# Tag Info

29

All of it can be simulated to a certain level of precision - given enough computing power AND correct experimental values for all the parameters. The tricky bit without tests is to get experimental values for eg. the thermal conductivity of Plutonium at TPa of pressure. Experimental tests can also only validate something to a certain level of precision - ...

20

To some extent this answer is echoing things that @Martin said... but from my own point of view. In my experience of (Monte Carlo) simulation, the model you implement captures your knowledge of the physics of the situation; and if your knowledge is "perfect", your calculation, with sufficient compute power at your fingertips, will also be "perfect". ...

16

Originally radioactive elements come from nature where they were very diluted and that's why they were secure. When these naturally radioactive materials like Uranium are used in processes like civilian nuclear energy production the resulting waste becomes many, many times more radioactive than the raw materials one started off with. Even after the ...

13

1) To define an angle for a nuclear reaction one has to have an orientation for the nucleus. This could be a magnetic moment or a dipole moment. 2) a photon carries away spin 1, i.e. angular momentum, and will leave a nucleus minus that angular momentum. As the word states, angles are involved, and the probability distribution for the gamma ray will in ...

13

Elements up to and including iron can be produced exothermically by fusion reactions in stars. Producing heavier elements is then endothermic. The reason for this is that the binding energy per nucleon is maximised in nuclei around the "iron peak". This means that if you tried to add something to an iron nucleus, the resulting nucleus would have a smaller ...

11

There are examples of nuclei whose emission is not isotropic in the presence of a magnetic field. Feynman gave an example of this during a lecture on symmetry in physical laws (vol 1-52). In particular in 52-7 he mentions an experiment in which the emission of an electron by a cobalt nucleus (Co-60) is asymmetrical with respect to the magnetic axis - more ...

7

I think anyone who says "there's no need to do experiments, we can simulate everything!" either: Doesn't know what they're talking about Is trying to sell snake oil Is a scientific fraud trying to push pseudoscience as actual science I have never seen a serious, honest scientist claim that simulation is sufficient substitute for empirical evidence, even ...

5

You can simulate everything to certain precision, but there is at least one aspect that remains unsimulated: reality. What I mean are the following points: When you want to calculate anything a little bit more complicated, at some point, you will use approximations. There are always good reasons for making certain assumptions, neglecting terms and ...

3

One on the problem is re-concentration, by the help of water circulation in the soil (possibly up to water sources) or by the help of small animals (then to food chain up to us). The stability of geological layers is not so easy to predict. Beside, the radio-activity of wastes can be a lot higher, and spreaded through a huge variety of chimical species, ...

3

Probably too expensive and disruptive to try to deal with nuclear waste that way. You're talking about processing through an enormous amount of earth and/or seawater. Note that nuclear waste includes not just material that was initially radioactive when it came out of the ground (e.g., uranium ore), but a lot more material as well. If a nuclear plant worker ...

3

Anna and Floris have given excellent descriptions of how the photon emission depends on the orientation of the nucleus, however there is another aspect of the question that I think is worth mentioning. If you conside an isolated nucleus, e.g. no magnetic field, then it will be in a suerposition of all possible orientations so overall the system is ...

2

Use the Evaluated Nuclear Structure Data File; search "by decay" and put the nuclide you'd like to start with in "parent." This will also tell you half-lives and Q-values. A few nuclides have multiple decay modes; for instance radon-221 usually beta-decays to francium-221, but alpha-decays to polonium-217 about 22% of the time. You may find other "forks ...

2

For gamma-ray wavelengths a much better alternative are Free Electron Lasers, since their gain medium is the Bestrahlung and synchrotron electron radiation inside the undulators. They also have the benefit of not being constrained to a nuclear energy state, and they can operate on a range of wavelengths

2

The application of active deconstruction schemes to manage nuclear waste has long history as a proposal, but has not yet been demonstrated as technologically practical. The usual schemes (i.e. the ones people have put time and money into and are still looking at) use electron beams (either directly or as a bremstrahlung source) because electron beams are ...

2

The elements that make up the bulk of the Earth were part of the presolar nebula. A similar (though not identical) mixture of elements is found in meteoritic material, which is thought to more accurately represent the mean abundances of that nebula (minus the volatiles) and indeed also agrees with the abundance patterns in the Sun. There are grains of ...

2

I've heard that the military has satellites orbiting earth with gamma detectors installed in them. The phenomenon of Gamma Ray Bursts was discovered when these satellites kept detecting gamma rays when no nuclear weapons were going off. See here: https://en.wikipedia.org/wiki/Vela_(satellite)

2

The transmutation of nuclear waste is a well developed research area. There was extensive work done a Dubna regarding this area. If you're looking to get into this area, there is the publication "Nuclear Methods for Transmutation of Nuclear Waste: Problems, Perspectives, Cooperative Research" published back in 1996.

2

I love the quote "Nobody believes an analysis except the person who did it. Everybody believes a test except the person who did it." Both simulation and test have serious shortcomings. You can't do many tests because they are expensive. Simulations do not incorporate all the physics. It is easy to decide incorrectly that some effect is not important and ...

1

I would say the maths and equations are pretty much identical except in H NMR you would use the gyromagnetic ratio for a proton, while in EPR you use the data for an electron. Both are spin 1/2 systems. In terms of medical imaging it is easier to pick H2O via pulse NMR (rather than continuous field i.e what chemists do for molecules etc) than observe free ...

1

For the lifetime of the neutron to be different, the weak interaction coupling constant would be different. As far as nuclei are concerned the unstable ones with beta decays would have different lifetimes. In general all weak interaction mediated decays would have different lifetimes.

1

Ryan is correct. In addition I would point to beta decay, in one form of which a neutron is transformed into a proton, inside the nucleus. This is called $\beta^-$ decay and is accompanied by the emission of an electron $e^-$ by the affected nucleus.

1

The halflife of the neutron is set by three things (more or less): the mass difference between the neutron and the proton, the number (two) of light particles that accompany the decay and the strength of the weak interaction. Changing number (3) effects the lifetime of all weak mediated processes, but all of them in the same sense. Changing (1) ...

1

The density of water as a function of temperature has a maximum around 4 degrees Celsius, so "hot" water is actually lighter than "cold" water. The mass defect is a very small quantity for most binding energies (as you devide by $c^2$). The mass defect of the proton and the neutron, each consisting of 3 quarks, is about 99% of their rest mass, the mass ...

1

Iron fusion can take place in stars - what you need is lots of iron and very high temperatures. These conditions exist in the cores of massive stars near the ends of their lives. For example alpha particles can fuse with an iron-56 nucleus to produce nickel-60 and then zinc-64; these reactions are barely endothermic. The problem is that there are competing ...

1

There are a fairly large number of replications of both the Nickel-Hydrogen variant and the original Fleischmann-Pons Palladium-Deuterium electrolytic cell variant. See this for a recent survey: https://www.academia.edu/17964553/Condensed_Matter_Nuclear_Science_October_2015 The results are becoming more mainstreamed (Wired, Forbes, Huffington Post), and thus ...

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