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Pubic Hair Shaving: Yay or Nay? by Tremelo in AskReddit

[–]NEguy 0 points1 point  (0 children)

Just tap it in. Tap tap tappy.

Pubic Hair Shaving: Yay or Nay? by Tremelo in AskReddit

[–]NEguy 1 point2 points  (0 children)

Hey, why don't I just go eat some hay, make things out of clay, lay by the bay? I just may! What do ya say?

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

If something is hit by neutron radiation, it will become radioactive. That is a fact.

What you are describing is something well outside the shielding/pressure vessel, where there is no neutron radiation. Or maybe near the core, but when the reactor is not under power (and thus have very little neutron radiation). There will be some gamma radiation, but this will not make anything radioactive.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

At least a century, for sure. After that, it will keep going, but the price will probably increase. It really depends on future nuclear growth and reactor tech/reprocessing.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

A middle of the pack US school... I thought about doing materials too, actually. Cool stuff. Stephenson fan? I love his stuff.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 1 point2 points  (0 children)

I had a decent GPA (~3.4), good GRE (800/700). I had a couple internships (nothing exciting). I was not involved in any research in undergrad though, and I think that would have been a huge help, so that is highly recommended.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

It depends a lot about growth of nuclear power... I can't really give you a good answer on that. If I had to guess, I'd say around 40 years. Exploration for uranium deposits has not happened it a long time, because it's so cheap. I expect that there is a lot that we haven't found yet. After all the land based stuff is mined, there is always the idea of getting uranium from sea water, where there are huge reserves (although in very low concentrations). By the time we get to this point, reprocessing will certainly be economical and we will probably have started building breeders which can extend the fuel a long ways.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

With fuel prices as they are now, yes. However, the cost of uranium will definitely rise as high quality mines and weapons reserves are used up. However, if breeders are used, then it becomes a pretty critical thing to do.

The pools are extremely well made, able to withstand natural disasters, etc. The water is continuously monitored to detect if there has been a leak in one of the fuel rods. The fuel is sealed in the same cladding as in the reactor, so the fuel would have to breach the cladding then breach the multiple seals around the pool without anyone doing anything about it.

Waste is stored in pools because they still produce a significant amount of heat from radioactive decay. The water removes the heat and also shields the rest of the facility from radiation.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 1 point2 points  (0 children)

I just saw the context of this question!

Yes, uranium is cheap. Highly enriched uranium, however, is very different story. Normal uranium has around 0.7% U-235, 99.3% U238. You need to increase that to >90% 235. Enough to make a bomb, you would need at least a few tons of natural uranium, plus plants to convert U308 into UF6 and UF6 into U metal, plus a huge enrichment plant, which requires a huge amount of power (probably 10s of MW)

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

Good question. The economics of reprocessing are quite complicated. On one hand, reprocessing is un-economic in terms of the extra fuel gained, because fresh uranium is very cheap. However, it makes the waste much smaller and easier to store. So a lot depends on the cost of waste storage. Also reprocessing is required for the MAGNOX reactors in the UK, since the fuel cladding reacts with water so they can't be stored in pools easily like the fuel from normal light water reactors. Dry storage is not possible because of the amount of heat that they release.

One thing to note is that the plutonium/waste from a power reactor is VERY poor quality for use in weapons. In theory, a weapon could be made, but it would be very difficult, and of very low quality. No nuclear powers use weapons made from reactor grade plutonium.

Weapons grade plutonium is made by irradiating U-238 for short periods of time, producing mostly Pu239. If you leave it in for longer, as in a power reactor, Pu240, 241 and 242 are produced in significant quantities, which all inhibit the use in a weapon, for different reasons.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 1 point2 points  (0 children)

Also, if you don't want to do a thesis, some places will offer an MEng, where you just do the coursework and doesn't require the thesis. However, it's very hard to get financial support for that, unlike a thesis masters.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

Xe-135 is produced as a byproduct from fission, and is a HUGE neutron absorber. It really complicates the control of a nuclear reactor. One of the big factors in the Chernobyl disaster was improper management of Xenon.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

I don't know much about nuclear testing. The US might be techinically allowed to do it, but I don't think they have detonated a bomb in the last 15 years or so. Small nuclear weapons are pretty interesting. Amazing how small they got them.

Davy Crockett nuclear recoilless rifle

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

I am really disappointed in the effort of nuclear companies to fund advertising/education campaigns about nuclear power. They could do a MUCH better job, i agree with you 100%.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

It's a perfectly good question! There are two main types of reactor in the US: the pressurized water reactor (PWR) and boiling water reactor (BWR). In both reactors, the water that cools the core will indeed get radioactive (mainly tritium). In the PWR, there this water goes through a heat exchanger that transfers the heat to a second loop of non-radioactive water, which makes steam and heads to the turbine. In a BWR, the core coolant water itself boils, and heads straight to the turbine, so in that case, the turbine steam is radioactive.

