Detailed analyses of key phenomena in core disruptive accidents of sodium-cooled fast reactors by the COMPASS code

A five-year research project has been initiated in 2005 to develop a code based on the MPS (Moving Particle Semi-implicit) method for detailed analysis of key phenomena in core disruptive accidents (CDAs) of sodium-cooled fast reactors (SFRs). The code is named COMPASS (Computer Code with Moving Particle Semi-implicit for Reactor Safety Analysis). The key phenomena include (1) fuel pin failure and disruption, (2) molten pool boiling, (3) melt freezing and blockage formation, (4) duct wall failure, (5) low-energy disruptive core motion, (6) debris-bed coolability, and (7) metal–fuel pin failure. Validation study of COMPASS is progressing for these key phenomena. In this paper, recent COMPASS results of detailed analyses for the several key phenomena are summarized. Simulations of GEYSER and THEFIS experiments were performed for dispersion and freezing behaviors of molten materials in narrow flow channels. In particular, the latter experiment using melt–solid mixture is also related to fundamental behavior of low energy disruptive core. CABRI-TPA2 experiment was simulated for boiling behavior of molten core pool. Expected mechanism of heat transfer between molten fuel and steel mixture was reproduced by the simulation. Analyses of structural dynamics using elastoplastic mechanics and fracture criteria were performed for SCARABEE BE+3 and CABRI E7 experiments. These two analyses are especially focused on thermal and mechanical failure of steel duct wall and fuel pin, respectively. The present results demonstrate COMPASS will be useful to understand and clarify the key phenomena of CDAs in SFRs in details.     

Pd-SiO2复合膜的氢气选择渗透特性

Palladium membranes were prepared on an a-alumina support by metal-organic compound chemical vapor deposition (MOCVD) method from palladium(Ⅲ) acetate precursor. Permeation properties of hydrogen and helium gas were studied as a function of the number of times of deposition of palladium on the peeling off phenomenon of palladium, which is common in electroless plated membrane, was observed. Silica was introduced into the pores to prevent the palladium grain from peeling off. The palladium-silica conjugated membrane does not show the peeling off phenomenon and can withstand the high temperature up to 800℃ which is the upper limit of our apparatus.The separation factor for hydrogen gas over carbon dioxide gas was improved with the increase of number of times of silica coating by sacrificing the H2 permeation and finally increased to four times. The improvement on the separation of hydrogen gas over carbon dioxide for pulladium-silica conjugated membrane was evaluated and a model of permeation pattern (palladium and silica) was proposed. This model suggests that the separation factor for hydrogen over carbon dioxide could be improved by introducing silica layer because the silica layer fills the pores and reduces the gas permeation without sacrificing the hydrogen permeation through the palladium region. These results indicate that the introduction of silica into the palladium grain is a promising means to improve the hydrogen separation performance of palladium based composite membranes.     

Fabrication of fluorinated polymer nanosheets using the Langmuir–Blodgett technique: characterization of their surface properties and applications

This review describes the bottom‐up design of ultra‐thin fluorinated polymer films. Fluorinated polymer assemblies offer unique and application‐oriented properties strongly correlated with surface chemistry. We focus on our recent topic of research, fluorinated polymer nanosheets, which are ultra‐thin polymer films fabricated from amphiphilic fluorinated polyalkylacrylamides using the elegant Langmuir–Blodgett technique. These fluorinated polymer nanosheets have excellent hydrophobicity, extremely low surface energy and a low friction coefficient. Therefore, fluorinated polymer nanosheets are attractive nanomaterials for surface modification in terms of tailoring of wettability, frictional properties, adhesion and surface chemistry. The nanocoating technique using reactive fluorinated polymer nanosheets and surface modification of hard disks and microchannels are also reviewed. Copyright © 2010 Society of Chemical Industry     

Comparison of performance between benzoindoline and indoline dyes in zinc oxide dye-sensitized solar cell

The cell performance of novel benzoindoline dyes on zinc oxide prepared by template cathode electro-deposition method was compared with that of known indoline dyes. Among cyanoacrylic, single and double rhodanine acetic acid derivatives, the cyanoacrylic benzoindoline dye showed better performance than the indoline dye (D131) due to larger J_sc value which comes from its positive E_ox level and bathochromic UV-vis absorption band.     

Unique structural features and electrical properties of electrospun conjugated polymer poly(3-hexylthiophene) (P3HT) fibers

This study examines and compares the internal structure conjugated polymeric fibers fabricated by electrospinning with cast films. Despite rigidity of polymer chain and the inability of its molecular chains to entangle to form viscoelastic jets, regioregular poly(hexyl-3-thiophene) (P3HT) exhibited the remarkable capability to be electrospun when the solution was subjected to gelation. In order to investigate the influence of additional mechanical stretching on the fibers, P3HT was electrospun with the aid of a rotating disc collector. Structure of electrospun fibers was probed via characterization techniques such as differential scanning calorimetry (DSC), Fourier transform infrared and photoluminescence (PL) spectroscopies. The findings indicated internal structural modifications developed within P3HT fibers, as a consequence of additional mechanical stretching induced by the rotating collector. Polarized FTIR and PL spectroscopies suggested that the molecular chains were aligned along the fiber axis. Electrical conductivity of iodine doped P3HT electrospun fibers was between 3 × 10³ S/m and 6 × 10³ S/m.     

Surface texture effect on scratch behavior of injection molded plastics

The influence of surface texture pattern, i.e. distance between spherical bumps on the scratch behavior of injection molded polypropylene and polycarbonate has been investigated using a progressive load scratch test according to ISO 19252. The results show that the scratch properties can be enhanced when the distance between spherical bumps decreased. To understand the influence of distance between spherical bumps, polarizing optical microscope was used to observe the subsurface deformation. It was found that the size and depth of the deformation zone become smaller and shallower when the distance between spherical bumps decreased. This is the evidence that less stress concentration was generated under a scratch tip when the distance became shorter. POLYM. ENG. SCI., 52:1862–1867, 2012. © 2012 Society of Plastics Engineers     

Novel drill bit with characteristic web shape for high efficiency and accuracy

This study proposes a novel drill design to reduce the cutting force and improve finished material surfaces. Drilling is a common procedure in manufacturing, and there is an increased demand to shorten the tact time by reducing the cutting force, and by prolonging the tool’s life. In this study, a new web shape was proposed based on the proposition to implement an additional cutting edge, complemented by experimental work. The results indicated that the cutting force decreased by more than 20%, and the circularity of the drilled holes was also improved.