Nuclear science help

A Geiger counter or other device for counting scintillations would register a particle where there was one. There are Beta particles going everywhere. It isn't a matter of simply detecting them but the matter of detecting many particles, which would indicate that a source of radioactivity was nearby. If your batteries are well shielded, then they would not release many particles into the environment where they could be detected. If the shielding is not good, then they would be easy to detect.

You might see if your fictional scientists could add subatomic particles to atoms such that they would become unstable isotopes that would have short half lives. Those isotopes could be made in an ordinary nuclear reactor and separated from the other atoms using chemical reactions. This is the current procedure for making materials for medical radiation treatments. I am oversimplifying, but the reactor adds the protons or neutrons and the chemical reactions separate the desired end products form the ones that are not wanted.

slhuang said:

Thank you SO SO much! That actually cleared up a lot of what I was confused about from my research, and you gave me a new direction to explore, too. SO much appreciated!

Repping you!

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I'm glad that I could help, but I think that something that would store energy in a more readily usable form would be better. There are lots of steps involved in getting useful energy from unstable nuclei. For example, storing anti-matter in a magnetic field in a vacuum such that you could squirt a stream of gas at it when you needed energy, and the resulting burst of x-rays would be absorbed by the walls of the chamber and bled off as electricity. There are a couple of sticking points, but it will work as long as you don't waste words describing it.

Our deep space probes all run off atomic batteries. Strictly speaking they are Radioisotope Thermoelectric Generators. They build up heat through atomic decay which is converted to electricity. Your OP's could detect the low-level radiation from one of the cells or the warm glow of one at work (thermal vision would pick them out).

slhuang said:

At what range could a Geiger counter (or other survey instrument) register the beta radiation from an atomic battery fueled by strontium-90?

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Beta-radiation, which is high-energy electrons, can be shielded by relatively thin metal. Chances are the power source would be housed in a metal container which would pretty much contain the radiation.

slhuang said:

I'm looking for a way to use "atomic batteries as power sources" as a plot device in a scifi story.

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The new Mars rover Curiosity is nuclear-powered (in contrast to the solar-powered Spirit and Opportunity), so it is independent of Martian temperature conditions. This kind of power-plant is today's technology, not the stuff of SF speculation.

slhuang said:

My first thought was to try to come up with some way of science-fictionally decreasing the isotope half-lives so the power sources would decay away in a matter of minutes. But from my research, the science didn't seem to agree with me being able to do that, even fictionally (if anyone knows of some way that would be halfway plausible, please let me know!).

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Your science is correct. Radioactive decay rates are among the most fixed of physical constants. We know of no way, short of annihilation of the atomic nuclei in a big reactor, to alter these constants.

slhuang said:

So then I thought, well, what about detecting them? Originally my power sources were all plutonium-238, but the alpha radiation wouldn't be detectable at all (right?).

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Probably correct. Alpha particles, which consist of two protons and two neutrons (essentially a helium-4 nucleus) can be blocked by a sheet of paper.

But remember that decay of heavy radioactive isotopes like Pu-238 is a multi-step process, commonly involving generations of daughter isotopes that may emit beta particles as well as alpha particles, and gamma-rays as well. The latter are much more difficult to shield.

slhuang said:

So I thought, what if I switched to strontium-90, which (I think) is used as a power source for atomic batteries but has beta decay instead? And whether the strontium-90 fuel would be detectable at any sort of range is where I'm stuck right now. My research suggests it may depend on the energy of the beta emission, and I can't find specifics for strontium-90.

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Actually, your research is highly admirable, and your questions sharp and germane. You might be surprised how many questions this forum gets that don't fall into those categories.

slhuang said:

Apologies if I'm showing appalling levels of ignorance, and thanks in advance!

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You have an appalling level of intelligence, and require complete vilification for that.

Beyond that, for the writing of SF, you might be overthinking the tech. The element handwavium (Hw in the Periodic Table) is highly useful.

caw


(Just for background, I'm a Ph.D. geologist, teaching introductory Physical Geology at the local university, and in that class I discuss radiometric decay and radiometric dating in some detail. I started post-high-school academic life as a physics major, until I discovered my hatred of math classes.)

Pu238 decays directly into Uranium-234. Uranium-238, the most common isotope of Uranium, also decays into U234 via an alpha and two beta steps. From there, the decay chain of U234 is shown in this ungodly long URL, with several beta steps involved:

http://www.google.com/imgres?imgurl...k0TUebgG83RiAL0mYDADg&ved=0CEMQ9QEwAw&dur=383

caw

slhuang said:

Thank you, BDSEmpire! Would you mind elaborating on how such detection of the radiation might work? That would be exactly what I'm looking for . . .

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A Geiger counter will start plinking away above background levels the closer you get to the radioactive source. It will click or chirp depending on what model you have. The faster the clicks/chirps, the more radioactive particles the detector encounters. Here is an overview: http://www.gammageigercounter.com/blogs/articles/6221820-how-does-a-geiger-counter-work

With that in mind, the range of detection is kind of a tricky problem. A thermoelectric battery is going to be reasonably well-shielded so that it doesn't irradiate the user. That means you won't detect much of anything from it unless you put the Geiger counter right on top of one. On the other hand the unit will *glow* in infrared light like crazy because it's going to be much hotter than the surrounding environment. There's a lot of waste heat involved with generating electricity. You can read about Russian terrestrial RTG's here: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#Terrestrial

Notice how inefficient they are for making electricity out of heat.

Firstly, just about anything is "science fictionally plausible" - what you might want is "scientifically plausible."

blacbird said:

...
The new Mars rover Curiosity is nuclear-powered (in contrast to the solar-powered Spirit and Opportunity), so it is independent of Martian temperature conditions. This kind of power-plant is today's technology, not the stuff of SF speculation.

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The technology has been around for a while - Pioneer 10 was launched in 1972:
http://en.wikipedia.org/wiki/Pioneer_10#Power_and_communications

Was there any protest over launching Curiosity? I recall in previous decades there were protests over launching spacecraft containing nuclear substances, over the possibility of a failed launch bringing it back to Earth and busting open, causing radiation leakage.

BDSEmpire said:

A Geiger counter will start plinking away above background levels the closer you get to the radioactive source. It will click or chirp depending on what model you have. The faster the clicks/chirps, the more radioactive particles the detector encounters. Here is an overview: http://www.gammageigercounter.com/blogs/articles/6221820-how-does-a-geiger-counter-work

With that in mind, the range of detection is kind of a tricky problem. A thermoelectric battery is going to be reasonably well-shielded so that it doesn't irradiate the user. That means you won't detect much of anything from it unless you put the Geiger counter right on top of one. On the other hand the unit will *glow* in infrared light like crazy because it's going to be much hotter than the surrounding environment. There's a lot of waste heat involved with generating electricity. You can read about Russian terrestrial RTG's here: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#Terrestrial

Notice how inefficient they are for making electricity out of heat.

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Yes, detecting the heat produced will probably be the best way to detect it.

I know you might already have your answer but my scientist husband suggested looking up the system the Mars rover Curiosity is using. It's based on a highly radioactive plutonium isotope.