/sci/ - Science & Math

y u no thorium?

Computer engineering student.

Can you tell me about the control systems used for reactors?

>>4587022
Please leave, adults are talking.

>>4587016
Got a friendly explanation for how an RF quadrupole works?

>>4587022

I actually think there are a lot more promising technologies out there, mainly Brayton-based HTGR using U-238 on the fast spectrum. Most of the challenges in designs are very similar to that of thorium, but there are fewer of them, mostly temperature/radiation tolerances of material. Thorium designs would still have to use steam generators in some way, shape, or form and Braytons are much more efficient in terms of overall cycle efficiency. Though, I am a fan of the modular ability of Thorium reactors.

>>4587026
As it stands in the US, the policy regarding digital systems is a little ass-backwards. For power generating plants, any digital system must use hardware and software designed when the original plant was built (so, in the US, we're talking 60s-70s hardware). For that reason, most control systems are mechanical with only electronic signals, and the actual control systems are operated manually (usually) with most operator judgement. The only exception is, there are reactor trip signals that will occur without operator input (usually a function of mechanical fail-safes).

>>4587037
No clue.

>>4587022

>>/reddit/

1. has there been any important progress in disposing used uranium rods?
2. one thing i've always wondered is why subs have nuclear reactors in them. lets say the reactor has a meltdown. would'nt the environmental damage be catastrophic? if not why don't we implement nuclear power on say aircraft carriers or a space ship?
3.the picture you have up. do you have to put on a scuba suit to work on them?
4. do you think nuclear energy will become a better option in the future?

>>4587016

how far is NE from ChemE
ChemE here and my school doesn't offer NE anymore, but its always made me curious

>>4587051
1. To be completely honest, no. If anything, we've taken a step backwards in terms of disposal in the US with the closing of Yucca mountain. As far as I can tell, long-term disposal consists of used assemblies sitting in cold water storage for years to come.

2. The simple reason is because they don't have to be refueled. And actually, most aircraft carriers in the US now are nuclear powered. The problem we have with outfitting spacecraft with reactors is getting everything there. If something catastrophic would happen while getting fuel to orbit, fuel grade uranium would be spread all over the Earth. But on naval systems, the reactors are rather secure. I know on US Naval vessels, if there were to ever be a loss of coolant, reactor containment can be completely flooded and recirculated to be rid of hot water. This actually ensures that the original core geometry is maintained and there is little to no fission-product migration.

3. No, usually, work is done after cold shutdown (only heat coming from fission products) and the pool is usually drained to the top of the fuel elements to accommodate for refueling or repair work.

4. IMO, it's always been the best option besides fossil fuels. The pros: carbon free (except for construction of plants), high fuel reserves, propensity for on-demand electricity in volume. The cons: long term waste disposal (in actuality, nuclear fuel contains less long-lived waste than coal slag, kilo for kilo). There's no way that renewables can supplant nuclear in terms of baseload capacity.

are you studying NukeE at the undergrad level? there's only a few universities that offer it.

when did you decide what NukeE was the most appealing degree for you?

>>4587060

I don't know how it could be a subset of ChemE. To be completely honest, I only needed to take chemistry 101 as a degree requirement. Unless you were studying materials science or fuel fabrication, there would be little information overlap. The closest engineering to nuclear would probably be mechanical, as there is a lot to learn from thermodynamics, heat transfer, fluid mechanics, etc.

>>4587047
>any digital system must use hardware and software designed when the original plant was built

What. The. Fuck.

That's so stupid I can't believe it. Modern digital control systems are going to be way safer than something mechanical from the 60's, plus they'll operate the reactor more efficiently and not require paying (as many) people to run them. What's the justification for this policy? Is there some provision for upgrading?

Another question..how are reactors evolving over time? With computers we have constant progress through scaling, is there an equivalent level of progress in reactor design? What country is driving progress the most?

>>4587071

Yes. I actually came to that conclusion after becoming interested in fusion energy some time ago. Unfortunately, across my entire undergrad career, I've only had one class that ever really gave some information on fusion. Additionally, there aren't very many engineers trained in nuclear, so there are tons of job opportunities. Surprisingly, NEs are used in many job sectors, not just power generation. Even so, I feel a bit specialized in nuclear and am trying to go to graduate school and study something more general, like power generating cycles as a whole in mechanical engineering.

>>4587079
It's basically a policy created in heavy NIMBY times. The idea was that newer digital systems wouldn't be compatible with the original plant designs and would be more prone to accidents. It's simply not the case. And yes, there actually has been tons of progress in reactor designs, mainly improving passive safety abilities in reactor designs. Take for example, the advanced boiling water reactor and its kin (ABWR, ESBWR, etc.) They're designed to act either completely on natural circulation (not relying on internal coolant recirculation pumps) or up to 1/3rd of their rated power (which is actually a fuckton, usually around 3GW). These passive designs of existing systems are being spurred by mostly US (GE-Hitachi, Westinghouse) and French (AREVA) companies. Other reactor developments, like alternative fuel systems (mainly Thorium) are being developed mostly internationally, in this case, the Indians. HTGRs that I mentioned earlier are US designs as well.

>>4587074

thats what I meant lol, chemE does a lot of heat transfer, and momentum transfer, and a lot of thermodynamics. I'm sure you learn it in a completely different context though

>>4587098
we do a lot of heat and thermo here as well. I'm just doing what i can to get to oak ridge or a national lab. Supposedly cheme's are in demand for a lot of the process work.

true or false: the title "nuclear engineer" is more appealing than what you actually study.

>>4587115

>>4587115
False. Fusion energy is in question.

>>4587115

Completely true, refer to what I said about choosing the major. In actuality, I learned a lot of interesting things that I thought would never learn in my studies, but it doesn't overcome the fact that I was thinking it would be very fusion heavy or studying something completely different from what I actually am. Truthfully, it seems that the study is bogged down by politics and environmentalism. I can't do cool shit because NIMBY/Greenpeace assholes ruined all the fun. I take some solace in the fact that I'm doing something that the majority of the population knows nothing about, though.

What do you hope to do when you receive your degree? Will you find a job or will you go straight to grad school?
Are nuclear technicians also nuclear engineers as in operation of a plant?

>>4587124
thanks for the honest answer. your humility is a rare but nonetheless welcoming sight on this board.

>>4587124
If i were to study NE at a school with a prototype fusion reactor,(also has fission reactor) would the curriculum likely involve fusion research/ learning, or no different. Also, Is it a good mix of science and engineering? Finally, what fields could nuclear engineers go into besides plant operation.

What are you plans for a job after school? I wanted to major in NE but chose physics instead so I could get a job easier (as I live in the US and people think nuclear plant disaster=nuclear explosion. also hippies). I'm spending my PhD days doing a lot of nuclear physics anyway but I wish I knew more about the equipment/technologies than just the QM that I do.

>>4587016
What school OP?

How many of your classes would you have been able to skip if you knew that your career was going to be designing dusty plasma fission fragment breeder reactors that will be entirely remote-operated and located on the moon, Mercury, and various other places where it's perfectly acceptable to just dump radioactive waste out the sides?

>>4587132
Well, I was hoping to go straight to graduate school for mechanical, but there have been some complicating issues. So, it looks like I'm going to have to find a job. I'd rather not work at a plant (btw, the technicians are not really engineers, to answer your other question. As an undergrad at my university, you can take a single class, and if you pass the final exam, i.e. the state certification exam, you can become a fully licensed operator technician). Right now I'm looking at plant design operations (like Rolls Royce or GE), General Atomics, various government jobs, or maybe even a research hospital (there are quite a few around where I live).

>>4587163
I can't imagine the the undergraduate curriculum would be much different. The fusion stuff is probably reserved for graduate students. If you're lucky, you might be able to do experiments/research on the tokamak (I'm assuming it's a tokamak unless you're looking at Berkeley, they have an inertial confinement reactor). Though, I did do a few experiments on the fission reactor at my school. And yes, I will completely agree that there is a LOT of engineering work with a lot of science. I'm almost done with my senior design project, which involved engineering systems to accompany a D-T accelerator neutron source. Some of the other possible fields I listed above. But surprisingly, the most well paid NEs work for oil companies, usually for surveying of wells. You can also go into reactor design, medical physics, etc.

