EDUARDO MAPRELIAN
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Artigo IPEN-doc 30242 RELAP5 code theoretical simulation of the experiment of natural circulation STAR2023 - SABUNDJIAN, GAIANE; BELCHIOR JUNIOR, ANTONIO; MAPRELIAN, EDUARDOStudies have been carried out on nuclear reactors with safety characteristics that do not depend on external intervention by operators or even on an external energy source. In this type of reactors, cooling is carried out by natural circulation, both during normal operation and during shutdown. For this reason, the STAR experiment was built in the IEA-R1 research reactor installed at the Institute for Energy and Nuclear Research (IPEN) – Brazil, with the aim of simulating experiments with the RELAP5 code in order to validate its models in two scenarios: total and partial emptying of the STAR. The results obtained with the RELAP5 code were compared to the experimental ones for the two proposed scenarios. These results showed that the mathematical correlations contained in RELAP5 are capable of reliably and safely reproducing the phenomenology of natural circulation in nuclear reactors.Artigo IPEN-doc 27183 Total and partial loss of coolant experiments in an instrumented fuel assembly of IEA-R1 research reactor2020 - MAPRELIAN, EDUARDO; TORRES, WALMIR M.; BELCHIOR JUNIOR, ANTONIO; UMBEHAUN, PEDRO E.; BERRETTA, JOSE R.; SABUNDJIAN, GAIANEThe safety of nuclear facilities has been a growing global concern, mainly after the Fukushima nuclear accident. Studies on nuclear research reactor accidents such as the Loss of Coolant Accident (LOCA), many times considered a design basis accident, are important for ensure the integrity of the plant. A LOCA may lead to the partial or complete uncovering of the fuel assemblies and it is necessary to assure the decay heat removal as a safety condition. This work aimed to perform, in a safe way, partial and complete uncovering experiments for an Instrumented Fuel Assembly (IFA), in order to measure and compare the actual fuel temperatures behavior for LOCA in similar conditions to research reactors. A test section for experimental simulation of Loss of Coolant Accident named STAR was designed and built. The IFA was irradiated in the IEA-R1 core and positioned in the STAR, which was totally immersed in the reactor pool. Thermocouples were installed in the IFA to measure the clad and fluid temperatures in several axial and radial positions. Experiments were carried out for five levels of uncovering of IFA, being one complete uncovering and four partial uncovering, in two different conditions of decay heat. It was observed that the cases of complete uncovering of the IFA were the most critical ones, that is, those cases presented higher clad temperatures when compared with partial uncovering cases, for the specific conditions of heat decay intensity and dissipation analyzed. The maximum temperatures reached in all experiments were quite below the fuel blister temperature, which is around 500 °C. The STAR has proven to be a safe and reliable experimental apparatus for conducting loss of coolant experiments.Artigo IPEN-doc 26349 Lower plenum holes for research reactor core flooding2019 - MAPRELIAN, EDUARDO; BELCHIOR JUNIOR, ANTONIO; TORRES, WALMIR M.Modern and high power pool type research reactors generally operate with upward flow in the core. They have a chimney above the core, where the heated fluid is suctioned by the pumps. It passes through the decay tank and is sent to the heat exchangers for the cooling and returns to the core. The pipes inside the reactor pool have passive valves (natural circulation valves) that allow the establishment of natural circulation between the core and the pool for the decay heat removal, when the pumps are inoperative. These valves also have the siphon-breaker function in case of Loss of Coolant Accidents (LOCA), avoiding the pool emptying. In some reactors, these valves are located above the core chimney to facilitate the maintenance. When a LOCA causes a water level below these valves, they loose the natural circulation function. If the water level is the same of the chimney top, the available fluid for the core cooling is only that contained in the chimney and core, and a significant quantity of water in the pool is unavailable for core cooling. To bypass this problem during the reactor design phase, the inclusion of small holes of 10 mm of diameter on the lower plenum lateral side is proposed. These holes will allow a flow path between the pool and the core. Theoretical calculations were performed and analyzed for different drilling configurations: 4, 6 8, and 10 holes. A theoretical analysis of the estimated