Bang,banging,banging more, badabang

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Bang,banging,banging more, badabang

Like when kids ask for more money but can't lend me cash if my wife has the bank card.

Gotcha

They want to deliver vast amounts of information over the Internet. And again, the Internet is not something that you just dump something on. It's not a big truck. It's a series of tubes. And if you don't understand, those tubes can be filled and if they are filled, when you put your message in, it gets in line and it's going to be delayed by anyone that puts into that tube enormous amounts of material, enormous amounts of material.

I mean i watch justin huhn on youtube. But mr higgs can probably break it down better than anyone on this site

take a hundred mousetraps place a ping pong ball on each one.

toss a pingpong ball into the mousetraps - suddenly there are pingpong balls flying everywhere.

change the pingpong ball to a neutron, the mouse traps into uranium atoms, and you get the general idea.

get enough material (mouse traps) close enough together, shoot a neutron (ping pong ball) into it and you get a chain reaction of atoms splitting part, causing other atoms to split apart, releasing energy in the process.

The story of nuclear fission is the story of a free neutron interacting with a heavy element.

Heavy elements are those with automatic masses (the sum of its protons and neutrons) greater than 200.

The most common heavy elements we think of are usually Uranium and Plutonium as they are two that work the best in reactors and bombs; Which are typically what we use fission for.

When a free neutron travels at just the right speed and distance from a heavy elemental atom of let’s say Uranium 235 (92 Protons with 143 Neutrons in its nucleus), the free neutron can be absorbed into the nucleus and immediately cause it to become unstable and split into two smaller “daughter” nuclei.  These can be a number of different smaller elements, but usually two and sometimes three.  

One possible product of a U235 fission is 1 Beryllium 145 atom and 1 Krypton 92 atom.  In addition to these two new daughter nuclei, the reaction also produced thermal light energy and 3- free neutrons.

These free neutrons produced by the fission reaction have the potential to cause more fissions.  In fact this is why nuclear physics was so heavily studied in the early to mid 20th century, the possibility of these free neutrons causing a chain reaction, releasing exponentially more energy than a chemical reaction.

If you have enough fissionable material, such as U235, in a small enough space, a series of fissions by the released neutrons from the first fission event can become a sustainable chain reaction.  The term for this is when the reaction becomes “critical”.  

The daughter elements produced by each fission are always unstable and highly radioactive, releasing alpha particles, which is two protons and two neutrons (a helium nucleus) or beta particles (a high speed electron) which changes these 1st generation daughter atoms into smaller, more stable atoms.

It is important to note that all elements heavier than Iron release more energy from their fission than it takes to produce the reaction.  All elements smaller than Iron requires more energy to produce a fission reaction than what is released from the reaction.

All atoms can be split or fissioned, but you only get a net positive energy release from the heavy ones.

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good to seen an old Arfcom original meme still in circulation

Fissile doesn't mean radioactive, it means that it can undergo fission with a thermal (AKA slow) neutron. U235, Pu239, etc. These are reactor fuels, and U235 is the only naturally occurring fissile material. U238, on the other hand, is "fissionable." It can fission, most likely won't, generally needs a higher energy neutron to have a decent probability to do it.

That said, yes, those materials are also radioactive. U235 does experience alpha decay and down the chain there's beta decays as well. Neutrons aren't given off during the decay, they come from the fact that U235 can also spontaneously fission. In fact, in a reactor of low enough enrichment, a neutron source is often employed to start the chain reaction. (They are no longer used in US commercial reactors). Alpha decay is when a helium atom is given off taking away 2 protons and 2 neutrons from the parent nucleus. These aren't neutrons free to cause fission, however.

The other stuff about fast vs slow neutrons, etc, is important to understand controlled nuclear fission and what I mention above about which materials fission with which neutrons can be explained by this neutron energy graph.

There's some good bits in there but to simplify it for commercial nuclear reactors, there are prompt neutrons (neutrons born directly from fission) and there are delayed neutrons (neutrons born from the decay of fission product daughters). Something like 99.5% of all neutrons are born prompt, but it's that .5% that are born delayed that allow humans to control the reactor. The absence of delayed neutrons is called "prompt critical" and we cannot control it.

While we have some experts here what exactly about radioactive material makes it carry so much energy?  Why can't you ram a particle into a chunk of aluminum and release the energy bonding those atoms for example?  Are they just impossible to split or somehow just carrying exponentially less energy to hold them together than uranium or something?

Nuclear fission is when the center of an atom, called the nucleus, splits into two smaller parts. When this happens, a lot of energy is released. It's like breaking a big piece of Lego into two smaller pieces and getting a big "POP!" sound and some energy.

