I sort of like the idea and also loath it because of the potential issues with "argh, I forgot to refuel". I'm also not a fan of implementing new systems purely as a money sink because it risks not solving the problem and affecting many more players. However I do love the idea of adding some new craftable components that aren't available as drops.
Off the top of my head a few ideas.
Probably the simplest option. New ship component that adds a fuel tank to ships with a level 4 Reactor. You "fill up" the fuel tank using fuel made from Liquid Petrochem and Radioactive. This works in a similar way to a repair kit in that a fuel canister fills a certain amount of the tank up and the Shipwright can make bigger cannisters.
Pros: Adds fuel tanks and fuel cannisters to the Shipwright profession. Even level 1 fuel cannisters would be useful
Cons: Fuel tanks could be a pain to refactor into existing ships
All reactors of level 4 and above have a built in fuel tank equal to 4 times the generation rate. You "fill up" the tank using fuel make from Liquid Petrochem and Radioactive. Fuel cannisters work in the same way as a repair kit in that they have a quantity that can be experimented with.
Pros: Everything from 1. Could have performance fuels for Interceptor chassis
Cons: Pretty basic system
Fuel Cell component that works in a similar way to chaff ammunition. For level 4 Reactors and greater you "slot in" a pair of fuel cells. The fuel cells would have a certification level that must match the reactor. When you're on your last cell you get a low fuel warning
Pros: Only one component added that's a sub-component. Bigger ships could fit more than 2 cells
Cons: No real way to experiment without giving high end SW's an edge. No low end SW option
Add in a new fuel tank, fuel container and injection system component. Fuel tank would work in the same way as suggestion 1. Fuel container would be made by a shipwright with the ability to experiment on the fuel quality. The injection system would control the maximum energy generation rate, fuel drain rate and the minimum fuel quality. Would be highly customisable so bigger bore pipes component would be more suited to big heavy ships and you'd need different injectors for higher energy generation reactors. Would mean you'd end up with injection systems suited to fast interceptors and ones suited to slow mining ships, you will also have Shipwrights being asked to make injection systems for specific ship reactors.
Pros: Loads of customisation. Novice shipwrights would still be able to participate. Higher end ships will need higher quality fuel (i.e. cost is exponential)
Cons: The most complicated system to understand and likely implement. Would be a pain to refactor into existing ships