Everyone these days wants to talk about Small Modular Reactors (SMRs) when it comes to nuclear power. The industry seems to have pinned its hopes for a ‘nuclear renaissance’ on the exciting new concept. Exciting as it may be, it is not exactly new: small reactors date back to the heyday of the atomic era. There were a few prototypes, and a lot more paper projects that are easy to sneer at today. One in particular caught our eye, in a write-up from Steve Wientz, that is described as an atomic outboard motor.
It started as an outgrowth from General Electric’s 1950s work on airborne nuclear reactors. GE’s proposal just screams “1950s” — a refractory, air-cooled reactor serving as the heat source for a large turboprop engine. Yes, complete with open-loop cooling. Those obviously didn’t fly (pun intended, as always) but to try and recoup some of their investment GE proposed a slew of applications for this small, reactor-driven gas turbine. Rather than continue to push the idea of connecting it to a turboprop and spew potentially-radioactive exhaust directly into the atmosphere, GE proposed podding up the reactor with a closed-cycle gas turbine into one small, hermetically sealed-module.
Bolt-On Nuclear Power
There were two variants of a sealed reactor/turbine module proposed by GE: the 601A, which would connect the turbine to an electric generator, and 601B, which would connect it to a gearbox and bronze propeller for use as a marine propulsion pod. While virtually no information seems to have survived about 601A, which was likely aimed at the US Army, the marine propulsion pod is fairly well documented in comparison in GE-ANP 910: Application Studies, which was reviewed by Mark at Atomic Skies. There are many applications in this document; 601 is the only one a modern reader might come close to calling sane.
The pod would be slung under a ship or submarine, much like the steerable electric azimuth thrusters popular on modern cruise ships and cargo vessels. Unlike them, this pod would not require any electrical plant onboard ship, freeing up an immense amount of internal volume. It would almost certainly have been fixed in orientation, at least if it had been built in 1961. Now that such thrusters are proven technology though, there’s no reason an atomic version couldn’t be put on a swivel.
Two sizes were discussed, a larger pod 60″ in diameter and 360″ long (1.5 m by 9.1 m) that would have weighed 45,000 lbs (20 metric tonnes) and output 15,000 shp (shaft horse power, equivalent to 11 MW). The runtime would have been 5000 hours on 450 lbs (204 kg) of enriched uranium. This is actually comparable to the shaft power of a large modern thruster.
There was also a smaller, 45″ diameter version that would produce only 3750 shp (2796 kW) over the same runtime. In both, the working gas of the turbines would have been neon, probably to minimize the redesign required of the original air-breathing turbine.
Steve seems to think that this podded arrangement would create drag that would prove fatally noisy for a warship, but the Spanish Navy seems to disagree, given that they’re putting azimuth thrusters under their flagship. A submarine might be another issue, but we’ll leave that to the experts. The bigger problem with using these on a warship is the low power for military applications. The contemporary Farragut-class destroyers made 85,000 shp (63 MW) with their steam turbines, so the two-pod ship in the illustration must be both rather small and rather slow.
Of course putting the reactors outside the hull of the ship also makes them very vulnerable to damage. In the 1950s, it might have seemed acceptable that a reactor damaged in battle could simply be dumped onto the seafloor. Nowadays, regulators would likely take a dimmer view of just dropping hundreds of pounds of uranium and tonnes of irradiated metal into the open ocean.
Civilian Applications
Rather than warships, this sort of small, modular reactor sounds perfect for the new fleet of nuclear cargo ships the UN is pushing for to combat climate change. The International Maritime Organization’s goal of net-zero emissions by 2050 is just not going to happen without nuclear power or a complete rethink of our shipping infrastructure. Most of the planning right now seems to center on next-generation small modular reactors: everything from pebble-bed to thorium. This Cold War relic of an idea has a few advantages, though.
Need to refuel? Swap pods. Mechanical problems? Swap pods. The ship and its nuclear power plant are wholly separate, which ought to please regulators and insurers. Converting a ship to use azimuth thrusters is a known factor, and not a huge job in dry dock. There are a great many ships afloat today that will need new engines anyway if they aren’t to be scrapped early and the shipping sector is to meet its ambitious emissions targets. Pulling out their original power plants and popping ‘atomic outboards’ underneath might be the easiest possible solution.
