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

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6
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1answer
417 views

Why does it take so long to make a nuclear bomb?

So as I know nuclear bombs are derived from fission reactions: By providing the nucleus with enough power to trigger a chain reaction. If uranium was present why does it take so much to make a nuclear ...
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2answers
112 views

Theoretic Mass Energy Conversion?

say you had a large quantity of a heavy element such as uranium... AND you put a massive amount of energy into it, so that it began to undergo nuclear fission and transformed to a significantly ...
2
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2answers
213 views

Why increase pressure to go from liquid to steam?

Assume the following phase diagram $T-H$ of water At a nuclear engineering course, I was told that in order to increase the performance of a pressurized water reactor, one has to increase the ...
0
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0answers
209 views

Constant Pressure lines in evaporation diagram

Assume that there is the following $T-H$ phase diagram with the constant pressure lines. Which is greater preasure? The preasure drops as we move to lower temperatures (i.e. from top to bottom)? ...
2
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1answer
108 views

neutron transport approximations for nuclear rocket modelling

I'm pretty ignorant regarding neutron and nuclear transport modelling, but i'm interested in trying to pursue it for a particular pet project. It regards modelling of nuclear reactions like those ...
3
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1answer
112 views

Containement system of a nuclear reactor: role of the water moderator

In a modern nuclear reactor for example a PWR there are multiple containment systems which prevent the release of radioactive material into the environment and shield the environment from the ...
11
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2answers
3k views

How would a black hole power plant work?

A black hole power plant (BHPP) is something I'll define here as a machine that uses a black hole to convert mass into energy for useful work. As such, it constitutes the 3rd kind of matter-energy ...
0
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1answer
532 views

Speed of neutrons in a nuclear reactor

How fast (in $\frac{\mathrm{m}}{\mathrm{s}}$) are typical neutrons before and after slowing down in a nuclear reactor (with U-235 and $H_2O$ as moderator)? Do you have any reference for the values?
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2answers
106 views

Why not assimilate nuclear waste into “igneous” rock?

I was reading a question about why not to drop nuclear waste into volcanoes; the short answer is it would come back out and not be rendered safe. Ignoring the cost and energy requirements, why can't ...
3
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1answer
230 views

How is it possible to calculate the energy liberated by a given fission process?

How is it possible to calculate the energy liberated by a given fission process? For example, in the fission of a $^{235}$U induced by capturing a neutron?
3
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1answer
317 views

Why is the total interaction cross section larger for incident particles with lower energy?

The cross section of a nuclear interaction is a measurement of the probability of that interaction occuring. These probabilities are typically presented in terms of barns ($10^{-28}$ m$^2$) as a ...
0
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2answers
89 views

Nuclear based wireless power?

I would like to ask if there is any Nuclear process which can be used to produce a wireless power ? Is there any nuclear process can be radiate to the environment with no harm to human beings? ...
8
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2answers
1k views

Military-grade U-235 uses

In the news it is often mentioned that some countries are going to enrich uranium to "military grade" (i.e. 80%+) and that it is possible to use it for a nuclear bomb. 1) Is that correct that there ...
2
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1answer
573 views

Why did the Hydrogen in Fukushima explode *outside* the reactor vessel?

As pointed out before, it orginated inside the reactor vessel but exploded outside: how did it get there? Did it pass the shell by diffusion or was it released by the engineers?
2
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2answers
341 views

Water-cooled fast neutron reactors

Can anyone explain why fast neutron reactor designs use sodium/lead/salt cooling, instead of water (heavy/light)? Is that because neutron absorption by water would not allow to break even in fuel ...
3
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1answer
330 views

Nuclear Salt Water Rockets: viability and follow-up

This is the original paper by R. Zubrin proposing the Nuclear Salt Water Rocket design. Basically the design is that a capillar set of pipes store a uranium salt-water solution, inside a cadmium ...
5
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1answer
276 views

What causes the structure visible in first few milliseconds of a nuclear explosion?

Following on from this question, here is a high-speed photograph of a nuclear explosion, taken about 1 ms after detonation: (source) As anna v pointed out, several similar images can be seen in a ...
2
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5answers
416 views

Thorium radioactivty vs Uranium radioactivty nuclear power

May i please open this question by asking that if you intended to answer this please could you provide links based on your answer. I have read ( and posted one ) on thorium and a lot of the answers ...
39
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8answers
14k views

What practical issues remain for the adoption of Thorium reactors?

From what I've read on thorium reactors, there's enormous benefit to them. Their fuel is abundant enough to power human civilization for centuries, their fission products are relatively short-lived, ...
14
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4answers
2k views

Why can't there be a trap door under nuclear reactors in case of meltdown?

This may be a naive question, but after the Fukushima Daiichi partial meltdown and studying the aftermath of Chernobyl it seems they could be helped by this idea. In Chernobyl, the liquidators that ...
1
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0answers
75 views

Properties of spilled spent nuclear fuel pellets

Can someone please explain to me the physics of a pile of spilled nuclear fuel pellets on the floor of a spent fuel pool? Specifically, what can we expect in terms of heat and radioactivity releases, ...
0
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1answer
223 views

Direct nuclear reaction in nuclear physics

Time taken to occur a direct nuclear reaction is very low $10^{-22}$sec . I want to know the Importance of direct nuclear reactions.
2
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1answer
1k views

Why are we not using thorium for energy? [duplicate]

Possible Duplicate: What practical issues remain for the adoption of Thorium reactors? I have been reading and watching a bit on thorium TH 90 and cannot understand why this is not being ...
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2answers
287 views

How to detect radiation on the metal (coin)?

