Kawaguchi Munemichi

• Doctor of Engineering
• Associate Professor at Hokkaido University

Sodium wetting experiments were performed to investigate the reactive wetting of metallic plating materials by liquid sodium at 250 C for the ultrasonic sensor of the under-sodium viewer. SUS304 stainless steel specimens were electrolytically plated with four metallic materials (nickel, palladium, gold, and indium) that have different solubilities...

For practical use of an under-sodium viewer, the behavior of sodium wetting is investigated by modeling the reactive and non-reactive wetting of metallic-plated steels by liquid sodium to simulate sodium wetting. The non-reactive wetting simulation results showed good agreement with Tanner's law, in which the time dependencies of the droplet radius...

A sodium–concrete reaction (SCR) is one of the important phenomena to cause the structural concrete ablation and the release of hydrogen (H2) gas in the sodium (Na) leak accident. In this study, the long-time SCR test had been carried out to investigate the self-termination mechanism under the condition to keep the temperature of Na on the concrete...

Fundamental experiments were carried out to investigate the self-termination behavior of sodium–concrete reaction (SCR). In the reference experiment, the reaction time was controlled to investigate the distribution change of Na and the reaction products in the pool and around the reaction front. The measured concentrations at the reaction front wer...

This study revealed melting behavior and thermal conductivity of four samples generated by sodium-concrete reaction (SCR). We prepared the samples using two methods such as firing mixtures of sodium (Na) and grinded concrete powder, and sampling depositions after the SCR experiments. In the former, the mixing ratios were determined from the past ex...

We performed thermodynamic and phase-field (PF) simulations to investigate micropore formation mechanisms in a pseudo-binary system, B2O3–UO2, during the solidification process. In the B2O3–UO2, a solid UO2 nucleation occurs in liquids below the melting point (Tm). As the temperature decreases further, a monotectic reaction (Liquid → S + Liquid#2)...

Two-types of phase-field (PF) calculations were developed to predict the crystallization of borides. The first calculation used an empirical PF mobility [Lexp = A(kBTΔT/6π²λ³η)B], which was determined from experimental crystal growth rates (vexp). The calculation results for various binary borides such as Li2O–2B2O3, Na2O–2B2O3, Na2O–4B2O3, K2O–4B2...

In the Fukushima Daiichi Nuclear Power Plant, a meltthrough severe accident happened in 2011. The fuel debris of various compositions, such as the core elements, the control rods, and the cladding tube, was solidified at the pressure vessel. Yusufu et al. made the simulated fuel debris of B2O3-UO2 and investigated the relationship between the micro...

We performed modeling of two- and three-dimensional phase-field methods (2D- and 3D-PFM) for crystal growth on the surface and in the volume of Na2O-2CaO-3SiO2 glass to investigate crystal growth behaviors under periodic temperature conditions. In this study, the periodic temperature conditions were set to 993 K for 180 s and 873 K for 252 s repeat...

Thermodynamic calculation of volatile radionuclides such as Cs, I and Te in a cladding failure accident of a sodium-cooled fast reactor has been conducted for the evaluation of an in-vessel source term. Important chemical reactions and chemical forms such as Cs, Cs2, Te, CsI, Cs2I2, Cs2Te, CsNa, NaI, Na2I2, Cs2Te, Na2Te, AgTe and Cs2MoO4 were sugge...

In a postulated accident of fuel pin failure of a sodium-cooled fast reactor, a fission product of cesium will be released from the failed pin as an aerosol such as cesium iodide and/or cesium oxide together with a fission product noble gas such as xenon and krypton. The xenon and krypton released with the cesium aerosols into the sodium coolant as...

A simple phase-field model (PFM) was used to calculate phase-field mobility, L, and crystal growth rates in crystallization of 11 oxides or mixed oxides in undercooled silicates, SiO2 and GeO2 liquids, and material dependence of the L was discussed to predict the temperature dependence of crystal growth-rates for unmeasured liquids. By comparing th...

In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released from the failed pin as an aerosol such as cesium iodide and/or cesium oxide together with a fission product noble gas such as xenon and krypton. As the result, the xenon and krypton released with cesium aerosol into the sodium coola...