Does NE do anything with Mass, energy, and momentum balance? I'd assume since mass conservation is an issue, you guys might not use it.

>>4587169
See above. The field is surprisingly versatile. Let's not forget that nuclear power is making a comeback in the US, despite Fukushima.

>>4587171
NC State

>>4587180
I have quite a few hardcore professors that are of the philosophy "If you don't want to come, don't." Which I have no problem with. I tend to skip some classes that are pretty much a professor reading off lecture slides (like any other class at college). If I were taking a class that allowed me to dump waste no one cares about, I wouldn't miss a minute. Except if we were dumping on the moon, I'd like to see the moon mined for 3rd generation fusion fuels sometime in the future.

>>4587187
Yes, actually. A lot of the intro NE classes are all about special relativity and nuclear theory. Not to mention the one medical physics class I took pounded the concept into my brain. Most of the intro classes feature the basics of nuclear science (special relativity, mass balances, various nuclear reactions including decay and transmutation, etc.).

>>4587201
>Except if we were dumping on the moon, I'd like to see the moon mined for 3rd generation fusion fuels sometime in the future.
Dude, it's the moon. There's no weather on the moon. Stuff stays whereever you drop it. You're not polluting "the moon", you're polluting a hole in the moon.

Anyway, it's never going to be a more practical to extract helium-3 from moon dust than to make it as a fusion or transmutation product. Maybe extracting it from a gas giant will eventually become a better idea, but I just can't see regolith mining as a sane way to collect helium.

>>4587253

YES! I completely agree. I've always been a bigger fan of mining it from gas giants (considerably higher concentration of He-3). I was actually trying to think of a design that would be a higher speed enrichment plasma enrichment method that would work in zero gravity just for that reason.

>>4587304
I'm personally not a big fan of helium-3 fusion.

To me, the whole damn point of fusion is neutron production. That's what it's good for. The easier it is to get neutrons, the more attractive fission is.

I thought we sorted this all out back when we were doing bombs.

>>4587405

Yes, but unlike fission (at least thermal fission that we work with), there is no shielding, or at the very least, moderation of neutron energy. A large part of materials research as it applies to nuclear engineering is preventing degradation of common metals under neutron irradiation. This one of the huge engineering obstacles facing fusion: high energy neutrons degrade (quite quickly) fusion reactor materials. Aside from fuel breeder blankets around from fusion cores, there's nothing preventing neutron flux from irradiating structural components and sensitive systems, such as the super conducting magnets used in magnetic confinement. That's why He-3 is a desirable fuel. The only downside is, some He-3 reactions are neutronic and can breed fuel which undergoes reactions which are also neutronic. It just so happens that the most energetic reactions (and the most promising ones) happen to be neutronic as well.

Hey OP, I live in SF and I've read every inch of your posts so far and I'm loving the ring of "Nuclear Engineer". I was swinging for Mechanical Engineering but I'm still in Community College so it's still changeable. Do you know anything about UC Berkeley's NE program? It's the only one in the bay area. I saw you mention that they had a different type of reactor, and I honestly had no idea what that meant. I'm fascinated by nuclear technology and have a good friend that was displaced by the Fukushima disaster but still clench my fist at greenpeace hippies.

TL;DR: Should I go to UC Berkley for NE or just go somewhere else for ME than worry about it in graduate school? Is UC Berkeley good for NE? Thanks!

>>4587501

It's totally up to you. Everything I've heard about Berkeley is excellent. If I'm not mistaken, they're one of the top 3 NE programs in the country. That being said, it's REALLY difficult to get into. IMO, it's probably easier to do a more general engineering (i.e. mechanical) as an undergrad and shoot for nuclear at the graduate level. At my university, that's actually what a lot of the graduate students have done: math, physics, mechanical engineering, chemical engineering, computer science, etc as an undergrad. I don't think it's common to go the other way around, which I've been trying to do (for a not too desirable outcome).

And sorry, I'm retarded, I thought the National Ignition Facility was located closer to Berkeley (it's an inertial confinement fusion reactor, i.e. it uses lasers instead of a plasma to initiate fusion reactions), but it's actually at Lawrence Livermore National Lab. Either way, there is a strong connection between the two.

Hope that helps.

>>4587527
It helps a lot, much obliged.

Explain how a fission fragment reactor works and why it's so efficient compared to conventional nuclear reactors.

those new lead cooled self contained reactors seem pretty awesome
do you think those will start seeing use any time soon

A practical tritium-deuterium fusion generator is developed.

How many fusions must you carry out to make a critical mass of Pu-239 from U-238?

Shipping out to be a Navy nuke in a couple months. Any advice? Sorry to be so vague, but anything would help.

Who would win in a race between you and a slow neutron?

>>4587592
To be completely honest, this is the concept behind how traditional fission reactors work (LWRs included). They idea is that when a nucleus fissions, it releases two (sometimes 3 or more) fission products that contain the majority of the energy of the reaction energy as kinetic energy. Since these fission products are large, they won't move far in the fuel lattice, and are forced to deposit their energy in the rest of the lattice. The net result (especially with a number of these reactions occurring at the same time) is that the fuel lattice starts to heat up significantly. The heat is then conducted through the fuel element, through the fuel cladding, and to the coolant of the reactor to heat it up.

>>4587599
Probably not. The same goes for Thorium and HTGRs. We can definitely do it, but there isn't enough pull to develop the technologies and not enough patience to counter act the bureaucracy which goes into having the design approved by the government. It will show promise as a test reactor, but not much more. Plus, I have personal beefs with liquid fuel/liquid metal cooled reactors.

>>4587615
To go from D-T to plutonium or uranium? A fuckton and it wouldn't even be worth it. Fusing anything above iron is an endothermic reaction, you would consume more energy producing it than you would get from burning it in a fission reactor. Might as well continue digging uranium out of the ground and transmuting it to Pu.

>>4587642
I know a few guys in my program that are either ex-Navy or currently in. By the end of it, you will know a fuckton about the operation of reactors (and cool little tidbits that are specific to mobile platform reactors), but don't expect to know a lot of the science or reactor physics behind it. You will know operation code, procedure and why one operating parameter will affect the other, but not much else. Also, if you're deployed, expect to be worked like a mule. I heard the shifts for Navy nukes are absolutely grueling.

>>4587652
Slow? The neutron. There is an ultra cold neutron source built around the research reactor at my university for the physics department. Against an ultra cold, I would win...maybe. I'm kind of a fatass.

>>4587664
>>To go from D-T to plutonium or uranium?
no, using the neutrons from the D-T reaction.

>>4587664
>>To be completely honest, this is the concept behind how traditional fission reactors work (LWRs included).

That is incorrect. HINT: fission fragment reactors might be able to obtain mass-energy conversion efficiencies as high as 90%.

>>4587670
>I heard the shifts for Navy nukes are absolutely grueling.

Yeah, I heard that too. Oh well, that's why the gods blessed us with hard liquor. Good luck with your midterm.

>>4587675
Critical mass has nothing to do with an outside neutron source, it is actually a mass of fuel. But you can induce fission (albeit only a few) from the 14.1 MeV neutrons. You'd be better off moderating to thermal (for Pu-239) or moderating to fast spectrum (for U-238). Unless you're in a favorable geometry though, don't expect to go critical, let alone maintain criticality.

