As an ex Navy nuke, I can tell you why. Navy nuclear power plants are much more expensive for MW than a civilian nuclear plant. There is a good reason. Navy nuclear plants have to operate like racecars (up power, down power), and at the same time be strong enough that if your ship is attacked, they have a reasonable chance to continue operating safely (propulsion equals life in the Navy). Civilian plants only have to operate at peak power (for the most part). They also don't have to be small enough to fit inside a ship, and resistant to damage that might occur in a war. If you lose power on a nucleared power ship in a tactical situation, you could very well end up dead (think submarines). If you lose power on a civilian plant, you can just fire up some peaking plants to take up the load on the grid.
That's not what I mean. I am not talking about that aspect of the design. I am talking about the safety aspects of the design, I should have been more specific. How the Navy Nukes set up the heat exchange design, and the separation of "contaminated" and "Non-contaminated" super heated waters ect. The overall design is a TON safer than "commercial" designs and more efficient. Who cares if it ends being more $$$ to build, if it get's us that much further off Oil which has strings attached to it that make Oil a LOT more expensive in any number of ways. It could be easily adapted, from what I understand, to Civvie uses.
Sorry for the confusion.