A couple of questions involving atomic bombs...
Just so I don’t get griped at, I tried to find this information. All I got was confusing formulas & such. So here are my questions:
1.) If you stand next to a chunk of Uranium, will you get radiation poisoning? Or does it have to be in a bomb? I suppose if you throw it at someone, you might give them a nasty bruise….
2.) Is one atom split in a nuclear bomb, or multiple atoms? Is one really that powerful?
For the record, I thought of these questions when I was half-asleep last night.
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10 Answers
1. Uranium emits neutrons, which are very harmful. In the bomb, it reaches critical mass and many times more neutrons are emitted. Standing next to one may not give you radiation poisoning (depending on how long you stand there), but it will dramatically increase your risk of cancer.
2. Many atoms are split. In a normal block of uranium, more neutrons escape to the environment than those that cause further fission events. Once critical mass is reached, few neutrons escape to the environment, so the number of atoms being split rises exponentially, which leads to an explosion. See this resource, which will be able to explain it all for you.
1) Uranium is radioactive, but just passing by it won’t give you radiation poisoning. It’s an exposure-over-time business, and is nowadays measured in grays. It used to be rads.
2) Multiple atoms.
Check out the Simple English Wikipedia entry.
This one talks about nuclear fission, the process used by many sorts of nuclear devices.
First question: No, as long as it’s pure Uranium, not spent nuclear fuel that contains fission products. Uranium itself doesn’t emit much strong radiation (gamma rays). The neutron flux from a subcritical mass is minimal. Just don’t eat it or breathe dust from it (toxicity and alpha particles).
Second question: It’s many atoms splitting. A chain reaction that causes the nuclear detonation. Technically, it’s known as a prompt supercritical condition in nuclear weapons. Nuclear reactors are designed never to exceed a prompt critical state, so physically cannot explode like a weapon.
(1) No. On both counts, actually (so long as the bomb isn’t detonated!).
The vast majority of natural uranium atoms are either U-238 (92 protons, 146 neutrons) or U-235 (92 protons, 143 neutrons) and both decay naturally by alpha particle emission very, very much more readily than by spontaneous fission. Alpha particles are naked helium-4 nuclei (2 protons and 2 neutrons). A sheet of paper or the dead cells in your epidermis are enough to stop an alpha particle. They also have long half-lives, which means the rate of this decay is quite slow. So even the sub-critical enriched uranium core (80%+ U-235) of a bomb is fairly safe to handle so long as you don’t have anything nearby generating free neutrons.
(2) Many, many more than one. But actually not that many compared to the total number of fissionable atoms in the bomb core.
@hiphiphopflipflapflop Alpha particles are still extremely dangerous, because they deposit all their energy in a small volume of tissue. They are generally stopped by skin, but they make you much more susceptible to cataracts if you receive exposure to the eyes. The neutrons emitted by the (proportionally) few nuclei that do undergo spontaneous fission are very dangerous though, as they are far more penetrating than alpha particles but still have a significant amount of energy to deposit.
@Draconess25 Here are four books on basic radiation safety, The math is not terribly complicated in any of them (the first listed is rather expensive, about $140) all are available through Amazon:
“Physics for Radiation Protection” James E. Martin
“Health Physics Solutions Manual”: Herman Cember
“Introduction to Health Physics” Herman Cember
“Radiation Detection and Measurement” Glenn F. Knoll
These are all standard texts for training of Radiation Control Technicians. If any part of the math stumps you, PM me, I’m good at explaining math over the internet.
@Draconess25 The books are good for the concepts. The math involved is pretty “plug and crank”. I’ll help you get over the rough spots.
1. Uranium for a bomb is purified, concentrated, and in this form is highly radioactive and dangerous. Uranium ore is dangerous, but only if you stay in contact with it for a long time.
2. Many atoms are split. First just one or two, then more and more as the explosion takes place. (1 begets 2, 2 begets 4, 4 beget 8, 8 beget 16, etc.) Imagine a room that has mousetraps all over the floor, end to end, side to side, and each trap has 2 ping-pong balls on it. Now throw 1 ping-pong ball into the room…
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