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The current status and the progress of R&D activities for a Fusion DEMO reactor in the QST Rokkasho Fusion Institute is reported. In order to advance the JA DEMO activity, not only Japanese domestic activity but also international collaborations of Broader Approach Activity and ITER related activities are conducted in the QST Rokkasho Fusion Institute. Activities for DEMO design and relevant R&D, design of a fusion neutron source and development of an accelerator, ITER-TBS, tritium handling technology and information technology infrastructures including a supercomputer system and a remote experimentation system are carried out for a Fusion DEMO reactor.

We present long-term density trends of the Earth's upper atmosphere at altitudes between 71 and 116 km, based on atmospheric occultations of the Crab Nebula observed with X-ray astronomy satellites, ASCA, RXTE, Suzaku, NuSTAR, and Hitomi. The combination of the five satellites provides a time period of 28 years from 1994 to 2022. To suppress seasonal and latitudinal variations, we concentrate on the data taken in autumn (49 < doy < 111) and spring (235 < doy < 297) in the northern hemisphere with latitudes of 0°–40°. With this constraint, local times are automatically limited either around noon or midnight. We obtain four sets (two seasons × two local times) of density trends at each altitude layer. We take into account variations due to a linear trend and the 11-year solar cycle using linear regression techniques. Because we do not see significant differences among the four trends, we combine them to provide a single vertical profile of trend slopes. We find a negative density trend of roughly −5%/decade at every altitude. This is in reasonable agreement with inferences from settling rate of the upper atmosphere. In the 100–110-km altitude, we found an exceptionally high density decline of about −12%/decade. This peak may be the first observational evidence for strong cooling due to water vapor and ozone near 110 km, which was first identified in a numerical simulation by Akmaev et al. (2006, https://doi.org/10.1016/j.jastp.2006.03.008). Further observations and numerical simulations with suitable input parameters are needed to establish this feature., 地球温暖化に伴う超高層大気の収縮をX線天文衛星で解明 --逆転の発想！捨てられた天体観測データを大気観測に転用--. 京都大学プレスリリース. 2023-02-24.

We report on the discovery of a new supergiant fast X-ray transient (SFXT), MAXI J0709$-$159, and its identification with LY CMa (also known as HD 54786). On 2022 January 25, a new flaring X-ray object named MAXI J0709$-$159, was detected by Monitor of All-sky X-ray Image (MAXI). Two flaring activities were observed in the two scans of $\sim 3$ hours apart, where the 2-10 keV flux reached $5\times 10^{-9}$ erg cm$^{-2}$ s$^{-1}$. During the period, the source exhibited a large spectral change suggesting that the absorption column density $N_\mathrm{H}$ increased from $10^{22}$ cm$^{-2}$ to $10^{23}$ cm$^{-2}$. NuSTAR follow-up observation on January 29 identified a new X-ray source with a flux of $6\times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$ at the position consistent with LY CMa, which has been identified as B supergiant as well as Be star, located at the 3 kpc distance. The observed X-ray activity characterized by the short ($\lesssim$ several hours) duration, the rapid ($\lesssim$ a few seconds) variabilities accompanied with spectral changes, and the large luminosity swing ($10^{32}$-$10^{37}$ erg s$^{-1}$) agree with those of SFXT. On the other hand, optical spectroscopic observations of LY CMa revealed a broad $H\alpha$ emission line, which may indicate the existence of a Be circumstellar disk. These obtained results suggest that the optical companion, LY CMa, certainly has a complex circumstellar medium including dense clumps., Comment: 13 pages, 10 figures, accepted for publication in PASJ (v2. author names in metadata are modified.)

核融合炉ブランケットはプラズマからの熱および中性子負荷を繰り返し受け、その第一壁はクリープ温度以上になることが想定されるため、クリープ疲労損傷の評価は重要な検討課題の一つである。本研究では、ブランケットの構造材料である低放射化フェライト鋼F82Hを用いて、ASTM規格に沿って、大気中かつ550℃の全ひずみ範囲1%の両振りひずみ制御条件において、圧縮保持時間180 sから1800 sまでのクリープ疲労試験を実施した。純疲労に比べて、圧縮保持の導入に伴い、寿命の低下が見られた。保時時間700 s以上のとき、寿命の低下は僅かであり、応力緩和の挙動や非弾性ひずみの増加は飽和する傾向が示唆された。, 第38回プラズマ・核融合年会

