Hello
The way I know radioactive batteries is made of Kr85. Kr85 is gaseous in nature,
disperses quickly in case of an accident, and is chemically and biologically
inert due to the fact that it is a noble gas. The amount used in batteries makes it
an extremely safe radioisotope. The way the battery works is very simple. Kr85
decays in a 0.617 MeV beta particle in each decay and a 0.514 MeV gamma ray in
38 % of decays. The half life of Kr85 is 10.74 year, so the battery
last a lot of time, maybe 15 years.
The Kr85 gas is enclosed in a photovoltaic cell. When a gamma ray is emitted,
it hits the photovoltaic cell and it is converted in electricity. The
photovoltaic is also enclosed in lead.... to be safer.... The energies of the
beta particle and gamma ray are low enough to stop in the lead. So, the
battery does not emit radiation. I don't now if this technology is in the market
because it is a relatively new research area. I've been heard a lot of it in
science community but it is the first time I heard it outside science. Maybe
you are talking about another type of battery. In this case, I think it is
not nuclear battery.
We can't forget about smoke detectors. Most of them are radioactive.
They have a small alpha source inside. These alpha source emits
alpha particles (helium nuclei) with few MeV of energy. These particles
stop in two inches of air or in a thin paper page. They can't go trough
the detector plastic body. So, we are safe. For curiosity, the way smoke
detector works is simple. As alpha particles has electrical charge, there
is a current between the source and the alpha particle absorver. if there
is smoke, the air density between the absorver and source will change and
the current will drop, and the detector will beep. Simple, isn't it?
To be more afraid of the world we live, we can forget the sun neutrinos,
the radioactive potassium in cement, the cosmic rays. Guys, I am getting crazy,
everything is radioactive .... just kidding....
Alex
[EMAIL PROTECTED] wrote:
>
> > PS: Avoid buying any active optical system, they usually use Radioactive
> > decay batteries... might never have to change the battery ever but.. maybe
> > your life won't be as long.
> > Or be carefull and check these with Meters for radioactivity.
>
> >Philippe, your remark about radioactive Russian optical systems, is it
> >serious, or you are only joking?
> >I have a Russian exposure meter (an Sverdlovsk-6) and I don't have a
> >Geiger radioactivity detector to check if it is radioactive or not.
> >It seems to use a common battery, but the curious thing is that this
> >battery is almost ten years old and it still works.
>
> If any part of your camera equipment were seriously radioactive, your film
> would have told you that a long time ago. I think this is an, um, Red
> herring.
> JJ
>
--
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Alexandre A. P. Suaide, Ph.D. mailto:[EMAIL PROTECTED]
Physics Department
University of Sao Paulo - Brazil Phone: 1-313-577-5419
Wayne State University - MI -USA ICQ number: 78139605
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