Scientists use this energy to do useful things, like making electricity in special power plants called nuclear reactors. They control the process very carefully to make sure it's safe. The energy that comes from nuclear fission can be very strong, so it's important to be cautious and use it responsibly.

In simpler words, nuclear fission is when the inside of an atom splits and makes a big boom, and people use that big boom to make electricity.

Summed up by a graph,

As nucleuses get larger and larger, they reach a point where the forces pushing them apart are barely restrained by the forces holding them together. There's a reason why those are the largest/heaviest elements in nature, larger ones are too unstable. There are weird eccentricities about odd and even atomic weights but that's the gist of it.

Add a destabilizing particle and energy to one of those nuclei of the heaviest and least stable isotopes, and the forces pushing it apart become greater than the forces holding it together, so it breaks apart into smaller pieces. Fission.

Some of the energy that was holding the nucleus together is released, as the combined smaller fragments do not need as much of that energy.

The amount of energy released from a single atom is vastly larger than even the most energetic chemical reactions. If I remember the comparison correctly, the highest energy chemical reaction is about 5eV per molecule in the reaction. Each fissioning atom releases about 200 million eV of energy.

The heaviest of the natural elements, Uranium, and the heavier synthetic elements like Plutonium are so unstable that instead of radioactive decay, they will occasionally undergo fission spontaneously.

As an aside, "As nucleuses get larger and larger, they reach a point where the forces pushing them apart are barely restrained by the forces holding them together." Smaller atoms are of course the opposite... the forces holding them together are much stronger than the forces pushing them apart. Which is why it's possible with a few of the lightest elements to get them to combine, or fuse, together.

(caveat: I'm not a theoretical physicist, the above does not describe or conform to the standard model or any other mathematical model of physics, it's just an attempt at a simplified explanation for lay persons)

It’s not hard.

Especially since it’s all theory anyway. Who can argue with you?

Spicy rock goes boom.

See above graph and JHMC79's explanation. I know the graph doesn't mean much to the laymen, but what it means is that the binding energy per nucleon for a given atomic mass becomes significant and you would end up putting much more energy into the process than you would ever get out.., if you could generate such energy in the first place. U235 is barely holding itself together as it is and just needs a tickle from a low energy neutron to get its game on. Hell, it'll do it itself sometimes too. It takes us little energy to split such atoms.

Haha one of my favorite lines, "That's why we call it reactor theory, not reactor fact."

Right...

So,
There are these things called atoms.  They have Protons and Neutrons at their center.  The number of Protons in the nucleolus, as the center is called, determines what Element it is.

Protons are Positively charged and Neutrons have no charge.  Like magnets... opposites attract and like charges repel each other.  So how can a nucleolus that's made of neutral and positively charged things stay together?  There is a force that's stronger than the repulsion.  It sticks them together but it only acts over a very short distance so you have to get them really close to get them to stick.

As more and more protons and neutrons are stuck together you get the heavier elements... and these elements become more and more unstable.  They're prone to breaking apart and becoming 2 lighter elements...  That's Fission... Division of the element.

When it breaks... It's messy.  The two elements don't have the same mass as they did when they were one element.  E=MC^2  Some of the mass was converted to energy.  Also some Neutrons tend to escape... until they collide with other atoms.

That collision can trigger other atoms to also split.  Which causes more to split... and more and more.  If this is allowed to happen then it does so in a fraction of a second and you get a Big explosion.

If you instead limit the amount of unstable material and place near it materials which absorb the escaping neutrons then you can limit the speed of the reaction so you only get an amount of heat you can manage.

Power plants use that heat to boil water and run the steam through a steam turbine to create electricity.

Don’t think of it so much as all radioactive materials having great potential to release energy via fission, but rather the atoms with the highest potential energy releases by fission all tend to be radioactive.

For instance Tritium, which they put in night sights, is radioactive.  It is merely a Hydrogen atom, or 1 Proton, but also with two Neutrons.  So Hydrogen-3.  These two neutrons in its nucleus makes it unstable and it is releasing energy in order to get to its most stable form, which is Hydrogen-1 or just Hydrogen.  Even though it is radioactive it has virtually zero potential to release energy by causing it to fission.

Also the daughter products of a U235 fission are incredibly dangerous with their level of radioactivity.  Cesium-137 and Strontium- 90 are killers but as they are about half the atomic mass of their parent, they also are not good for fissioning for energy release.

