Goin' Nu-Klee-R

[don]

yes, we're #1 . . . .

[ASH]

Re: Goin' Nu-Klee-R

That's cool. The record only goes up to 1998, but I think it missed one. I guess it wasn't officially confirmed, but in September 1979 there was an explosion over the Indian Ocean which is thought to have been a clandestine South African/Israeli nuclear test. I remember when South Africa's Deputy Foreign Minister claimed the test in 1997, but was unaware that he later retracted the statement. Certainly both South Africa and Israel built bombs, and it would have been a little odd to stake their security on untested designs.

[don]

Re: Goin' Nu-Klee-R

That's cool. The record only goes up to 1998, but I think it missed one. I guess it wasn't officially confirmed, but in September 1979 there was an explosion over the Indian Ocean which is thought to have been a clandestine South African/Israeli nuclear test. I remember when South Africa's Deputy Foreign Minister claimed the test in 1997, but was unaware that he later retracted the statement. Certainly both South Africa and Israel built bombs, and it would have been a little odd to stake their security on untested designs.

I thought the same thing ASH. They couldn't be that sure of their proficiency.

[c1ue]

Re: Goin' Nu-Klee-R

From what I understand, unless you're North Korea, the purpose of the tests is to see how well your design specs mimic the strength of the explosion - not the runaway chain reaction itself.

After all, if 2 semi-literate Japanese can start a chain reaction in a bucket with a shovel, surely someone with the right materials can do better:

http://iopscience.iop.org/0952-4746/19/4/603

Tokai is about 130 km northeast of Tokyo, and 13 nuclear facilities are located there including the Japan Atomic Energy Institute (JAERI) and the Japan Nuclear Cycle Development Institute (JNC). JCO Co. Ltd (previously called Japan Nuclear Fuel Conversion Co.) operated the uranium processing plant. It has been found since the accident that the company used a hidden procedure for handling uranium for seven or eight years, and on that day three workers deviated even further from the company's unauthorised work manual, bypassing a part of the procedure and using stainless steel buckets to put uranium nitrate into a precipitation tank instead of a solution tank. They were working on the refining of uranium fuel for the Joyo experimental fast breeder reactor in Ibaraki Prefecture by hand, and they mixed 16 kg of 18.8% enriched uranium, which is nearly seven times the allowable amount of 2.4 kg of uranium, into the tank. The two workers beside the tank (Mr O, age 35, and Mr S, age 39) saw a blue flash with a sound like `bashi' and fled from the site. The third person (Mr Y, age 54) stayed outside of the room and also saw a reflected blue light on the wall. The three men escaped from the control area, and at the decontamination room one of them (Mr O) fainted while Mr Y tried to use the telephone to report the accident. Mr O, who received the most radiation, suffered vomiting and convulsions. Other workers came into the area and took them outside after hearing the alarm from an area monitor at the site. Mr O vomited several times as they waited for an ambulance a few tens of metres away from the accident site. During the trip to Mito Hospital Mr O vomited and suffered diarrhoea. Mr S also vomited but had no diarrhoea.

...

A pair of workers was sent to the plant nine times to halt the chain reaction. At 6 am Friday, 1 October, the nuclear chain reaction was stopped by draining the cooling water around a precipitation tank by blowing the water away from the cooling water jacket with argon gas. The chain reaction lasted for roughly 16 hours. Within two hours of the release of the cooling water the neutron monitor at the plant read zero. This was confirmed by the neutron monitor at the plant at 6:15. The workers who risked exposure to high levels of radiation received doses in the range of 50 to 100 mSv. JCO employees injected a boron solution into the precipitation tank to ensure that the criticality stopped.

The size of explosion - as it is a function of how much enriched material is squashed together as tightly as possible - thus is more complicated; modern nuclear fission weapons probably use something like the shaped charge principle to maximize density. In turn the fusion bombs use the fission reaction to achieve the temperatures necessary for the even larger energy output of fusion.

[vanvaley1]

Re: Goin' Nu-Klee-R

I'd be interested in seeing a similar map of how many nations and/or states declared bankruptcy over a period of time. Ditto currency 'changes'. van

[ASH]

Re: Goin' Nu-Klee-R

From what I understand, unless you're North Korea, the purpose of the tests is to see how well your design specs mimic the strength of the explosion - not the runaway chain reaction itself.

You're quite right that yield is what they'd be testing for. As you say, the problem is that the assembly may blow itself apart before much of the 'fuel' has been consumed, resulting in what is for all intents and purposes a 'dud'. It's easy to calculate how much energy you should get from a certain mass of fuel, but the actual yield is dominated by how far the reaction gets before the fuel is blown apart. Since the yield is sensitive to the symmetry and precise timing of the implosion -- and one is interested in imperfections which are hard to simulate -- I'd think that at least some testing is necessary. You want to know whether your method of assembly is good enough to get a bang rather than a whimper.