New Nuclear Battery Lasts 12 Years (15)

1 Name: Sling!XD/uSlingU 2005-05-17 14:45 ID:vySYXEuh
"A new type of battery based on the radioactive decay of nuclear material is 10 times more powerful than similar prototypes and should last a decade or more without a charge, scientists announced this week."

"The technology is called betavoltaics. It uses a silicon wafer to capture electrons emitted by a radioactive gas, such as tritium."

"Tritium is a radioactive form of hydrogen. Mixed with chemicals that emit light, it is used to illuminate exit signs without electricity -- the sort commonly found in schools and other public buildings."

""It is safe and can be implanted in the body," Fauchet said. "The energetic particles emitted by tritium do not penetrate inside the skin.""


2 Name: !WAHa.06x36 2005-05-19 13:20 ID:d5M74XvX

Tritium has ridiculously low-energy beta emission, which makes it pretty ideal for these things. I have a little vial of tritium gas here, surrounded by phosphor that makes it glow, and the radioactivity of it is not detectable.

I do suspect that to get any kind of useful energy out of it, you'd need quite high activities, which is a bit of a problem. I wonder in what form the tritium would be kept in the battery - having it as a gas seems too problematic, even if it would be good in case it leaked - it'd rise and dissipate pretty quickly.

3 Name: !WAHa.06x36 2005-05-19 13:22 ID:d5M74XvX


> ""It is safe and can be implanted in the body," Fauchet said. "The energetic particles emitted by tritium do not penetrate inside the skin.""

Bad, bad phrasing.

4 Name: Sling!XD/uSlingU 2005-05-19 16:13 ID:Q+yURkhH

I have no doubt that in ideal conditions it's all fine. My concerns are with disposal and accidents.

What will happen to used nuclear batteries?

Let's say there's a car crash and the battery shield is crushed. Now what? It can't dissipate if the battery is inside the body. Surgery is gonna be messy, I think.

5 Name: !WAHa.06x36 2005-05-20 12:59 ID:d5M74XvX

Hydrogen inside the body would either escape, or get turned into water, which would be recycled out of the body soon enough. Well, that's my guess, anyway. I see mention of a biological half-life of 5 days for tritium. The effect would probably be a lot less significant than the effect of having a pacemaker in the first place, or being in a car accident.

As for disposal - in the best case, batteries would be recycled, and the remaining tritium would be extracted for use in new batteries. In the worst case, they end up in landfills and the tritium is released into nature, where it will probably end up as water. The question is whether the amount of tritium water that would accumulate is significant or not. I really don't know the specifics of that, but here's some background:

Tritium is produced in the upper atmosphere by interactions between nitrogen and cosmic radiation. Tritium is also released by nuclear power plants, enrichment of weapons-grade fissionables, and by the various tritium-powered signs and markers. Atmospheric nuclear tests in the 1960s apparently raised atmospheric levels of tritium by several orders of magnitude. None of this is considered a health problem, apparently.

My guess is that it would be hard to raise the naturally occuring level of tritium to the point that it would be hazardous, even if you dumped all the tritium batteries in landfills. But I couldn't say for sure.

6 Name: Alexander!DxY0NCwFJg!!muklVGqN 2005-05-22 03:12 ID:Heaven

I believe anyone carries around quite an amount of radioactive potassium. Any effect from tritium should be very very small compared to that of the longer-lived potassium. I don't know this for certain, but I'm quite confident I'm right about this..

7 Name: !WAHa.06x36 2005-05-24 14:30 ID:d5M74XvX

Radioactive potassium in the body is the cause of some significant percentage of the yearly radioactive dose. I forget exactly, but something around 50% is probably not too far off.

The question from a radiological safety point of view is how big the dose from tritium would be in comparison to this, and other natural sources. I still don't really know, but since tritium would most likely appear in the form of water in nature, and since water isn't retained in the body (I keep wanting to make some sort of horribly immature joke here), you'd need a constant external exposure to tritium for long-term exposure (as opposed to elements like strontium-90, which are taken up and stored in the body).

8 Name: Sling!XD/uSlingU 2005-05-24 20:14 ID:uhW7CP/l

"Tritium is not obtainable by the amateur. Tritium requires a $40,000 dollar license from the U.S. Nuclear Regulatory Commission, with secure facilities and weekly medical exams because of its radioactivity."

Waha, do you have a license for that lamp? :P

9 Name: !WAHa.06x36 2005-05-25 12:22 ID:d5M74XvX

That's nonsense. Even in the US, you can obtain things like tritium location markers with some minor paperwork hassle. Large-scale use of tritium probably requires a permit, though. In Europe, tritum novelty items are completely unregulated.

> Tritium key chains are banned in the US as a "frivolous" use of tritium, but you can legally buy location markers and such like provided you certify that they will be permanently affixed in a stationary location, which is registered with the government.

It's those damn puritan Americans! Can't have tritium, is obviously too much fun!

10 Name: Sling!XD/uSlingU 2005-05-25 14:47 ID:Heaven

Actually they are regulations in Europe too.
"Safety licences are not required in the following cases:

  • trade in compasses and similar products containing tritium light ampoules if the activity of tritium in gaseous form is below 10 GBq" - Radiation Act, Finland.

It's just that they are more sensible on this side of the ocean.

I wonder how much light a 10-GigaBecquerel lamp gives out?

11 Name: !WAHa.06x36 2005-05-25 15:35 ID:d5M74XvX

10GBq of 18 keV decays makes... 0.029 milliwatts (thank you Google) in pure radiation power. On top of that you get some sort of conversion efficiency when changing the radiation to light.

Not a whole lot. Your average LED is 40 milliwatts.

12 Name: Sling!XD/uSlingU 2005-05-25 20:14 ID:Heaven

I see. Not very exciting.

13 Name: !WAHa.06x36 2005-05-25 20:47 ID:a/RuIMwc

Incidentially, any CRT would have a far higher activity than that - "18keV beta particles" is just short for "electrons that have the same kinetic energy as if they had been accelerated by 18 kilovolts". A CRT will accelerate electrons with something close to that, and in far greater amounts - witness the shine coming off the screen, that's a whole lot more than 0.029 milliwatts. 18keV electrons are all around you - any time you get a static shock, you're getting hit by electrons at even higher energies than that.

Tritium is only dangerous because it can be ingested, and even then it's not very dangerous.

14 Post deleted by moderator.

15 Name: Mad Scientist 2006-01-21 09:24 ID:Heaven


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