Sure, there are disadvantages to dusting off this hack — and we think a good case can be made that turning a turboprop into a ship-sized outboard ought to qualify as a ‘hack’. For one thing, 5000 hours before refueling isn’t very long. Most commercial cargo ships can cruise at least that long in a single season. But if swapping the pods can be done in-harbor and not in dry dock, that doesn’t seem like an insurmountable obstacle. Besides, there’s no reason to stay 100% faithful to a decades-old design; more fuel capacity is possible.
For another, most of the shielding on these things would have been provided by seawater by design, which is going to make handling the pods out of water an interesting experience. You certainly would not want to see a ship equipped with these pods capsize. Not close up, anyway.
Rather than pass judgement, we ask if General Electric’s “atomic outboard” was just way ahead of its time. What do you think?
No. nobody wants to talk about something with the words smart and reactor in it. where the “smart” part is arguably more dangrous that the “reactor” part. Its in the engineering departement of the chemical “things i dont work with”. Brrr.
ignore. i misread the word “small”. phew…
Message received, your “Precocious and Clever AI-Enabled Micro-Reactor MKII” is completed and in the mail. It should reach you under its own power and navigation in under two business days
Just put SMRs in ships and make them modular. We don’t need the ‘smart’ part, in fact ‘smart’ is not desirable in a nuclear reactor control scenario.
agreed. I wouldn’t expect anyone to risk their life maintaining an unshielded reactor. there’s little weight penalty for shielding in a container ship so put the reactor inboard somewhere and run coaxial power cables to the outboard motor.
If the reactor is inboard, I’m not sure if there’s much remaining appeal to an outboard motor. That seems to combine the installation difficulty of inboard with the water resistance downside of the outboard pod.
Devil’s advocate: one of the problems I see is that it would be very tempting to re-use it as something else if it is not designed for a very specific task of turning a propeller at variable speeds.
You could imagine one docked in a port of some country being surreptitiously used as a power plant, overloaded and under-maintained until it melts down. Or other possibilities… Of course you could do the same with a propeller pod, hooking it up to a big dynamo and pulling it above-water, but it would be more difficult and obvious.
Using them in merchant ships seems reasonable-ish as long as everything is working normally, but of course, when something goes wrong is when the real design challenge comes. I thought of the Evergiven stuck in the Suez canal. What if that boat also had an atomic pod underneath? Maybe it sits high enough that the pods wouldn’t bottom out, but the shallow water didn’t have enough volume to keep the reactor cool when stopped.
What about End of Life? Lots of boats end up run aground onto some ship-breaking beach in a developing country. You want to make 100% sure the reactor pods are reclaimed before that point.
Would every ship so equipped now become a good target for bad peeps looking to make “dirty bombs” ?
Don’t worry, the unshielded reactor would fry any frogmen trying to take it off the ship.
It’s not an OHSA hazard, it’s a security feature!
Make it into a drone with its own rudder and explosive bolts so it can separate and be remotely recalled to a friendly port as a submarine in the event of any shenanigans
Or in the event of failure to pay for the subscription? :-)
Of course! Or if they are shipping anything that would make me errr I mean whoever owns it lose value in the stock market…
The 601B power package has an obvious application – nuclear powered torpedoes that could run indefinitely.
Sink a ship halfway around the world? No problemo…
Given the current interest in submersible “drones”, we may see this kind of thing again (provided they’re not already being developed).
Weapons that cost more than the ship one’s hitting generally isn’t a good idea.
The ship one is hitting is almost certainly a nuclear aircraft carrier worth over $10B, so the math still checks out.
But I presume that use case is already covered pretty well by missiles.
Put a nuclear bomb in one, what does an enemy port city cost?
Close–weapons that cost more than the potential damage the target could cause if it is not interdicted are a bad idea
That was in the applications document!
It was the 60s, you think they were going to pass up the chance to sell the US government on a new doomsday weapon? There were cruise missiles and a tilt-rotor. Just stop and think of that for a second: nuclear V-22. With 60s controls. I said the outboard was the only halfway sane idea in the box, and I meant it!
