I figured out how to make an "antimatter trap" and I know I had a checkpoint to consume some antimatter, but I kept trying to put the "antimatter trap" into a vehicle. It kept not working. I ended up only figuring out that the antimatter trap had to be burned (charged?) in a reactor and then the result is "antimatter". That is actually the burnable fuel for vehicles.

This seems like it could somehow be better explained, because every other thing you stick into a reactor gets consumed as basically the final process, but for an antimatter trap burning it in a reactor is actually part of the chain of making the antimatter.

The breeder cell is not the final product either. It's more expensive for less energy than the basic fusion cell. The whole point of it is not to burn it but to get the spent breeder cell which converts your surplus deuterium into more valuable tritium. So 50% of the nuclear fuels are like this.

The description of an antimatter trap is: Used in a reactor to collect antimatter fuel ([item=nullius-antimatter]).
The description of antimatter is: An extremely dense, powerful vehicle fuel collected by an antimatter trap ([item=nullius-antimatter-trap]).
I'm not sure how these descriptions could be more explicit about this than they already are.

Not to mention the built in game engine feature of showing you what the burnt result is for solid fuel items. This is an important field that you can't really ever just ignore since you need a plan for dealing with it. You should already know to look for it before antimatter, since most solid fuels in Nullius have spent results like this.

I just think it's confusing. Every other reactor fuel you start with it "bright", you burn it in the reactor, and you have a spent "dull" canister that you then have to reprocess. And yes, when you reprocess the breeder cell you get tritium, but that's no different than a zillion other loops in the game.

With the antimatter it starts "dull" and you stick it into the reactor and that makes it turn "bright". It's the opposite of everything else.

I did eventually figure it out, but I still say it's confusing because it goes against every other thing the game has taught you so far about how to use reactors.