Yes. There are the chemical Sulfur-Iodine and the Hybrid Sulfur processes. Those processes use heat to do the water splitting. But IIRC you need a lot of heat like 800ºC.
Most nuclear reactors can't do 800ºC. You need a high temperature reactor core. Like one of the helium gas moderated reactors.
There are other hybrid processes which use electricity and heat to do the electrolysis step but this is a work in progress research. Not done at scale.
Yes but like I said most of these processes require 800ºC or more. You can only do that in a Generation IV nuclear reactor designed for it, or with solar thermal if you want "clean" hydrogen.
Pressurised water cooled reactors can't pull more approx. 320 celsius.
They have narrow termperature range.
Old designs, like molten salt, graphite - helium,Lead-bismuth eutectic could, just to name few.
All of them capable to reach above 800 C, molten salt was tested on 882C. in the 50s.
The engine of the Russian 9M730 Burevestnik should work on the temperature required for Sulfur - Iodine process.
PRoblem is :
1 . They usually work on atmospheric pressure, it makes them cheap to manufacture and resilent for many accident , but makes easy to defuel / refuell them for Pu making during energy production
2. Molten salt can be reprocessed during normal operation, menas there is no fission products in the reactor, making impossible Fukushima or Chernobil style accidents, where the Cs-137 contaminated huge areas. But it means a molten salt reactor could make the fines possible Pu for the bomb in normal production, with the available equipment , with little notice and require no modifications.
Interestingly, the Molten Salt Reactor experiment was terminated immedietly after the signature of NPT. It was decomissioned before the effective date of treaty .
Boiling water with nuclear power is like cutting butter with chainsaw . Primitive, and inefficient.
A combined sulfur iodine, with He turbine + tertiary steam generator could reach efficiency in the 70% range.
