You included my sentence: "Efficiency really matters when we have >1000 GW of installed nuclear capacity." I wanted to address that: efficiency matters. Ineffi

You included my sentence: "Efficiency really matters when we have >1000 GW of installed nuclear capacity." I wanted to address that: efficiency matters. Inefficient technologies will hit some constraints if not others. We may run out of time: A pressure vessel production cycle is over one year[1]. By the time we reach >1000GW someone may make fusion practical or China's competent nuclear industry may start selling MSRs to everyone. We may run out of highly skilled people required to build and operate these complex machines. The safety is highly dependent on operations and management throughout the life cycle of complex machines. From manufacturing to operations there is tiny margins for error. (Not a physical constraint.) LWR technology is associated with military ships and submarines, no one shares it. Few countries control the technology and there are only a few places in the world to make pressure vessels. (Not a physical constraint.) We may run out of waste disposal sites. A geological repository needs special rock formations away from earthquake zones. The article is written by a nuclear industry professional who tells that routine things done by the nuclear industry today when applied to MSR is a "disadvantage". They open the lid of an LWR every 18 months and replace/shuffle highly radioactive fuel assemblies and say that it is a disadvantage for them to replace graphite. That is totally unfair. [1] VVER pressure vessel production cycle needs 3 years. https://www.youtube.com/watch?v=91yVhrSZ5jQ https://www.youtube.com/watch?v=91yVhrSZ5jQ NuScale pressure vessel R&D: https://www.energy.gov/sites/prod/files/2016/10/f34/02%20-%20EPRI%20SMR%20Reactor%20Vessel%20Manufacture-Fabrication-Demonstration%20Project_0.pdf https://www.energy.gov/sites/prod/files/2016/10/f34/02%20-%2... TL;DR Even small pressure vessels (used by nuscale) have lead times of about a year. A megafactory can build like 1 or 2 vessel per month. At 1.5GW/year/factory, we need like 22 factories to keep up with the production schedule if we need to reach 1000 GW of small-LWR capacity within, say 2050.