Abstract
The source term for the JRTR research reactor is derived under an assumed hypothetical severe accident resulting in generation of the most severe consequences. The reactor core is modeled based on the reactor technical design specifications, and the fission products inventory is calculated by using the SCALE/TRITON depletion sequence to perform burnup and decay analyses via coupling the NEWT 2-D transport lattice code to the ORIGEN-S fuel depletion code. Fifty radioisotopes contributed to the evaluation, resulting in a source term of 3.7 × 1014 Bq. Atmospheric dispersion was evaluated using the Gaussian plume model via the HOTSPOT code. The plume centerline total effective dose (TED) was found to exceed the IAEA limits for occupational exposure of 0.02 Sv; the results showed that the maximum dose is 200 Sv within 200 m from the reactor, under all the weather stability classes, after which it starts to decrease with distance, reaching 0.1 Sv at 1 km from the reactor. The radiation dose plume centerlines continue to the exceed international basic safety standards annual limit of 1 mSv for public exposure, up to 80 km from the reactor.
Highlights
In comparison to power reactors, research reactors are small and contain smaller inventory of fuel and radionuclides, they have a higher number of reported accidents. e lack of containment building, proximity to densely populated areas, and high burnup cores, coupled with life extension, have raised worldwide interest for indepth safety evaluation of these systems
Core Inventory. e core fission product inventory calculations have been performed using the SCALE/TRITON depletion sequence, based on reactor maximum full power operation. e activity of 200 fission products has been tracked, accounting for the maximum possible activity in the core. e reactor core radionuclide inventory available for release to the environment is classified into eight groups, based on the NRC regulatory guide 1.183 [12] and is shown in Figure 5 e complete list of the fission products inventory and the their release fractions is included in Supplementary appendix 1 [20]
Fifty radioisotopes are selected for the source term evaluation, based on their yield, half-life, and radiotoxicity due to both inhalation and ingestion. e activity released in the form of noble gases and other aerosols is presented in Table 3, assuming the core remains exposed and all fission products are released to the atmosphere
Summary
In comparison to power reactors, research reactors are small and contain smaller inventory of fuel and radionuclides, they have a higher number of reported accidents. e lack of containment building, proximity to densely populated areas, and high burnup cores, coupled with life extension, have raised worldwide interest for indepth safety evaluation of these systems. In 2008, the international atomic energy agency (IAEA) published a research reactor safety report [1] It aims to provide safety analysts, regulators, and reactor operation staff and management, with the essential calculation methods and techniques for evaluating the source term and analyzing the radiological consequences of accidents in research reactor. Foudil et al have estimated the source term and doses for the NUR research reactor under a hypothetical severe accident [2]. Muswema et al carried out a study to drive the source term and analyze the radiological safety for the TRICOII research reactor in Kinshasa [3]. Charalampos et al published a study about source term derivation and radiological consequences for the Greek Research Reactor [4]. Ullah et al carried out a study to evaluate the source term for the upgraded LEU Pakistan Research Reactor-1 [7]
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