H2-induced thermal treatment significantly influences the development of a high performance low-platinum core-shell PtNi/C alloyed oxygen reduction catalyst

In the purpose of maximizing the utilization of noble metal Pt in oxygen reduction catalysts, we illustrate a synthesis method of preparing the low-platinum PtNi/C alloyed oxygen reduction reaction (ORR) catalyst, which is developed through the H₂-induced treatment to a glucose reduced PtNi/C alloy. After post-treatment with H₂/N₂ mixture gases, this catalyst displays excellent ORR catalytic activity and durability for the synergetic influences of electronic and geometry effects on catalysts during the alloying. Specifically, the as-prepared PtNi/C (350°C-6 h) sample delivers preponderant ORR activity with only 53.5% Pt usage than the commercial Pt/C. The specific activity and mass activity are corresponding 7.49 times and 3.5 times to the commercial Pt/C. This catalyst exhibits excellent ORR catalytic activity after 10 000 potential cycles in acid, which benefits from the well alloyed core-shell structure of PtNi/C. H₂-induced thermal treatment has significant effects on the development of high performance low-platinum PtNi/C alloy catalyst, and plays the significant role in the formation of well-alloyed core-shell structures. The lowered d-band center is believed to facilitate ORR catalysis through weakening the adsorption of intermediate oxygen species on the alloyed Pt surface. Therefore, PtNi/C(350°C-6 h) alloyed catalyst possesses outstanding ORR catalytic activity with much lower Pt loading.     

Performance enhancement of biodiesel fueled SOFC using paper-structured catalyst

In this study, performance of solid oxide fuel cell (SOFC) connected with paper-structured catalyst (PSC) was evaluated in the direct feed of wet oleic fatty acid methyl ester (oleic-FAME, C₁₉H₃₆O₂), which is a mono-unsaturated component of practical biodiesel fuels (BDFs), in the steam to carbon ratio (S/C) range between 2.0 and 3.5, and high current density of 1 A cm⁻² (at 0.7 V) was recorded at 800 °C. Long term stability of oleic-FAME fueled SOFC was achieved by the incorporation of PSC into SOFC even under severe operating condition prone to coking (direct feed of unsaturated hydrocarbon with carbon number 19 and low S/C ratio of 2.0). After 100 h test, coking was not observed in both SOFC anode and PSC.     

Measurements of 131I in the thyroids of employees involved in the Fukushima Daiichi nuclear power station accident

The Great East Japan Earthquake Disaster on 11 March 2011 caused an unprecedented accident at the Fukushima Daiichi nuclear power station operated by Tokyo Electric Power Company (TEPCO). Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency performed internal dose measurements of 560 employees involved in the accident during the period from 20 April to 5 August in 2011 at the request of TEPCO. The present paper describes our measurements of ¹³¹I in the thyroid that is the predominant contributor to the internal dose. These measurements were carried out using an HPGe detector installed in a low-background shielded chamber made of 20-cm-thick steel and the detector was placed adjacent to the subject's neck. The typical minimum detectable activity of this technique was 10 Bq for a counting time of 10 min; however, this sensitivity made it difficult to identify a residual thyroid content of ¹³¹I corresponding to a committed effective dose of 20 mSv for late subjects. This paper discussed technical issues experienced through the measurements such as the influence of ¹³¹I in the rest of the body, the calibration phantom of use, and so on.     

Evaluation of liquefaction probability of earth-fill dam over next 50 years using geostatistical method based on CPT

A method for evaluating the liquefaction probability of an earth-fill dam over the next 50 years is presented through the use of a geostatistical method for the measured values from cone penetration tests (CPTs). In particular, this paper discusses a new procedure for evaluating the liquefaction probability based on CPTs. Although the fines content, F_c, and the N-value are required in the Japanese standards to evaluate the liquefaction risk, the number of test data is not enough for the statistical modeling. Herein, F_c and the N-value are derived directly from CPTs. The statistical modeling procedure for F_c and the N-value is the unique point of this study. Since CPTs can be conducted with short intervals, especially in the horizontal direction, the geostatistical parameters can be determined, and the geostatistical simulation method is applicable for evaluating the liquefaction probability. In addition, since the frequency of the seismic load at the studied site will affect the liquefaction probability, the seismic hazard should be evaluated properly. An illustrative example, assessing the liquefaction probability of an earth-fill dam in Japan, is presented to demonstrate the capability of the proposed method. Finally, the spatial average of the liquefaction probability of the dam over the next 50 years is calculated. The proposed procedure is confirmed to work well for actual design problems.     

