60 MW output from a combustion engine means rougly 3x the mechanical energy output for the same amount of Joules input with an electric engine.
These reactors are supposed to be a max of 4 containers in size.
So ~12 of them would be ~48 containers = 4x6x2 = ~80 ft x ~60 ft x ~30 ft = 144k cuft.
Though, I doubt you'd want to stack them like that, and I imagine you'd need more than just the reactors to replace the engine.
But more importantly - container ships need space and weight for ~66k gallons of diesel per day - about ~3M gallons total. That's an additional ~401k cuft for diesel, and ~13,500 tons... Each TEU is 22 tons - so you could probably carry an additional 600 TEU (or ~3.5% more).
[1] https://www.amusingplanet.com/2013/03/the-largest-and-most-p...
[2] https://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA9...
IIUC, 18,000 TEU ships have engines that generate ~60 mW - and use about 66,000 gallons of diesel per day.
That's ~$90M in fuel per year, which could be replaced by ~12 of there reactors.
That's $7.5M per year. If these can be purchased for less than $20M - with an 8-year life-span and $2M for fuel and operation per year - then maybe it could work??