Radiological Dispersion of I-131, I-133 and I-135 Isotopes Due to Hypothetical Accidental Release from Nigerian Research Reactor-1

Abstract

Nuclear accidents are known to be associated with severe radiological contamination of the environment. The severe nuclear disaster in April 1986, following the unit 4 power reactor accidents in Chernobyl nuclear power plant and the 2011 Fukushima Daiichi nuclear power plant accident left an indelible scar on the civilian applications of nuclear technology. After every nuclear accident, Iodine is known to be the immediate radionuclide to be detected in areas surrounding the nuclear reactor site owing to its fast mobility in air. Because of its radiological concern, pharmaceutical approaches have developed for immediate response to the release of iodine following a nuclear accident. Since Pharmaceutical approach to radiological response is not the best global practice, it is imperative to carryout hypothetical studies to establish safe distances around any nuclear facility vis-à-vis the release of Iodine in the event of an accident. In this study, the source terms of I-131, I-133 and I-135 isotopes from the Nigeria Research Reactor-1 were calculated using TRITON-ORIGEN coupled computational sequence. The concentrations of the radionuclides in air at different distances from the reactor were determined using Hot-Spot computer code. The results showed that the concentration of I-131, I-133 and I-135 were greatest at 10 m from the reactor and decreases with distance as expected. However, the concentrations of I-131 at distances 10-300 m from the reactor were higher than the Derived Air Concentration (DAC), indicating that the possibility of radiation hazard at this perimeter exist. Further assessment of the radiation impact showed that the Total Effective Dose (TED) due to the released Iodine isotopes was [[EQUATION]] at 10 m which is not good for members of public and [[EQUATION]] at 300 m thereby indicating that the public area (300 m) is safe from radiological health risks due to the released radioactive Iodine isotopes.

Keywords: Iodine, Accident, Source term, Radionuclides, NIRR-1, Effective Dose