I know this doesn't answer the electrical power output, but basic physics confirms the 220 W thermal power output as follows:
40K Ci = 1.5E15 dps
average energy per dis. = 945000 eV (1/3 Bmax for Sr+Y)
Flux = 1.4E21 eV/sec
Power = 220 J/sec or 220 W (1.6E-19 J=1eV and 1J/sec=1W)
Brian
> Jack,
>
> One of my colleagues in the calorimetry section of my group at LANL
> calculated a maximum power of 2.3 Watts/gram for Sr90 in equilibrium with
> it's daughters. That figure was based on maximum Q values, so I divided by
> 3 for a rough average value. That gives a specific power of about 0.77
> Watts/gram. The specific power of Sr90 is 141 Ci/g (from the 1970 RHH, the
> only copy I have at hand), so the power per unit activity should be 0.00546
> Watts/Ci. A 40,000 Ci source would therefore produce about 220 Watts of
> power. That's a lot of power; it's enough to make me ask if anyone can find
> any errors in what I've done above.
>
> Phil Hypes
>