The Ghana Research Reactor-1 (GHARR-1) core was modified with an addition of a 9.0 mm layer of beryllium to the top shim tray to compensate for reactivity loss due to fuel depletion after 19 years of operation. Neutronic and kinetic parameters have been predicted using Monte Carlo N-Particle Code version 5 (MCNP5) to determine whether they were within acceptable operating margins. Excess reactivity, control rod worth, moderator reactivity coefficient, delayed neutron fraction and neutron generation time have been predicted as 3.86, 6.98, −0.1218 mk/˚C, 8.17507 × 10 −3 ∆k/k, and 8.147 × 10 −5 s respectively. These parameters compared favorably with those provided in the initial Safety Analysis Report.

The Program for the Analysis of Reactor Transients/Argonne National Laboratory (PARET/ANL) code was used to predict the thermal hydraulic behaviour of the Ghana Research Reactor-1 after adding 9.0 mm of beryllium to the top shim tray of the core. The core was analysed for reactivity insertions 2.1 mk, 3.0 mk, 4.0 mk, 5.0 mk and 6.7 mk, respectively. The reactor is still safe to operate in the range 2.1 mk to 4.0 mk. However, 2.1 mk would be ideal since the reactor automatic shutdown (SCRAM) is set not to exceed 120% of reactor nominal power.