Run Your Laptop On Nuclear Energy

Reader zymano points to this news.com artcle on innovations in portable power sources. Would you feel comfortable with a radioactive power source inside your laptop or cellphone?

Comments

Beta particles...

[crc32]

These things are so weak that even a sheet of paper will block them. These things will probably be encased in metal and plastic. Everyone who is concerned about radation near their bodies should be more worried about the antennas than the isotopes. If these things can be shown to be safer than Lead, or Nickel-Cadmium (both extremely toxic, even in miniscule amounts), then these may be the next wave of power generation...

Radiation

[starsong]

The radiation mentioned in the article is just the emission of beta particles -- in other words, ordinary electrons. At the energy levels associated with atomic decays they would be stopped by a thick piece of paper, to say nothing of human skin.

So this actually sounds like quite a novel and safe approach. It's not like they're shoving a few pounds of plutonium into the thing and trying to get energy from the heat -- like NASA does on space probes.

More info from Cornell

[nystul555]

Here's more info, straight from Cornell.

http://www.news.cornell.edu/Chronicle/02/11.7.02 /t iny_battery.html

http://www.news.cornell.edu/releases/Oct02/canti le ver.ws.html

It seems to me that this should be safe. They note in the article that they are only creating batteries which use Beta radiation, which is too weak to hurt you. If that is true, then yeah, I would use them, if it meant my laptop or cellphone would last for 10 or 20 years.

Re:More info from Cornell

[moderators_are_w*nke]

I could be wrong on this one (I'm no physicist), but I was under the impression that alpha particles were unable to penetrate skin (because they're too big), whereas beta particles and gamma rays can. If this is right, any power device containing a beta emitter would need to be lead lined.

An alpha particle needs to come into contact with live cells to cause damage, so you'd have to swallow the emitter or stick it in youe eye before it did any damage.

alpha, beta, gamma

[tbmaddux]

Something wrong here. From the original article:

Lal said that he chose only isotopes that emit beta particles because their energy is small enough not to penetrate skin. Radioactive material can emit beta particles, alpha particles or gamma rays--the last two of which are carry enough energy to be hazardous, said Lal.

Alpha particles are helium nuclei, and cannot penetrate the skin. Alpha emmitters aren't much concern unless ingested or inhaled. Beta particles are electrons, they can penetrate the skin and/or burn it. So either it's really an alpha emitter and harmless, or it's a beta emitter and of concern.

Re:alpha, beta, gamma

[RealityProphet]

TVs, monitors, and other CRT devices emit electrons all the time, and at high voltages. As far as I know (and care) they are stopped and rendered harmless by the flimsy plastic casing of the monitor and of course by the phosphors on the screen that luminesce when they are hit by them. So when they say they don't have to worry "as much" they are probably saying that 3" lead casings will not be necessary.

Re:alpha, beta, gamma

[Idarubicin]

True, as far as it goes. Alpha particles outside the body are indeed quite harmless--they cannot penetrate the dead skin cells of the epidermis, they don't even travel very far through air. If ingested, alpha emitters are often quite a bit more dangerous than other radioisotopes, because alpha particles deposit all of their energy over a short path. If these short paths intersect cell nuclei, this process can lead to mutation and ultimately cancer.

Betas come in a range of flavours. They are indeed electrons, ejected at high speed from radioactive nuclei. The amount of kinetic energy that they carry depends on the radioactive species under consideration. Phosporous-32 is quite potentially dangerous, it emits betas with an energy of about 690 keV (IIRC). These will penetrate skin quite easily. I mention P-32 because it is frequently used in molecular biology. In the lab, compounds containing P-32 must be stored encased in plexiglass (thickness varies with concentration and quantity of isotope), and shielding employed by researchers.

The batteries that they're working on at Caltech are based around Nickel-63. Ni-63 has a beta decay energy of up to 17 keV. That's pretty pathetic, and it won't penetrate skin. It's actually annoying for researchers for a different reason: you can't detect it with a Geiger counter because the weak betas won't penetrate the window at the end of the Geiger tube. If you spill a compound containing Ni-63, it's harder to find all of it when you clean up. (P-32, on the other hand, gives quite a nice signal.)

So: Alphas are harmless outside the body, and bad if ingested. Betas may or may not be harmless outside the body (Ni-63 is, P-32 isn't) and are bad if ingested--though not as bad as alpha emitters. The section of the article to which you allude was badly written, but it wasn't as far wrong as it could have been.

