[pierrem15]

Depends on the design: all will produce some quantity of neutrons-- one of the key features of this design is that it converts a sufficient quantity of the neutrons into additional tritium and deuterium, producing some of its own fuel.

In any case, we're talking about something having low level radioactivity for 100 years, not 'glow in the dark' for 10,000 years. The small amount of really nasty stuff has a very short half life, so you store it for 90 days and bury it in the desert. It would probably be lower than the background rate in many places, like the White Mountains in NH or central VA.

[from occupied ga]

In any case, we're talking about something having low level radioactivity for 100 years

Not necessarily. It depends on what materials the thing is made of. For example, any cobalt in the structure will be activated to cobalt-60 half life 5+ years, and carbon will get activated to C-14 half life of 5760 years. Then there is neutron embrittlement of any steel structure.

What isotopes were you referring to?