Calculation of the power and absolute flux of a source driven subcritical assembly using Monte Carlo MCNP code

• Reactor power was calculated using MCNP criticality and fixed source simulations.
• The effective multiplication factor (Keff) was calculated.
• The radial and axial absolute neutron fluxes were estimated using point detectors.
• Both methods were compared and showed an adequate agreement for the power and fluxes.

The reactor power is an essential parameter used for calculating the coefficients of a nuclear reactor such as the absolute flux, reaction rate, power density, fuel burn-up, and the source term. The power is dependent on the driving neutron source strength in the subcritical reactors. In this work, MCNP5 code based on Monte Carlo method was used to model the 3D configuration of the subcritical assembly and its driving source. The aim of this paper is to calculate the amount of energy produced by the subcritical assembly, to estimate the absolute neutron flux along the radial and axial axis, and to determine other coefficients such as Keff and ν. Using MCNP, the reactor power and flux computations were performed using two methods: the fixed source (nps) calculations and the criticality (Kcode) calculations. This research compared the results obtained from the two methods, and discussed any significant deviation in the computation results.