Monte Carlo modeling of the Pakistan Research Reactor-1 (PARR-1)

Pakistan Research Reactor-1 (PARR-1) is a swimming pool type research reactor established in 1965. Originally, it was designed to operate at 5 MW utilizing 93% Highly Enriched Uranium (HEU) fuel. Due to proliferation concerns, the reactor core was converted to LEU core in 1992, utilizing Uranium Silicide (U3Si2-Al) fuel having 235U enrichment of 19.99% and with an up graded operating power of 9 MW. The first LEU core was operated at full reactor power (9 MW) composed of only fresh fuel and is termed as first high power core. The objective of this article is to develop the detailed model of this first high power core of PARR-1 employing Monte Carlo N-Particle (MCNP5) computer code. The MCNP5 is equipped with the cross-section library ENDF B-VI. To validate the MCNP model, the simulated values of initial criticality with control rod positions, excess reactivity, shutdown margin and combined control rod worth are compared with the published work. The relative error in criticality is 2.6% (with control rod positions 51.6% out of the core), 2.7% in excess reactivity, 6% in the shutdown margin and 3.3% for combined control rod worth has been observed. This model shall be applied to predict the power profile, peaking factors and feedback reactivity coefficients of the reactor in future.