thuanjinkee t1_j7ikvqi wrote on February 7, 2023 at 1:22 AM

Reply to comment by [deleted] in Rolls-Royce Nuclear Engine Could Power Quick Trips to the Moon and Mars by darthatheos

Hmm sell them as sealed units and you might have a safe product there. There's some progress on thermophotovoltaic cells (like solar cells except they operate in the IR spectrum) that could make a solid state no-moving-parts RTG about 20x to 40x more efficient than the old voyager RTGs.

ShadyRedditInvestor t1_j7iq4tn wrote on February 7, 2023 at 2:04 AM

Efficiency isn't really the thing...the actual plutonium oxide pellet they use for RTG's only gives off a total of about 40-60 watts. Doesn't matter how good your collection is, they'll only run the equivalent of a single 60w incandescent bulb assuming absolutely perfect conversion.

Even if you had theoretically perfect insulation, you're just going to make the the alpha decay happen faster.

thuanjinkee t1_j7j7hjg wrote on February 7, 2023 at 4:21 AM

One pellet is 60w, but you use more than one pellet.

ShadyRedditInvestor t1_j7j7vmj wrote on February 7, 2023 at 4:25 AM

ah yes, exactly what we want, a proliferation of millions of orphan sources of enriched uranium. Small scale nuclear is probably the way forward, but RTG's in grandma's basement aren't it, chief.

Shrike99 t1_j7mj99t wrote on February 7, 2023 at 9:44 PM

It's still extremely inefficient. 100kg worth of plutonium pellets in some RTGs will produce about 50 kilowatts of thermal power. 100kg of plutonium in an SMR on the other hand could easily provide 500 megawatts of thermal power.

The average US household has an average power draw of about 1.3 kilowatts, so assuming 100% conversion efficiency in the above cases, the RTGs could power about 38 houses while the SMR could power about 38,500 houses.

Given how expensive plutonium is, that thousand-fold difference makes RTGs a complete non-starter. And in practice an SMR would actually use uranium which is much cheaper, making things even worse.

e36freak92 t1_j7im7vz wrote on February 7, 2023 at 1:33 AM

Rtgs don't put out much .energy though. Fine to run some spacecraft instruments. A house? Maybe not so much