COMPARISON OF DOSE RATES CALCULATIONS WITH MEASUREMENTS AT A CASTOR HAW 20/28 CG CASK

The Federal Office for Radiation Protection (BfS) as the competent authority for package design approval in Germany is using the SCALE code system (SCALE = Standardized Computer Analyses for Licensing Evaluation) developed by Oak Ridge National Laboratory (ORNL) as a calculation tool for the shielding evaluation and in particular to decide whether a new package design meets all applicable dose rate limits of the transport regulations. At PATRAM 2001 satisfactory results have been presented for model calculations with SCALE 4.4a compared with measurements in the neutron and gamma field caused by a CASTOR IIa cask which is used for spent fuel elements [1]. In continuation of this work the paper presents the comparison of dose rates calculated by SCALE 4.4a with the measured ones at a CASTOR HAW 20/28 CG. This type of CASTOR cask is used for the transport and interim storage of vitrified high active waste (HAW) from reprocessing. For the calculations the SAS4 sequence of SCALE 4.4a has been used. The 28 HAW canisters as well as the basket and the cask body have been modelled in detail by MARS geometry. The measurements were carried out in January 2003. The main conclusions of this comparison will be described.