I've got metal coin : http://www.worldpeacecoin.org/ Ruble/dollar, a coin of disarmament with certificate. But, I am very spleeny person, I fear of it's radiance level and I don't know if I can trust ...
3
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1answer
66 views

The synthesis of $^{254}\text{No}$

How is $^{254}\text{No}$ synthesised? Could you explain the reaction where it is preceded by $^{208}\text{Pb}(^{48}\text{Ca}, 2\text{n})$? References to articles are well enough—I was somehow unable ...
1
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1answer
156 views

Is there a good summary of all nuclear fusion approaches?

I am pretty sure, that during last 60 years of well-funded research a lot of ideas on nuclear fusion were already tried and ruled out. Is there some summary describing all of them and why they ...
2
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3answers
445 views

Nuclear physics problem, Why do we use high weight atomic elements?

So as far as I know, nuclear fission uses high weight atomic elements to manufacture power. If the risk of runaway reactions are a major reason for not expanding this technology, why don't we use ...
1
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2answers
93 views

Statistical Weighting Factor on thermal neutron importance

The problem is concerning the use of a thermal fluxed squared weighting factor in a thermal reactor. I have seen in sources the thermal flux in a reactor is squared as a statistical weighting factor, ...
1
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1answer
151 views

How does the curiosity rover get it's power? [duplicate]

Possible Duplicate: Mars Curiosity Power System I found a web page that said it uses Plutonium. I am sure it's not based on fusion or fission. What is the basic idea on which the power ...
1
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0answers
88 views

scaling laws for density and temperature of high-energy explosions

I'm wondering if there are heuristic ways to derive how the peak density and temperature of nuclear explosions scale with the amount of fissile/fusible material. Does it matter what the explosion ...
6
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1answer
1k views

Nuclear fuel pellets - when does the chain reaction start?

Questions about nuclear fuel: Does nuclear chain reaction start in fuel pellets even before they being installed in reactor? If not, why not? My understanding is that since the fuel pellets are ...
2
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2answers
91 views

critical density to create macroscopic nuggets of nuclear matter

Is there a critical size that an hydrogen bomb detonation needs to have in order to produce neutron-degenerated matter? Does anyone knows if matter in this state would be stable at ambient ...
3
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2answers
856 views

Nuclear reactor control rods

What is the relation between control rods surface exposed into a nuclear reactor and neutron energy? Is it linear? I mean, how do neutron absorbing rate change with the progressive immersion of ...
2
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1answer
77 views

Boiling water reactor

What are the typical power densities in conventional boiling water nuclear reactor per cubic centimeter of fission material?
2
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2answers
496 views

Russian Doll Teller Ulam?

Can you trigger a thermonuclear explosion from a smaller thermonuclear explosion in a scaling way, so that starting from a small laser ignited fusion within a small fissile container, using the X-rays ...
2
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4answers
339 views

Why was PACER abandoned?

The PACER project is described in this question: How much of the energy from 1 megaton H Bomb explosion could we capture to do useful work? Why was it abandoned? It seems that it is the only readily ...
2
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2answers
529 views

If there is a meltdown at the Fukushima reactors, would the control rods melt also?

According to the reports, the shutdown procedures at all the Fukushima reactors were successful, and all the control rods were fully inserted. So - if there was a meltdown, would the control rods ...
1
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2answers
243 views

Is it viable to convert nuclear waste into safe isotopes?

I read that powerful pulsed lasers can change isotopes: J. Magill, et. al.: "Laser transmutation of iodine-129". Did anyone estimate what would be the energy costs to transmutate 1 kg of fission ...
2
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0answers
241 views

How viable is reuse of nuclear waste at this point, and what are future prospects? [closed]

I keep seeing documentaries describing the pile-up of nuclear waste from nuclear power stations in the US and in other countries. Countries such as Finland are working to deposit waste in old mines in ...
3
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2answers
395 views

How much radiation exposure in the US was caused by the 105 nuke tests in the Pacific?

Between 1947 and 1962 the US conducted 105 tests of nuclear weapons in the "Pacific Proving Grounds". I'm wondering how much radiation exposure resulted on the west coast of the US. These were part of ...
11
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3answers
3k views

Why didn't the control rods in Fukushima shut down the reactor?

With all the hubbub over the reactors in Japan and nuclear safety, I was wondering why the insertion of the control rods in Fukushima did not shut down the reactor? Shouldn't they slow the fission ...
1
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0answers
225 views

How big is a nuclear reactor pressure vessel? [closed]

With all the sudden discussion related to Nuclear power, safety, fuel, waste, etc, there's one question whose answer has so far eluded me. How big (height and diameter) is the actual pressure vessel ...
4
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6answers
781 views

Is there any inherent danger in operating a Thermonuclear Reactor?

Nuclear fusion research appears to promise sustainable, practically unlimited energy, and according to ITER it will be a perfectly safe, non-polluting source of energy. My question is if there are ...
0
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3answers
5k views

Why build nuclear reactors on shorelines?

While not directly a physics question, I can't think of forum better capable of answering my question. In discussions over Japan's nuclear reactor situation the observation was made that reactors ...
0
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1answer
879 views

Conceptual problems in nuclear physics for students?

Is there any good reference for conceptual problems for students which learn nuclear physics first time? I am not searching problems that involve difficult calculations. Quite the converse, they ...
2
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1answer
307 views

Fukushima - Isn't the hydrogen presence a proof of meltdown?

As I understand, the hydrogen is produced by water thermolysis, which need quite high temperature. This temperature is close to previously observed corium temperatures. So: Is the eutectic ...
4
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3answers
650 views

What is generating the hydrogen that has exploded in the Fukushima reactor?

The explosions at the Fukushima nuclear reactors were caused by a build of hydrogen. I was wondering where this hydrogen came from. This question Fukushima - Isn't the hydrogen presence a proof ...