This is just a speculation. What if we were to use the heat from fission to generate hydrogen instead of electricity? Would that help at all?
For instance a high enough temperature will cause water to dissociate.
For instance a high enough temperature will cause water to dissociate.
The idea is that a lot of the energy to split the hydrogen and oxygen can be provided as heat; that means you need a lot less electrical energy. To a rough approximation, for every three units of heat energy produced by a nuclear plant, you get one unit of electricity, so the process could in theory considerably reduce the cost of zero-carbon hydrogen.
In practice, it seems like it's going to be very hard for a nuclear plant to beat an electrolyser that runs when near-free solar electricity is available.
As you say, if you get hot enough you can do away with electrolysis entirely. A little bit of casual reading suggests that the temperatures required by a naive approach are in excess of 2000 degrees Celsius, far, far beyond the point where any existing or near-term reactor design would turn into a puddle of very radioactive molten metal.
But if there is another chemical method that used thermal energy in the process to produce hydrogen then there might be some possibilities in the idea.
Currently green hydrogen plants are expanding and ammonia | methanol marine fuel ships have been built and trialed - there are contracts signed and in the works to both build a 4,000 km HVDC "suncable" and to ship hydogen products longer distance.
However, I appreciate the point made about hydrogen escaping and causing embrittlement of materials.
Electricity is really just another means to the same end. You can't use all of the energy generated by a power plant, at the plant site, so you transport the energy to places where it's needed.