ANDRE SILVA DE AGUIAR

ANDRE SILVA DE AGUIAR

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Consequence analysis of a Station Blackout in Brazilian nuclear power plant Angra 2
2022 - AGUIAR, A.S.; LEE, S.M.; SABUNDJIAN, G.
The article consists, through a Severe Accident, evaluating the impact of radionuclides released into the atmosphere in the vicinity at Nuclear Power Plant. The source term used in present work is obtained by means of proportionality between Angra 1 and Angra 2. That is, the source term of Angra 2 is calculated based on its activity estimated from numbers of fuel pellets of both power plants and the already known activity of Angra 1. This calculation resulted in total activity of Angra 2 equivalent to 146.18% of activity of Angra 1. The results indicate that for severe accident scenarios, the protective measures to be adopted will be general emergency; and the impact area, which currently has a distance of 5 km, would become greater than this value.
Whole body dose due to station blackout at Angra 2 nuclear power plant
2021 - AGUIAR, A.S.; LEE, S.M.; SABUNDJIAN, G.
Calculation of the dose for public individuals due to a severe accident at the Angra 2 nuclear plant, Brazil
2021 - AGUIAR, ANDRE S. de; LEE, SEUNG M.; SABUNDJIAN, GAIANE
Through a severe accident at nuclear power plant Angra 2, the whole body dose effective of the individuals members of the public located in the Emergency Planning Zones (EPZs) will be calculated, and later, the protective actions in these EPZs will be analyzed. Two different scenarios of radionuclide release into the atmosphere will be considered. In the first scenario, 2 h of the release of Xe, Cs, Ba, and Te, and the second scenario, 168 h of release.
Assessment of potential risk and radiological impact of accidental release from the ARGONAUT reactor
2019 - SOUZA, PAULA C.A. de; AGUIAR, ANDRE S.; HEIMLICH, ADINO; LAPA, CELSO M.F.; LAMEGO, FERNANDO
In the early days of nuclear energy in Brazil, a reactor designed at the Argonne National Laboratory, originating the name ARGONAUT from the combination of the name of the Laboratory with the initials of Nuclear Assembly for University Training, reached criticality at the Institute of Nuclear Engineering. The Argonaut is a water moderated research reactor, which uses uranium enriched to 20% (235U) with prismatic graphite reflectors, designed to provide a thermal neutron flux up to 1010 n.cm-2.s-1 at an operating power of 5 kW. The presence of a nuclear research facility at the campus of Federal University of Rio de Janeiro (UFRJ) still cause concerns about radiological safety of the community around, even though this facility has been securely operating for more than fifty years. Besides, there were questioning about the potential risk of this facility to the IEN´s workforce by the Central of Harmonization Unit of Brazil (CGU). Thus, the present work aims to assess the potential risk of radiological accidents. Previously, the potential accidents evolving Argonaut reactor were considered to be the insertion of excess reactivity, catastrophic rearrangement of the core, graphite fire and fuel-handling accident. However, a recent accident scenario reassessment concluded that a severe physical damage of the core after reactor shutdown should be the emergency situation with the greater potential risk among the feasible postulated accidents. According with the shutdown procedure, the water, used as moderator and coolant, drains out of the core and the concrete covers (each weighing 2.5 tons) are routinely removed from the top of reactor using a crane. The damage caused by the failure of the crane dropping the covers on the core would lead to breaking of the aluminum coating and the nuclear fuel plates with their release to the reactor room. This study assesses the radiological impact to workers and members of the public caused by partial inventory release to the atmosphere. Generic gaussian model was used to estimate the relative concentrations of air at ground level through the calculation of dispersion factors derived from wind data. For the dose calculation, the conversion coefficients by inhalation and plume immersion established by the ICRP were used. The results show that potential risk is above 1/10 of the limit of annual dose for workers, while they stay below the limit for members of the public, within a radius greater than 1 km.
Analysis of the protective actions in the Emergency Planning Zones (EPZs) in the Angra dos Reis region through the calculation of the dose for public individuals due to a severe accident at the Angra 2 Nuclear Plant
2019 - AGUIAR, ANDRE S.; LEE, SEUNG M.; SABUNDJIAN, G.
This work presents the results of the computational simulations of the consequences of a severe accident in Angra 2 nuclear power plant. The severe accident was supposed to be caused by a rupture of 380cm2 in the primary reactor coolant system resulting in loss of coolant. Since the area of the rupture is quite smaller than the total flow area of the pipe of the primary coolant system, 4418cm2, the accident is classified as a small break loss of coolant accident. However, this rupture by itself would not bring the system about a severe accident, which must involve a considerable damage in the nuclear core. Thus, some boundary conditions were added to the problem in order to set a scenario of this kind of accident, which was simulated by means of the MELCOR code. The results obtained by this code show that the release of the radionuclide to the environment starts at the opening of the containment relief valve, and this valve, in turn, opens when the containment pressure reaches 7bar, at 168 hours after the break of the pipe of the coolant system, according to the simulation. The program used for calculation of the release of the radionuclides to the surrounding region of the nuclear plant was the CALMET/CALPUFF code, so that the atmospheric and transport model were elaborated for this code. A source term was used in order to carry out an analysis of the protective actions in the emergency planning zones by means dose calculation for individuals of the public, and it was based on two different scenarios: first scenario, release of the total activity to the atmosphere of Xe, Cs, Ba and Te, after 2h simulation and second scenario, release of the total activity to the atmosphere of Xe, Cs, Ba and Te, after 168h of simulation.