>>4587682
OHHHH, I see what you meant. That's sort of a roundabout way of doing things though. There already exist plasmatic ion engines like that that do reach extremely high efficiencies, but they typically use gaseous ions (hydrogen or helium). I don't see what the point would be for using one of those in an actual spacecraft unless you were utilizing spent fuel from a reactor already inside a spacecraft. The other problem is, for that to be used as a propulsion system, it has to be used in a near perfect vacuum, i.e. only in space. Look up VASIMIR or anything that Ad Astra company is doing and you'll see what I mean.

hmm so what don't you like about liquid metal cooled reactors
reading the wikipedia page with my limited knowledge makes them seem so perfect at least for some applications like remote areas

>>4587822
Well, sodium is one thing. If you have a loss of coolant accident with it, you can't cool it with anything else that's abundant (i.e. water) because of the risk of sodium fire. Additionally, you'd still need steam generators (again, a fire hazard with sodium).

With lead specifically: "Due to (n,gamma) reactions and minimal scattering in the coolant, lead-cooled fast reactors can have a positive Void coefficient, which is extremely unsafe." It would be a bit time consuming explaining why this is unsafe, but I'll leave it at that. Also, lead reactors are most useful in subcritical reactors, not particularly power generating ones.
All around, I still prefer straight Brayton cycles, which would best be used with helium as a coolant.

olly olly oxen freeeeeeeeeee

What's your perspective on the viability of fusion? Laser ignition, tokamak?
I'm in high school with plans of taking Purdue's nuclear fusion course of study for undergrad. Is this a good idea?

>HTGRs that I mentioned earlier are US designs as well.
And the Germans, man.
We had a fully functioning working commercial operated High-Temperature, Helium cooled pebble-bed reactor. It was purpose-built as a Thorium thermal breeder.
And then, two years after it was done, Chernobyl happened, and everyone went crazy and it was shut down and never heard from again ;_;

>>4587699
For an aspiring nuclear engineer, you don't seem too sharp.

He's obviously talking about breeding a bare spherical critical mass worth of plutonium fuel from depleted uranium using a fusion neutron source.

It's a question about the proliferation threat of fusion technology.

A natural or depleted uranium neutron multiplier would make a tremendous amount of sense for a D-T tokamak: you need some neutron multiplier to breed enough tritium (from lithium) to sustain operation, and using uranium would also provide a tremendous boost to power output and could breed large amounts of plutonium very quickly.

Tokamak technology doesn't have to reach net positive fusion power output to become a proliferation disaster. All it needs to be is a cost-effective source of high-energy neutrons.

>>4589156
>Tokamak technology doesn't have to reach net positive fusion power output to become a proliferation disaster.
Well, that's kind of retarded.
You can build a perfectly fine Plutonium breeder RIGHT NOW using only Natural Uranium.
A functioning Tokamak on the other hand is an incredible complicated, highly advanced and expensive and most importantly still non-existent device.

>>4587699
>I don't see what the point would be for using one of those in an actual spacecraft
Uh... ever heard of specific impulse?

Something like a nuclear salt-water rocket might be more practical for interplanetary flight, and a quartz bulb rocket might be more suitable for terrestrial launch, but a fission fragment rocket would actually have sufficiently high specific impulse for practical interSTELLAR travel.

The other advantage of a fission fragment rocket is that you can extract electrical power from the ion stream at very high efficiencies with a very simple apparatus, getting large amounts of electrical power essentially as a byproduct of the propulsion apparatus.

You can also do a hybrid system, using the fission fragments to heat a propellant such as water or hydrogen, for when you need high thrust, such as making planetfall or during emergency maneuvers.

>>4589244
>You can build a perfectly fine Plutonium breeder RIGHT NOW using only Natural Uranium.
It's slow, you need a LOT more uranium, and you need to dissipate a lot more energy and deal with a lot more waste.

Fission doesn't crank out the neutrons like fusion does. Breeder reactors that actually manage to produce more fuel than they consume are quite challenging.

>A functioning Tokamak on the other hand is an incredible complicated, highly advanced and expensive and most importantly still non-existent device.
...and I was talking about the dangers of developing the technology, not the dangers it poses in its current state.

If a tokamak isn't going to make it far easier to breed weapons material, then it CERTAINLY isn't going to be a cost-effective source of electrical power.

I'm back but on my phone so I'll make this quick. Transmuting DU to Pu takes a very high neutron flux and Tokamaks don't have high neutron fluxes, D-T accelerators have comparative fluxes ~10^14 and that's not even enough to make medical isotopes, you need actual reactors to do that, so no it's not a proliferation risk. In response to rocket man, I understand exactly what you are saying but its already being done without needing nuclear fuel. Go look up Ad Astra, they're doing the same thing with helium-hydrogen plasmas, including bridging the gap between high SI, low thrust to low SI, high thrust systems. Adding nuclear fuel to the mix needlessly complicates the system.

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>>4590338

Tell me, OP, what do you know about Thorium?
Why isn't there more reserach into it?
Why aren't there any Thorium reactors?

>>4590327
>Transmuting DU to Pu takes a very high neutron flux and Tokamaks don't have high neutron fluxes, D-T accelerators have comparative fluxes ~10^14 and that's not even enough to make medical isotopes, you need actual reactors to do that, so no it's not a proliferation risk.
I'm sorry, but this is wrong and dumb. You don't need high neutron *flux*, you need a high total number of neutrons.

If the flux is lower for the same neutrons/s, that's actually much better for breeding plutonium, since a transmuted uranium nucleus is less likely to absorb additional neutrons before it decays to plutonium, and the plutonium is less likely to fission before it can be processed out of the breeder blanket.

D-T accelerator neutron sources and tokamaks are not even close to being the same thing.

It's amazing how people can get through school without actually understanding anything.

>>4590327
>its already being done without needing nuclear fuel. Go look up Ad Astra, they're doing the same thing with helium-hydrogen plasmas, including bridging the gap between high SI, low thrust to low SI, high thrust systems. Adding nuclear fuel to the mix needlessly complicates the system.
Uh... adding nuclear fuel to the mix provides the energy.

Yeah, there are some ion drives out there which feature comparable reaction mass velocity, but they are extremely low-thrust systems, because they rely on weak power sources like solar panels.

Proposals for fission fragment rockets usually involve power outputs on the order of a gigawatt. There's just no comparison.

And sticking a conventional nuclear reactor on a spacecraft with a VASIMR thruster is how you "needlessly complicate the system". It's a significant increase in mass and a significant reduction in energy efficiency.

>>4590379

I'm not saying they're the same thing, I'm saying that they don't even have a comparative source strength, in fact, the entire point is to minimize neutron flux in a tokamak (btw, flux is directly correlated to source strength...you're an idiot, so I know it can be difficult for a person like you to understand). It takes a LOT of time to breed plutonium in reactors, which, comparatively have the highest neutron strength/flux of any source.

Take a look at the attached image. 10^15 (reactor) > 10^13 (neutron flux of a tokamak). The accelerators listed are mostly spallation sources, so they're for the most part discounted from this discussion. Also, Z-pinch is irrelevant because it's pulsed and not continuous source.

Now, let's think about this for a second. Not only do reactors have a higher neutron density, but they're also operating on a thermal spectrum. With D-T energy neutrons (14.1 Mev) you're going to end up fissioning more U-238 that transmuting it. You are much better off having U-238 absorbing under thermal conditions.

In summation, you're a fool for thinking that tokamaks are a proliferation risk both for the reasons listed above and with the fact that current research for tokamaks is based on limiting neutron flux.

>>4590338
>>4590354

See my first response in the thread.

>>4590447
Fair enough, I will concede the point. But I'm still a bigger fan of having the power producing reactor separate from the propulsion system (i.e. not using fission product dust as a propellant, instead using the existing helium-hydrogen propellant).

>>4589117
You're right, and if I'm not mistaken the French actually built the first high temperature system that was a Brayton-Rankine cycle hybrid. It was decommissioned because of a water leak into the Brayton side which was corroding the fuel. I think the South Africans are working on a gas reactor as well.

I'm currently a junior studying Nuc E.

What would you say were your most challenging courses?
Your favorite/most interesting courses?
Your least favorite courses.

I just recently got an internship in the reactor engineering dept. at a plant. Any idea what the hell I will be working on?