So awesome… Wish we still had that kind of engineering insanity. Still not even remotely close to Project Pluto, the autonomous unshielded nuclear ramjet that you simply put into a holding pattern over your enemies until they sprouted a third eyeball and an arm growing out of their back, until finally it ran out of enough fissile material to push itself around at mach 9 or whatever unholy speed it was designed for, and augered into the ground instantly transforming whatever area that happens to be into another Chernobyl.
Also it was coated in gold. Just a tremendous flex. A Vehement Chariot of the Gods.
I find Project Pluto very funny, in the same kind of horrifying way that “Doctor Strangelove” is funny. It particularly amuses me that they were never able to flight-test the thing because doing so was almost equivalent to declaring nuclear war on whoever was underneath.
The Ruskies made one, a render anyhow.
Propaganda for domestic Russian consumption.
Useless.
Well, if anything, it should be a nuclear microreactor of some sort with an obscene amount of shielding. Like, it should be able to take a direct hit from a tank cannon without leaking.
Certainly an achievable engineering problem. I think “can fall from orbit without cracking” is a good benchmark to aim for
seems with more ships using electric thrusters and eliminating the drive shaft, you would be better off just replacing one of the generators for an smr. you still use the ship’s power grid and thrusters and just requires hooking up some cables and coolant loops.
I’m currently working part time on the NS Savannah, the world’s first nuclear merchant ship. It operated in the 1960s though the early 1970s. It was part of President Eisenhower’s Atoms for Peace program. Sadly, it did not inaugurate the era of nuclear merchant ships as hoped but maybe it will happen soon. But in any case, it’s a beautiful piece of mid-century design and fun to tinker around on.
https://en.wikipedia.org/wiki/NS_Savannah
As a kid in the early 60’s I watched a half hour show on it. So exciting then. It had cranes for cargo, pre container days. Seems so quaint now.
Fun fact: It was proposed, designed, built and launched in less than four years: during the same president’s term.
Good luck getting that done these days. At least in the US. China, however, …
Monkey’s paw moment at the end there
Can’t wish this one away though.
You mean the Chinese are going to be able to implement bad ideas without thinking them through and we now don’t?
I’m not sure about the second part though.
Just we already lost the money on a nuclear powered merchant ship and see that costs have only gone up, while $/tonmile is down.
For costs, looking at nuclear navy, which is a best case for merchant shipping.
They’re much more likely to just let it rust and ‘collect insurance’ as endgame.
The popularity of anything nuclear is in my experience direct inversely proportional to global stability.
Same was/is true for space garbage cleaning.
I’m trying to remember some science fiction book or show, I thought it was the Foundation series but apparently that’s wrong…
Basically there are spacecraft in it which had FTL drives, but the FTL drives belonged to some neutral faction, say space-Switzerland, and they very jealously guarded the drives. They were in a sealed-off module that was attached to the ship and had their own crew inside who were all space-Swiss and had their own loyalties, and going from one section of the ship to the other from the inside was not possible.
If the commander of the ship ever did anything the space-Swiss really didn’t like, they would simply activate the drive and jump away, but only transporting the drive module of the ship, leaving the rest of the hulk torn open venting atmosphere into space, stranded.
Anyway, this reminds me of that. If you’re a container ship and you’re doing something the people who lease you the drive don’t like, they could send it a command to detach and sail home on its own, leaving you adrift somewhere off the coast of Somalia. Pretty cool, lots of potential.
I figured it out… I’m thinking of the Claudia Unit from Last Exile. It’s not an FTL drive, it’s the antigravity module, so if the guild doesn’t like what you’re doing they detach the antigrav and pull out, and the rest of the warship falls out of the sky like a stone.
This also resembles ideas in the Ringworld series (particularly book 2) in which the reclusive Puppeteer species is far ahead in starship technology, but is so risk averse that they rely on other species to staff their exploration ships, while one unfortunate Puppeteer captain cowers the whole voyage in an impenetrable safe room. So our human protagonist is constantly stuck between the danger of the job, and the danger of his paranoid Puppeteer captain venting the ship’s atmosphere to prevent a perceived mutiny.
Nice, yeah I remember that series too, very inventive
Those pods would have such a pretty Cherrnkov glow when steaming at night. Imagine the curious squid in port shortly after shutdown.
