The study of radiation and radioactive materials and their creation, safety, and applications.
Questions tagged [nuclear-engineering]
478 questions
15
votes
4 answers
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 cleaned up the disaster tunneled concrete under the…
Michael Papile
- 253
11
votes
3 answers
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 reaction so far that cooling is not needed? Why do…
Ziplin
- 253
11
votes
4 answers
What is the minimum amount of fissile mass required to acheive criticality?
Wikipedia gives the following definition for critical mass.
A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction.
No mention is made of a neutron moderator in this definition. If critical mass…
Alan Rominger
- 21,047
8
votes
2 answers
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 are no nuclear warheads in service made of U-235,…
BarsMonster
- 2,371
7
votes
4 answers
Neutrons reflective materials in nuclear reactors
Nuclear reactors are driven away from criticality with the use of control rods which absorb neutrons. In case of overheating and melting of the core, the control rods may not be inserted any more leading to a disaster.
A subcritical mass can be made…
DarioP
- 5,185
6
votes
3 answers
scrap iron for stopping a meltdown
Would it be possible in a Fukushima-style meltdown to halt the process (edit: I mean halting the meltdown process, not the actual nuclear processes) by dumping large amounts of iron into the vessel? The iron would melt and mix with the uranium,…
cassius
- 437
5
votes
3 answers
Is a Rubbia thorium reactor safer than other modern reactor types?
I keep wondering how a Rubbia thorium reactor would handle a natural disaster of Fukushima level intensity. As I understand it the nuclear chain reaction would stop instantly if the power is cut, but nasty waste products such as Uranium-233 would…
Stein Åsmul
- 427
4
votes
3 answers
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 of meltdown? suggests that the hydrogen is caused by…
Chris Fewtrell
- 183
2
votes
0 answers
How big is a nuclear reactor pressure vessel?
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 of a conventional BWR or PWR? I've seen, now,…
Eric B
- 121
2
votes
1 answer
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?
wnrph
- 1,287
2
votes
1 answer
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 temperature of the corium of those type of reactors known…
shellholic
- 125
2
votes
1 answer
Smallest possible size of nuclear reactor
I recently began playing Fallout 4 and asked myself a question: Would it be possible to build a power armor with todays technology?
I did some investigation on servomotors and stuff and came to conclusion that it would be theoretically possible to…
Martin Tausch
- 121
2
votes
0 answers
How viable is reuse of nuclear waste at this point, and what are future prospects?
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 geologically stable regions, and I was under the…
Stein Åsmul
- 427
1
vote
0 answers
Could a long wire of uranium control nuclear reactions?
If you fashioned a very thin wire of uranium, perhaps coated in Lead, then started a nuclear chain reaction at one end, could you create a sustainable safe nuclear power?
Since the nuclear reaction is forced into 1 dimension essentially, could it…
user84158
1
vote
0 answers
Is it plausible for water to be more irradiated than air 200 years after a nuclear war?
Assuming I am alive 200 years after a nuclear war, fought with today's nuclear weapons. Is it plausible that while I can be outside and breath the air unharmed, diving under or drinking water will irradiate me to a much stronger degree?
Is this…
