MWresearch

Hmm. Well from my research there is usually only such an enclose to reflect neutrons in order to increase the probability of a chain reaction with a smaller mass, as well as an additional casing to increase the thermonuclear yield with fusion such as with hydrogen. Compression or at least density changes can occur due to velocity as well as a decrease in temperature.

Ok. Well what made you think I was talking about an implosion weapon then? I'm just talking about a regular critical mass chain reaction, but the density does play a factor in that in terms of the number of U235 isotopes in a given volume. That's why the gun situation works, the velocity compresses the pieces together.

It doesn't need to be nanosecond accurate, you only need to bring two sub-critical pieces together at a high velocity for a millionth of a second which total critical mass or more once together. You could easily assume the height from 30,000 feet is enough from data you can google and looking at past experients. Putting all of that under precise control to generate electricity in a nuclear reactor so you don't blow up a city full of civilians is what requires a lot of maths.

It might be more of an industry secret than a national secret.

In any case, I will simply have to wait for someone qualified to provide accurate answers.

It does depend on other variables, but I still can't find a clear relationship. And, why would it be classified when you can google how to make an atomic bomb with descriptions on the refining process? Making an atomic bomb isn't the hard part, its getting concentrated U235 at all. Luckily, I don't need any physical material in the realm of the imaginary and theoretical.

The critical density does deal with the actual number of uranium atoms, it is completely possible the sphere parameters are affected by the grade and neutron reflected but that information was not stated as being directly related to the statistics I saw.

It says on Swansont's profile that he or she specializes in atomic physics, maybe someone could get him or her to comment.

Critical density is the ratio of mass to volume of a fissile material necessary to create a chain reaction in that fissile material. The critical density itself is related to the critical mass. The reason why density matters is because of the grade of fissile material and its environment. If only say, 20% of the isotopes of uranium are 235, you will need to compress a smaller mass of the uranium to make it critical or use neutron reflectors, and as the temperature of fissile material increases which it often does when trying to sustain a chain reaction, its density also decreases which makes a chain reaction less probable. But I am not an expert myself, that's just what I gather from research.

Some of the information I cannot find. Even if an article gives me information about a density relationship like the one you stated which I also found in Wikipedia, it won't specify the grade of Uranium or environmental conditions or sometimes not even the isotope.

Hello, I am working on theoretical research for what is turning into somewhat complicated nuclear physics. I am not a nuclear physicists, so I would appreciate help with finding the information I need. First and foremost piece of information I need to solve my system of equations is the critical density of Uranium 235.

I cannot find this information directly in books or the internet. However, online articles suggested statistics from bare spheres. It was suggested by Wikipedia that the critical conditions for an unspecified grade of Uranium 235 at an unspecific temperature (but I am assuming room temperature) and an unspecific pressure (but I am assuming 1 atmosphere) was 52000 grams in a sphere 17 centimeters large. But to me, this information seems inaccurate.

I calculated the natural density of pure Uranium 235 to be approximately 18.075g/cm^3. The density of elemental Uranium with mixes of different isotopes is 18.95-19.01 g/cm^3 with Uranium 238 being the most common isotope. So, it makes sense that the natural density of pure U235 is around 18g/cm^3.

With that said, it seems illogical that the critical density solid Uranium is 52000g/(4/3*pi*(17cm)^3)=2.526g/cm^3. The bare spheres were not in environments of exceedingly high temperatures in a vacuum, so I cannot figure out how the density of solid Uranium in spherical shape could be that dramatically lower in only that specific experiment.

Does anyone know of credible resources where I can find the information I am looking for and explain this discrepancy?