ADIMIR DOS SANTOS

ADIMIR DOS SANTOS

(Fonte: Lattes)

ORCID

ScopusID

ResearcherID

Resumo

Possui graduação em Bacharelado Em Física pela Universidade de São Paulo (1975), mestrado em Reatores Nucleares de Potência e Tecnologia do Com pelo Instituto de Pesquisas Energéticas e Nucleares (1978) e doutorado em Nuclear Engineering pela University of Wisconsin – Madison (1984). Atualmente é PESQUISADOR TITULAR III do Instituto de Pesquisas Energéticas e Nucleares, professor titular da Universidade de São Paulo e Revisor de periódico da Progress in Nuclear Energy. Tem experiência na área de Engenharia Nuclear, com ênfase em Tecnologia dos Reatores. Atuando principalmente nos seguintes temas: SENSITIVITY ANALYSIS, TRANSMUTATION, THORIUM, U-233 BREEDING. (Texto extraído do Currículo Lattes em 28 set. 2021)

Página do item completo

Resultados de Busca

Agora exibindo 1 - 10 de 56

Zero-power noise up to 100 kHz in the IPEN/MB-01 research reactor facility
2021 - SANTOS, DIOGO F. dos; SANTOS, ADIMIR dos
Subcritical noise experiments at frequencies up to 100 kHz employing two distinct boron dilution in the reactor tank water (286.8 and 578.6 ppm of natural boron) were performed in the IPEN/MB-01 reactor. The Auto Power Spectral Densities (APSD) were inferred employing the IPEN/MB-01 Correlator and were best described by a four-mode decay model up to about 70 kHz. The analyses reveal that the first two modes were related to thermal neutron and the other two to the fast ones. The coupling between thermal and fast neutrons was weak, and they could be considered uncoupled. A two-region two-group kinetic model was built and for the first time important parameters, such as the subcritical reactivities, generation times, and the prompt neutron decay constants all in the core and reflector in the 286.8 ppm case were inferred. The experiments can be considered unique of its kind and the theory/experiment comparisons reached good agreements.
APSD up to 100 kHz dataset measured in the IPEN/MB-01 research reactor facility
2020 - SANTOS, DIOGO F. dos; SANTOS, ADIMIR dos; DINIZ, RICARDO
The data presented in this work are from the very accu- rate reactor noise measurements performed in the IPEN/MB- 01 research reactor facility. The quantity inferred from the measured data was the Auto Power Spectral Density (APSD) with the frequency range extended up to 100 kHz. The core configuration considered a short version of the IPEN/MB-01 core, consisted of a 26 ×24 rectangular array of fuel rods with control banks totally withdrawn. The measured reactiv- ity excess for this configuration was equal to (10 ±3) pcm. The subcriticality was reached by poisoning the reactor wa- ter with boric acid (H 3 BO 3 ) in the concentrations of 286.8 and 578.6 ppm of natural boron. The main goal of these experiments was to test subcritical configurations with uni- form poisoning. The average temperature for the experiment with 286.8 ppm of natural boron was (19.82 ±0.37) °C and that for the 578.6 ppm was (19.89 ±0.09) °C. The core was driven by the 241 Am-Be start-up source ( ∼1.0 Ci) of the facil- ity placed in the reflector. The APSD (in units of count 2 /Hz) was inferred employing the IPEN/MB-01 Correlator. The basic measured data arise from the pulses of two 3 He Centronic detectors placed in the reflector region.
New delayed neutron group constants and covariances for LWR core applications, combining summation calculations and integral experiments
2020 - LECONTE, P.; ARCHIER, P.; DE SAINT JEAN, C.; DINIZ, R.; SANTOS, ADIMIR dos; FAUTRAT, L.; FOLIGNO, D.; GESLOT, B.; GILAD, E.; TAMAGNO, P.; TRUCHET, G.; ZOIA, A.
IPEN/MB-01 reactor experiments with nickel reflectors
2019 - SILVA, GRACIETE S. de A. e; MURA, LUIS F.L.; FUGA, RINALDO; SANTOS, ADIMIR dos
