Monte Carlo Calculation Procedure and its Implementation for Radiation Load Estimation on Russian VVER Reactor Equipment

A prediction of radiation load parameters (fluence, fluence rate, neutron energy spectrum) of reactor components, e.g. reactor pressure vessel (RPV), of Russian VVER reactors is regulated by the requirements of the Russian normative documents. One of the key measures is the validation of calculated procedures by ex-vessel neutron activation measurements at VVER nuclear power plants. The neutron dosimetry research for every reactor component includes validation calculations by appropriate codes.
The standard method was based on the three-dimensional (3D) synthesis method with input from results of calculations from the deterministic code DORT coupled with the BUGLE-96T library. It was identified in comparison between experiments and calculations that this method gives different results outside the active core. Hence, the usage of a 3D code is essential. For this reason, the Scientific and Engineering Centre for Nuclear and Radiation Safety (SEC NRS) wants to use the Monte-Carlo code TRAMO for own fluence calculations. Thus, the purpose of this work is the possible application of TRAMO for expert calculations of radiation load parameters of reactor components of all VVER reactor types, the verification of results by comparison with other codes (deterministic and Monte-Carlo) and the validation by neutron activation measured data. The paper presents possible options of the new version of TRAMO for neutrons fluence calculations suggested by SEC NRS.