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jamiecarl09 t1_j7hivff wrote

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

Do you think once the company has SMR's, they aren't going to dump more money into R&D for microreactors?

With the amount of talk around mining asteroids, if RR developed a spacefairing propulsion system they'd explode in market value.

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[deleted] t1_j7hvidk wrote

[deleted]

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thuanjinkee t1_j7ikvqi wrote

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.

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ShadyRedditInvestor t1_j7iq4tn wrote

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.

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thuanjinkee t1_j7j7hjg wrote

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

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ShadyRedditInvestor t1_j7j7vmj wrote

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.

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Shrike99 t1_j7mj99t wrote

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.

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e36freak92 t1_j7im7vz wrote

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

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[deleted] t1_j7htp2z wrote

RR SMRs is a separate company to RR now (majority owned by RR still), so SMRs and microreactors will be developed concurrently and independently.

Either way, if they wait until SMRs hit the big time to dump money into microreactors it will be far too late and Westinghouse (eVinci) or someone else will have already dominated the market.

The space propulsion side is really nothing to do with RR and I don't think they are developing it as there is no expertise for that. They are simply providing new reactors, as they have done for 60 years.

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ProjectDv2 t1_j7jrldg wrote

I don't think a company known for designing engines for automotive, marine, and aeronautic applications deciding to develop engines for interplanetary applications is nearly as farfetched as you believe it to be.

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[deleted] t1_j7jsv1e wrote

Not farfetched at all, just it isn't happening at present. If they start hiring space propulsion experts tomorrow then it wouldn't shock me, but they don't have any today.

The RR microreactor will power someone else's nuclear propulsion tech.

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JPhonical t1_j7myxvo wrote

>The space propulsion side is really nothing to do with RR

RR is currently studying nuclear propulsion for the UK Space Agency: https://www.rolls-royce.com/media/press-releases/2021/12-01-2021-rr-uk-space-agency-launches-first-study-into-nuclear-power.aspx

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[deleted] t1_j7oi8h5 wrote

The study is "nuclear power for space exploration", it touched on propulsion but that was the extent of the effort.

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JPhonical t1_j8cir2n wrote

Here's an article with a quote from Jake Thompson, Head of Innovation Products and Services at RR, " We’re working on nuclear thermal propulsion; really efficient, fast transport for space travel."

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