In researches and developments (R&Ds) on sodium (Na) management technology, the experimental data related to a cold trap and a plugging meter have been accumulated in each country because the impurities such as sodium oxide (Na2O), sodium hydride (NaH) and/or sodium hydroxide (NaOH) in Na coolant accelerate the corrosion on the stainless-steel surf...

This study developed phase-field method (PFM) technique in oxide melt system by using a new mobility coefficient (L). The crystal growth rates (v0) obtained by the PFM calculation with the constant L were comparable to the thermodynamic driving force in normal growth model. The temperature dependence of the L was determined from the experimental cr...

In decommissioning sodium-cooled fast reactors, the operators can be exposed to radiation during dismantling of cold trap equipment (C/T). The C/T is higher dose equipment because the C/T trapped tritium of fission products during the operation to purify the sodium coolant. In this study, thermal decomposition temperature and rate of sodium hydride...

In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released from the failed pin as an aerosol such as cesium iodide and/or cesium oxide together with a fission product noble gas such as xenon and krypton. As the result, the xenon and krypton released with cesium aerosol into the sodium coola...

Sodium-concrete reaction (SCR) is one of the important phenomena during severe accidents in sodium-cooled fast reactors owing to the generation of large sources of hydrogen and aerosols in the containment vessel. In this study, SCR experiments with an internal heater were performed to investigate the chemical reaction beneath the internal heater (8...

Sodium-concrete reaction (SCR) is one of the important phenomena during severe accidents in sodium-cooled fast reactors (SFRs) owing to the generation of large sources of hydrogen and aerosols in the containment vessel [1–3]. In this study, SCR experiments were performed to investigate the chemical reaction beneath the internal heater (800 °C), whi...

Sodium (Na) has been used as the coolant of fast reactors for the various merits. On the other hand, it is postulated that steel liner may fail and lead to sodium-concrete reaction (SCR) during the Na-leak accident. Because of release of hydrogen gas due to the chemical reactions between Na and concrete components, SCR is one of the important pheno...

The CONTAIN-LMR code, which had been originally released from Sandia National Laboratories (SNL) in the U.S.A., has been developed in the Japan Atomic Energy Agency (JAEA) to evaluate ex-vessel severe accident progression in a liquid metal fast reactor (LMFR). As a part of several studies in JAEA, this paper mainly describes a state of the art of a...

A computer code, CONTAIN-LMR, is an integrated analysis tool to predict the consequence of severe accident in a liquid metal fast reactor. Because a sodium-concrete reaction behavior is one of the most important phenomena in the accident, a Sodium-Limestone Concrete Ablation Model (SLAM) has been developed and installed into the original CONTAIN co...

The experimental study on wetting behaviour between liquid sodium and various plated stainless steel has been conducted to improve the wetting between the sodium and the stainless steel. The wetting was estimated by spreading area of sodium which was dropped on the specimens and was improved drastically by plating with well-dissolved element in sod...

We have studied the Ce-cite substitution effect by R(¼ Pr, Nd) ion on the multipole interactions in CeB 6 . We found that T Q of Ce 0:9 Nd 0:1 B 6 in magnetic fields is higher than that of Ce 0:9 Pr 0:1 B 6 and the magnetization is larger in the former than in the latter. The larger suppression of T Q in Ce x Pr 1Àx B 6 suggests the larger reductio...

121;123 Sb nuclear quadrupole resonance (NQR) measurements have been performed for a polycrystal-line sample of Yb x Fe 4 Sb 12 with x % 0:89. Five well-separated NQR lines were observed above 18 K, which are explained by the quadrupole frequencies 121 Q ¼ 38:96 MHz, 123 Q ¼ 23:64 MHz, and the asymmetry parameter ¼ 0:37. The NQR lines broaden after...

We report the competition and coexistence between the Kondo effect and anisotropic gap induced by the antiferromagnetic ordering in CexNd1-xB6. Although the competition between the Kondo effect and superconducting gap have been reported extensively, such a competition in the antiferromagnetic Kondo compounds has been scarcely reported. The gap (Del...