In the validation and verification processes of calculation methodologies and associated nuclear data libraries, the existence of experiments that can be considered benchmarks is of fundamental importance. For this purpose, a set of experiments with heavy material nuclear reflector was performed in the IPEN/MB-01 reactor using nickel plates properly inserted in the west face of the reactor core. A total of 32 plates around 3 mm thick were used in the experiment. The axial width and length were sufficient to cover the entire active reactor core. For each plate placement step, reactivity measurements were made due to their insertion in the core; as well as of the critical position of the equally removed BC1 and BC2 control rods. It could be observed that the increase of neutron absorption and consequent decrease of neutron moderation dominated the whole physics of the problem when few plates of reflective material were inserted (about 3 plates). Thereafter, neutron reflection became important overcoming neutron absorption; the reactivity increased until it surpassed the situation without plate (excess reactivity zero) obtaining an increase (net gain) of reactivity with the 32 plates inserted (about 295 pcm). Therefore, it was observed that the reflected nucleus became more reactive than the nucleus without reflective material. The theoretical analysis using MCNP-5 and ENDF/B-VII.0 nuclear data library showed the physical aspects of neutron absorption and reflection in the heavy reflector considered; however, it presented a discrepancy when fast neutron reflection dominates the physical phenomenon of neutron transport. In order to verify the impact of other models of thermal scattering of hydrogen in water for the computational simulations of the experiments, three models were considered, besides the one used by the ENDF/B-VII.0 library: ENDF/B-VII.0 scattering law; new evaluation of the S (alpha, beta) for hydrogen bound in water performed in Bariloche Atomic Center, Argentina; and the calculated with new released evaluations for (235)U, (238)U and (16)O.
Monte Carlo modeling of the new plate-type core for the Brazilian IPEN/MB-01 research reactor
2019 - JOÃO, THIAGO G.; SANTOS, DIOGO F. dos; ROSSI, PEDRO C.R.; SOUZA, GREGORIO S. de; SANTOS, ADIMIR dos
After 30 years of operation, the IPEN/MB-01 research reactor is about to receive a new plate-type core. This replacement is due to the Brazilian Multipurpose Reactor (RMB) needs, the largest project in nuclear engineering taking place in Brazil. The RMB will be a 30MW open pool-type research reactor, keeping the core in a 5x5 configuration (23 fuel elements, made of U3Si2-Al fuel plates, with 3.7 gU/cm3, 19.75% enriched in U-235 and two extra positions available for materials irradiation). The radioisotopes production, material irradiation, nuclear fuels structural testing and the development of scientific and technological research using neutron beams are the main targets of the RMB enterprise. In this way, in order to verify, experimentally, the calculation methods and data libraries used for the Brazilian Multipurpose Reactor design, reactor cell and mesh structures, control rods effectiveness, isothermal reactivity coefficients and core dynamics due to reactivity insertions, the IPEN/MB-01 new plate-type core is being implemented at the Nuclear and Energy Research Institute (IPEN/CNEN-SP), SP-Brazil. It´s a tank-type research reactor. The core has a 4×5 configuration, with 19 fuel elements (U3Si2-Al, 2.8gU/cm³ and 19.75% enriched in U-235), plus one aluminum block (internal irradiation position). As burnable poison, cadmium wires were used, once they are also employed at the RMB project to control the power density and the excess of reactivity during its operation. The core is reflected by four boxes of heavy water (D2O) and its maximum nominal power is 100W. Thereby, a Monte Carlo modeling was developed using the Monte Carlo N-Particle code (MCNP), along with NJOY, for processing the materials nuclear cross sections. This modeling for the IPEN/MB-01 new plate-type core is presented and some neutronic calculations were also depicted in this paper.
Subcritical boron experiments in the IPEN/MB-01 reactor