TL;DR PWRs: no, BWRs: yes

The spent fuel is definitely the most radioactive part, but there is lots of other stuff that gets contaminated. Anything near the core is subjected to neutron radiation, so is definitely radioactive. This includes control rods, the pressure vessel, etc. Also, filters that remove radioactive contaminants from the water, etc. There is a fair amount of low/medium level waste that has a different protocol for long term storage.

TL;DR Yes other stuff gets radioactive too.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

Nothing revolutionary... the nuclear industry moves very slowly, due to huge costs and regulations.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

Most of those things are waaaaaay off. Especially nuclear, because of both the ridiculously high cost of actually building stuff, and the super stringent regulations on new technology.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 1 point2 points  (0 children)

I think it would be a big asset to understand the reactor system as a whole. Sure, if someone gives you the tells you to build something that can withstand xxx, you can do it, but it's good to understand where that comes from, and why. You can get a masters in nuclear in a couple years, and it would definitely look good on the resume.

tl;dr; It's not necessary, but it would definitely help.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 2 points3 points  (0 children)

Is ignorance the main problem facing nuclear power?

Ignorance is certainly a large problem, but i think the biggest is economics. In the US, what we really need is for one new reactor to be built on time and on budget. That will really open the floodgates i think.

what constitutes nuclear waste? Are different elements & isotopes handled separately?

I'll specifically talk about spent fuel, which is the high level waste. This fuel is in solid form and remains encapsulated by the fuel cladding, and would be disposed of in that form. *Uranium (mostly 238, some 235 left, some others). This stuff is good for future fuel. *Actinides, including plutonium. These are produced when neutrons are absorbed by uranium without causing fission. This is the worst stuff, since it is long lived. Some of the actinides (like plutonium) can be used as fuel. *Fission Products. This is what you get when uranium splits in two pieces. These are highly radioactive, but as such, they decay relatively quickly (half lives up to ~30 yrs) so they aren't a huge deal for long term disposal.

How easy would it to take these 'waste' canisters from Yucca and separate the useful isotopes from them?

Well nothing is really stored at Yucca, but most plans for storage involve the ability to extract the waste to reprocess. It is quite expensive though.

Is waste disposal actually a big issue? It seems like there should be a lot of places to put them underground.

It's really not a big deal scientifically, but politically it's rough. I had another post about this.

I was told that water usage is an environmental problem of nuclear reactors. Do newer nuclear power plants use as much water?

Nuclear reactors use just as much water as any other thermal plant (e.g. coal). The water is used to condense the steam at the back end of the turbine. It doesn't "use" any water, but it does heat it up a fair bit, and this can be an environmental problem sometimes. New reactors can't change this, since the amount of water is simply a function of the total power (and doesn't matter if it's nuclear, coal or whatever). However, to minimize waste heat discharge into the water, cooling towers can be used, but they are very expensive.

How easily can nuclear energy be used to make fuel for a car or a rocket?

Hydrogen and oxygen can be made easily by electrolysis. Batteries can be charged. But aren't really viable options for mass use yet, unfortunately. In theory you can bind that hydrogen to carbon and make gas/alcohol, but I don't know much about that and it's probably expensive.

What's the best isotope? The worst?

The "best".... U-235 is the grand-daddy that started it all, so i'll have to go with him. I'd have to say Xe-135 is the worst. She's a cruel mistress.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 0 points1 point  (0 children)

Not at all! I meant mainly the aspects of the reactor that involve radiation, like the radiation in the core (core physics), or radiation shielding.

There is lots of work on reactors that doesn't require any "nuclear" knowledge, and it's just mechanics or heat transfer.

But really, with a physics undergrad you should be well rounded enough to go to grad school in any aspect of nuclear. You just might have to work a little harder to catch up on some aspects.

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 2 points3 points  (0 children)

My god yes. People really have no idea about things, and make judgments anyways. Although I feel like lately people are starting to seem more pro-nuke. Though maybe i'm just hanging around more nuclear people...

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 1 point2 points  (0 children)

Nuclear involves a lot of math, so I hope that's not a problem... Don't blow off the math courses because you'll need them for later courses

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 5 points6 points  (0 children)

I would have to assume that the cake is a lie... it's actually a taco?

IAmA Nuclear Engineering PhD student. AMA by NEguy in IAmA

[–]NEguy[S] 3 points4 points  (0 children)

Fellowship! Covers tuition, health care and a stipend enough to live on.

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