Because wilful ignorance is so much better than realism , right ? <| sep |> This looks a bit like an elephant <| sep |> Great job and nice pics . How long did that take ? You should be ready for the Davis Double next year . <| sep |> Hot water as no real risks . It ' s preferred to use hotter water as its less stress on the mechanical components . The only too hot is that your piping may not be rated for those temperatures . But for emergency core cooling systems , typically the class I piping is rated at reactor pressure and the class II piping is rated at max containment temperature and pressure plus head of the pump . There ' s really not a lot you can do for maintenance to prevent this issue . The only potential may be to anneal the vessel , but that has its own risks too and hasn ' t been performed outside of Russia on a large commercial unit to my knowledge . Steel gets brittle when it is cold , not hot . Hot makes the steel more ductile and flexible , making it more resistant to pressure and temperature shocks . Too cold is the only thing you worry about .