Dose rate outside cryostat of the SEAFP-2 fusion plant

Abstract

The results of biological dose rate calculations for different locations in the vicinity of the concrete shield wall of the cryostat pit of the SEAFP-2 fusion plant are given in this paper. The plant model assessed considers low-activation martensitic steel for first wall and blanket, Li 17Pb 83 as breeder/multiplier material and water as coolant. For many analyses in the frame of the SEAFP-2 programme, one-dimensional modelling of the geometry is adequate. So far an infinite-cylindrical model representing the radial build at the plant mid-plane from the central solenoid up to the cryostat concrete wall was used. Dose rates are evaluated both during plant normal running operation and after plasma shutdown before long term maintenance activity. Contribute due to neutrons and gamma-photons are considered through a coupled n– γ Sn transport calculation. Effects of streaming due to penetrations are also evaluated. Radioactive decay of materials is included. The radiation transport analysis has been performed with the Bonami-Nitawl-XSDNRPM calculation sequence of the Scale 4.4 code system, using the Vitamin (ENEA) library, based on ENDF/B-VI cross section data. The Anita-4M code (with the FENDL/A-2 activation data library and the FENDL/D-2 decay data library) has been used for activation calculation to evaluate the gamma sources due to material radioactive decay. The dose rates outside the cryostat concrete wall have been obtained with the XSDOSE code using ANSI standard neutron and gamma flux-to-dose-rate factors.