Monte Carlo Fluence Calculations and Spectrum Adjustment for the Pressure Vessel of the VVER-1000 Balakovo-3 (Invited Paper)

The neutron embrittlement problem of current pressure vessel reactors is of great safety and economic concern. It culminates in Russian VVER-type reactors. Compared with Western pressurized water reactors, the shorter distance to the core results in substantially higher neutron fluences for the pressure vessels. In the case of the VVER-1000, the increased content of nickel and the position of a weld at a height near to the maximum flux are additional, unfavorable pecularities. These circumstances caused the embrittlement problem of VVER pressure vessels to become the objective of many international research collaborations. The reactor dosimetry group of Forschungszentrum Rossendorf participated in the Interlaboratory Reactor Dosimetry Experiment Balakovo-3 with Monte Carlo fluence calculations, activation measurements and with spectrum adjustments. The paper describes the specific features of the methods applied, presents and discusses the results and draws conclusions with respect to further investigations.