MITSUO YAMAGUCHI
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Artigo IPEN-doc 26783 New plate-type core of the IPEN/MB-01 research reactor facility for validation of RMB project2020 - SANTOS, ADIMIR dos; YAMAGUCHI, MITSUO; FANARO, LEDA C.C.B.; SANTOS, DIOGO F. dos; SOUZA, GREGORIO S. de; JUNQUEIRA, FERNANDO de C.; SILVA, GRACIETE S. de A. e; BELCHIOR JUNIOR, ANTONIO; PRADO, ADELK de C.; JOAO, THIAGO G.; ROSSI, PEDRO C.R.The IPEN/MB-01 research reactor had its first criticality in November 1988 and, ever since, has been of major importance in Brazilian reactor physics researches, achieving international level for experiments comparison and validation (benchmarks). In this facility it is possible to build many different core configurations (i.e., rectangular, square and cylindrical), once versatility and flexibility were both taken into account on its initial project. The core is a fissile material assembly, inserted in a water tank, where the chain reaction is self-maintained and controlled at low power levels, so that, in normal operation, the feedback effects of temperatures are negligible. The core is intended for neutrons simulation of light water moderated reactors allowing the experimental verification of the calculation methods, reactor cell and mesh structures, control rods effectiveness, isothermal reactivity coefficients and core dynamics due to reactivity insertions. The first standard IPEN/MB-01 core had UO2 rod-type fuel, 4.3 % enriched in U-235 and using B4C and Ag-In-Cd rods for safety and control of the reactor. The facility is located at IPEN/CNEN-SP (Nuclear and Energy Research Institute), in Sao Paulo - Brazil. Within the scope of the new research reactor project, the Brazilian Multipurpose Reactor (RMB), it was designed a new critical configuration for the IPEN/MB-01. After thirty years of work, the rod-type fuels were replaced by plate-type fuels, in order to validate the RMB calculation methodologies, as well as the nuclear data libraries used. The RMB is an open pool-type reactor with maximum power of 30 MW, being the core a 5x5 configuration, consisting of 23 fuel elements, made of U3Si2-Al, having a medium density of 3.7 gU/cm3 and 19.75% enriched in U-235, and two positions available in the core for materials irradiation devices. The production of radioisotopes, silicon doping, neutron activation analysis, nuclear fuels and structural materials testing and the development of scientific and technological research using neutron beams are the main targets of the RMB enterprise. The new IPEN/MB-01 core has a 4×5 configuration, having 19 fuel elements, consisting of U3Si2-Al, 2.8 gU/cm³ and 19.75% enriched in U-235, plus one aluminum block. The IPEN/MB-01 new plate-type fuel assembly uses Cadmium wires as burnable poison, as the one used in RMB core for controlling the core power density and excess of reactivity during its operation. The core is also reflected by 4 boxes of heavy water (D2O), inserted in a moderator tank of light water. The maximum nominal power is 100 W and, for a safe operation, the critical assembly has both safety and auxiliaries’ systems. This paper presents a description of the new core and the principal neutronic parameters. The new core of the IPEN/MB-01 will be certainly a world class benchmark core for the core physics calculation of research reactors.Artigo IPEN-doc 24804 Thermal hydraulic analysis improvement for the IEA-R1 research reactor and fuel assembly design modification2018 - UMBEHAUN, PEDRO E.; TORRES, WALMIR M.; SOUZA, JOSE A.B.; YAMAGUCHI, MITSUO; SILVA, ANTONIO T. e; MESQUITA, ROBERTO N. de; SCURO, NIKOLAS L.; ANDRADE, DELVONEI A. deThis paper presents the sequence of activities to improve the thermal hydraulic analysis of the IEA-R1 research reactor to operate in safe conditions after power upgrade from 2 to 5 MW and core size reduction from 30 to 24 fuel assemblies. A realistic analysis needs