Seismic loads for crack stability assessment, in a review of leak-before-break (LBB) applicability

This study was performed to define the seismic loading conditions for use in the crack stability assessment of a BWR for the applicability of the leak-before-break (LBB) criterion. The LBB has been applied to the design of Class 1 piping in Japanese light-water reactors. Crack penetrated condition with detectable leak in the LBB applicability review is classified into the Level C service condition. Here an S₁-earthquake (maximum design earthquake) is currently assumed, rather than an S₂-earthquake (extreme design earthquake). In order to justify this assumption, the frequency of an S₁-earthquake occurring during coolant leakage due to crack propagation was determined. The frequency of coolant leakage from Class 1 piping must be less than that of the Level C service condition (2.5 × 10⁻² to 1 × 10⁻⁴ per year) in order to assume that an S₁-earthquake is appropriate. Accordingly, the frequency of coolant leakage from Class 1 piping was calculated using a probabilistic fracture mechanics (PFM). The results of this analysis indicate that the frequency of coolant leakage from Class 1 piping is less than the expected occurrence of an S₁-earthquake. As the results, it is concluded that the assumption of the seismic loading employed in an LBB applicability review should be appropriate.     

Hollow cathode atomic source applicable to gas,liquid residue,and solid sample phases

ABSTRACT

We have developed a compact DC-glow discharge hollow cathode atomic source without requiring extensive chemical pretreatment. This system is intended for laser absorption spectroscopy to function as the source of neutral atoms. Our investigative focus is on elements found in nuclear power related environments, particularly in the context of Fukushima Daiichi decommissioning. The elements constituting the samples are identified through investigating the emission produced by the relaxation of the sample atoms after being sputtered by Ne and Ar discharge. The emission spectrum was observed in pure substances and also compounds related to materials such as stainless steel, control material, cladding material, seawater, and concrete, which are expected to constitute the majority of radioactive wastes. In particular, brass and salt, compounds consisting of two elements, were sputtered to produce single atoms of each element. With a copper pipe as an example, the emission efficiency was also investigated, through which the optimal experimental conditions for sputtering were identified. It was found that sputtering would be likely to cause a reduction in pressure, and that emission intensity is related to the electronic temperature during discharge. In addition, this system is not restricted by sample shape or electronic conductivity, with only minor pretreatment.     

Formation of BCC TiFe hydride under high hydrogen pressure

We investigated the hydrogenation of a binary TiFe alloy at 5 GPa and 600 °C by in situ synchrotron radiation X-ray diffraction measurements. After formation of a solid solution of hydrogen in TiFe, an order–disorder phase transition in the metal lattice of TiFe occurred, which yielded a BCC TiFe hydride. The unit cell volume of the BCC hydride increased by 21.0% after the hydrogenation reaction. The volume expansion was larger than that of a γ-hydride TiFeH_1.9 prepared by hydrogenation near ambient conditions.     

Superconductivity of ternary rare-earth compounds

A theoretical discussion of ternary rare-earth compounds which enter the superconducting state at a temperature T _c 1, then ferromagnetically order at T _M < T _c1,is given. The local moments of the rare-earth elements couple to the superconducting electrons so that as T _M is approached from above, the growth of spin fluctuations suppresses the superconductivity, then completely destroys it at T _c2(>T _M ).Expressions for the phase diagram, several thermodynamic quantities, the upper critical field, and the dilution effect are derived.This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Science Division.     

外加横向磁场下Bridgman法生长HgCdTe晶体的实验研究

介绍了自行研制的可以施加横向磁场中的垂直Ｂｒｉｄｇｍａｎ法晶体生长装置，该装置磁场强度可在０－０．６Ｔ范围内连续调节，生长区温度梯度达４０－７０℃／ｃｍ，不同磁场强度下进行了ＨｇＣｄＴｅ晶体生长实验，通过测量分析， 轴赂和径向组分分布的变化与磁场的关系，实验结果表明，由于磁场对熔体中热对流以的作用，尤其是横向磁场怀流甩的相互作用，在一定程度上改变生长界面的形状，从而改善ＨｇＣｄＴｅ晶体径向组分分布     

An XOR‐based parameterization for instruction register files

The instruction register file (IRF) shortens and obfuscates instruction sequences by compressing multiple instructions into a packed instruction. The IRF could improve its efficiency by parameterization, but the previously proposed parameterization techniques did not extract the similarity of instructions well. In this paper, we propose an XOR‐based parameterization to utilize the limited capacity of the IRF more efficiently. According to our evaluation, with an improved algorithm of instruction selection, our approach makes 20.2% more dynamic instructions IRF‐resident than the previous techniques. It also reduces the number of instruction fetches from the cache by 6.3% on average. We also confirmed that the hardware overhead of our parameterization was about a quarter of the previous one. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.