2019 - SANTOS, A. dos; SOUZA, G.S.; SANTOS, D.F.; ANDRADE, D.A.
Macroscopic (APSD and CPSD) and microscopic (Rossi-α) neutron noise experiments were performed in the IPEN/MB-01 reactor in order to measure subcritical reactivities. Subcritical states of up to around -6600 pcm were reached with insertion of boric acid (H3BO3) into the moderator tank. The subcritical kinetic model of Gandini and Salvatores was employed to infer the relative power between two consecutive subcritical cases, the subcritical reactivity (𝜌gen), and the subcriticality index (𝜁). This experimental methodology to measure these parameters was successfully employed in a previous experiment performed in the IPEN/MB-01 reactor. The measured subcritical reactivities are in good agreement for the APSD and Rossi-α cases. However, some drawbacks were found for the CPSD cases due to difficulties in the establishment of the cutoff frequency. The MCNP6.1 calculated subcritical reactivities were in a good agreement to APSD´s and Rossi-α measurement values. The ENDF/B-VII.0 nuclear data library was employed in all cases.
Procedimento para análise de propagação das incertezas nas massas de combustível do reator IPEN/MB-01 tipo placa
2018 - YAMAGUCHI, MITSUO; SANTOS, ADIMIR dos
Este relatório apresenta um procedimento para analisar a propagação das incertezas nas massas do combustível do reator IPEN/MB-01 tipo placa.
Procedimento para análise de propagação das incertezas nas massas de combustível do reator IPEN/MB-01 tipo placa
2018 - YAMAGUCHI, MITSUO; SANTOS, ADEMIR dos
Este relatório apresenta um procedimento para analisar a propagação das incertezas nas massas do combustível do reator IPEN/MB-01 tipo placa.
Procedimento para análise de propagação das incertezas nas massas de combustível do reator IPEN/MB-01 tipo placa
2018 - YAMAGUCHI, MITSUO; SANTOS, ADEMIR dos
Este relatório apresenta um procedimento para analisar a propagação das incertezas nas massas do combustível do reator IPEN/MB-01 tipo placa.
The experimental determination of the 238U(n,gamma) and total fission reaction rates along the pellet radius of the IPEN/MB-01 reactor
2017 - MURA, LUIS F.L.; SANTOS, ADIMIR dos; DOMINGOS, DOUGLAS B.; ROSSI, PEDRO C.R.; JEREZ, ROGERIO
This work presents a new experimental approach to determine experimentally the reaction rate along the pellet radius of a research reactor facility. The methodology employs concentric hollow cylindrical lead collimators together with gamma-ray spectrometry in a special kind of HPGe detector for the discrimination of very low gamma energy emitted by Np-239 and Mo-99. The U-238 neutron capture and total fission rates were inferred, respectively, from the 106.2 keV gamma emitted by Np-239 and from the 140.51 keV gamma-ray emitted by Mo-99. These lower gamma-ray energies allow the thickness of the lead collimator to be small enough so that the correction factors applied to the procedure were minimized. This kind somewhat challenging experiment was successfully performed at the IPEN/MB-01 research reactor facility. The experiments are claimed to be well-defined, and they are suitable for a benchmark. The measured values of the total fission rates are mainly due to the thermal fissions in U-235 since in the IPEN/MB-01 reactor nearly 85% of the total fissions occur in the thermal neutron energy region. The theoretical analyses were performed using MCNP-5 together with the ENDF/B-VII.o library. The analyses reveal a very good agreement between the calculated and experimental results for the U-238 epithermal neutron capture reaction rates. However, the same can not be said for the thermal reaction rates which show discrepancies both in magnitude as well as in the shape of the attenuation of the reaction rates inside of the fuel pellet. The suspected reason for these discrepancies is the shape of the U-235 cross sections below 0.3 eV which might be different from that adopted in the ENDF/B-VII.o library. (C) 2016 Elsevier Ltd. All rights reserved.