Validation of the code ETOBOX/BOXER for UO2 LWR lattices based on the experiments TRX, BAPL-UO2 and other critical experiments

The EIR codes system for LWR arrays is based on cross sections taken out of ENDF/B-4 and ENDF/B-5 by the code ETOBOX. The calculation method for the arrays (code BOXER) and the cross sections as well were applied to the CSEWG benchmark experiments TRX-1 to 4 and BAPL-UO/sub 2/-1 to 3. The results are compared to the measured values and to some calculations of other institutions as well. This demonstrates that the deviations of the parameters calculated by BOXER are typical for the cross sections used. A large number of critical experiments were calculated using the measured material bucklings in order to bring to light possible trends in the calculation of the multiplication factor k/sub eff/. First it came out that the error bounds of B/sub m//sup 2/ evalu-ated in the measurements are often optimistic. Two-dimensional calculations improved the results of the cell calculations. With a mean scattering of 4 to 5 mk in the normal arrays, the multiplication factors calculated by BOXER are satisfactory. However one has to take into account a slight trend of k/sub eff/ to grow with the moderator to fuel ratio and the enrichment. (author)