Can I ask where you are doing your undergrad?

>>4590810

I would say my most difficult and challenging course was reactor physics/neutronics. The math was extremely interesting, but solving eight group diffusion equations aren't fun at all.

My favorite courses are thermohydraulics/reactor design/reactor systems. Unfortunately, at my university it's taught by a total hardass so it's next to impossible to get out of those courses with A's, but either way they're still my favorite.

I go to NC State.

>>4590810

Oh ya, I also have no earthly idea what you would be doing at the plant.

>>4590827
Thanks, I'm actually doing Nuc E and M E but I've mainly been taking ME classes so far.

Looking forward to my Nuc classes although they sound tough.

What do you plan to do once you graduate?
Do you have a job lined up or are you considering grad school?

>>4590833

I was looking to go to grad school to do ME studying heat transfer and energy conversion schemes, but there's been some complicating issues so I'm probably getting a job. I haven't applied anywhere yet, but there are a few places I'd really like to work: government jobs, plant design, etc.

>>4590840
Heat transfer is interesting stuff.

Good luck wherever you end up.

Have you considered generation?
It seems like that's where the money's at, I'm hoping to go the SRO route one day.

>>4590842

I've considered it, and NC actually has quite a few reactors in the general area, but I heard it's kind of a high stress job. The chances of it are extremely low, but I don't want to have a Condition III or condition IV event happening on my watch...I'd probably shit my pants and kill myself.

Do you think the ITER fusion reactor will work when switched on in 2019

>>4590859

I think it has a fairly high chance of producing net positive power output, but it's still going to need to be pulsed. It will be able to prove a lot of things and help improve metallurgical sciences in high-energy neutron environments. We'll no for sure if magnetically confined fusion will be viable once DEMO is built, and there's no need to pulse the reactor.

>>4590683
Can't even read the fucking chart you post yourself?

>flux density neutrons/(cm^2*s)
>ILL - 10^15
>ITER - 4*10^13

>Intensity, 10^17 neutrons/s
>ILL- 10
>ITER - 1800

The ILL's flux is 25 times higher than ITER's, yet the ITER makes 180 times as many neutrons.

Total neutron production and neutron flux are COMPLETELY different numbers. A tokamak is going to have relatively low flux because its fuel is a plasma with extremely low density. Even though a lot of neutrons are being produced, the production is spread out over a big area.

Keep in mind, as well, that the discussion was about higher-output, technically mature, power-generating tokamaks of the future, which would be more powerful than the ITER.

You should choose a new career, because at this level of stupidity, if you manage to weasel your way into a job, you're going to get people killed.

>With D-T energy neutrons (14.1 Mev) you're going to end up fissioning more U-238 that transmuting it.
First of all, moderating neutrons isn't exactly rocket science.

Secondly, uranium is cheap, so U-238 fission is HIGHLY desirable when breeding fuel, which is a big part of why most breeders are fast reactors. It gives you one or two more neutrons than you started with and now they're all slowed down considerably. Ideally, every fast neutron would fission a U-238, so you'd get 2 or 3 slower neutrons to breed plutonium with.

Aw, look at all the wibble particles moving faster than light.

>>4590859

Will it work? Define: "Work".

Work = Fusion reactions. Yes, of course. We've been making fusion reactions for many decades now. But that's not the problem with producing sustainable fusion power.

Work = Fusion reactions CONTAINED. No, of course it won't work. The ITER will run the reactions slightly longer, before they INEVITABLY escape the containment, and the reactions either cease or cease to be energy-positive. That's always been the problem: Humans can't CONTAIN THE REACTION.

Stars only get fusion started and sustained since they CONTAIN THE REACTION by using a million trillion trillion tons of mass. Well, we can't use star-sized masses to make useful fusion. Obviously.

But we CAN make use of a nearby, fully functional fusion reactor: THE SUN, a star named "Sol". But there's a big, big economic problem with that: You can't put a meter on it. So 99.9% of the time we just pretend it's not there for the purposes of power production, and get the maximum amount of money we can from the stupid consumers.

>>4591466
Holy shit man, try and stop being a fucking armchair know it all, it's quickly becoming obvious that you're pulling shit out of your ass and/or wikipedia.

If you want to play this game, I'll bite. Yes, neutron source strength will be higher in a Tokamak, but you said it yourself, they will be more spread out since it's a plasma. If you knew anything, you would know that reaction rates are calculated using FLUXES not strength (the simple reason being that cross-sections are inverse areas, so a flux times a cross section gives you a reaction rate). Either way you try and spin it, you're looking at the higher FLUX to give you a higher transmutation rate, i.e. you're looking at reactor level fluxes. Mature technologies are still irrelevant because you can have higher neutron fluxes with low power fission reactors than low power fusion reactors (the 1-MW reactor at NCSU is pulling 10^15 n/cm^2*s at any given point, two orders of magnitude higher than the 50MW ITER complex). Even so, the ITER flux is within the plasma itself. Sticking DU in there will cool down the plasma so that you can't maintain that flux.

>>4591891
>>4591466

So what if moderation isn't that hard? If you want to argue about breeding Pu with fast neutrons, you're a fucking moron with the point you made. U-238 has a TINY fast absorption (without fission) cross-section, compared to a HUGE absorption under thermal/resonance spectrum. You make the argument that you would want that U-238 to fission with fast energies, but what you don't understand is that the resultant fission neutrons ARE ALSO FAST! Besides, yes you can moderate 14.1 MeV neutrons, but you know what also happens? You have spatial attenuation with the amount of moderator you need to moderate from 14.1 MeV down to thermal, leading back to the first part of the argument.

So, please stop while you're ahead. It's obvious that you're either 1. a moron or 2. a troll. Come back when you can find something other than wikipedia/actually have a degree in a relevant subject.

>>4591744

I sure hope you're not the same guy talking about breeding U-238 using tokamaks. If you are, please leave. If not...

The whole point of ITER is to prove that you can keep operation around for some amount of time, in ITERs case - 40 minute pulse segments. You're using the word "contained" to hinge your argument, when strictly speaking, not even fission reactors "contain" the driving force of their reactions (neutrons). Unlike fission, however, it's actually almost irrelevant that neutrons are lost, as the actual fuel is maintained within the plasma under magnetic conditions. Furthermore, what does escape can be used in breeder blankets to produce secondary fuel that is still contained by the plasma. Even further, ITER is designed to contain and remove useless fusion products (helium). At this point, it's more a matter of maintaining material tolerances, as I stated before. ITER is merely a stepping stone to full time D-T reactions in the DEMO project, set to go online ~2040.

How much do you get into the actual history (as in economic and political aspects, not just scientists and engineers) of nuclear energy?

Basically, I'm curious if you've any reason why we use shitty upscaled submarine nuclear reactors and not purpose designed ones for large scale energy production.

Also what are your thoughts on using thorium versus uranium?

And finally, how come no one has made a big water tank, dropped some radioactive material in it, and then dropped the hot side of a stirling engine into it, then hooked that up to a generator? Seems like it would be all kinds of easy to make sure that it never overheated, and while it may take a bit to get up to a usable level, it could stay there for a very, very long time.

>>4591942
Oh and I meant the thorium with respect to the nontechnical side of nuclear energy (as you covered the technical side). Sorry I wasn't quite clear there and just realized that.

Can you recommend a website or book to learn the absolute basics about NE (or rather, the jargon used by nuclear engineers broken down for non-engineers who have work with them)?

Also, any stereotypes about nuclear engineers that you've found to be particularly true? Anything that stands out as particularly true for NE as opposed to other engineering fields?

>>4591971
>>4591942

We usually don't get into the politics or economics of it. Actually, I'm lying, it's all about some regulatory bullshit, but never really anything about why (with the exception of medical physics and some systems stuff, but not much).

Most industrial power generation is VASTLY different from naval systems on naval platforms. The biggest difference can be seen in enrichment of fuels. Mobile reactors usually enrich up to 80 to 90% (or so I've heard) where in the US, industrial power is around 4% enrichment, so there's a huge difference.

