Re: Sr-90 RTG power

[Ted de Castro <tdc@XRAYTED.COM>]

But that doesn't answer the question - the question is the electrical

power output from the device.



Thanks for doing the calculation that I was too lazy to get around to

doing - but I'd like to get a handle on the efficiency of the

thermocouple conversion as well.



Since I would suspect that a Buoy would need a few 10's of watts to

operate - that would suggest thermocouple efficiencies on the order of

10%.



I don't know thermocouple efficiency - but understand it to be very

inefficient.  I am also told that a newer process which uses wavelength

conversion to reradiate in the IR spectrum that a PV can use is more

efficient than these devices - and I know that the BEST PV is about 10%

efficient.



Let's hope someone here has the operational numbers - it will be very

interesting.



Phil Hypes wrote:

> 

> 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

> 

> >From: Jack_Earley@RL.GOV

> >Reply-To: Jack_Earley@RL.GOV

> >To: radsafe@list.vanderbilt.edu

> >Subject: RE: From AP and AOL about Sr-90 exposure of lumberjacks in Georgi

> >a

> >Date: Tue, 8 Jan 2002 08:58:35 -0800

> >

> >Several people have discussed these lost and found RTGs w/ me privately,

> >and

> >a couple have expressed an interest in the power level produced by one of

> >these w/ 40K Ci of Sr-90. Anyone have a ballpark idea?

> >

> >Jack Earley

> >Radiological Engineer

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