EFFECT OF HAFNIUM CONCENTRATION ON NUCLEAR PERFORMANCE OF BLANKET MATERIALS CONTAINING ZIRCONIUM - A SENSITIVITY ANALYSIS OF TBR TO HAFNIUMCONTENT IN LITHIUM METAZIRCONATE

The reduction of hafnium content in blanket materials containing zirco nium is costly. Therefore, a sensitivity analysis was performed to est imate the impact of hafnium content on nuclear properties of lithium m etazirconate, a promising breeder material candidate for fusion reacto rs. This paper summarises the results of extensive shielding neutronic analysis and transmutation-activation calculations aiming to evaluate the tritium breeding ratio, the inventories of various radionuclides, and the surface gamma-dose rate. Attention has been mainly focused on the activation inventory variations resulting from hafnium content in lithium metazirconate breeding material. Different design configurati ons including homogenised solid breeder mixtures of Li2ZrO3 and struct ural materials and a separate beryllium multiplier zone have been asse ssed. Hf contents up to 3% have been assessed, resulting in a TBR redu ction up to 10%. The Hf content provokes a noticeable increase of the level of the equivalent contact dose.