[en] A Steam Generator Tube Rupture (SGTR) accident with total loss of High-Pressure Safety Injection (HPSI) is one of the beyond Design Bases Accidents (DBAs). In most Probabilistic Safety Assessments (PSAs), this accident was considered as a core damage sequence without additional operations actions to prevent core damage. Primary background of this estimation was based on the simple fact that this sequence was a beyond DBA. From the major view-point of DBA, a main purpose of SGTR accident analysis estimates whether the amount of radioactive materials to be released to the environment satisfies a design limitation. On the other hand, from the viewpoint of PSA, especially level 1 PSA, a main purpose of it estimates whether this sequence results in core damage. Because PSA should consider all risk factors including severe accident risk, the release amount of radioactive materials suggested in the design limitation of DBA is considerably less than that treated in PSA. This accident regarded as a core damage sequence because of a beyond DBA resulted in conservative estimation. Therefore, we need to identify whether this accident sequence is spontaneously reached in core damage or not. The present study primarily focused on the understanding of thermal hydraulic behavior of this sequence in order to establish realistic bases of PSA. A thermal hydraulic analysis of a SGTR without HPSI sequence has been performed using MARS2.1 thermal hydraulic code. The analysis was applied to Ulchin units 3 and 4 that was one of the Korea Standard Nuclear Power plants (KSNPs). Single-tube guillotine break at hot-leg side in a steam generator during full power operation was assumed. We also assumed that Reactor Coolant System (RCS)'s coolant charging system and Auxiliary Feedwater system (AFW) were available and no operators' actions were considered. The result of the analysis showed that no core damage was occurred during 24 hours and RCS maintained a high-pressure state. This result means that operators should perform additional actions in order to achieve a safe plant state. We identified that the previous estimation of the accident sequence was more conservative than result from the present study. However, to obtain a precise estimation of the sequence, it is necessary that additional thermal hydraulic analyses have to be performed. We expect that our tentative effort assists an improvement of the current PSA models

[en] Highlights: • Loop thermosyphon was used in the heat dissipation of concentrating solar cells. • The heat transfer effect of acetone thermosyphon is the best. • The fin structure was optimized by the method of numerical calculation. • The influencing factors were analyzed by orthogonal analysis. - Abstract: The loop thermosyphon was used in the heat dissipation of concentrating solar cells, to solve the problem of the high temperature of solar cells and their low efficiency. In this paper, a loop thermosyphon heat exchanger was designed and the effect of working fluid on heat transfer performance of loop thermosyphon was studied through experiments and the best working fluid was selected. The results show that the heat transfer effect of acetone as the working medium is better than that of water and ethanol. Acetone loop thermosyphon can be used for 7 times concentrating photovoltaic cells cooling, while the ethanol loop thermosyphon can be used for 3 times and the water loop thermosyphon only used for 1 time. The heat transfer characteristics of the fin with natural convection were studied by numerical calculation, and the fin structure was optimized. The influencing factors were analyzed by orthogonal analysis.

[en] Fe₃Al composite materials with 40, 60 and 80 wt.% Fe₃AlC_0.5 were fabricated by self-propagating high temperature synthesis (SHS) casting processing and analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microhardness, bending strength and wear rate of the composites were measured. The materials mainly consisted of Fe₃Al and Fe₃AlC_0.5 phases. The adherence of the reinforcement and the matrix was good. There were no cracks at the interface of the phases in the materials. Hardness of the composites increased with Fe₃AlC_0.5 fraction. Bending strength of the composites was high and that of the composite with 60 wt.% Fe₃AlC_0.5 was the highest. Wear rates of the composites were low and those of the composites with 60 and 80 wt.% Fe₃AlC_0.5 were lower than that of the composite with 40 wt.% Fe₃AlC_0.5

[en] Proteomic analysis, which combines two-dimensional electrophoresis (2-DE) and mass spectrometry (MS), is an important approach to screen proteins responsive to specific stimuli. Benzo[a]pyrene (B[a]P), a prototype of polycyclic hydrocarbons (PAHs), is a potent procarcinogen generated from the combustion of fossil fuel and cigarette smoke. To further probe the molecular mechanism of mutagenesis and carcinogenesis, and to find potential molecular markers involved in cellular responses to B[a]P exposure, we performed proteomic analysis of whole cellular proteins in human amnion epithelial cells after B[a]P-treatment. Image visualization and statistical analysis indicated that more than 40 proteins showed significant changes following B[a]P-treatment (P<0.05). Among them, 20 proteins existed only in the control groups, while six were only present in B[a]P-treated cells. In addition, the expression of 10 proteins increased whereas 11 decreased after B[a]P-treatment. These proteins were subjected to in-gel tryptic digestion followed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) analysis. Using peptide mass fingerprinting (PMF) to search the nrNCBI database, we identified 22 proteins. Most of these proteins have unknown functions and have not been previously connected to a response to B[a]P exposure. To further annotate the characteristics of these proteins, GOblet analysis was carried out and results indicated that they were involved in multiple biological processes including regulation of transcription, cell proliferation, cell aging and other processes. However, expression changes were noted in a number of transcription regulators, including eight zinc finger proteins as well as SNF2L1 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 1), which is closely linked to the chromatin remodeling process. These data may provide new clues to further understand the implication of these proteins in cellular responses to carcinogen exposure as well as the molecular mechanisms of B[a]P-induced mutagenesis and carcinogenesis

