/sci/ - Science & Math

[Anonymous No.7183927]

Ask me anything about radiation/radioactivity

[Anonymous No.7183937]

Ok. Been looking at fusion facilities (esp. 7-W). All seem to be plasma based held by supercooled mag fields. (Except for the ignition facility).
We need fusion for energy.
If successful, how is the heat going to be transferred out of the tokamak to enable 'work' to be done?
ie arent they a waste of time/money?

[Anonymous No.7183946]

>>7183937
it depends on the fuel cycle utilized. the easiest to achieve "ignition" is D-T, but 80% of fusion energy comes in the form of high energy neutrons. so you need a typical thermal cycle to handle the energy conversion into electrical power. this is done within the blanket region of something like a tokamak (ITER), where you will also get additional energy from lithium proction in the blanket region (but only if you use Li-6, Li-7 is endothermic, Li-6 is exothermic). there are other fuel cycles specifically D-He3, where almost the entirety of the fusion energy produced is carried by charged particles. this allows for direct conversion via charged particle collection, with conversion efficiencies (theoretically) in the 90+% range (experimentally, depending on budgeting limitations, theyre mid-70%)

[Anonymous No.7183953]

I have heard that radiation is used for true random numbers. How is radiation random?

[Anonymous No.7183958]

>>7183946
it also depends on the device. magnetic mirrors, and other linear devices are especially well-equipped to handle direct conversion, due to the inherent particle leakage associated with their designs (they have good energy confinement, but poor particle confinement, whereas toroidal devices such as tokamaks have good particle confinement but poor energy confinement). mirror devices have inherent particle leakage from the ends of the devices, and this particle leakage (typically lower energy particles that have relaxed more inwards into the center of the device, which actually has the effect of increasing the total amount of energy/particle in the device as time goes on) can be captured by direct converters

[Anonymous No.7183960]

>>7183953
we can't predict its occurrence on a case-by-case basis.

[Anonymous No.7183991]

Very stupid question that I know 5 secs on google can answer, but...

Why is radioactivity harmful? Why, exactly, does being near a rock of Plutonium kills you?

[Anonymous No.7183996]

>>7183991
>Why is radioactivity harmful?
energy deposition
>being near a rock of Plutonium kills you
it won't. it's an alpha emitter, so it's radiation is only really dangerous if it's ingested, but if injested, alphas typically are the most dangerous

[Anonymous No.7184002]

>>7183996
>energy deposition
Additional information?

[Anonymous No.7184011]

>>7184002
it's like a bowling ball hitting the pins. it transfers its energy, via coulombic interactions and nuclear collisions, to other atoms/molecules in your body (for alphas and betas). gammas transfer energy when they interact via the photoelectric effect, compton scattering, and pair production. neutrons can interact via collisions, and can induce nuclear reactions. it's also how we kill cancer with radiation therapy. the radiation is used to kill local cancerous cells, which can both both prevent reproduction of, or eradicate, the cancer cells

[Anonymous No.7184052]

Question
What is the difference between Half-life and Mean-life? Why aren't they the same value? Keep in mind I am a really stupid layperson.

Also, I read somewhere that nuclei with even (or was it odd) numbers of hadrons tend to be more stable. Something to do with quantum numbers or whatever. Why is that?

[Anonymous No.7184065]

>>7184052
half life is the time it takes for half of the remaining radioactive material to decay. mean life is the average lifetime of all atoms of a particular isotope (the average amount of time any given atom of that isotope remains before decaying). mean lifetime is also the inverse of the isotopes decay constant.

[Anonymous No.7184395]

>>7184065
Sweet. Thanks man. I have another question, but it's not exactly about radioactivity. But maybe you might know.
Ok so I read that diprotons are extremely unstable, and they decay into two protons in much less than a billionth of a second, so how does deuterium form in stars? I mean, websites say beta-plus decay occurs, but any info on diprotons says they just decay into two protons almost immediately. I can't find any experiments which show diprotons decaying into deuterium.

