Questions tagged [nuclear-engineering]

The study of radiation and radioactive materials and their creation, safety, and applications.

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Why doesn't the water in a Light Water Reactor split to $\rm H_2$ and $\rm O_2$?

Intuitively I'd expect a nuclear reactor to produce gamma and neutron radiation powerful enough to knock hydrogen atoms/nuclei (or electrons) off $\rm H_2O$ molecules, some of which could recombine ...
Qwertie's user avatar
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What is "point of interest" and why isn't there a Zref for determining electron beam quality with TRS 398?

What is "point of interest" and why isn't there a Zref for determining electron beam quality with TRS 398? ((To what depth do you put the ion chamber when you do high energetic electron ...
medical physics's user avatar
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Green's function for a Hirsch-Farnsworth fusor

I'm writing a proposal for building a Hirsch-Farnsworth fusor at my university using a vacuum chamber, deuterium, and high voltage power. A loop of wire inside the chamber is set at a negative voltage ...
Tyler Mark's user avatar
22 votes
4 answers
6k views

Why don’t nuclear reactors burn through most of their fuel before discarding it?

The question: Why don’t nuclear reactors use more of the fuel, eg, 50%, 80%, before discarding it? It looks like there is plenty of energy left, and uranium is expensive. Also, there would be an ...
11111's user avatar
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2 answers
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Is fuel pellets a cylinder shape to decrease the critical mass?

A cylinder, especially a thin rod is a terrible configuration to have a self sustaining nuclear chain reaction. Cylinder pellets are used in nuclear reactors. A sphere is a much better packed ...
nammerkage's user avatar
1 vote
2 answers
166 views

Elevated Geiger Counter Radiation Reading for Envelope?

TL;DR: I'd like someone to run an experiment to prove that it is possible to induce a static electric charge on a plastic bubble mailer envelope (such as through rubbing with a plastic grocery bag or ...
jun192022's user avatar
-4 votes
2 answers
93 views

why are nuclear fallout shelters really necessary when radiation fades with distance so quickly? [closed]

why are nuclear fallout shelters really necessary when radiation fades with distance so quickly? it diminishes with the inverse square law. I1xD1^2 = I2xD2^2. (Standard procedure is to measure ...
Fyodor's user avatar
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Power from CNO Cycle Fusion

There are all sorts of projects trying to get power from fusion reactions. The best known and funded are the Tokamaks, big expensive crush Deuterium and Tritium (He3 sometimes) plasmas and spew ...
MongoTheGeek's user avatar
1 vote
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Why does the addition of flourine salts lower the melting point of thorium?

I recently read an article on Thorium reactors by John Suchocki (unfortunately, a link would only lead to a paywall). In it, he mentions that in the production of Thorium reactors, "The thorium ...
Robert Goddard-Wright's user avatar
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$\rm NaI$ detector calibration with $\rm Cs$-137 and $\rm Co$-60 using Genie-2000 software [closed]

I have tried to calibrate the NaI detector with the NIM set, Cs-137, Co-60 radioactive sources and Genie 2000 software. I used Cs-137 first and corrected the channel energy then used the Co-60, only ...
DrrMickey's user avatar
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What does a symmetrical explosion mean in the context of preventing accidental nuclear weapon trigger?

I just watched a video entitled This Is the Real Risk We Face with Nuclear Weapons. In the video, it referenced a "broken arrow" incident where a US B-52 was carrying a nuclear weapon met ...
dazzleworth's user avatar
1 vote
1 answer
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How to use point-kinetics approximation to go from diffusion to point kinetics?

I understand that we get to point kinetics by neglecting spatial dependence in the diffusion equation, but I'm somewhat stuck on the details here. Robert E. Masterson's Introduction to Nuclear Reactor ...
lcleary's user avatar
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Need Recommendations for Nuclear Reaction Modelling Software

Working on a project where I need to model nuclear reactions with different fuel pellet shapes. Does anyone have recommendations for software that's good for this? Any advice or experiences are also ...
5 votes
3 answers
2k views

Can the neutrons in a nuclear reactor be collimated?

N.B. I am not a physicist. My layman's understanding of a nuclear reactor is essentially that neutrons are doing one of 4 things at any given time in the reaction chamber: Flying freely around. ...
ConnieMnemonic's user avatar
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1 answer
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Why lasers are used in inertial nuclear fusion?

Why in inertial fusion are used laser rays but not, for example, merely focused light? Is there a problem with precision of focusing or power density?
Nonexistent user's user avatar
-1 votes
1 answer
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For Fermi's CP-1 experiments, why didn't they use much smaller slugs of natural uranium?

The Chicago Pile experiments used natural uranium slugs that were ~1.5 inches in diameter. The slugs were surrounded by graphite to slow down the naturally occurring neutrons to be able to affect ...
Young Jun Lee's user avatar
-3 votes
2 answers
97 views

How many typical nuclear power plants does it take to power 1 billion typical cellphones per year? [closed]

Not asking for an exact answer clearly. Let us say that a cellphone user typically watch like 2 hours of video per day and it is say on an iPhone of your choice. How much power would be needed to ...
mjs's user avatar
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Kramer's Equation at max Energy for photons is giving Intensity = 0, how is this possibe?