leakage rate during normal operation and evaporation and replacement rates during a hypothetical LOCA were performed. The calculation results showed that the four configurations analyzed are able to supply the water evaporated from chimney. An experiment is being proposed to validate the theoretical calculations and the considered hypotheses.Tese IPEN-doc 24978 Experimentos de perda de refrigerante total e parcial no reator IEA-R12018 - MAPRELIAN, EDUARDOA segurança de instalações nucleares é uma preocupação mundial que tem crescido, sobretudo, após o acidente nuclear de Fukushima. O estudo de acidentes em reatores nucleares de pesquisa tal como o Acidente de Perda de Refrigerante (APR), considerado por muitas vezes um acidente base de projeto, é importante para garantir a integridade da instalação. O APR pode levar ao descobrimento parcial ou total do núcleo do reator e, como condição de segurança, deve-se garantir que haja a remoção do calor de decaimento dos elementos combustíveis. Esse trabalho teve o objetivo de realizar experimentos de descobrimento parcial e total no Elemento Combustível Instrumentado (ECI), construído no Instituto de Pesquisas Energética e Nucleares (IPEN), a fim de estudar os possíveis APRs em reatores de pesquisa. Uma seção de testes, denominada STAR, foi projetada e construída para simular os APRs. O ECI foi irradiado no núcleo do reator IEA-R1 (IPEN) e inserido na STAR, que ficou totalmente imersa na piscina do reator. No ECI, foram instalados termopares para medição das temperaturas do revestimento e do fluido em várias posições axiais e radiais. Foram realizados experimentos para cinco níveis de descobrimento do ECI, um total e quatro parciais, em duas condições distintas de calor de decaimento. Na análise dos resultados, verificou-se que os casos de descobrimento total foram os mais críticos, ou seja, as temperaturas do revestimento foram as maiores quando comparadas com os casos de descobrimentos parciais. Adicionalmente, foi realizada a simulação numérica de dois experimentos com o código RELAP5, cujos resultados demonstraram ótima concordância com os dos níveis experimentais, e temperaturas maiores que as experimentais. As máximas temperaturas do revestimento alcançadas em todos os experimentos ficaram bem abaixo da temperatura de empolamento do combustível, que é de 500°C. Assim, a STAR provou ser um aparato experimental seguro e confiável para a realização de experimentos de perda de refrigerante.Resumo IPEN-doc 24578 Experiments of loss of coolant in the IEA-R1 reactor2017 - MAPRELIAN, E.; TORRES, W.M.; BELCHIOR JUNIOR, A.; UMBEHAUN, P.E.; SANTOS, S.C.; FRANÇA, R.L.; PRADO, A.C.; MACEDO, L.A.; SILVA, A.T. E; BERRETTA, J.R.; SABUNDJIAN, G.The Loss of Coolant Accident (LOCA) has been considered Design Basis Accident (DBA) for several kind of reactors. The test section for experimental (STAR) for simulation of LOCA, using the Instrumented Fuel Assembly (IFA) EC-208 was designed, assembled, commissioned, and used for the experiments at the IEA-R1 Reactor. The experiments were performed for five different levels of fuel uncovering and two heat decay conditions. The five levels consisted of one total and four partial uncovering of the IFA. The results obtained for each experiment were the section level and 13 IFA temperatures. A data acquisition system was used to record the process parameters. The STAR section has proved to be a very safe and efficient tool for fuel uncovering experiments to obtain thermal-hydraulic data for research and development, and for the data to be compared with safety analysis code calculations.Relatório IPEN-doc 21433 Estudo da cadeia industrial dos equipamentos utilizados na cogeração de instalações comerciais e de serviços2014 - RIBEIRO, MARIA A.M.; MAPRELIAN, EDUARDOArtigo IPEN-doc 21115 Commissioning of the star test section for experimental simulation of loss coolant accident using the EC-208 instrumented fuel assembly of the IEA-R1 reactor2015 - MAPRELIAN, EDUARDO; TORRES, WALMIR M.; PRADO, ADELK C.; UMBEHAUN, PEDRO E.; FRANÇA, RENATO L.; SANTOS, SAMUEL C.; MACEDO, LUIZ A.; SABUNDJIAN, GAIANEArtigo IPEN-doc 08677 Interface MS Excel para o codigo COBRA2002 - MAPRELIAN, E.; BAPTISTA FILHO, B.D.Artigo IPEN-doc 19468 Test section for experimental simulation of loss of coolant accident in an instrumental fuel assembly irradiation in the IEA-R1 reactor2013 - MAPRELIAN, EDUARDO; TORRES, WALMIR M.; UMBEHAUN, PEDRO E.; TEIXEIRA e SILVA, ANTONIO; SABUNDJIAN, GAIANEArtigo IPEN-doc 09548 The mass velocity effect on the overtemperature protection limit in PWR reactors2003 - MAPRELIAN, E.; BAPTISTA FILHO, B.D.
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