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Questions tagged [nuclear-engineering]

The study of radiation and radioactive materials and it's creation, safety, and applications.

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Why the National Ignition Facility try to use 192 laser beams to trigger ignition without heat capsule?

In the discussion of the question "Nuclear Fusion with extremely high pressure and low temperature", the conclusion is only ultrahigh pressure cannot trigger fusion. But why does NIF try to use 192 ...
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is possible to create a nuclear fusion using simple electric arc discharge?

If we have a simple discharge tube filled by deuterium gas or even heavy water, and put tungsten electrodes close to each other to create a huge electric field, then using a megavolt generator to ...
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Discussion about a new nuclear fusion design [duplicate]

Let me clarify here, this is not cold fusion. D&T gas will be compressed very rapidly and its temperature will increase very fast. So, I don't think this is a duplicate question. I have a new ...
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28 views

How does the shape of a radioactive material effect its critical mass?

If critical mass is defined by the amount of fissile material required to sustain nuclear fission. Assuming a subcritical mass object, and knowing radioactive materials can merely by chance break ...
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Proton-Proton, CNO, or white dwarf matter fusion reactor: Is it vaguely possible?

I understand that all efforts at present to make fusion work as an energy source have used light nuclei other than protons due to the fact that the cross section of the proton-proton reaction is just ...
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How does the shape of radioactive material effect its critical mass?

If critical mass is defined by the amount of fissile material required to sustain nuclear fission. Assuming a subcritical mass object, and knowing radioactive materials can merely by chance break ...
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47 views

What is the time for sufficient decay of plutonium to render an implosion type fission bomb ineffective

Plutonium decays leaving helium. In a mass of metallic plutonium, some of the metal will decay resulting in helium. This makes the plutonium spongy after time. Presumably this sponginess would ...
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Electronically controlled fusion reactor

It seems that currently, only two types of fusion reactor styles are being used for large scale testing: the Stellarator and the Tokamak. Both of these and a whole bunch of other designs have been ...
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30 views

Determination of Dead time of a Geiger Muller counter using the two source method

While determining the dead time of a GM counter using the two source method, why do we ensure that only two sources are placed in the counter at all times i.e. while determining the counts when both ...
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Heavy water neutron slowing equation

How can I find some equations about neutron slowing effects of heavy water? how much heavy water is required to slow down a given percentage of neutrons to a required degree(For example how can I keep ...
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78 views

How do we contain nuclear fusion?

I understand that here on earth we create fusion at temperatures that are much hotter then our sun. What I want to know is how we contain those high temperatures safely. Also if any one can give an ...
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34 views

Heating effect of fast neutrons in Fast Breeder Reactors

Do fast neutrons play effective(meaningful) role in heating up the water in Fast Breeder Reactors? If so, how much do they?
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Why is Neon not used as a coolant for gas cooled nuclear reactors?

What is the reason that Neon is not considered as good coolant for gas cooled reactors? I haven't found any research nor experiment with Neon in this field. As I checked out Neon has small neutron ...
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78 views

Introduction to nuclear physics

I want to self-study nuclear physics in order to understand nuclear reactors and nuclear weapons, what books can you recommend?
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How is fusion reactor fuel initially accelerated?

If, in a nuclear fusion tokamak reactor, you start with neutral fuels, how do you accelerate the atoms fast enough to start the reactor? Or do all of the particles have to ionized to begin with?
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Interpertation of Motron Number

The Reynolds number is interpreted as the ratio of inertial to viscous forces in a flow. Are there similar interpertations for The Motron Number?
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Why do some gases transfer radioactivity and some don't?

I have recently read that helium is going to be used as coolant in Generation IV nuclear reactors, because Helium is radiologically inert (i.e., it does not easily participate in nuclear processes ...
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What are the issues in highly enriched nuclear reactors?

The kinds of reactors used in submarines and rockets, are known to have highly enriched uranium ~80% and CO2 as the moderator in subs, and carbon(graphite) I guess in rockets. What are the extra ...
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Why do we not use cold neutrons in nuclear reactors?

Typical nuclear reactors use neutrons in the $10^{-2}$ eV range (thermal neutrons) which corresponds to a fission cross section of a few hundred barns. What stops us from using a super-cold moderator, ...
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Which elements or isotopes can be analyzed by Neutron activation analysis (NAA)?

Some sources name only a handful, but that might refer to the use of optical film. Others state more than 70. I would like to know which elemets or isotopes can be detectet/imaged by NAA.
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What determines direction of plasma current in tokamaks?

Plasma current is used to ohmically heat fusion plasmas and provide stabilization of grad-B drift in tokamaks as the resulting poloidal motion of the charged particles results in the particles ...
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Does plutonium need to be squeezed to produce an uncontrolled chain reaction?

I guess what I am asking is if in theory you could start with a certain amount of plutonium would it explode with out being squeezed together as is done in an atomic bomb ? Normally what happens ( ...
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How is energy actually extracted from fission?

Every source I can find right now just says something like 'energy/ heat is released by nuclear fission' but I can't find a description of the specific mechanism. I know that the energy 'conversion' ...
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2answers
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Why is specific nuclear activity (Bq/kg) not considering the surface area (cm^2)?

I have some basic questions regarding nuclear radiation: How come the specific activity (Bq/kg) only depends on the mass number and halftime of the emitter? Therefore, the emitted ions (let's say ...
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Optimal Deuterium-Deuterium fusion pressure equation?

I am building a Hirsch-Farnsworth Fusor (a simple D-D fusion reactor) and was wondering if there is an equation or algorithm that could be used to calculate the optimal pressure for deuterium-...
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What is the difference in energy density between molten salts and liquid metals?

