Further development, validation and verification of the Monte-Carlo code TRAMO on ex-vessel experiments of the Greifswald NPP

TRAMO is a Monte Carlo code which is specially designed for geometries of nuclear power plants. In recent years, TRAMO has undergone a number of technical developments. In addition to the conversion to modern Fortran, standardized models for VVER-440 and VVER-1000 for the evaluation of monitor experiments on the surface of the reactor pressure vessel were developed, and the corresponding pre- and post-processing was automated. The new TRAMO version is continuously validated and verified. Here we present comparisons with experimental data from unit 1 of the Greifswald nuclear power plant and with MCNP calculations. Earlier calculations with TRAMO showed good agreements in the middle region of the fission zone, but significant deviations outside. A possible explanation is the wrong documentation of the experimental data – especially the heights of the monitors. Assuming a downward shift of the monitor positions by about 24cm, experimental and calculated data show very good agreement.