Near-Surface Alloying, of Neutron Absorbing Elements into Zirconium-Alloy Fuel Clad Material

摘要

Long-lived fuels require the use of higher enrichments of ~(235)U or other fissile materials. Such high levels of fissile material lead to excessive fuel activity at the beginning of life. To counteract this excessive activity, neutron absorbing elements known as integral fuel burnable absorbers (IFBA) are added to the UO_2 fuel pellets. The two commonly used IFBA elements are gadolinium and boron. The incorporation of IFBA into the fuel has to be performed in a nuclear-regulated facility that is physically separated from the main plant. These operations tend to be costly because of their small volume and can add from 20 to 30% to the manufacturing cost of the fuel. Other performance issues that impact cost are the reduction in fuel melting point due to IFBA additions, buildup of rod internal pressure and parasitic neutron absorption at fuel's end-of-life.