[Anonymous No.7184421]

>>7184395
its all probabilistic stuff. the formation of D is much less probabilistic than the two protons fusing and then decaying back to two protons again. just like in D-T fusion, the products are almost always an alpha and a neutron, but one in every several thousand or so times, the product is a short-lived He-5 and a gamma.

[Anonymous No.7184428]

>>7184421
Thanks man, that's interesting. Yes I see it makes sense. Quantum mechanics is pretty awesome.

[Anonymous No.7184477]

>>7183927
what is that gif?

[Anonymous No.7184493]

>>7184477
Uranium in a cloud chamber

[Anonymous No.7184858]

>>7183996

You're giving a technical answer to a simple question.

>>7183991

The charged particles that come zipping out of radioactive material can physically damage your DNA, causing cancer.

Radiation strong enough that it kills you in the short term does so by basically cooking you.

[Anonymous No.7185224]

>>7183927
I HAD to make a webm from that video

[Anonymous No.7185533]

>>7184858
energy transfer is the simplest, most bare-bones answer there is. and it's not just charged particles, gammas, x-rays, neutrons, etc are also all forms of ionizing radiation

[noko No.7185542]

>>7183927
what do you think about muon or pion therapy, should they be researched more?

[Anonymous No.7185586]

>>7183927

no joking, I want to build a home nuclear reactor, even just as a demonstration device. I've been looking into Strotium-90 because it's readily available, any advice?

Also, I'm coming into this project with significant EE experience, I've built my own Farnsworth Fusor among other things like radios, diesel-electric generators and batteries.

[Anonymous No.7185594]

>>7185586
SOMEBODY just got added to a bunch of watchlists...

[Anonymous No.7185598]

>>7185586
what would you use Sr-90 for? it's just a beta emitter.

[Anonymous No.7185602]

>>7185594

it's legal to possess small amounts of radioactive material, including strotium-90 which can be shipped directly do your door

>>7185598

because it's readily available, and there exist soviet RTG designs that utilize it

I'm just making a simple demonstration device, not an actual power plant.

[Anonymous No.7185603]

>>7185224
there was already one m8 :^)

[Anonymous No.7185604]

>>7185602
oh so you just want an RTG, not a fission device

[Anonymous No.7185607]

>>7185604

yes, I should have made that clearer

[Anonymous No.7185609]

>>7185603
mine is higher res and longer
eat a dick

[Anonymous No.7185615]

What metals survive long time radiation exposition in terms of corrosion/damage?

[Anonymous No.7185617]

>>7185586
Do nuclear radioisotope count as a nuclear reactor?

Anyway to op, why aren't more nuclear isotopes used to produce energy? sure you can't really control the speed of the reaction, but the inherent safety and power density should be more than enough to raise interest.

[Anonymous No.7185625]

>>7185607
the output energy/power density isnt that high so youd need quit a bit of Sr to get any significant power output from an rtg, there just isnt enough heat generated from small amounts of it. it would be much more useful in a betavoltaic.
>>7185617
theyre useful for smaller, or portable devices, but for large scale energy production theyre not good enough.

[Anonymous No.7185629]

>>7183927
What is void coefficient?

[Anonymous No.7185638]

>>7183927
>>7185224
How large a portion of the traveling particles are we seeing vs the actual amount?

[Anonymous No.7185642]

>>7185615
it depends what kind of environment. 316 stainless and tungsten are used as plasma facing materials in ITER, but irradiation causes swelling, embrittlement, creep, blistering, etc. there are also alloys like TZM. there is no one best, it depends on the heat flux its exposed to, type of radiation exposure, and other stuff
>>7185629
basically the response of a reactor to increases/decreases in "voids"in the coolant/moderator. these typically come from nucleate/film boiling on fuel rods. its basically a measure of the change in reactivity corresponding to changes in void fraction.

[Anonymous No.7185651]

>>7185638
well assuming thats U-238, with a specific activity of about 33 microcuries/gram, theres about 12000 decays per second/gram.