In my occasional discussions of energy and transport, the suggestion that nuclear power might run shipping is proposed.
OK, let's consider that.
Our Nuclear Marine Experience: 400 ships, 170 active, most subs
The number of present nuclear powered ships peaked around the late 1980s, with virtually all in navies, most being submarines. As of 1989, there were over 400 nuclear submarines operational or being built. Some 250 of those have been scrapped or cancelled. Which leaves us with about 150 remaining. There are an additional ten nuclear powered aircraft carriers in the US navy. France has one, and both China and India plan at least one nuclear powered aircraft carrier each.
The US had nuclear-powered cruisers, but all have been scrapped. Russia has four battlecruisers (of which one is active), and seven nuclear icebreakers, and, if I'm reading the Wikipedia page correctly, an additional containership, Sevmorput.
Several commercial nuclear powered ships were built, the [Savannah](https://en.wikipedia.org/wiki/NSSavannah)_ by the US, and single ships by both Germany, the Otto Hahn, and Japan, Mutsu. All proved uneconomical, the Mutsu had major technical issues, and were either scrapped or converted to conventional fossil propulsion.
We're left with what looks like about 170 nuclear powered ships which are operational.
The Global Shipping Fleet
The best source I've found for current shipping industry statistics is the United Nations Council on Trade and Development's Review of Maritime Transport: 2014. Total fleet size 47,601 registered ships, totaling 1.68 million deadweight tons. By type and deadweight tonnage:
- Container: 12.8%
- Dry Bulk: 42.9%
- General Cargo: 12.8%
- Oil Tanker: 28.5%
- Other: 11.2%
Incidentally: I was shocked a few years back to discover that oil tankers were a third of shipping capacity. That's fallen slightly since, but what the UNCTAD report reveals is that oil tankers have fallen from fifty percent of total tonnage in 1980. Container ships have grown from 1.6%, dry bulk are up from 27.2%. General cargo have declined from 17%.
Prices tend from $18.5 million for a smaller dry bulk carrier to $120 million for larger supercarriers, should you be in the market.
What Floats Can Sink...
But the interesting quote I've just run across, and the inspiration for this post, is this, from "Monsterwellen", by Donovan Hohn in Outside magazine:
> This is one reason merchant seafaring is still, by some accounts, the world's second-most-dangerous occupation, after commercial fishing. According to Imperial College London, 200 supertankers and container ships have sunk in the past two decades due to weather. Wolfgang Rosenthal, a scientist at the European Space Agency, which studies sea conditions via satellite, estimates that two "large ships" sink every week on average. Most of these, he says, "simply get put down to bad weather.'
Which gets us to the idea of nuclear propulsion in general marine use.
First, we're talking a massive number of vessels. The fifty largest containership operators have 4,348 vessels, with 18.8 million TEU (twenty-foot equivalent) capacity (a "standard" shipping container is actually 40 feet long, the shorter 20-foot units appear "stubby", but are the standard for measurement).
To be practical, nuclear propulsion would have to be applied to at least ten times, and possibly 100 times, the number of vessels ever nuclear powered, and 25x the number currently operating. And we'd be looking at losing multiple hulls, with active reactors, per year. Due to conditions which are all but impossible to mitigate.
On safety grounds, commercial nuclear marine propulsion looks like a loser.
Image credit: NS Savannah, US Government photo, via Wikipedia.