Does sodium-potassium and lithium liquid metal mixture (NaK-Li) or transport molten salts (LiF-NaF-ZrF4) have a higher energy density? How much higher? Also, could either of these coolants be used in ...
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Observations of a mushroom cloud

In this video of a nuclear bomb detonation/mushroom cloud, a few peculiarities arise and I simply had a couple questions pertaining to observations in the animation: Following the detonation, the ...
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What is realistic minimum possible size, weight and power output of an atomic battery for 100kWh? [closed]

AFAIK atomic batteries could become a single unit nuclear reactor, but what it is smallest feasible configuration by our current knowledge? (even at conceptual design level)
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Nuclear fusion difficulties

What is it that make nuclear fusion so difficult at low temperatures? There is plasma existing at low temperatures, so what does it make for fusion to be so difficult to reach at ambient temperatures?
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4answers
122 views

Nuclear Physics Modeling Software

I have a nuclear reactor design I would like to model. I would like to show the individual atoms and how they interact with each other in the reactor (specifically, I would like to model decay modes, ...
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1answer
55 views

Control of Nuclear Fission

What is it precisely which prevents current technology in nuclear fission from controlling the size of fission products; in other words, why is it not feasible, presuming that such an approach would ...
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1answer
89 views

Can radioactive decay particles be modeled as plasma?

Since plasma is simply ionized gas (ie. charged particles), with the exception of neutron ejection (no charge) and gamma radiation (photons), can the natural decays of an isotope be modeled as plasma? ...
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What is the shelf-life of a gravity-powered uranium bomb?

Inspired by this Worldbuilding question about making a booby-trap with a very long shelf life. The idea is to suspend one lump of fissile material say $3/4$ of a critical mass above another of the ...
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Are the magnets in tokamaks variable in strength?

For example, if the plasma inside is beginning to terminate and collide with the walls of the confinement vessel, can the magnets account for this and realign the plasma?
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How many inches of lead would it take to stop the gamma rays equal to 8 inches of concrete ?

I have searched high and mighty on google and it is hard to find a comparison chart of different materials and their effectiveness to stop radiation from fallout. I am assuming the fallout source is ...
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What's the critical mass of elemental natural uranium? [closed]

What's the critical mass of elemental (ie metallic), natural (ie unenriched) uranium? If this isn't possible at standard temperature and pressure, how could they be changed to make a critical mass? Eg,...
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What would happen if you detonated a nuclear bomb inside a tank of liquid hydrogen?

Say you had a large bomb - take the 50 megaton Tsar Bomba. You then proceed to place it in the center of a spherical tank containing liquid hydrogen, and then detonate it. Could you start a fusion ...
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Nuclear reactor in a cruise missile. How?

So it is declared, that there are cruise missiles with nuclear reactors on board. As I understand, when it's working, the neutrons keep flying from off the fuel. Neutrons give induced radioactivity. ...
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How are cages in fusers protected against ion damage?

I have a simple question. Nuclear fusers (like the Farnsworth Hirsh design) use charged cages to accelerate deuterium ions to high enough energies to fuse and produce neutrons and energy. While these ...
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How can we make a nuclear weapon more effective in shielding us against asteroids?

I know that nuclear weapons do not produce the nuclear blast as it would at see level. But would the thermal blast produce any trust to push any asteroid away? If so, how could we improve the ...
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How is the radius of a nuclear disaster affected area calculated?

For example, take the Chernobyl disaster of 1986. The government evacuated a $30\,{\rm km}$ radius. I don't understand why $30\,{\rm km}$, I mean it's radiation, right? It can travel at speed of light....
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What happens to molecules when a neutron is captured?

What happens to a molecule during neutron capture? Does the process release enough energy to break the molecule bond? In fission this is obviously the case, since the compound nucleus forms and then ...
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Calculating the energy produced in watts in Alcator C-Mod

I calculated the energy in joules that a deuterium-tritium fusion reaction releases and found 2.81829046e-12J. I then read on some MIT articles that the Alcator C-...
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How ready is the current fusion reaction technology for the mass production of electricity?

Could you give a clear summary statement about the maturity of the controlled fusion reaction technology and its readiness for the mass production of electricity? There are many articles on internet ...
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Why it took such a long time for an army of physicists to realize the atomic bomb, while in theory it seems pretty easy?

I think most of us know about the construction of the first atomic bomb at Los Alamos, with Robert Oppenheimer (who said he became "The destroyer of worlds", which goes to show he regretted his ...
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Nuclear Fusion: Why is spherical magnetic confinement not used instead of tokamaks in nuclear fusion?

In nuclear fusion, the goal is to create and sustain (usually with magnetic fields) a high-temperature and high-pressure environment enough to output more energy than put in. Tokamaks (donut shape) ...
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1answer
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How to excite high spin nuclear state from ground state?

For example, the ground state of a nuclei is $0^+$, and we can excite $1^-$ state with a circular polarized gamma photon, which has a spin angular momentum $1\hbar$. This satisfies the selection rule ...
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Nuclear state notaion $J^\pi$

I have learned from nuclear physics literature that a nuclear state can be denoted as $J^\pi$, where $J$ is the spin and $\pi$ is the parity, such as $0^+, 1^+$. But when I read some papers on nuclear ...
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Why can't we harness the energy from neutron + protium = deuteron reaction?

The answer to this physics se question, established that 2.2Mev (Mega electron volts) of energy is emitted as a gamma ray photon when the hydrogen atom nucleus oka protium absorbs a slow moving free ...
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Could we create our own mini star?

If NASA were to work together with other space programs, could we accomplish the task of creating a mini star in the future. It wouldn't be huge, under a mile in diameter. We could make a core of ...