonsense. The abundance of paranoia that pervades the internet, while amusing, is still a little disturbing. I suspect these views are generated by individuals who feel they've lost control of their lives. This is troubling enough but what's worse is it appears as if it's becoming epidemic.
 

Offline syhprum

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Re: Hitting a Barn - is this answer to a Conspiracy Theory?
« Reply #5 on: 03/02/2015 15:49:54 »
I feel that the author of this nonsense has more knowledge of nuclear matters than he lets on about, did he talk about "barns" or did this creep in later.
Of course the Hiroshima bomb was pretty inefficient from a technical point of view only about 2% of the potential energy liberated
« Last Edit: 03/02/2015 15:53:48 by syhprum »
 

Offline Colin2B

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Re: Hitting a Barn - is this answer to a Conspiracy Theory?
« Reply #6 on: 03/02/2015 16:31:47 »
I feel that the author of this nonsense has more knowledge of nuclear matters than he lets on about, did he talk about "barns" or did this creep in later.
Hi Syphrum
I inserted barn into the title in the hope it would jog someone knowledgeable to confirm my assumptions, but confuse any trolls.
The original author or the web site had clearly read up on reactor technology and (along with spin off forum) was making the assumption:
reactors work this way, it is impossible for a bomb to work like a reactor, therefore bombs can't work!
Clearly false logic and I was just looking for confirmation that the way I think a bomb works is correct.
Glad to hear everyone shares my views on this nonsense, but such sites can make an interesting mental exercise occasionally.
 

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Re: Hitting a Barn - is this answer to a Conspiracy Theory?
« Reply #6 on: 03/02/2015 16:31:47 »

 

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