Can you keep nuclear bombs without having an active reactor?

Following Larry Derfner’s post, I wondered whether Israel could close down its reactor and keep some of the nukes it is said to have, perhaps as a first step on the road to a nuclear-free Middle East.

I asked Dr. Avner Cohen whether it’s possible to keep the bombs without an active reactor (according to foreign sources, Israel is said to have between 100 and 400 nuclear bombs). Here is his immediate response:

Theoretically, it’s possible to hold a simple nuclear weapon – meaning a “Nagasaki” (Plutonium) bomb and even a “Hiroshima” (enriched Uranium bomb) for a [long] period of time without a reactor. More sophisticated weapons – like the kind Israel is said to have – requires another material, called Tritium, albeit in very small quantities (several grams). Tritium has a relatively short life expectancy, meaning that it requires maintenance and replacement. Tritium is produced in a reactor or an accelerator.