Assessment of Uncertainty in the Calculation of Neutron Fluence on the VVER-440 Reactor Pressure Vessel Due to Uncertainties in Neutron–Nuclear Interaction Cross-Sections

An assessment of the uncertainty in the calculation of fast neutron fluence on the reactor pressure vessel of the second unit of the Armenian Nuclear Power Plant (ANPP) was conducted, considering uncertainties in neutron–nuclear interaction cross-sections. Using the Monte Carlo method, the most sensitive region of the reactor to changes in neutron interaction cross-sections was identified. The results indicate that the primary source of fluence uncertainty is in the neutron absorption cross-section in the fast neutron energy region, especially in hydrogen. Data received have significant importance for the long-term safety assessment and life extension of these types of reactors.