# Plutonium and energy

1. Mar 18, 2013

### Numeriprimi

I don't know a lot of about radioactive decay of particles, but I have a crazy question. Theoretically - plutonium 237 has a warm effect. I get a heat energy when I catch it through lead. How much plutonium I need to some power (eg electrical device - 2kW)? What do you think?

Thanks and sorry for my bad English.

2. Mar 18, 2013

### Staff: Mentor

Several have been used on various space probes. But they have used Plutonium-238 instead of 237. P-238 has a half life of over 80 years, almost idea for space missions. However P-237 only has a half life of around 45 days, which means that while it would put out far more power, you simply aren't going to be able to make enough of it for any power generation purpose. That's also an important thing to consider. Plutonium isn't naturally abundant. All of it is made artificially.

From here: http://en.wikipedia.org/wiki/GPHS-RTG

Note that RTG's are very inefficient, and only 300 watts of electrical power are generated from the 4,400 watts of thermal power.

3. Mar 19, 2013

### Numeriprimi

Hmmm, interesting, thanks :-)
And how to determine the power (P) of plutonium?(without loss)

4. Mar 19, 2013

### DrDu

Take the energy freed in one decay, e.g. from the isotopes list in
http://de.wikipedia.org/wiki/Plutonium
and calculate the activity of the given amount N (in atoms) of the Pu isotope from the half-life
$A=N/t_{1/2} \cdot \ln 2$
and multiply the two to obtain the power.

5. Mar 19, 2013

### DrDu

Btw, the sowiet marine has used Strontium-89 based SNAPs (systems for nuclear auxiliary power) to power light houses and these are now rotting around all over the former SU posing a major thread for nuclear terrorism.

6. Mar 20, 2013

### Numeriprimi

Hmmm, this is a general formula? Is any intelligible page where is more about the formula?

7. Mar 21, 2013