One reason I like to give for not using thorium comes from obtaining the fuel itself. Sure, thorium is more abundant than uranium, but it's actually much more diffuse. To pull it up out of the ground would require a reworking of the existing nuclear mining/fuel fabrication industries (which are currently very well established).

>>4591974
I unfortunately haven't happened upon any particular stereotypes. With regards to books, there are some pretty good intro ones by Raymond L. Murray. He was an old department head, and from what I heard, pretty much a bro. He passed recently though. There's another good intro book that was in my second nuke class that's incredibly handy for theory and basics of the science called "Fundamentals of Nuclear Science and Engineering" by Shultis and Faw. It's surprisingly in depth, yet rather simple and has some of the most comprehensive mass tables and cross-section tables I've seen outside of the chart of the nuclides.

>>4592001
>reworking of the existing nuclear mining/fuel fabrication industries
You don't need to do that. Thorium gets produced on the side of mining other stuff. And while it doesn't produce as much thorium as uranium mining produces uranium, you don't need as much thorium to produce the power as with uranium.

Also, since thorium is so low-activity, minimal precautions are required for working it.

>>4592031

I will agree that it was low radioactivity, but I will disagree on your other points. There may already be thorium mining operations, but compared to uranium they are very low volume. Last figure I looked at was about $250,000/year to satisfy the yearly need. Also, if I'm not mistaken, industrial power reactors require about $1 million every 1 and a half for their uranium fuel needs. Assuming their roughly the same price per quantity, this would indicate that the volume of thorium mining is nowhere near that of uranium and would need to be adjusted if Thorium becomes as commonplace as uranium.

>>4587016
>Thorium designs would still have to use steam generators in some way, shape, or form and Braytons are much more efficient in terms of overall cycle efficiency. Though, I am a fan of the modular ability of Thorium reactors.
Where did you hear such silliness?

>>4587664
>Plus, I have personal beefs with liquid fuel/liquid metal cooled reactors.
Such as?
Also, you appear ignorant if you conflate sodium cooled reactors with liquid fluoride reactors. Entirely different beasts.

>>4587993
To be fair, the CANDU has a positive void coefficient, but IIRC a lot of it is from delayed neutrons, so the time to correct in an accident is quite large, which makes it relatively safer than say a lead cooled reactor.

>>4592060

Educate me, how will you pull useful power from liquid thorium reactors without using a turbine?

>>4592079
I didn't. I have my own problems with sodium (risk of fire if in contact with water, which is needed desperately in a loss of coolant accident). And there actually have been a serious of problems with liquid FUEL reactors, mostly that there are corrosive problems (even with Hastalloy), and some of the fission products are water soluble. In traditional LWRs, there are multiple protections against fission product migration. I understand that liquid (metal) coolants and liquid fuels would more than likely freeze on escaping from the vessel, but the vessel (and containment) are only two protections against fission product migration. With liquid fuels, you remove one of those safeguards. It's even worse when the fuel itself is corrosive.

>>4592044
Why would you assume that price per quantity is remotely similar? In any event, overall cost is the more important factor, and when you consider the wild differences in the costs of using something that can be weaponized into a nuke versus something that can't (I'm speaking here about things such as security precautions) and the safety differences (thorium can't go into meltdown), I think you can offset the onetime costs of retooling the production end. GE won't like that, but they can go fuck themselves.

>>4592088
Well, you also have to realize that CANDU has significantly lower enrichment, providing a significantly lower positive reactivity of the fuel elements themselves.

>One reason I like to give for not using thorium comes from obtaining the fuel itself. Sure, thorium is more abundant than uranium, but it's actually much more diffuse. To pull it up out of the ground would require a reworking of the existing nuclear mining/fuel fabrication industries (which are currently very well established).

You need to do some more research.

For starters, the fuel cost of a modern nuclear plant is only about 1/7 of the end cost of the produced electricity. The fuel costs are mostly negligible.

Also, because the fuel is liquid fueled, except the thorium fuel to be vastly cheaper, because you don't have to make fuel rods to exactly standard to survive neutron flux for decades, both in the reactor and in the cooling pond for centuries to come.

>>4592090
>Educate me, how will you pull useful power from liquid thorium reactors without using a turbine?
Change of claim. You said that LFTR must use a steam turbine, and can't use a supercritical CO2 turbine. This is simply false. One of the major benefits of LFTR is the higher reactor temperature allowing higher efficiency brayton turbines.

>>4592090
>And there actually have been a serious of problems with liquid FUEL reactors, mostly that there are corrosive problems (even with Hastalloy),
Again this conflation of all liquid fuels. Pray tell, point me towards a single operational reactor that had such problems. There isn't a single operational liquid fluoride reactor. There was the experiment reactor back in the 60s/70s, and 20+ years later after inadequate care there was problems, but going forward I see no reason why it isn't solvable.

>and some of the fission products are water soluble. In traditional LWRs, there are multiple protections against fission product migration. I understand that liquid (metal) coolants
Again this fixation on metal coolants. There are no metal coolants in a LFTR.

>and liquid fuels would more than likely freeze on escaping from the vessel, but the vessel (and containment) are only two protections against fission product migration.
That's why you use a secondary salt heat loop, to keep the water well away from the core.

>With liquid fuels, you remove one of those safeguards. It's even worse when the fuel itself is corrosive.
Water itself is amazingly corrosive, you know that right? It's a solvable problem.

>>4592044
I've heard anecdotes that a single rare earth metal mine in the US, a single site, would supply the world's supply of thorium if all energy use was nuclear thorium from a year of mining.

Thorium scarcity is not a concern for thousands of years, and maybe maybe millions.

The reason for the low mining is that it has no use nowadays, and most places treat it as nuclear waste, requiring special disposal, which is somewhat insane.

>>4592100
Interdasting...I was unaware that there were designs that incorporated Braytons into LFTR. But my point still stands about HTGRs. Single loop Brayton's will have higher efficiencies (especially if you use the same working gas) than hybrid systems like an LFTR would use, simply because of losses in heat exchangers.

>>4592094
>the fuel costs are mostly negligible

WHOA WHOA WHOA. That is not true. I was actually wrong on the original figure I quoted. For LWRs, fuel is on the order of $45 million/year for 1100 MWe plants. Currently, Uranium is trading at around $55/pound. A source for thorium is a bit sketchy right now, but that's about $20/ounce. I know the point has been beaten to death that the only reason thorium isn't cheaper is because it's not mined as much, but that's exactly my point. There would be a HUGE short term investment for retooling and re-strategizing in mining of nuclear fuel. Also, I understand your point about fuel fabrication costs being cheaper, but I don't understand how you can get that there would be less of it.

>>4592044
Thorium has marginal use right now. There's immense amounts of it in tailings and refinery sludge.

Also, thorium is relatively cheap. Way cheaper than uranium. And as it needs no enrichment like uranium, this only makes it cheaper.

It's low activity is reflected by it's use in certain alloys and gas mantles.

>>4592128
>Interdasting...I was unaware that there were designs that incorporated Braytons into LFTR.
There's a lot of designs out there. There's no reason it cant use a supercritical CO2 turbine. Of course, it's not an off-the-shelf component, so it's just another thing that can go wrong in research, so maybe probably the first LFTR (if ever) will have a standard steam turbine.

Also, really, trying to optimize the 1/7 cost of levelized electricity is silly. Thorium will be plenty available. Hell, plenty of places in the US would /pay/ you to take it, if the payment was less than what the US might charge to properly dispose it. There are no fuel fabrication with thorium in the traditional sense. You just need to make it into thorium fuel, then dissolve it in the salt. As opposed to the quite stringent requirements in manufacturing solid fuel rods as they have to last forever and a year.

The much more important aspect to consider is the cost of the plant itself. As a LFTR will run at atmospheric pressure, there is every reason to think that it will be much smaller, and thus probably much cheaper.

