Sfidis sientifichis e tecnologjichis inte prospetive di un mont cence armis nucleȃrs

After a long time, nuclear disarmament has now moved into the mainstream of international politics, with strong commitments by political leaders and becoming the focus of intense debate and discussion, with several institutions seriously studying approaches and possible concrete initiatives. The paper first recalls historical important steps in this direction: the 1945-6 initiatives toward international control, the Reykjavik Meeting and the recent Hoover Initiative. The military confrontation during the cold war resulted in the creation in several countries of huge arsenals of nuclear weapons of different kinds; in addition, exorbitant quantities of fissile materials have been produced. Fissile materials, ordinarily plutonium and highly enriched uranium (HEU), are the essential ingredients in all nuclear weapons. Their production is the most difficult step in making these weapons. The paper provides with an introduction to nuclear weapons, fissile materials, their production and their use in nuclear weapons and an overview of the status of fissile-material stocks worldwide. The several scientific and technical challenges facing the transition to a secure and stable nuclear weapon free world are then considered. These include the mechanism shaping the disarmament progress, the issue of reversibility, the management and elimination of fissile material stocks, the risks of nuclear weapon reconstitution or proliferation using material and capabilities in civilian nuclear energy programs and the definition of proper safeguards. Specific attention is paid to the disposal of HEU, including that for non-weapon production, in particular for naval propulsion, research reactors and medical isotope production. The problems of separated plutonium and of its increasing stocks from civilian power reactors are underlined, together with the approaches to plutonium disposal, which leave a lot of space to deeper researches. The scientific community has performed several studies on the technical aspects of the various relevant problems, suggesting solutions and workable approaches, but much more research and thought is strongly needed to support a realistic approach to a world free from nuclear weapons.