COMPARATIVE RADIOLOGICAL ASSESSMENT OF SICF SIC COMPOSITES AS STRUCTURAL-MATERIALS IN NUCLEAR-FUSION TECHNOLOGY/

The fusion technological consequences of the radioactive decay behavio ur of SiC-based structural material were analysed based on a complete chemical analysis of an industrial SiCf/SiC composite. Radioactivation simulation was performed with the FISPACT-2 code and EAF-2 cross-sect ion library, taking n-spectra from the SEAFP reactor study for first w all and blanket. The decay of radioactivity in SiCf/SiC. after shut do wn and derived radiological quantities are presented and compared with those of SEAFP structural materials. The effective dose equivalent (E DE) to the population from accidental release of activated material wa s computed with the GENII code. SiCf/SiC performs favourably. Contact dose rates and gamma-dose rates inside the plasma chamber are given. A ssuming an upper limit of 10(4) Gy h(-1) for robotized maintenance, Si Cf/SiC renders the first wall a zone where immediate repair would be p ossible. For this short-term activation limit, an elemental ''critical list'' is presented. Long-term decay heat generation and contact dose rates show which material fulfils waste limits. Although Al-26 is gen erated in the first wall, (SiCSiC)-Si-f is a safely disposable materia l, owing to other characteristics such as inertness against corrosion.