Results of irradiation tests of KU-1 and KS-4V silica glasses as ITER candidate window materials

Previous irradiation tests have shown that KU-1 silica glass may be used for ITER diagnostic windows in the spectral region of 0.35–2.5 μm. To help clarify the possibility of increasing this spectral range to the UV region irradiation tests of KS-4V high purity silica in Co60 gamma source and nuclear reactor were undertaken. KS-4V has an order of magnitude lower induced absorption in UV range compared with KU-1 after gamma irradiation up to 3 MGy, but there is no marked difference in transparency of KU-1 and KS-4V silica glasses after reactor irradiation up to F>0.1≅3×1016 n/cm2 (Dγ≅1 MGy) although induced absorption of KS-4V is slightly lower. In situ tests of transparency degradation under neutron and gamma irradiation of KU-1 and KS-4V silica glasses in UV range will be necessary for final clarification and ITER database preparing.