IE = KZ(Em – E) where IE is the intensity of photons with energy E, Z is the atomic number of the target, Em is the maximum photon energy, and K is a constant. As pointed out earlier, the maximum ...
medical physics's user avatar
2 votes
2 answers
168 views

What would happen if the fuel rods in a nuclear reactor were completely depleted?

My understanding is that in commercial nuclear reactor operations, fuel rods are not used up to the point where they're fully depleted and unable to support fission, but are replaced while they still ...
mkay's user avatar
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Tritium Decay and He-3, $n$ reaction

I have two separate questions that I have simply not been able to find any answers to: With regard to Tritium decay to He-3, I'm a bit confused as to why Tritium is unstable based on its $n$ to $p$ ...
Chris's user avatar
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Can you theoretically form plutonium 238 form plutonium 239? And if so then how and what are its limitations?

Basically if we could convert plutonium 239 to 238 then we could create space fuel from nuclear waste but if it is possible then what are its limitations due to which this process is not generally in ...
Fun with Science's user avatar
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1 answer
69 views

Why does the mass deficit exists? [duplicate]

Everyone knows Albert Einstein's famous formula: $E = m * c^2$ In nuclear fission, we make use of it by converting mass into energy. But what is the mass that gets converted? Of course, when nuclei ...
dark_ursus's user avatar
0 votes
1 answer
228 views

How does a nuclear reactor start? [closed]

okay first I want to say I know there is a lot of video on YouTube that show a reactor starting but I was wounding like how it starts if anyone has like a diagram or something of the process of a ...
Hugo ADAMS's user avatar
13 votes
1 answer
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Is it possible to make an all natural smoke detector from Brazil nuts?

After reading about Brazil nuts, I discovered they have very high levels of radiation due to trace amounts of Ra-226 and Ra-228 and their decay products. A kilogram of the nut, for instance, gives a ...
user148298's user avatar
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1 answer
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Why isn't there Bremsstrahlung Radiation for Energy less than 20 keV for Tungsten?

https://www.researchgate.net/figure/Bremsstrahlung-and-characteristic-radiation-spectra-are-shown-for-a-tungsten-anode-with_fig4_8365056 Fast electrons produce X-rays in the anode of an X-ray tube ...
medical physics's user avatar
5 votes
2 answers
183 views

Why doesn’t proton emit in nuclear fission instead of neutron emission?

I was wondering in a nuclear fission, why does the neutron get emitted but not the proton? Is there any case where in a nuclear fission, proton emission happens?
Fisica Amante's user avatar
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Why one curve is up and other one is below for the same or different compound nucleus and why the curve shape is like this?

the plot is potential vs deformation, I want to know why there is difference between two potential vs deformation curves for the same and different compound nucleus and why the shape is like that.
Avi agrawal's user avatar
4 votes
1 answer
77 views

How much Uranium would a country like Iran need to produce for supplying its Technetium needs?

This is not a question about politics, although the motivation is a political situation. Iran, which enriches Uranium to a level of $60\%$ $\rm{^{235}U}$, is claiming it has civilian uses for this ...
einpoklum's user avatar
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Why it is not possible to reach the sun if we are able to create plasma? [closed]

if we are able to create plasma in isolated environment possessing temperature much more than temperature of sun then why are we not able to create something that can go to the sun?
Mohammad Sameer's user avatar
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2 answers
354 views

In nuclear weapons, why does levitating a pit improve compression?

Levitated pits were introduced after after solid pits. In this design the tamper is separated from the fissile with an airgap. From the Nuclear Weapon Archive: The original Fat Man pit design used a ...
Jane Bass's user avatar
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Difficulty in choosing which RF 13.56 Mhz Plasma Jet configuration to use

Can anybody explain why we can't use Molecular gases as our operating gas when we choose figure 1? Is it possible to use figure 1 using molecular gases such as O2 and Air or should we stick to the ...
Ireneo de la Cruz Jr.'s user avatar
2 votes
2 answers
313 views

What is the practical implication of positive void coefficients in certin types of nuclear reactors? [closed]

One difference between the Chernobyl disaster, on the one hand, and the Three Miles Island and the Fukushima disaster, on the other, is that Chernobyl's RBMK reactor design implied a positive void ...
erised's user avatar
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1 answer
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Are there any research mentioning the principle of tornados or maelstroms in plasma physics related to fusion?

There are many different ideas and concepts related to design of fusion reactors and handling plasma confinement, but what about designing one around the principles of a maelstrom or a tornado? Is ...
Andreas Zita's user avatar
8 votes
4 answers
2k views

Non-irradiative methods to create radioactive isotopes?