There's still a lot of unknown. You either need to fix the plumbing problem / neutron flux wall problem, with a 2 fluid design, or you have to fix the hard problem of separating thorium and uranium out from the fission products for a 1 fluid design.

>>4592148
Err, to fix that:
No isotropic separation / enrichment required with thorium.
No solid fuel fabrication requirements for longevity and safe confinement of fuel. Instead, it's just a hunk of solid metal you can dissolve in a salt.

>>4592111

Fine, forget ANYTHING I said about metal coolants.

Let's focus specifically about the molten fuels. I understand that water is also corrosive (please, I'm not retarded) but those have been very well investigated. The same cannot be said about salt fuels. You said it yourself, there is not a single molten thorium reactor currently in operation. Also, despite what you said, there were still materials problems due to the, get this, FISSION PRODUCTS within the fuel.

>>4592140
See above.

>>4592117
I wouldn't go THAT far. As for the radioactivity, it's an alpha emitter. It's treated as nuclear material because it has one of the more energetic reactions and can cause major damage if ingested.


To all, I'm probably going to be getting to sleep soon. It's 4AM where I am.

>>4592180
>I wouldn't go THAT far. As for the radioactivity, it's an alpha emitter. It's treated as nuclear material because it has one of the more energetic reactions and can cause major damage if ingested.

Another anon here. I've heard this, but I really have to wonder. Let's assume LNT is bogus, because it is, and remember that its half life is measured in billions of years. How bad is it, really, even when ingested?

Of course, it is chemically toxic, but let's ignore that for now.

>>4592180
>if ingested
Stop eating the nuclear fuel!
No! Bad Сергей! Bad!

>>4592180
>Let's focus specifically about the molten fuels. I understand that water is also corrosive (please, I'm not retarded) but those have been very well investigated. The same cannot be said about salt fuels. You said it yourself, there is not a single molten thorium reactor currently in operation. Also, despite what you said, there were still materials problems due to the, get this, FISSION PRODUCTS within the fuel.

Yep. Just don't be saying it can't be done until we try.

>>4592191
Depends on the activity and the amount ingested. Alphas tend to be around the same energy, usually around 4-5MeVs. Just look up Aleksander Litivinko, dude got FUCKED up by ingesting high activity polonium-210 once.

>>4592193
But think about it...it takes years to develop that kind of technology and it's vastly different from what exists now. The chances of it becoming common, at least in the US is incredibly low.

>>4592207
>But think about it...it takes years to develop that kind of technology and it's vastly different from what exists now. The chances of it becoming common, at least in the US is incredibly low.

One of the major drives of the LFTR community IMHO is trying to develop a power plant that is cost competitive with coal. If we don't do that, then global warming will happen. Simple human greed will carry the day. That's why I care. That's why I try to raise consciousness about LFTR, as it appears to be our best bet to solve that goal.

Of course, I'm all for whatever promising research there is. Unfortunately there is a bunch of research into shitty "green" stuff like solar and wind, and basically no money going towards nuclear research, which makes me a sad panda.

>>4592207
The activity of thorium is REALLY low:
http://energyfromthorium.com/tech/physics/activity1/

>>4592215
Baby steps. That's why I suggest fast-spectrum U-238 HTGRs. Fuel we already use, high efficiency gas cycles, with the ability to bring in hybrid Rankine systems. IMO, HTGRs have a higher chance of integrating with current systems and it's something that's not as far off from LWR compared to any kind of thorium reactors.

>>4592224
Perhaps, fast spectrum reactors have higher safety concerns though. Harder sell to the public perhaps. Maybe safe enough in practice. Also /potentially/ more of a proliferation thread than a LFTR. I don't know enough to comment here.

>>4592230

All the current designs don't provide an adequate method of recovering the riskful actinides from the fuel. In that respect, thorium actually seems to be more of a proliferation risk that HTGRs.

>>4592241
Meh. If it's pure thorium to U233, aka no U238 in the mix, and you don't do protactinium separation, then the U232 contamination helps stop proliferation pretty well, so I've head.

"Of course, I'm all for whatever promising research there is. Unfortunately there is a bunch of research into shitty "green" stuff like solar and wind, and basically no money going towards nuclear research, which makes me a sad panda.
Because not wanting to contaminate the planet with your idiotic radioactive materials and killing people with cancer is SO shitty. Faggot.

>>4592246
Look. Solar and wind cannot cut it. They simply can't. If you want always-on powers, the intermittent power supply of solar and wind are insufficient. The power storage solutions simply aren't there.

Thus, nuclear is the only alternative.

To put that in perspective, it produces less radiation than a coal plant (though in much higher concentrations). Technology exists which can get the waste down to only about 300 years before it's back to the radiation levels of uranium ore that you dig out of the ground, so waste disposal really isn't an issue.

And cancer? Please. Apart from Chernobyl which doesn't count for so many reasons, the amount of people who've died from nuclear power radiation accidents is less than 10.

More people die each day from solar and wind.

>>4592255
LOL! Look up Hanford much? HUNDREDS of people have died from cancer thanks to "green runs." How about all of the people who died in Hiroshima and Nagasaki? Or the soldiers this country tested nuclear affects on? You people make me sick.
Your "facts" are bollocks.

>>4592255
And Chernobyl doesn't count?! All those DEAD PEOPLE don't count? What the fuck is wrong with you?

>>4592270
>cites link about warfare experiment accident
>cites nuclear bombs
So, as I said, excluding Chernobyl, which doesn't count for various reasons, less than 10 people have died radiation related deaths from nuclear power accidents.

>>4592272
Chernobyl was a completely dumbfuck reactor built in the most retarded way possible. It had a positive coefficient of reactivity. Never in the last 40 years has such a reactor been built.

>>4592270

Why the duck would bombs count towards the death toll of a power generation method? Also it still wouldn't work out because of petroleum based explosives and good old horrible napalm.

>>4592274
You can't just go around NOT counting that people were needlessly sacrificed for this horrific power. Any nuclear related death it a tragic death.
Did you know that the International Atomic Energy Agency IAEA ADMITS that for "each relicensing [of a Nuclear Reactor ] is expected to be responsible for . . . 12 cancer deaths per reactor." From the NRC factsheet, look it up if you don't believe me.
Nuclear energy was my topic of choice for much research.

Source: http://www.tmia.com/old-website/accident/whatswrong.html

>>4592281
12 deaths vs. how many for oil?

>>4592281
>You can't just go around NOT counting that people were needlessly sacrificed for this horrific power. Any nuclear related death it a tragic death.
Sorry, no. You don't get to include nuclear bomb deaths unless I get to include every death that ever happened because of a tank, truck, aircraft, and so on. If so, then I win. Dresden, for example, was far worse than either nuclear bomb on Japan. Get your war atrocities straight, son.

>>4592272
>>4592270

Pro-tip: There have only been three deaths in the US directly related to reactor incidents, and it was the same incident.

More people will develop cancer because of using tanning beds than Fukushima and Chernobyl COMBINED.

The increase in cancer rates due to TMI was also negligible.

Sorry, try again.

>>4592281
>12 deaths per reactor
That's based on the LNT, which is more or less complete bullshit. Try again son.
http://en.wikipedia.org/wiki/Linear_no-threshold_model

P.S.S. It was the NRC, not IAEA.
"Even under normal operating circumstances nuclear plants release radiation. The NRC acknowledged that 12 people are expected to die as a direct result of normal operation and releases for each commercial nuclear reactor that is granted a license extension of 20 years."

>>4592287
You people are so fucking blind. "Oh, it's all bullshit." Explain that to my family, downwinders of Hanford, who have, for the most part, ALL gotten cancer that was not caused by genetics. Explain that to all of the family's who lost loved ones in Japan and Three Mile Island.

>>4592289
Stop mixing claims. I'm sure the Hanford experiment released dangerous amounts of radiation.

LNT is bullshit, and that "expected 12 radiation deaths per reactor due to trace radiation release" is completely bullshit.

>>4592288

Much more die from wind turbine fires.