Re:alpha, beta, gamma

[panurge]

The point is that alpha particles are helium nuclei. That's a gas, folks. It builds up pressure inside the shield till it ruptures and lets the radioactive source out. Betas are electrons, and if you use a nickel isotope none of the products are gaseous, so no pressure buildup. You cannot use tritium because, even if you use a solid like calcium tritide, the decay product of tritium is helium 3 - which is a gas, and so builds up pressure again. Forget all this range in air stuff, it's good old Boyles Law.

Not necessarily dangerous

[pclminion]

Did any of you actually read the article? They've chosen particular isotopes which emit only beta radiation, because beta radiation cannot penetrate the skin (well, ok, high-energy betas can, but I assume they've chosen isotopes that produce low-energy betas). Beta radiation is composed of fast electrons -- that's it!

I would definitely be cautious using a battery like this, but I wouldn't be automatically opposed to trying it. Besides, if lots of radiation was leaking out of this thing, then that would be a pretty inefficient battery, wouldn't it?

Not a nuclear engineer...

[dbarclay10]

I'm not a nuclear engineer, but I *have* spent many hours studying CANDU nuclear reactors.

So, the answer to the question in the post? Yes, I would(!!) feel comfortable walking around with what these guys are talking about in my pocket.

The fact is, you get more radiation from a digital watch than you do living as near a CANDU reactor as you're allowed to live (about a kilometer). These people don't screw around. In the current global climate of anti-nuclear-anything, they'd be idiots to even contemplate cutting a corner. And, hell, most of these people are good people - the sorrow they'd feel at anybody having died because of their designs would be real, and it would be deep. As far as the companies are concerned, you can't have a plant meltdown and then just rebuild it. Chances are, you have to build an entirely new facility somewhere else, since the original area is waaay too contaminated.

I fully expect that the people working on these batteries have the same mind set - they just don't dick around. (And from the papers I've read, that does seem to be the case.)

Re:Potential Risk?

[DirtyJ]

I don't see them being so quick to remove a similar hurdle for nuclear fuel.

Why not? What are you going to do with a radioactive lump of stuff? I suppose you could try to choke someone with it or shoot people with beta particles...

This isn't the same sort of material that gets used in nuclear weapons; it's just isotopic material which decays with a characteristic timescale so that a steady stream of particles shoot away from it. You can use the momentum imparted by these particles to power a small generator - sort of like water turning a turbine in a dam or something (not exactly, but you get the picture...).

Re:Nuclear powered cellphone

[Tackhead]

> Screw that. I want the manufacturer, a government agency, and a dozen or so independent on-profit organizations to guarantee it is safe. I mean, we saw well letting the company tell us what is safe worked with tobacco. ;)

Actually, this is one of the few cases wherein if you don't trust the gub'mint (setter of standards for rad-leakage) or the corporates (laptop manufacturer), you can just as easily verify for yourself.

Alpha: If you're not convinced from the laws of physics that alphas will be stopped by the casing of your laptop, build a cloud chamber with some dry ice and alcohol, and sit your laptop on top of it. Observe the lack of straight fat traces emanating from your laptop.

Beta: Ditto. You can also build a detector for charged particles out of gold leaf and leave it next to your laptop for a few hours, or you can just eyeball your cloud chamber for longer traces with occasional kinks as electrons are deflected in the medium.

Gamma: OK, your cloud chamber won't work as well here, so drop $300 for a pocket geiger counter from a place like Edmund Scientific. (It slices, it dices, it's something no kid who grew up during the Cold War should be without! :-)

Cloud chambers are easy to build, and fun to watch. Get an old radium-dial watch or clock, place a blue LED next to it, and you've got yourself a "nuclear lava lamp".

Case modders alert! You could replace the top flat part of a PC with it and the cool air from the base of the chamber would ooze down into your case, providing a little bit of extra cooling. along with one hell of a l33t case mod - permanently mount your rad-source in the middle of the chamber, mask off and paint a "radioactive" symbol in the plexiglass cover, with a small source directly beneath the center of the rad-symbol, and illuminate it with a one of those traffic-light/borg-cube-green LEDs, and bring a few blocks of dry ice to the LAN party! W00T!

OK, back on topic. The bottom line is that measuring the amount of ionizing radiation leacking from a nuke-powered laptop is trivial, and if you compare the (lack of) radiation coming from your laptop from the (big pile of) background radiation coming from the bricks in your house, the glaze on your grandma's dishes, and the potassium in that bundle of bananas, or just from living in the Rockies, you just might learn something about risk assessment - something about which those in the knee-jerk anti-nuclear movement would prefer to keep you in the dark.

Re:An atomic pile the size of a walnut?

