The world needs sealed, passively safe reactors that can be mass produced (at least in the tens of thousands), last for some number of years (10-15-20) and then

The world needs sealed, passively safe reactors that can be mass produced (at least in the tens of thousands), last for some number of years (10-15-20) and then gets shipped back to have its fuel reprocessed at some appropriately secured central location. Traditional nuclear power plants are a risky proposition today because they are large, complex, expensive, and they take a long, long time to complete. Not least because they futz around with refueling and cooling spent fuel onsite. The long completion time means they are hard to finance, you will have one or more (financial) black swan events (eg financial crisis, wars) during the construction period, and there is no such thing as someone who has prior experience building a power plant before starting because the same power plant is never built twice in consecutive generations. Even the "serial produced" ones are different. The only way you can make nuclear cheaper is to get the manufacturing and commissioning time down to 1-2 years and no more than 3 years. Which means they have to be small and as simple as possible. Size is only relevant as a means to achieve simplicity. Mobility and widely distributed operation are pointless goals in themselves. That might be a possibility to investigate later, but it is not important initially. If someone starts talking about a mobile power plant they have 100% the wrong focus. First there must be a power plant. And when you have one, you probably really, really want to bolt them down so they don't go missing.