You mentioned aluminum.  Yes, it can be fissioned but the energy required to split the atom is exponentially higher than what is released as it’s atomic mass is less than Iron’s.

Yes, the higher the atomic mass, the more trapped energy there is to exploit via fission.

First, radioactive does not equal fissionable or fission.

The mechanism is somewhat similar though.

Nuclei are composed of positive protons, and neutral neutrons. As elements get larger (more protons) they need more neutrons to keep the forces in balance. When the numbers of neutrons are off though, the forces are out of balance, and eventually that nucleus will expel energy and maybe particle to get to a more stable configuration. The expelled energy/particle is "nuclear radiation".

The energies that are there within every nucleus are enormous for such a small amount of matter. It is literally the energy of eons of stars bundled up into tiny bundles.

The balance of forces that hold nuclei together versus push them apart make that a lot more difficult.

When people think of nuclear fission they probably are thinking of a fission chain reaction, not just the fission process itself. Yes it's possible to fission an aluminum atom, but only Uranium (or the synthetic element Plutonium) can create a self-sustaining fission chain reaction. A fission chain reaction is a neutron expelled from a fissioning atom going on to hit another nucleus and create another fission, and so on and so on. If that happens at least once for every fission, you have a self-sustaining chain reaction. You need a sufficient quantity of those atoms of fissile material, arranged into a suitable geometry to get a self-sustaining chain reaction, known as a critical mass.

They have more energy holding them together versus pushing them apart.  As elements get larger, the balance changes progressively toward the forces pushing apart, so that at Uranium you have an element that is barely stable. There is a quirk/eccentricity in the forces such that nuclei with an odd number of particles are less stable than those with an even number. The discovery of fission was the discovery of a mechanism to push some Uranium atoms (the odd size ones) beyond the point of stability, so that they break apart. Some serendipity was involved in discovering how to make it happen.

Tiny twists of matter bump and make big boom. Big boom is useful.

TELL ME HOW A NUCLEAR REACTOR WORKS OR ILL HAVE YOU THROWN FROM THIS HELICOPTER

I believe Vogtle 3 & 4 use a Californium source for first core startup.  Are you referring to secondary sources?

It's a reactor, so spicy rock gets hot, put spicy rock in water and make hot water.

Good info. Just mansplained all of that to the wife against her will.  She didn't seem to think knowing all that was as important as I did lol.

I think this goes above mansplaining, and falls into the deeper territory of nerdsplaining.

Radon in the ground is from radioactive decay of Uranium which eventually produces radium which decays to radon.

Fission would mean the Uranium is split and is a different process than decay.

A boy radioactive atom and a girl radioactive atom fall in love...

Nuclear fission is not theory. It happens and we use it every day in nuclear power plants all over the world and have even used it as a weapon of war twice. The first weapon used fissioned U235 and the second weapon fissioned Pu239.

Yes

The forces required to create or destroy an element are enormous for example the elements in the periodic table up to and including iron can form in a conventional star like our sun, the remaining elements require forces more typical of collapsing stars and black holes.  There are other interesting oddities such as the Oddo-Harkin effect where elements with even atomic numbers are more abundant than those with odd atomic numbers - thought possibly due to proton - pairing producing a more stable configuration.

Tiny pieces of rock atoms pop off and knock tiny pieces of atoms off others nearby unless something catches or slows them down. The process get really hot and if you get near it it will kill you.

Serious question here:

How was he not exposed to all sorts of radiation anyway just handling a plutonium ball in close proximity?

Alpha emitters are boring unless ingested

Understandable way....well, take beans and mix it in your chili. Once it's inside your body it changes the molecular structure and when you run to the bathroom -

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Lucky for you it's theoretical.

So it's all just made up anyway

A portion of US Navy Surface Warfare qualifications is knowing the fission process in some detail.

Rocks make steam, steam spins turbines, turbines spin reduction gears that make the propellers go round-n-round.

Bottom photo is likely Slotin, who was warned his carelessness with criticality demonstrations would get him killed.

This is pretty good.  It is technically incorrect.  Plus you need to explain in a way GD would understand.

When you go to a Chilli cook off and you decide to eat two bowls.  8 hours later there is a release of radioactive energy.  Generally enough to lift you off the toilet seat.

One atom enters, two atoms leave.

My favorite thing about those photos is the coke bottle.

Not quite right.  Decay neutrons do not have enough energy to cause fission.

Reactor Operator / RO instructor here.

But my grilled cheese is hardly melted!

Yes.

Kharn

I’ve watched HBOs Chernobyl 5 times so I’m pretty much a SME

Yes