[samael]

Asimov's Foundation books. When the Empire collapses, the Foundation manages to hold on to some of the technology that would otherwise have been lost.

Atomic Batteries and Medical Physics 101

[CharlieO]

OK - How Atomic Batteries Work and Medical Physics 101 :)

Medical Physics

The damage done to human tissue is a function (~linear) of the amount of energy deposited by the radiation into the tissue.

This is a function itself of:

1) The amount of energy depositied by the radiation per unit of path length.
2) The length of the path in the body.

Also of interest in practical situations is this also applies to shielding i.e. if the shielding is such that the energy is enirely deposited in the shield materiel then the radition is fully shielded. If not then you have attenuated the radiation.

On one hand massive particles like Alpha Particles are 'safer' because they deposit energy quickly (they interact fairly strongly with matter), so can be stopped by very small masses like paper/foil/skin epidermis. On the other hand high energy Alpha Particles can be very dangerous if not shielded because they can carry a lot of energy into the body due to thier mass, and deposit it there as the tissue stops the particle.

At the other extreme Gamma Radiation is 'bad' because it doesn't lose energy very easily (becasue they don't interact as strongly with matter) so they cannot easily be shielded, but will at least not deposit the whole of the energy in the tissue but pass through it. Unfortunatley of course gamma radiation is highly energetic so it can still deposit a lot of energy.

So the risk of medical damage from a radioactive source is function of
1) The strength of the emmission
2) The type of emmission
3) The amount of shielding between the source and you

It is not just the radition type.

As already stated the biggest risk is when radioactive substances are ingested such that they stay in the body for some time, as this increase the energy depositied into the tissue - alpha emission is particularly bad here because it will deposit the whole of the energy into the surrounding tissue.

In this instance you may well find that a low energy beta source is a better choice, because with a low energy alpha source the raditation may not even make it out of the source's casing.

Atomic Batteries

For the interested 'atomic' batteries generaly work by using a radioactive source to heat a shield material around it. This heat can then be turned into electricity by putting a thermocouple matrix in the shield material, with the hot junction in the material, and the cold junction outside.

Now in this case we need a lot of energy in the shield material, but enough to get out of the sources casing, so low energy beta is good here.

It is safe, because the whole point of the design is that the radiation is shielded, thats how you recover the energy into electricty. You will get very very little external radiation from a well designed atomic battery.

This is not new technology, deep space probes have been using them for years because solar cells would be useless in the outer solar system

The characteristics of this sort of power generation is that it is physically small, long lasting but low current. This is ideal for portable devices, but not usable really for transport or power devices.

Practically you would probably need another battery like LiIon such that the LiIon cell is trickle charged all the time, but can supply surges of power.

This would be great in a cellphone where the LiIon battery would supply the high power needed for transmiting during the calls, and the atomic battery would supply enough to charge the LiIon and do standby - phone not got enough charge, just leave it for an hour. Conceptually you may never need to charge the phone, or change the battery, it could be fitted for life in the phone.

The challenge is finding the right materials and making it mass producable. On space probes its easy because you can cool the cold junction in the vacuum of space and make it efficient, plus you don't really care about the cost or making 1000's of them a week.

Not forever

[roman_mir]

All protons in our universe will decay in about
10^33 years from now.

alphas, betas, and gammas OH MY!

[Jubedgy]

"...chose only isotopes that emit beta particles because their energy is small enough not to penetrate skin. Radioactive material can emit beta particles, alpha particles or gamma rays--the last two of which are carry enough energy to be hazardous..."

Really gamma rays (ie photons) are the only form of radiation we'd have to worry about. They have such low specific ionization (# of ions created (due to photointeractions in this case) per cm trraveled that they can go right through your body...ionizing stuff which shouldn't be and making you sick (or worse).

The other two, beta (electrons or positrons) and alpha particles (essentially helium-4 w/o the electrons) have such high specific ionizations (due to their charges) that they will not penetrate past your skin. In fact, alpha particles won't even penetrate your DEAD skin! IMHO, I consider alpha particles are much safer (unless you swallow the emitter ) in that you could hold those 'batteries' in your bare hand and not have live skin be touched whereas the beta particles WOULD reach live skin.

In any case, all of this is just probability so 'safe' is a relative term. Economically, many more nuclides beta decay (specifically beta minus decay) than anything else so that is probably the real reason: easier and cheaper to get enouogh of the right nuclide...but I applaud the efforts at trying to show the general public that at least one type of radiation isn't so bad.

You can bet as soon as these decay-powered batteries are available I'll be the first in line to get one =)

--Jubedgy

Re:An atomic pile the size of a walnut?

