Why Nuclear Powered Merchant Ships Probably Aren't Going To Happen

Today I saw a meme floating around suggesting that we deploy a fleet of nuclear powered merchant ships to solve our environmental crisis.
I like nuclear power in general; however, I really don’t see this as a cost effective solution. There are a lot of huge problems with doing this that I can’t see a good fix to without spending more money than would be economically feasible.
First of all, let’s talk about security first. You’d need more than a few security guards to ward away just a half-dozen pirates. This is a floating multi-billion dollar target we’re talking about. Not only is there a cost-value associated with the ship, there’s also the chance of capturing enriched nuclear fuel. You also get spent fuel thrown in for free. That makes it have military value. I can already see people ready to comment on nuclear icebreakers. Russian nuclear icebreakers are all government owned. If anyone attacked those, it’d be an act of war taking place within Russian territorial waters. Privately owned and operated merchant ships operating in international waters are a completely different matter.

Ok, so we provide NATO escort for this container ship sufficient to ward off any small nation-state that has aspirations of becoming a nuclear power.
What about the design? OK, we need to design a new class of container ship with a powerplant that uses a nuclear reactor. Keep in mind that military shipboard reactor plants are all totally classified so you’re doing a lot of work from the ground up. The engineroom and powerplant will have to be designed from the ground up while incorporating lessons learned from other accidents. It might be possible to incorporate design decisions from the NS Savannah nuclear demonstration vessel to save costs; however, there’d have to be a lot of work done to bring it up to modern standards while also keeping it competitive. Don’t forget that any nuclear accident on a merchant vessel may instantly spell the end of this class of freighter. The design has to be perfect the first time. That’s a non-trivial problem. Throw some money at an army of engineers and you can solve it…eventually.

This is the image that sparked this little rant.
This is the image that sparked this little rant.

What about the fuel load? If we’re going to operate a mobile nuclear platform that won’t be refueled every 6-18 months like a commercial plant, we have to load more fuel. This provides greater energy density at the cost of … well, dollars. A lot of dollars. Why can’t we refuel every year? Unless your aforementioned army of engineers can figure a better way than what we’ve been doing for decades (not likely), shipboard reactor refueling is a massive overhaul event often considered one of the most difficult engineering tasks of our generation.
Speaking of the fuel, where does the fuel come from? Is the US going to enrich fuel for the entire world? Who is going to store it once it’s used up. For the non-engineers, spent fuel is potentially far more dangerous in the wrong hands than unspent fuel.
I already see some people mumbling about Thorium. Thorium sounds pretty great in theory; however, it’s still mostly theoretical. We’ve never seen full-scale commercial deployment. We’ve seen very small scale laboratory tests. I would be over the moon if we started developing Liquid Fluoride Thorium Reactors for actual commercial or industrial use … but it just hasn’t happened yet. No one seems willing to take the risk to see how this technology will pan out. Anyway, back to our nuclear merchant ship.
Ok, we solved all of the engineering problems on the ship at a large cost. We have our fuel stored on our new class of merchant vessel that will have sufficient military escort to ward off a sizable attack.
Where do they port at?
Nuclear vessels have different berthing requirements compared to non-nuclear. This is both an engineering, financial, and political question. Many (if not most) ports lack nuclear-quality services. Many countries explicitly ban nuclear vessels. The variables here are too varied to discuss but it most definitely a non-trivial problem.
Ok, for the sake of argument we’ve upgraded our major shipping ports with radioactive waste storage, high quality pure-water systems, and whatever else might be required to berth one of these vessels.
Who crews it?
We’re going to have to create a new academy for training nuclear-qualified sailors worldwide. How is clearance to nuclear spaces determined? Is the undesignated seaman picked up from your dubious country of choice going to be allowed to be on the fire party for the engineroom still? This isn’t a terribly difficult problem to solve but it definitely adds some significant complexity to the problem.
For anyone still reading, I submit this last question: With all of the costs and challenges I outlined, who is going to finance billions of dollars of research to create multi-billion dollar merchant ships that are far, far more expensive to operate than conventional ships all in the name of the environment?
I think we need to spend our efforts elsewhere for now.

5 Responses

  1. Dave
    Dave at |

    Good points all around.
    Consider this, rather than burning new nuclear fuel, why not plop a Gen IV reactor in there. All the same hurtles exist, with the exception of where to get the fuel. We already have a stockpile of spent nuclear fuel, why reprocess and recycle it? We could also throw some weapons grade fissile elements into the fuel mix. The fuel becomes inert, it is far more efficient, and there is the added bonus of a shorter half life waste.
    As for how to get this technology off the ground… It all has to come from a government. No commercial company has pockets deep enough to prototype and produce this type of technology… And even if they did the NRC and other regulatory entries would find their hands.

  2. A. Lo
    A. Lo at |

    Honestly, I could see a potential use for things like NuScale’s SMR for this sort of application. Especially since it’s not a highly-enriched fuel design.
    Skyballing some ideas here…
    The reactor compartment is a sealed unit, i.e. the only entry is via the refueling access. Which gets used every 24 months or so, given the expected 100% power runtime of a 160 MWth/50 MWe system. That’s consistent with the design intent for the NuScale SMR. When it’s time, just pop open the reactor compartment, pull out the entire spent reactor module, and insert a new one. Or do a conventional robotic refuel. Either one works.
    The reactor design is fairly “safe” to start with, as far as SMRs go. Set it up with an armored citadel to monitor the plant, automate to the maximum extent possible, and rig with halon/flood extinguishing systems in lieu of a firefighting party for immediate response. Stuff works, so, use it. Basically, make the plant self-sustaining as far as operations go.
    Power-wise… 50 MWe should be able to provide all the electric drive requirements for a cargo ship, but I’m not a naval architect, so don’t quote me on it. But a quick google indicates that it’s comparable in scale to the largest diesel engines out there. And if you need… Make a two-plant vessel. Modular reactor, woo-hoo!
    This has been a skyball. Commentary and criticism is invited!


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