[en] Impurity gases such as Ne, Ar, Kr, or Xe are injected to the main chamber of a fusion reactor to reduce the heat load to the divertor plate. Part of these noble gases are activated in the divertor area and can potentially be a risk of mobilization and release to the environment in case of an accident. This paper describes the assessment of the radioactive nuclides generated from the impurity gases. In the assessment, the neutron energy spectrum calculated from a three-dimensional MCNP-5 model is used to determine the induced radioactivity of the gases using a DCHAIN-SP code with the nuclear library FENDL/A-2. It is found that under practical irradiation condition, Ne and Ar can be used as impurity gases without a safety constraint. When using Kr, it is necessary to limit the irradiation time in the vacuum vessel, and/or take measures for radioactive decay by the recovery and storage of used activated gases. Xe is not recommended to use as an impurity gas for divertor radiative cooling because of toxic nuclides production. (author)

[en] Since June 2014, the Higashidori Nuclear Power Station had been taking the assessment of the on-site fault in the conformity assessment of the new regulatory standard. After that, although the assessment of the fault located directly under key facilities ended in 2018. We are taking an assessment of active fault examination considered as an epicenter at present. This document is a summary of the supplementary survey including geology survey such as reflection survey and boring exploration for active fault assessment that has been conducted since March of this year. (author)

[en] Pipe wall thinning is an aging process that has a significant effect on the safety and safe operation of power plants and its appropriate management is an issue common to all electric power companies. Tohoku Electric Power Co., Inc. has been putting an emphasis on pipe wall thickness management since 2006, when a through-hole possibly due to droplet-impact erosion was found in the vent piping of high-pressure feedwater heater No.2 at Onagawa Nuclear Power Station unit 2. Following this incident, extensive revisions were made to the pipe wall thickness management program and we have been making efforts to improve the efficiency of the management. This report addresses such issues. (author)

[en] With the rapid progress of the utilization of Information Technology (IT), IT infrastructure (network environment and information system) became crucial as a lifeline for promoting business. At the same time, changes in the circumstances surrounding the IT infrastructure globalize the threat of cyber attacks and increase the risk of the information security such as unlawful access to an information system, viral infection, an alteration of a website, disclosure of subtlety information, destruction of an information system and so on. Information security measure is an important issue in Japan Atomic Energy Agency (JAEA). In order to protect the information property of JAEA from the threat, Center for Computational Science and e-Systems (CCSE) has been taking triadic measures for information security: (1) to lay down a set of information security rules, (2) to introduce security equipments to backbone network and (3) to provide information security education. This report is a summary of the contents of the information security education by e-learning. (author)

[en] Air-conditioning duct is difficult to predict the date to occur of corrosion such as affect the function. Therefore, the current conservation method is mostly corrective maintenance. Therefore, we used the test pieces of six types and ACM-sensor in order to solve the corrosion speed from corrosion environment and relationship of corrosion quantity of test pieces. In addition, was used the duct molded articles various in order to check the corrosion degree of when processed the duct. As a result, we were selected crust body constituting a duct and optimal combination of the flange by solve the corrosion speed of the test pieces various. Thus, it performs preventive disposal before to occur of corrosion such as affect the function by predicting the duct life from corrosion speed, and lead to stability and safe operating by appropriate maintenance of equipment. (author)

[en] Electromagnetic acoustic transducer (EMAT) provides non-contacting measurements and is often applied to monitoring in high temperature environment. Electromagnetic acoustic resonance method (EMAR) is transmits an ultrasonic burst wave, and the driving frequency of bust wave is swept. Then signal amplitude of each frequency is computed by the superheterodyne processing at the interval. Pulse-EMAR method is transmits an ultrasonic pulse wave propagating, but the pulse wave is not swept. Then echo waves received is analyzed by Fast Fourier Transform. Finally, the superposition of the nth compression (SNC) for data processing is applied to evaluate wall thickness for two methods, In this study, the influence of bottom shapes is evaluated using EMAR method and Pulse-EMAR method. And therefore the specimens of three types which are with inclined bottom, R shape and scale-like shape are prepared. Influence of bottom shape appears as an attenuating of peak value of SNC, a widening of the full width at half maximum, and peaks of multiple. (author)

[en] Liquid droplet impediment erosion (LDI) is a pipe wall thinning phenomena that a droplet accelerated by steam flow attacks pipe surface. It is difficult to evaluate LDI behavior in the system of NPP. Therefore, in current pipe wall thinning management, the pipe element is replaced conservatively when it is recognized to become thinner by pipe wall thinning measurement result. If LDI behavior at each point of the system can be estimated, it is possible to measure the pipe wall thickness and replace the pipe element at an appropriate time. CRIEPI has constructed the evaluation system for LDI by using flow dynamics. In this paper, following items are described; /the applicability of the LDI evaluation system by a comparative verification between pipe wall thinning rate calculated by LDI system and that by actual measurement result / establishment of remaining life assessment method of pipe in LDI environment by using LDI model. (author)

[en] The 3-D structure of the high-speed liquid droplet-vapor two-phase pipe flow characteristics and LDI erosion behavior in a power plant is numerically predicted by integrated parallel CFD analysis. Governing equations of two-phase flow taking into account the condensed liquid-droplet generation, vapor-liquid phase change in conjunction with the coupled Euler-Lagrange dispersed two-fluid model were developed. Furthermore, data on such factors as the droplet impingement pressure, droplet diameter, and pipe thinning rate (erosion rate) by LDI which are difficult to confirm by experiment, were acquired. (author)

[en] The 3-D structure of the high-speed liquid droplet-vapor two-phase pipe flow characteristics and LDI erosion behavior in a power plant is numerically predicted by integrated parallel CFD analysis. Governing equations of two-phase flow taking into account the condensed liquid-droplet generation, vapor-liquid phase change in conjunction with the coupled Euler-Lagrange dispersed two-fluid model were developed. Furthermore, data on such factors as the droplet impingement pressure, droplet diameter, and pipe thinning rate (erosion rate) by LDI which are difficult to confirm by experiment, were acquired. (author)