nuclear should not be used to generate hydrogen - if at all it should be used the same as hydrogen would be used: to bridge gaps when not enough renewable energy is available

Nuclear power can definitely not fill this role of a fast switching on and off tool, it works most efficient as a steady long term output. Technically it can stop sending electricity to the grid, but that wastes all the heat that keeps being generated and is immensely inefficient. Heat storage in liquid salt seems to be an upcoming thing for nuclear power, but is not used there yet.