[en] Ultrathin Gd metal was evaporated on GaAs surface covered with native oxides. X-Ray photoelectron spectroscopic studies revealed that GaAs-native oxides could be reduced during the deposition of Gd metal. However, the elemental forms of Ga and As were not observed but the oxidation of Gd metal was confirmed from LMM Auger electron spectra, Gd 3d _5/2, and O 1s photoelectron spectra. The Gd coated GaAs substrates were heated at 400 deg. C and Gd₂O₃ films were successively deposited with a well developed crystalline state. This reductive metal deposition prior to oxide formation improved interfacial quality of GaAs without previous chemical etching or passivation. Capacitance-voltage (C-V) measurements at 1 MHz indicated that a good interfacial state between Gd₂O₃ and GaAs could be obtained appropriate for metal-oxide-semiconductor (MOS) applications through a two step deposition of Gd and Gd₂O₃

[en] The joint strength and fracture surfaces of Sn-37 mass% Pb and Au stud bumps for photo diode packages after isothermal aging testing were studied experimentally. Al/Au stud bumps and Cu/Sn-37 mass% Pb solders were adopted, and aged for up to 900 h to analyze the effect of intermetallic compound (IMC). The joint strength decreased with aging time. The diffraction patterns of Cu₆Sn₅, scallop-shaped IMCs, and planar-shaped Cu₃Sn were characterized using transmission electron microscopy (TEM). The formation of Kirkendall voids and the growth of IMCs at the solder were found to be a possible mechanism for joint strength reduction

[en] A WIMP-model-independent method is used to examine the existing evidence for low mass dark matter. Using XENON100's recent result of 224.6 live days × 34 kg exposure and PICASSO's result that was published in 2012, we have obtained constraints on the couplings |a_n| < 0.4 and |a_p| < 0.3, corresponding to spin-dependent cross-sections of σ_n<2.5×10"-"3"8 cm and σp<1.4×10"-"3"8 cm"2 for a WIMP mass of 10 GeV/c"2. It is shown that the spin-independent isospin-violating dark matter model also fails to reconcile the recent result from XENON100 with the positive results from DAMA, CoGeNT and CDMS-Ⅱ. (authors)

[en] Variance-based sensitivity analysis has been widely studied and asserted itself among practitioners. Monte Carlo simulation methods are well developed in the calculation of variance-based sensitivity indices but they do not make full use of each model run. Recently, several works mentioned a scatter-plot partitioning method to estimate the variance-based sensitivity indices from given data, where a single bunch of samples is sufficient to estimate all the sensitivity indices. This paper focuses on the space-partition method in the estimation of variance-based sensitivity indices, and its convergence and other performances are investigated. Since the method heavily depends on the partition scheme, the influence of the partition scheme is discussed and the optimal partition scheme is proposed based on the minimized estimator's variance. A decomposition and integration procedure is proposed to improve the estimation quality for higher order sensitivity indices. The proposed space-partition method is compared with the more traditional method and test cases show that it outperforms the traditional one

[en] The main experience of establishment and operation for Dongfang boiler group Co LTD's nuclear power equipment quality assurance system, and the several fields will be strengthened are introduced

[en] Alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) induces cellular stress leading to chromosomal aberrations, mutations and cell death. Previous reports from our laboratory have shown that low concentration of MNNG induces untargeted mutation (UTM), which occurs on intact DNA in mammalian cells through changes in gene expression profile. It also causes the activation of cAMP-protein kinase A (PKA) and up-regulation of POL-β, which is demonstrated to play a role in DNA repair system. In order to find out the possible initial signal involved in UTM, we try to investigate whether the activation of PKA-CREB signal pathway is closely related to DNA damage. Our data shows that the treatment of low concentration MNNG (0.2 μM) activates PKA-CREB pathway in a comparable level both in a nuclear and enucleated cell system. And similar to the cell response caused by UV, the clustering of cell surface receptors of epidermal growth factor (EGF) and tumor necrosis factor α (TNFα) was also observed in cells exposed to MNNG. It was further demonstrated that the clustering of the surface receptors is independent of the genomic DNA damage, as this phenomenon was also observed in enucleated cells. These observations indicate that the initiation of signal cascades induced by low concentration of MNNG might be associated with its interaction with cell surface receptors and/or direct activation of related signal proteins but not its DNA damaging property