Shipbucket

An example of a vesse with 2 reactors are the large Soviet/Russian submarines (e.g Typhoon Class).

That thread is kind of confusing. There's a lot of stuff about plutonium and space reactors. The formula I assume I'm supposed to look for eludes me.

What I found much more helpful was to study the integrated SMR designs I intend to use as the basis for the reactor plant. Looking at several designs across multiple sources, it seems that a reasonable power/weight estimate would be an 80-100 MWe reactor weighing around 650-750 tons at power. Of course, one has to factor in the system around it as Heuhen mentioned, but a lot of this would also apply to a conventional powerplant, with the exception of perhaps the electric turbine. By comparison, a single Wärtsilä-Sulzer RTA96-C diesel engine weighs upwards of 2,000 tons, plus around 18-20,000 tons of HFO on the largest vessels (and it appears these fuel tanks aren't exactly small), which would no longer need to be carried on a nuclear vessel.

I don't know the exact totals of each (conventional and nuclear) in terms of weight, and I may well be missing something, but a cursory look at the main components involved (installed power and fuel load, assuming similar "guts" around each and adding a turbine for the nuclear plant) suggests that the weight of a reactor plant wouldn't pose any major issues, and might even end up saving weight.

I should note that the only design where I'm looking at installing two reactors is the 20,000+ TEU class. These are larger and heavier than even aircraft carriers, which already use two reactors.

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and there creat nuclear icebreaker

Yes, the icebreakers of Arctica Class.

Some things to keep in mind for the economies of a nuclear powered merchant vessel...

• You will have about 30% more engineering staff, and these people will have specialized skills so they will earn more than your typical marine engineer.

• There are additional shoreside support requirements for refueling and radioactive waste water disposal. Notice that the Russian vessel typically operates from Murmansk which has the support facilities built up for the nuclear icebreaker fleet. If you are going to operate in other parts of the world, you would have to build that infrastructure.

• Insurance costs will be significantly higher than a comparable conventionally powered vessel. I don't know if there is protection and indemnity (P&I) insurance club (group) that would be willing to accept the open ended risk of a nuclear accident.

• End of life disposal costs. You can't just run these ships up onto a beach in Bangladesh or Turkey

• Fuel costs are fairly low at the moment, or at least compared to what they were in 2008 (approx. $600/mt for diesel). I don't know what the break even point is for fuel to justify the other expenses.

Just some additional thoughts.

These are serious enough to consider about the economics of a nuclear merchant vessel.

... and probably the main reason we don't have any "practical nuclear merchant vessels"...

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Thanks for the advice. These concerns are generally answered in the context of my AU, where the civil marine nuclear propulsion program has substantial governmental support and necessary infrastructure built up. In an near-future Earth AU... all signs point to extensive intergovernmental cooperation and an expansion of the role and resources of the IAEA (which I'm in already in favor of, anyway).

Interestingly, I just stumbled across this old thread from over two years ago which involves something very similar to what I'm trying to do. I'm especially looking at the critiques and how the OP addressed them, so as not to repeat the same mistakes needlessly.

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I will be transferring this to a Personal Designs thread soon, but I have a pretty good outline of what I want my vessel to look like. I'm starting with the 20,000+ ULCV, as that seems the most straightforward to nuclearize. I'm still not totally decided on 1 vs. 2 reactors, but they are to be navalized variants of a land-based integrated SMR design such as the Russian VBER-300 or Korean SMART reactor in the 100 MWe range.

This is the colored-in hull design:


And this is a false-color "sandbox" version with some modified reference images in case anyone wants to edit the design or see things more clearly:

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At last a drawing after 6 pages of conversation. Look forward to see her finished!