Study of the efficiency of the biological shielding of the WWER-440 NPP primary cooling circuit

Calculational and experimental data on the γ-fields in rooms behind the biological shielding of the WWER-440 reactor NPP primary coolant circuit are compared. The experiments were performed at the units 3 and 4 of the Novo-Voronezh NPP at 60-100% power rates. The calculations were conducted with the help of new NC and CONTUR computer codes. The results demonstrate that none of the conditional gamma sources contributes more than 60% of the total power rate. When corrected for gamma screening by different structural materials the experimental and calculational spatial dose rate distributions coincide within the error bars of the measurements (+-20%) and the calculations (+-35%). The analysis has shown the experimental validity of the calculational technique and the right choice of initial data