The best part is that water makes such great shielding that it would be safe until you get close enough to be pulled into the propeller, just like pools filled with blue Cherenkov light on land. They make for great swimming, and they’re nice and warm
A few things rather optimistically skirted over here;
Presumably not actually true as you would certainly need control & monitoring of the small nuclear reactor you’d strapped to your ship.
I suspect retro-fitting better fuel & emissions control systems to the existing engine is a far more attractive prospect than ripping it out (or leaving it as dead weight) and bolting a nuclear reactor on.
The slow speed diesels have phenomenal thermodynamic efficiency, all things considered, so there is not much room for improvement. The only way to improve them in terms of CO2 emissions would be to start cutting bunker fuel with veggie oil.
You’re very right that some things were optimistically skirted over. This is a blog post, not a white paper, so I chose to focus on the positives.
I’ve boarded ships where every member of the crew seemed to speak a different language, and when quizzing the “ship’s engineer” about where basic things like ballast tanks or piping were located, they would have to pull out manuals that looked like they’d never been opened before.
“Unlike them, this pod would not require any electrical plant onboard ship,”
Modern ships are power hungry. Even those that use diesel to power the propellers still need electrical power to run the various sensors and ancillary equipment. I don’t see a lot of benefit therefore in splitting off the propulsion unit. Electrical motors are more controllable and flexible. You have more choice in positioning of the generators as well. Yes a SMR as a replacement for the diesel generators to for pollution reduction could be interesting, but I think the outboard concept solves nothing and was invented at a time before modern power electronics were invented
General Electric’s 1950s work on airborne nuclear reactors produced the first molten salt reactor.
My absolute favorite was SLAM, a Mach 3 nuclear ramjet powered cruise missile that flew at high altitude until nearer to the targets (it carried 16 nukes) at which point it transitioned to terrain following at 150 meters. They actually developed and tested the nuclear ramjet. There’s an hour long documentary I saw about it on TV many years ago. Incredibly impressive and it really pushed the state of the art. Once launched and its reactor activated it was incredibly radioactive with its unshielded nuclear ramjet.
Project Pluto
https://en.wikipedia.org/wiki/Project_Pluto
There is a Sci-Fi movie called “The Lost Missile” that probably had some in that secret program and the also secret spysat program wondering if there had been leaks because the missile in that was very roughly like SLAM and one of the northern US radar installations briefly involved in the film was called “Keyhole” which was the classified designation of the US’ brand new spysat program.
I’m surprised the ATB (Articulated Tug and Barge) model wasn’t mentioned. They’re a niche workaround to avoid regulatory hurdles but they do have their advantages in that they add flexibility to a fleet. Its essentially a detachable engine room; like an outboard motor big enough to be its own boat. If a barge is down for maintenance and refit, it doesn’t necessarily mean the tug portion is.
A similar method might make sense with nuclear maritime power. It would mean smaller cargos but potentially higher speeds and access to shallower draft ports.
Let’s begin with merchant vessels. There are all sorts of penny-pinching ship owners out there. Well-documented are poorly-maintained ships that leak long trails of pollution easily visible from space. And given the mixed reputation of companies who decommission such ships, gee, what could possibly go wrong? So these pods might be better off on well-protected, military vessels, which, of course might become engaged in combat. QED. There is a third option: an international agency that employs naval commandos to rescue nuclear pods that fall into the wrong hands. Merchant ships are already tracked by satellites for insurance reasons. Whew, I can finally imagine a viable application. (Such a rescue, soon to be a major motion picture?)
But at least let me express an opinion that historically, Three Mile Island (TMI) was a really unfortunate, small-fish accident that yielded a big-ish overreaction. Modular, nuclear reactors finally offer the potential to be safe, reliable, and made in factories. True, we still haven’t solved the long-term waste storage problem, (mostly due to lack of political will: NIMBYs certainly won the day in Nevada), but other than that, nuclear energy truly is “green energy” not subject to the whims of weather. Coal-burning power plants might well have gone away sooner too, if only nuclear power had not gotten a black eye in the 1970s. Heck, anyone remember “Nuclear Magnetic Resonance” (NMR)? It had to be renamed “Magnetic Resonance Imaging” (MRI) because after TMI, the word “nuclear” became, well, um, radioactive.
The UN really is on a roll being idiotic isn’t it? Man, you’d think they would worry the US might get aggressive over the competition in the field.