You don't have to process high level wastes on your ship, but you do with tritium. Even if you don't plant to extract the tritium from the blanket modules, you do need to recycle the unburnt fuel (the burn-up fraction is at best a few percent).
Tritium is radioactive hydrogen: it's a gas that explodes in air at low concetrations, it reacts with organic compunds, it has high mobility in pretty much any material, by decaying it produces Helium bubbles that can embrittle metals, its β radiation crack glasses etc.
You don't have to process high level wastes on your ship, but you do with tritium. Even if you don't plant to extract the tritium from the blanket modules, you do need to recycle the unburnt fuel (the burn-up fraction is at best a few percent).
Tritium is radioactive hydrogen: it's a gas that explodes in air at low concetrations, it reacts with organic compunds, it has high mobility in pretty much any material, by decaying it produces Helium bubbles that can embrittle metals, its β radiation crack glasses etc.