Reactor vessel shielding with radioactive waste materials as burnable poisons.

摘要

An increasing concern in the nuclear industry is damage to reactor pressure vessels as a result of neutron fluence. This phenomena can significantly shorten reactor lifetime and, in some situations, has the potential to become a serious safety concern. As a result, finding methods to alleviate this problem is important to both current and next generation reactors. One technique discussed in this report and is currently being explored is to replace some of the outermost fuel pins with absorber pins that serve as an expendable shield for the reactor vessel. However, this concept is not new. The early US Department of Energy (DOE) production reactors at the Hanford Site used materials such as thorium and lithium to protect structural components from excessive neutron flux. In addition this shielding was used to produce special nuclear materials. While the production of special nuclear materials may no longer be of interest there may still be ways to put neutron shielding materials to good use. One possibility would be to use long-lived waste isotopes, such as (sup 99)Tc and (sup 129)I, as target materials that would be transmuted into shorter-lived waste forms. This would have the benefit of shielding the reactor vessel and, at the same time, eliminating the need for long-term storage of these problematic isotopes.