[Docrates]

Noy quite. When this happened, the Empire hadn't entirely collapsed yet, and the technology used by the Foundation was developed by them through renewed ingenuity (unlike the empire who ran machines but had no idea how to build new ones)

If I'm not mistaken, this happened when the foundation expansion first encountered the decaying empire.

Re:indistinguishable from magic

[Idarubicin]

Slashdotters SHOULD know better. If we're half as smart as we think ourselves, then we ought to be able to distinguish between beta radiation, infrared radiation, etc. and also the safe energy levels of each type of radiation

You're right; we ought to know the basics about different types of radiation--it should be part of every science curriculum. As for knowing safe levels, well...that's a little different.

Deciding whether or not the beta emitter in the battery is actually 'safe' or not requires a little bit of background knowledge. High energy beta emitters like P-32 are actually potentially dangerous. P-32 betas will go quite a distance in air, and even to a significant depth in skin. P-32 in a thin lead lining is even more dangerous, because betas slowed down by lead emit x-rays and gammas.

On the other hand, the source for these batteries (not mentioned in the original article) is Ni-63. Its maximum beta decay energy is about 3% that of P-32, and its betas will be stopped by a sheet of paper or the dead layer of skin. But who here has decay energies memorized? I know I had to look up Ni-63.

So: not all betas are harmless, because not all betas are created equal. Actually, linear accelerators are used to generate high energy betas (up to about 20 MeV) for use in clinical radiation therapy (for cancer treatment). Those little guys can still deliver an appreciable dose down to about ten centimetres in to a tissue volume.

So--you're right. We do have a responsibility to inform the public when we know what we're talking about. I don't think I'd feel very confident discussing safe levels of microwave or infrared exposure. Or UV, for that matter. I know quite a bit more about X-rays and gammas, since I've worked with medical physicists.

Knowledge like booze. Know your limits. Yeah, I know. It's a crappy analogy. Sue me. (But IANAL.)

Non-thermal atomic batteries

[XNormal]

It is possible to convert the radioactive decay directly into electric energy without going through heat. Alpha and Beta particles are charged and they are released at relativistic speeds. This create a magnetic field that can be harnessed.

See U.S patent 4,835,433 "Apparatus for direct conversion of radioactive decay energy to electrical energy".

This technology has been demonstrated to be an order of magnitude more efficient that RTGs.

Re:why not?

[H1r0Pr0tag0n1st]

How about in your chest cavity? Most pacemakers are powered by small radioactive batteries. And these are implanted in the body.
So haveing somehting like this in a cell phone or a laptop really wouldn't bother me.

Re:why not? -- Won't work for Laptops

[Cougar1]

Unfortunately, such a battery would be too big for a laptop (unless you can significantly reduce the power requirements). Based on Cornell's press release, they plan to use Nickel-63 with a half-life of about a 100 years. So how much Nickel-63 will they need?

Looking at a handy dandy table of the isotopes gives a half-life of 92 years and a decay energy of 67 keV per disintegration for Nickel-63. Also, it has an atomic mass of 63 g/mol. 1 Joule equals 6.24E+15 keV, so to produce 1 Joule of energy you would need:

6.24E+15 kEV/67 keV/disintegration = 9.32E+13 disintegrations

One Watt is a J/s, so to produce a Watt of power you would need 9.32E+13 disintegrations per second. So, how much Nickel-63 is needed to get this many disintegrations per second?

9.32E+13 / (1-exp(1/2903299200*ln(2)) = 3.90E+23 atoms

(Note 2903299200s = 92 years). Dividing by Avogadros Number and multyplying by the atomic mass gives a mass requirement of 40.8g for each Watt. A typical laptop computer consumes ~50 Watts giving a required mass of ~2 kg.

While a bit high, this probably isn't too bad, especially since future technologies can probably lower the power requirement to 10-20 Watts. However, the above calculations assume 100% efficiency. I have no idea what the actual efficiencies are, but they are likely to be less than 50% since the proposed battery uses a mechanical process to produce the electricity. This alone would double the mass. In addition this is only the mass of the nickel. The other components and any shielding are likely to double or triple the mass, so the overall battery would likely weigh 8-12 kg (18-26 lbs). Much too heavy for a laptop.

This is not to say there aren't many very low-power applications for which such a battery would be ideal, but a laptop isn't one of them unless the power requirement can be dropped below about 10W.

Re:More importantly....

[maydog]

No they dont, I should know - I build and test them. Pacemakers have a Lithium Iodide battery and most Defibrillators (implantable) use SVO or MnO2 batteries. Still the can have lifetimes 7-10 years depending on the amount of therapy needed.