I'm pretty sure they essentially are "one time use" only.
Extremely simplified:
They run for 20-30 years without refueling, which means the reactors/system could be built more compact, a higher level of safety and require less maintenance / monitoring / fine-tuning.
All those parameters are connected in an equation which means if you want higher safety you have to make another parameter "worse". By making the system "one time use" you set the "refuelability" and "repairability" parameters to the lowest and can therefore up the other parameters.
Also, military requirements are very different from civilian.
So Microsoft is essentially doing what Google and Apple have been doing for years and we think Microsoft are anti consumer because of this?