>>4592289
Again, there WERE no deaths related to TMI...not even cancer related. There WAS no fission product migration, even the site you listed says so. TMI was a PWR and the coolant leak was on the secondary side in the feed control system...all coolant that escaped was radiation free, bro.

>>4592286
On a scale of 1-10, how much do the common misconceptions of nuclear power bother you?

>>4592291
How is it mixing claims? Anything to do with creating nuclear power/energy is dangerous and you idiots like to pretend that it doesn't hurt anyone because of your bullshit research and the lies the government likes to tell you.

>>4592295
>Anything to do with creating nuclear power/energy is dangerous and you idiots like to pretend that it doesn't hurt anyone because of your bullshit research and the lies the government likes to tell you.
Yes it's dangerous. I prefer to live in the real world where we chose the least dangerous / most good option. Nuclear is the least dangerous / most good option.

>>4592295
Creating oil energy is dangerous!

http://www-958.ibm.com/software/data/cognos/manyeyes/visualizations/2e5d4dcc4fb511e0ae0c000255111976

>>4592294
Probably about a 12. What's funny is that even the most hardcore environmental engineers/environmentalists I've met will concede at some length that nuclear is the only viable alternative to fossil fuels in terms of baseload power. I've even had at length conversations with recruiters from Greenpeace who will concede the point. Anyone who thinks that nuclear is more dangerous than any other power production method is seriously retarded.

>>4592300
Really? Amazing. I still meet plenty of people who are deluded enough to think solar and wind can cut it. So the people in charge of the false propaganda campaigns will actually admit otherwise.

Godddamnit. I hate my species sometimes.

"The public was assured the government would follow up with meticulous studies of the health impacts of the accident.
http://nukefree.org/news/peoplediedatthreemileisland
Research has shown that we have MORE than enough wind on this planet to provide electricty for the whole world. But people don't want to give up on their precious oil and, apparently, would rather have people dying of radiation sickness than concede that it's extremely dangerous and hazardous.
In fact, the state of Pennsylvania hid the health impacts, including deletion of cancers from the public record, abolition of the state's tumor registry, misrepresentation of the impacts it could not hide (including an apparent tripling of the infant death rate in nearby Harrisburg) and much more.

The federal government did nothing to track the health histories of the region's residents.

In fact, the most reliable studies were conducted by local residents like Jane Lee and Mary Osborne, who went door-to-door in neighborhoods where the fallout was thought to be worst. Their surveys showed very substantial plagues of cancer, leukemia, birth defects, respiratory problems, hair loss, rashes, lesions and much more."

I've been in this thread posting for a while.

Сергей, you seem like a pretty cool guy. Keep up the good work.

>>4592306
>Research has shown that we have MORE than enough wind on this planet to provide electricty for the whole world.
Yes, harvesting it cost effectively while maintaining always-on power is the problem. You can't.

>>4592306
>Research has shown that we have MORE than enough wind on this planet to provide electricty for the whole world.
I'd love to see your source on this one.

>>4592313
In the most asinine interpretation, it's more than true. If you add "cost effective" and "maintain always-on supply", the it's quite false.

>>4592289
And you don't think that you blaming nuclear reactors for your family's cancer rates is slanting your view of things in any way at all?

Also, let's think about this for a moment: the world energy usage is around 10-12 terawatts/year. There are only two possible sources of energy that can provide for that if we get rid of fossil fuels (which I can promise you that coal, even "clean coal" can be shown to "kill" more people than radiation has ever dreamt of in any form). Those are nuclear and solar. Solar implies storage problems, also it's nonviable for many locations once you get past temperate zones, and even in temperate zones it'll need to take a form other than photovoltaics (most likely some form of thermal capture). More to the point, even with full insolation, it can only keep up for so long. We. have. to. have. more. power. Or do you want rolling brownouts to kill people in hospitals and other sundry nasty effects of power shortage? This will happen in the fullness of time, incidentally. Not may, will. Especially with China and India hitting their stride.

Biofuels you say?

Nope. It would take replacing half of all of the plant life on the planet just to keep up with current usages -- and that's assuming being able to do something like brazil with their sugar cane everywhere -- which won't happen.

Wind is nonviable as well. At most it can account for about 7% of the world's energy needs and only in very specific places.
Geothermal is in a similar spot. And you can't just make it all in one place and pump it across the planet because of transmission losses. Hydro only accounts for something like 3% of the world's energy and won't make any more unless we start making a fuckton of lakes wrecking ecologies.

The closest thing we have to a satisfactory conclusion is nuke and solar together.

>>4592304
If I'm not mistaken, even Greenpeace has come out slightly in support of nuclear power recently. That still doesn't stop me from trolling them about Keystone XL and drilling off the outer banks of NC.

>>4592306
hehehe, I kept reading the NRC fact sheet and got to the point about Dr. Wing that authored that study. My interim professor for my health physics class is the operating health physicist for UNC hospital. He said he went to a talk Wing gave...turns out he went out to something like 12 standard deviations of the data to prove the lung cancer increase.

>>4592307
Thanks bro, I actually post in /sci/ quite often, back in when thorium got huge on the board I was telling Nuka what books to pick up about neutronics and heat transfer as it related to nuclear. I'm thinking about putting on a trip.

>>4592306
>most reliable studies
>by local residents
And they definitely went about it with scientific precision and impartiality.

>very substantial
Compared to what? Needs more statistics.

>plagues
Very biblical.

>The closest thing we have to a satisfactory conclusion is nuke and solar together.
Meh, I'd just drop the needless "solar" part.

Sure, use solar where it makes sense, which is barely anywhere. I grant that some isolated areas, or in the tropics, it might make sense. That's about it.

>>4592316
Definitely. The great thing about wind power is that it's really easy to calculate how much power you get out of it. I did an hour-long presentation on wind power for a class two semesters ago, and ended up calculating that for a home that has an energy usage of 1kW average (pretty typical for North America) you'd need a 13.6m (a whopping 44 feet) turbine and a constant wind speed of 7.1mph.

>>4592320
>12 sigma
Jesus Christ. How was that even published? Was it published?

>>4592330
Those length numbers are for diameter, sorry.

Point being, it's impossible for those conditions to ever be met practically.

>>4592327
I gotta disagree with that. Well, since I said it in the first place I guess that's pretty obvious, but it's actually viable in a lot more locations than just the tropics/deserts, just not necessarily in the current forms of the technology. This becomes especially true if we finally get fresnel lenses and passive cooling correct for PVs and ever get stirling engines to a point where they can be economically produced. Hell, even in areas with lower insolation values, you could get a decent throughput using a PV array to electrolyse salt water into hydrogen and chlorine, and then burn the hydrogen as a secondary thermal source for a huge thermal collector that powers a stirling engine to help make sure it keeps running at night. Expensive as hell to set up at the moment, but it is workable, and at non-optimum PV locations too.

>>4592332
No clue, but it probably was if that NRC "fact sheet" website discusses it (but doesn't cite). And don't quote me on the exact number, but it was something extreme. The point is that a lot of these "studies" grab at straws when it comes to mass exposure to radionuclides. It turns out that it's EXTREMELY difficult to accurately measure mass exposure.

But I'm finally going to sleep. I might be back posting tomorrow, but I've got two more physics midterms on friday that I actually need to study for.

I'm not sure if it was asked before- sorry for that- but how small can a nuclear reactor be? I know they fit them into submarines, but what is the smallest viable size of nuclear reactors.

Also a noob question: are there nuclear batteries?
>Implying I don't know that this question is dumb

>>4592340
>Also a noob question: are there nuclear batteries?

That would be incredibly unsafe. It's a lot easier to just have a nuclear facility make the energy, then transfer the energy to a portable form like a battery.

>>4592340
Shit, I guess I can answer one more question.

The smallest LWR that was ever built was SL-1. I mentioned it earlier when I said there was only one reactor incident in the US that directly caused loss of life. It was a trashcan sized reactor that had a single control element which was pulled out too far during operation. For that reason, there has to be more than one control element for any reactor built in the US.

