With a half-life of 12 years and the time interstellar voyages take, you can just let your tritium sit around for a while. (In addition to what the other comment said about separation actually being relatively easy.)
Depending on your fusion reactor, you might actually highly value any tritium produced, instead of seeing it as a nuisance.
> Your fuel still gets consumed, so you still can't rely on your fuel as the main form of shielding. Towards the end of your journey, your rocket is approximately 0% fuel. And at the point of highest speed, before you start decelerating, it is roughly 50% fuel.
With a nuclear engine you make a difference between fuel and propellant. When you fuse your hydrogen into helium, you still have the helium afterwards.
I haven't run the numbers to see how your fuel consumption would compare to your propellant consumption for a reasonable fusion powered rocket. Though I suspect that you also need oodles of propellant, given how the rocket equation works.
For the first part of your journey you could rely on passive shielding via your propellant. For the latter part, you could use more costly active shielding like a big magnetic field or ablative shields in front of your main rocket etc.
Basically, you would still want to use your propellant as free shielding as much as possible.
Depending on your fusion reactor, you might actually highly value any tritium produced, instead of seeing it as a nuisance.
> Your fuel still gets consumed, so you still can't rely on your fuel as the main form of shielding. Towards the end of your journey, your rocket is approximately 0% fuel. And at the point of highest speed, before you start decelerating, it is roughly 50% fuel.
With a nuclear engine you make a difference between fuel and propellant. When you fuse your hydrogen into helium, you still have the helium afterwards.
I haven't run the numbers to see how your fuel consumption would compare to your propellant consumption for a reasonable fusion powered rocket. Though I suspect that you also need oodles of propellant, given how the rocket equation works.
For the first part of your journey you could rely on passive shielding via your propellant. For the latter part, you could use more costly active shielding like a big magnetic field or ablative shields in front of your main rocket etc.
Basically, you would still want to use your propellant as free shielding as much as possible.