the knowledge of the actual operation conditions (heat flow, flow rates) beyond the geometric data and the uncertainties associated with manufacturing and measures. A dummy fuel assembly was designed and constructed to measure the actual flow rate through the core fuel assemblies and its pressure drop. First results showed that the flow distribution over the core is nearly uniform. Nevertheless, the values are below than the calculated ones and the core bypass flow rate is greater than those estimated previously. Based on this, several activities were performed to identify and reduce the bypass flow, such as reduction of the flow rate through the sample irradiators, closing some unnecessary secondary holes on the matrix plate, improvement in the primary flow rate system and better fit of the core components on the matrix plate. A sub-aquatic visual system was used as an important tool to detect some bypass flow path. After these modifications, the fuel assemblies flow rate increased about 13%. Additional tests using the dummy fuel assembly were carried out to measure the internal flow distribution among the rectangular channels. The results showed that the flow rate through the outer channels is 10% - 15% lower than the internal ones. The flow rate in the channel formed between two adjacent fuel assemblies is an estimated parameter and it is difficult to measure because this is an open channel. A new thermal hydraulic analysis of the outermost plates of the fuel assemblies takes into account all this information. Then, a fuel design modification was proposed with the reduction of 50% in the uranium quantity in the outermost fuel plates. In order to avoid the oxidation of the outermost plates by high temperature, low flow rate, a reduction of 50% in the uranium density in the same ones was shown to be adequate to solve the problem.Artigo IPEN-doc 21604 Neutronic analysis of a U-Mo-Al fuel and europium as burnable poison2016 - MUNIZ, RAFAEL O.R.; SANTOS, ADIMIR dos; YAMAGUCHI, MITSUO; ROSSI, PEDRO C.R.; DOMINGOS, DOUGLAS B.; MURA, LUIS F.; TEIXEIRA e SILVA, ANTONIOCapítulo IPEN-doc 10982 Critical loading configurations of the IPEN/MB-01 reactor with a central cruciform rod2005 - SANTOS, A.; ANDRADE e SILVA, G.S.; FANARO, L.C.C.B.; YAMAGUCHI, M.; JEREZ, R.; ABE, A.Y.; FUGA, R.; SIQUEIRA, P.T.D.Capítulo IPEN-doc 15546 Reactor physics experiments in the IPEN/MB-01 research reactor facility2010 - SANTOS, ADIMIR dos; ANDRADE e SILVA, G.S.D.; FANARO, LEDA C.C.B.; YAMAGUCHI, MITSUO; JEREZ, ROGERIO; DINIZ, RICARDO; MENDONCA, ARLINDO G.; ABE, ALFREDO Y.Capítulo IPEN-doc 15610 Reactor physics experiments in the IPEN/MB-01 research reactor facility2009 - SANTOS, ADIMIR dos; ANDRADE e SILVA, G.S.D.; FANARO, LEDA C.C.B.; YAMAGUCHI, MITSUO; MENDONCA, ARLINDO G.; CARNEIRO, ALVARO L.G.; JEREZ, ROGERIO; DINIZ, RICARDOCapítulo IPEN-doc 15609 Critical Loading configurations of the IPEN/MB-01 reactor with UOsub(2) and UOsub(2)-Gdsub(2)Osub(3) rods2009 - SANTOS, ADIMIR dos; ANDRADE e SILVA, G.S.D.; FANARO, LEDA C.C.B.; YAMAGUCHI, MITSUO; JEREZ, ROGERIO; FUGA, RINALDOCapítulo IPEN-doc 14657 Reactor physics experiments in the IPEN/MB-01 research reactor facility IPEN(MB01)-LWR-RESR-001 CRIT-COEF-KIN2006 - SANTOS, ADIMIR dos; ANDRADE e SILVA, G.S.D.; FANARO, LEDA C.C.B.; YAMAGUCHI, MITSUO; JEREZ, ROGERIO; DINIZ, RICARDO; KURAMOTO, RENATO Y.R.Capítulo IPEN-doc 13926 Reactor physics experiments in the IPEN/MB-01 research reactor facility IPEN(MB01)-LWR-RESR-001 CRIT-COEF-KIN2008 - SANTOS, ADIMIR dos; ANDRADE e SILVA, G.S.D.; FANARO, LEDA C.C.B.; YAMAGUCHI, MITSUO; JEREZ, ROGERIO; DINIZ, RICARDO; KURAMOTO, RENATO Y.R.Capítulo IPEN-doc 13927 Critical loading configurations of the IPEN/MB-01 reactor with UOsub(2), stainless and copper roads LEU-COMP-THERM-0442008 - SANTOS, ADIMIR dos; ANDRADE e SILVA, G.S.D.; FANARO, LEDA C.C.B.; YAMAGUCHI, MITSUO; JEREZ, ROGERIO; ABE, ALFREDO Y.; FUGA, RINALDO