And yes, there are actually nuclear batteries. They commonly use long-live alpha emitting nuclides (commonly used in space craft). The alphas create heat by depositing kinetic energy in the casing and thermocouples use the heat to produce current. They're rather inefficient but nifty for space craft. Before that idea, NASA considered launching chickens into orbit to create heat.

Nuclear batteries? Why not?
They couldn't work the same way as a reactor (which basically, generally works by using the energy released by the nuclear reactions to boil water to make steam which spins a turbine, which turns a generator that makes electricity--same process as a coal fire plant or a NG fire plant or really most every other power plant type out there barring the exotic types).

But you could make one using a thermocouple: basically two different metals that have the right mix of properties so that when they are brought together and one is kept a different temperature from the other it'll create electricity.

The problem with doing that would be since it's inclosed, you'll have heat bleeding over to the cold side, so you'd only be able to use the battery for a little while (depending on how big of a load you had on it) before it got the entire thing warm enough to keep the electricity from being made.

But you could always just throw it into a freezer for a little bit and it'd be usable again.

I'm not really sure how strong of a battery you could make like this--likely not very strong at all, but it *is* possible. Might be some other ways I don't know about too.

>>4592349
>nuclear batteries
Actually, that would be the nuclear pacemaker.
http://osrp.lanl.gov/pacemakers.shtml

>>4592349 It was a trashcan sized reactor that had a single control element which was pulled out too far during operation.

Please correct me if I'm wrong but I believe SL1 had 9 control rods, however, the centre rod alone could raise the reactivity to catastrophic levels on its own, even with the other 8 rods fully inserted. The crew were well aware of this and often joked that they'd pull it out if the ruskies ever came over the horizon. It's never been clear whether the incident was an accident or an extreme suicide.

Battery-guy here.Thanks for the answers. Science is so exciting!

Sergei, how do you enjoy your field? Is study ridiculously hard or is it okay? I've been out of HS for close to a year and I am juggling choices, but I have been very interested in nuclear engineering for some time. Sorry I can't really help you too much

What is your opinion on Fast Neutron Reactors? France is actually developing the Advanced Sodium Technical Reactor for Industrial Demonstration or ASTRID to replace the Phénix reactor and it is planned to be a 600MW FNR prototype reactor for commercial use.

Also what do you think of france reliance on nuclear energy, which represent about 75% of its energy consumption?

Anyone interested in the topic (although, it's equally populated with health physics) should read Proving the Principal. It's free:
http://www.inl.gov/publications/

>>4592404
>The victims were Army Specialists John A. Byrnes (age 27) and Richard Leroy McKinley (age 22), and Navy Electrician's Mate Richard C. Legg
>Leroy

>>4591891
This is just completely fucking idiotic.

Yes, with a higher flux, you'll get a higher rate of transmutations for a given sufficiently small transmutation sample, but as you make the sample larger, change it from an isotope production cylinder to a breeding blanket, the highest available flux matters less and less, and the total neutron production matters more and more.

See, the larger you make your target mass, the less of it fits in the volume where the maximum flux is available. If you put a great big breeder blanket around a little reactor with high maximum flux, most of it will actually be exposed to a much lower flux, because flux falls off with distance.

A high flux is important for inducing transmutations in a small sample. That's why it's desirable for producing medical isotopes with short half-lives: you want as many transmutations as possible in the smallest volume and the shortest time period, so you can rapidly get a high concentration of the desired isotopes so it's feasible to extract a worthwhile amount of them before they decay.

A high flux is NOT desirable for breeding plutonium. Uranium is cheap, so it's easy to make a big breeding blanket, it's important to give the transmuted U-238 time to decay through both steps without capturing any additional neutrons, and important to have a low probability of the plutonium fissioning before it can be processed out. A LOW flux but HIGH total neutron production with FAST neutrons is ideal.

This retard does not know his shit. He's a fucking parrot: memorizes stuff that he's told will be on the test without understanding it.

It's a goddamn horror of the modern age that people can go through their education like this and get degrees in things they don't understand.

Bumping post systems test!

>>4592404
You're right, it did. The incident actually created the "stuck rod" criteria wherein the most negative reactivity rod has to be stuck out of the reactor, and the remaining rods must compensate and bring the reactor to shut down.

>>4592417
I would definitely say that it's a lot harder than other engineering fields, maybe not the hardest thing though. The biggest problem I have is the people who teach it. You can probably get by doing this or that, but some profs really come down hard on you for some things.

>>4592422
Again, I have qualms against sodium, but I do believe fast reactors are the way to go. I also like the modular ability of them. Granted, ASTRID may be only 600MW, but that's right in between test reactor and current plant power outputs. This could be indicative of the next generation of nuclear plants (Gen 3+ or Gen 4). As to France's reliance on nuclear, I think it's pretty fucking awesome. With that high of a percentage though, it means they have to provide some load follow capability with nuclear, which is difficult, given transients and fission poison build-up in short periods of time. The real kicker though, is the fact that now that Germany has no nuke power, they're going to end up buying a shitton of electricity from France, which, more than likely, will be produced through nuclear.

>>4592417
Not OP, but I did want to point out that depending on your money situation, you might actually find a pretty decent route to head into this field by joining the navy as a nuke tech. You'll get a lot more of the practical side of the house, but a lot of hands on, and what makes things better: you can actually complete a *lot* of your course load while you're in and for free, then use the GI Bill to pay for finishing when you're out. This would take you about 8 years (assuming you've got to take two years worth after your service, but it's entirely possible you could actually complete the degree while in--difficult but possible), of which 5 years will be hands on experience with a nuclear reactor. Hell, and even just with that experience and training, you can get a nice job afterwards without a degree.

>>4592980
Son, pull your head out of your ass.

The concept between medical isotope production is much the same. Take Tc-99m for example. I use it because it's analogous to the breeding process of U-238 to Pu-239, that is if you're simply exposing it to a flux and are not extracting it as a fission product. Mo-98 is the starting material, which then undergoes neutron capture to Mo-99, which then beta decays to Tc-99m. It doesn't matter what the sample size is, what matters is that you have a significantly high enough flux to first GET it to transmute to Mo-99. The same thing happens with U-238, you're not going to have any significant reactions if there is not significant flux. Even if you LOWER the flux, the chance of transmuting it twice stays the same (U-239 has an order of magnitude larger capture cross section than 238). So you're argument is null and void.

Also, you bring up breeder blankets, but you also brought up spatial attenuation (again, you call me the parrot). You're going to need XBOX HUEG amounts of a breeder blanket to moderate from Tokamak energies down to the energies needed so that U-238 only ABSORBS and doesn't fission. Additionally, you want a low irradiated time for Pu-239, necessitating a HIGHER flux on a specific portion of breeding material to get the higher reaction rate.

>>4593098
>>4592980

Since you're so keen on breeder design, let's bring up another plutonium breeding reactor. Our old Chernobly favorite, the RBMK. Surprisingly, the RBMK is a THERMAL reactor design. Not only that, it uses naturally enriched Uranium indicating that FLUX levels were significantly high enough (even with graphite in an XBOX HUEG configuration, which is a questionable moderator) to induce fission in U-235. Not only that, but it provided just enough moderation for U-238 to capture in its own resonance/bordering on fast range. The whole reason there was a problem in Chernobyl is because graphite has a positive moderator coefficient, meaning that it becomes more efficient at moderating neutrons to THERMAL as it heats, facilitating almost prompt critical levels.

So please, stop reading wikipedia, go to school to get a degree (and, if you have one, pray tell what it is), and pick up a goddamn book sometime.

>>4593103

Sorry, it wasn't the graphite with the positive moderator temperature coefficient, it was the positive void coefficient, which allowed neutrons to still be moderated under steam conditions of the coolant.

My point still stands though.

Would you consider working for one of the LFTR research groups like FliBe if they offered you a job?

What do you think about the traveling wave reactor?