Developing skills for neutronic modelling of nuclear power reactors in South Africa

Gezekile Nyalunga, Vishana Naicker, Maria du Toit


In recent years, due to economic and social infrastructure development and growth, South Africa has been facing growth in energy demand. Addressing this demand includes building more coal power stations, however with attention paid in designing them to reduce greenhouse gas emissions. A second response is to deploy more power sources using renewable and nuclear energy. The South African government has plans to add about 9.6 GW of nuclear energy to the electricity grid. Accepting that South Africa will seek an international vendor or vendors to supply nuclear plants, a certain degree of localisation of manufacture and operation should be planned. One localisation task that can be actively pursued is reactor analysis, including criticality, burnup, shielding and accident analysis of the reactor. Such development of expertise will support both economic and safety aspects of building and running a nuclear reactor. With this in mind, neutronic analysis of the VVER 1000 reactor was initiated. The government’s intention to build a new fleet of reactors means it is important that the VVER-1000 reactor be included in studies done by the reactor analysis group at the School of Mechanical and Nuclear Engineering at the North-West University. The analysis was performed using MCNP6 for the cold zero power state at the beginning of cycle with the specifications obtained from the open literature. The input file was generated using the in-house code NWURCS. To ensure accuracy and precision of the results produced by the MCNP6 code, convergence studies of the MCNP6 models were carried out. Once a satisfactory model was obtained, the critical reactor state was calculated by adjusting the boron concentration in the water. Furthermore, the control rod worth, reactivity coefficients and beff were also calculated and are reported in this paper.


Neutronics; PWR; VVER-1000; MCNP6; criticality; reactivity coefficient

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