[pfdietz]

> microreactors don't seem to have any inherent disadvantages

They have diseconomies of scale. Some of the costs of a nuclear power plant scale sublinearly with power. Neutron economy is improved in a larger core. Larger turbines are more efficient than smaller turbines. It doesn't take 1000x as many operators to operate a NPP with 1000x the power output.

[roenxi]

Is that relevant? The economics of nuclear plants doesn't have anything to do with efficiency as far as I'm aware, the fuel costs are relatively negligible. They can afford to be horribly inefficient if they can get economies of scale producing the plant. So you can use inefficient turbines and have bad neutron economy and it wouldn't change the economics by anything in particular.

You'd also probably find similar issues with diesel generators, but small diesel generators do roaring trade and have great commercial applications.

[pfdietz]

Cost is not only relevant, it's paramount. Efficiency is only important insofar as it affects overall cost.

Diesel generators have the advantage of being very cheap -- an order of magnitude cheaper than NPPs per unit power output -- and of having much of their total cost being fuel cost, so they can operate at lower capacity factor. But even so, we don't see large power plants composed of arrays of diesel microgenerators.

(The solution for current higher capacity factor diesel users, like say remote operation at mines, would be to supplement them with renewables and storage to reduce fuel costs. This is already happening.)

A significant problem with any small power plant is fixed costs. A 1 MW(e) plant (Antares is said to be between 100 kW(e) and 1 MW(e)) making power at 90% capacity factor and selling at $0.05/kWh will gross about $400K/year. A single full time employee, like a security guard, will cost a good chunk of that.

[roenxi]

> Cost is not only relevant, it's paramount. Efficiency is only important insofar as it affects overall cost.

Oh sorry, I thought you were talking about efficiency. Ok, what is the cost is for these plants?

> A single full time employee, like a security guard, will cost a good chunk of that.

I dunno, a 1MW nuclear plant could end up being pretty small. It might easily be economic to install them places that already have security guards.

[mandevil]

Back in the 1950's, as part of a study for putting ICBM bases in Greenland, the US Army built a 2MW reactor (PM-2A) and deployed it to the test base (Camp Century) in Greenland. It powered the camp for about three years, modulo a little problem where it was shut down for a while after a prototype (SL-1) killed two soldiers and a sailor in Idaho. In addition, the Navy operated another one (PM-3A, 1.75MW) for a decade in Antarctica at McMurdo Sound, until they cut it up and brought it back to the US. There was also the MH-1A (10MW- and the only one I've mentioned that used LEU instead of bomb-grade HEU) sitting on a freighter in Lake Gatun to power parts of the Panama Canal Zone.

All of these reactors were built in the early 1960's and the last (MH-1A) was retired in 1978. All of them were operated in places that had lots of soldiers around (though McMurdo and Camp Century relied more on being really difficult to get to than actual sentries) And they were never replaced. Because even having guards already paid for didn't help the economics of the situation. Maybe things are different now. But I've yet to see any evidence for it.

[pfdietz]

The SL-1 accident was something. One of the casualties was missing for a short time until they found him speared to the ceiling by a control rod that had been ejected from the reactor.

They were all buried in shielded caskets, several feet deeper than normal.

[pfdietz]

Microreactors have been tried before by the military, for use at bases, which have guards. They not only didn't make sense to install, they didn't make sense to continue to operate once installed.