I do not know if this is a bug or something that was done on purpose. I mod my ships with the 1GW reactor to begin any game. I also place in my holds 2500 heliotrope fuel, as this upgrades the reactor. In version 0.97, when I go to refuel, the fuel "window" tells me that I can not use this type of fuel.
Is this a bug or was it intentional? 1GW is still plenty of reactor but I liked the idea of being able to upgrade the reactor.
Thanks
Bug or on purpose?
Well, i'm not sure, but I think the level of Heliotrope fuel has been decreased to 5 to make way for the new fuels. The Hyperion (1GW) reactor can only use fuels levels 6-9. This will be the probably the source of the problem, though I don't know if this was intentional or accidental.