Spontaneous phase and morphology transformations of anodized titania nanotubes induced by water at room temperature

We report a spontaneous phase transformation of titania nanotubes induced by water at room temperature, which enables the as-anodized amorphous nanotubes to be crystallized into anatase mesoporous nanowires without any other post-treatments. These mesoporous TiO(2) nanomaterials have a markedly improved surface area, about 5.5 times than that of the as-anodized TiO(2) nanotubes, resulting in a pronounced enhanced photocatalytic activity. The present approach not only allows a flexible control over the morphology of TiO(2) nanostructures but can fundamentally eliminate the need for high temperature operations for crystallizing amorphous TiO(2).     

Radiation protection at nuclear fuel cycle facilities

Radiation protection methodologies concerning individual monitoring, workplace monitoring and environmental monitoring in nuclear fuel facilities have been developed and applied to facilities in the Nuclear Fuel Cycle Engineering Laboratories (NCL) of Japan Atomic Energy Agency (JAEA) for over 40 y. External exposure to photon, beta ray and neutron and internal exposure to alpha emitter are important issues for radiation protection at these facilities. Monitoring of airborne and surface contamination by alpha and beta/photon emitters at workplace is also essential to avoid internal exposure. A critical accident alarm system developed by JAEA has been proved through application at the facilities for a long time. A centralised area monitoring system is effective for emergency situations. Air and liquid effluents from facilities are monitored by continuous monitors or sampling methods to comply with regulations. Effluent monitoring has been carried out for 40 y to assess the radiological impacts on the public and the environment due to plant operation.     

Experimental Study of the Relation Between Heat Transfer and Flow Behavior in a Single Microtube

The flow boiling heat transfer in microchannels have become important issue because it is extremely high-performance heat exchanger for electronic devices. For a detailed study on flow boiling heat transfer in a microtube, we have used a transparent heated microtube, which is coated with a thin gold film on its inner wall. The gold film is used as a resistance thermometer to directly evaluate the inner wall temperature averaged over the entire temperature measurement length. At the same time, the transparency of the film enables the observation of fluid behavior. Flow boiling experiments have been carried out using the microtube under the following conditions; mass velocity of 105 kg/m² s, tube diameter of 1 mm, heat flux in the range of 10 ~ 380 kW/m² s, and the test fluid used is ionized water. Under low heat flux conditions, the fluctuations in the inner wall temperature and mass velocity are closely related; the frequency of these fluctuations is the same. However, the fluctuations in the inner wall temperature and heat transfer coefficient are found to be independent of the fluctuation in the mass velocity under high heat flux conditions.     

Hydrogenated Hydroxy-Terminated Polyisoprene as a Fuel Binder for composite solid propellants

The synthesis and application of hydrogenated hydroxy-terminated polyisoprene (HHTPI) to a fuel binder of composite solid propellants were attempted. An HHTPI prepolymer was synthesized through the hydrogenation for the hydroxy-terminated polyisoprene (HTPI) in the presence of nickel and zirconium catalysts over kieselguhr in 2.0 MPa hydrogen and at 443 K – 453 K for 24h. A prepolymer of a number-averaged molecular weight 2500–3800, provided a viscosity level required for the use of a fuel binder from which solid propellant can be possibly made by means of direct casting method. Thermal stability and aging characteristics of HHTPI elastomer against environmental attacks are superior to those of HTPB. Some plasticizers and bonding agents can bring about the acceptable mechanical properties to the propellant grains mainly composed of HHTPI, ammonium perchlorate and aluminium powder. The linear burning rates of HHTPI-based propellants are at the same level with that of HTPB-based propellants. However, the composition that gives the maximum performance with HHTPI-based propellants, shifts to 1–2 wt% fuel-rich side from the most adequate fuel content 12 wt% in HTPB/AP/Al. The HHPTI propellants indicated the similar burning rate as HTPB-based propellants in the linear burning rates in spite of the comparatively poor ignitability. Nevertheless, the static tests of 100 mm dia. sounding rocket motors are successfully performed by an ignition operation at the pressurized condition. The ballistic performances are not inferior to those of the HTPB-based propellants.