My understanding is that the primary methods with which one can create a radioactive isotope are 1) just waiting for the isotope you want (by means of nuclear decay), or 2) some kind of induced ...
DataScienceNovice's user avatar
0 votes
2 answers
132 views

How does the second stage of a fusion bomb create and maintain the needed pressure?

My understanding of the second stage of a thermonuclear bomb is as follows: X-rays from the first stage compress the "tamper", thereby igniting the fission sparkplug, and that the resulting ...
user56834's user avatar
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24 votes
15 answers
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Why are nuclear fusion reactors difficult?

The first fission bomb was created in 1944, and the first fission reactor in 1951 (and actually productive one in 1954). This delay seems possible to explain by there being a larger amount of initial ...
user56834's user avatar
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1 vote
1 answer
111 views

Is there a minimum mass required to create an atomic bomb? [closed]

I have heard that there is a minimum mass of fissile material required to produce an explosion. If so why would this be? Is it true North Korea found a way to overcome this?
Derek Seabrooke's user avatar
9 votes
3 answers
445 views

How did Enrico Fermi compute when the Chicago Pile-1 nuclear reactor would become critical?

I'm trying to understand the first nuclear reactor, the Chicago Pile-1, specifically the math Fermi did to figure out when the reactor would go critical. There's a nice report available from Fermi, ...
Stephen W.'s user avatar
34 votes
4 answers
6k views

Why is water a good neutron absorber?

I've seen this question asked multiple times, and the answer is never detailed. I initially assumed that either hydrogen or oxygen had relatively large neutron absorption cross sections, however that ...
ryani42's user avatar
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1 vote
2 answers
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Are there any calculations that "backup" magnetized inertial fusion by steam pistons?

Piston driven MTF can generate fusion. General Fusion has released data on the plasma confinement that they do in their machines, so there is no doubt to the feasibility of the approach. Nonetheless, ...
Evamentality's user avatar
1 vote
1 answer
61 views

The Orion Project --- do the predicted speeds violate the Tsiolkovsky Equation?

I understand that a conventional rocket may move faster than its thrust but IIRC the equation developed in the 19th century the speed is limited to 4/3 the thrust speed. Now, I understand that the ...
releseabe's user avatar
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1 vote
2 answers
143 views

NIF Ignition Achievement

Although the National Ignition Facility achieving positive energy output is hailed as an achievement in fusion energy, I am curious whether their configuration could ever be adapted to produce ...
RC_23's user avatar
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1 vote
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Length of light burst of concentrated emission from hydrogen bomb in outer space

Imagine a large hydrogen bomb in outer space. Behind it is a huge mylar parabolic mirror. (Aimed anywhere, for instance at a star system we want to communicate with.) The bomb is placed in the focus ...
Prof. Falken's user avatar
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2 answers
112 views

Why can't high-level nuclear waste be disposed of by bombarding troublesome isotopes with neutrons, protons and gamma rays (photodisintegration)?

Why can't isotopes with long half-lives be radiated with free protons, neutron radiation and gamma rays (photodisintegration) in order to transmutate those isotopes into something either stable (or ...
Kurt Hikes's user avatar
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0 votes
1 answer
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Would a fusion reactor using Helium-3 get some of its energy from fusing it with free neutrons?

I know that He-3-based fusion is supposed to be aneutronic, but aren't there still some free neutrons? Would this make a noticeable difference in heat/energy produced? Also, couldn't helium-3 be ...
Kurt Hikes's user avatar
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0 votes
1 answer
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Heat transfer in fission nuclear reactors [closed]

In a nuclear fission reactor, the fissile material and the water that is heated up are separated by a physical barrier. That barrier would allow for the transfer of heat via radiation (of photons) and ...
anonymous's user avatar
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4 votes
1 answer
161 views

What enabled ignition at the NIF?

The National Ignition Facility achieved breakeven on December 5th, obtaining more than 3 MJ from an input of 2.05 MJ. What have they been doing differently, starting this summer? Laser shots this year ...
J_H's user avatar
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1 vote
1 answer
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How to calculate radioactivity concentration of components in reactor?

I understand the reactor parts will become radioactivity because there are neutron flux in reactor. How should we calculate the reactivity of reactor parts? For example lets say there is a reactor ...
jjk's user avatar
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-1 votes
1 answer
153 views

Why don't we use nuclear fission to generate the necessary temperatures needed for nuclear fusion? [closed]

We can control the energy generated by nuclear fission by limiting the amount of neutrons release. Those extremely high temperatures will be more than sufficient to incite a nuclear fusion process.
Beginnis's user avatar
1 vote
1 answer
61 views

Conversion of Reich-Moore resonance parameters to neutron cross section?

For the Single-Level Breit-Wigner (SLBW) formula, the peak resonant neutron cross section is related to the total width, $\Gamma = \Gamma_{(n)} + \Sigma_{r}\Gamma_{(r)}$, reported as GT in ENDF. For ...
unclearnuclear's user avatar

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