A NEW 3D REACTOR MODEL FOR CRITICALITY SAFETY ANALYSIS OF NIRR-1 USING SCALE 6.2.3
Abstract
Detailed 3D model was developed for the Nigeria Research Reactor (NIRR-1) recently converted to 12.5% enriched UO2 core during the last quarter of 2018. The KENO3D module of SCALE 6.2.3 was used to visualize the geometry of the system before the criticality safety analysis was performed with the KENO-VI module of the code. This model consists of over 10 different units that are properly placed at their exact position on the global unit. The coordinate of each fuel pin was calculated using the radius of the circle and the pin angular positions. Several reactor physics parameters generated include k-effective values by generation run, the average k-effective, the neutron lifetime, the generation time, the average number of neutron per fission in the system, the average energy group at which fission occurs, and the energy of the average lethargy causing fission in the system. Some of this information was used to determine how fast or thermal the spectrum of the modeled system was. A plot of average k-effective versus the number of generation run was used to determine whether the calculations performed using the input prepared for the modeled NIRR-1 system has source convergence difficulties or not.
References
Chakrov, P. and Hanlon, T. (2018): Nigeria Converts its Research Reactor from HEU to LEU Fuel, Department of Nuclear Energy, International Atomic Energy Agency, Retrieved from the web in 2019 and available at https://www.iaea.org/newscenter/news/nigeria-converts-its-research-reactor-from-heu-to-leu-fuel
FSAR (2005): Safety Analysis Report for Nigeria Research Reactor-1, Center for Energy Research and Training, Ahmadu Bello University Zaria, Nigeria.
Jonah, S.A. and Balogun, G.I. (2005): Current Status of the Nigerian MNSR (NIRR-1) and the feasibility for conversion to LEU. Paper presented at 2005 international RERTR meeting and available at https://www.rertr.anl.gov/RERTR27/PDF/S10-4_Jonah.pdf
Ibikunle, K. Ibrahi, Y.V. and Jonah, S.A. (2016): MCNP Calculation of Core Physics Parameters of NIRR-1 Core Using Manufacturer’s Recommended Value of 13% Enriched UO2 Fuel, European Research Reactor Conference, Berlin Germany, 13-17 March, 2016, PP 140 -146
Salawu, 2013: The study of research reactor for core conversion of NIRR-1 from HEU to LEU fuel, PhD thesis, Department of Physics, Ahmadu Bello University Zaria, Nigeria.
Rearden, B. T. and Jessee, Eds, M. A. (2016): SCALE Code System, ORNL/TM-2005/39, Version 6.2.1, Oak Ridge National Laboratory, Oak Ridge,
Tennessee (2016). Available from Radiation Safety Information Computational Center as CCC-834
Yahaya, B. Ahmed, Y.A., Balogun, G.I. and Agbo, S.A (2017): Estimating NIRR-1 burn-up and core life time expectancy using the codes WIMS and CITATION, Results in physics, vol.7, pp 596-603.
FUDMA Journal of Sciences