核融合炉開発において、エネルギーの取出しを担うブランケットは重要な開発項目である。日本は構造材料に低放射化フェライト鋼(F82H)を用いた水冷却ブランケットを第一案としており、炉外の冷却水配管にはオーステナイト系ステンレス鋼の使用が予定されている。二つの鋼材の配管に共通の冷却水が流れるために、双方の材料の健全性を維持可能な水化学条件を見出す必要がある。本研究では、構造材料やその接合部の腐食特性や環境脆化に関する基礎データを取得することを目的とし、室蘭工業大学、量研、大阪大学が共同し、研究を進めており、各大学にて取り組んでいる原型炉ブランケット構造材料であるF82Hの高温高圧水腐食に関する研究成果と、量研で開発中の腐食試験装置について紹介する。, 第38回プラズマ核融合学会年会

幅広いアプローチ（BA）活動の一環として、照射組織評価手法構築のため、これまでイオン照射試験材についてX線回折法やラマン分光法の適用を検討している。本研究では東京大学HITでイオン照射したF82H鋼酸化皮膜やステンレス鋼について、新たにラマン分光測定やGIXRD測定を実施し、それらの有効性や研究進捗状況について報告する。, 令和3年度 材料照射研究会「原子力イノベーションを見据えた材料研究」

The compatibility between the DEMO divertor’s cooling water and cooling component major candidate, the ITER-grade CuCrZr alloy, was investigated. The water chemistry is expected to be hydrogen-dissolved, yet available data that are within DEMO divertor’s design specification is very limited. This investigation aims at understanding the corrosion behavior and performance of CuCrZr alloy. Results showed that the weight loss of specimens in hydrogen-dissolved condition is smaller than that of in oxygen-dissolved and degassed condition (dissolved hydrogen/oxygen < 5ppb)., The 20th International Conference on Fusion Reactor Materials (ICFRM-20)

The water-cooled system using high-temperature pressurized water is a primary candidate for the blanket and divertor of the Japanese fusion DEMO reactor. Both reduced activation ferritic/martensitic steel (RAFM) (for blanket and divertor) and the copper alloy (for divertor) are used as the key structure of cooling pipes. The water chemistry of these systems needs to be decided based on the corrosion behavior of these materials, especially depending on the dissolved oxygen (DO) level. This study aims to summarize the evaluation results of high-temperature pressurized water corrosion of RAFM and copper alloys with varied DO conditions., The 20th International Conference on Fusion Reactor Materials (ICFRM-20)

Strict control of tritium migration is an essential requirement for every blanket concept in a fusion reactor. Tritium permeation barriers (TPBs) have been developed in particular for liquid lithium-lead blankets using ceramic coatings; however, recent DEMO reactor design activities initiate an argument that a TPB is necessary also in solid breeder blankets. The previous studies revealed that reduced activation ferritic/martensitic (RAFM) steels and ceramic coatings reacted with solid breeder lithium ceramics under the blanket conditions, indicating the reactivity of solid breeders and its effect on tritium permeation should be taken into consideration. Moreover, not only the RAFM steel but the TPB will be exposed to pressurized water in a case where the TPB is applied to the cooling side. In this study, compatibility tests with pressurized water and lithium ceramic pebbles have been carried out for the investigation of the chemical stability of the TPB coatings and the effect on hydrogen isotope permeation in the Water Cooled Ceramic Breeder blanket., The 20th International Conference on Fusion Reactor Materials (ICFRM-20)

F82H鋼は核融合DEMO炉ブランケット構造材料の第一候補材料であり、高温かつ高照射量環境下で使用される。また、ブランケット筐体内をPWR相当の冷却水を循環させることで、材料の除熱、ないしは、熱エネルギーの取出しが行われる。そのため、材料の照射耐性や腐食特性評価等の評価が進められているが、これらは、F82H鋼に対する照射や腐食の単独影響であって、これらの相乗効果に関する評価については、研究知見が少ない。このことから、本研究では、高温高圧水中での腐食試験によってF82H鋼に酸化皮膜を成膜し、その後、皮膜に対して高温イオン照射を実施することで、照射下における酸化皮膜の相安定性に関わる基礎知見の拡充を研究目的とした。, 日本金属学会2021年秋期大会

In this study, creep-fatigue (CF) tests on F82H at 823 K were conducted according to the standard specimen and requirement of ASTM. Tension holding (TH) showed higher lifetime than compression holding (CH). Compared with 9Cr-1Mo-V steels, CF lifetime degradation was not observed at the holding time less than 0.05 h in case of CH and 0.17 h in case of TH. CF damages were summarized from the CF test results by Campbell method. The obtained damages distributed around CF damage envelope of Grade 91 in ASME NH. CF damage of cylindrical water-cooled ceramic breeder (WCCB) test blanket module (TBM) container at the zenith of hemisphere body under the ITER thermo-mechanical load was calculated. The calculated damage located within of the damage envelope of Grade 91. It was indicated that the present design of cylindrical WCCB TBM might resist CF interaction under the ITER thermo-mechanical load conditions.

Reduced activation ferritic/martensitic (RAFM) steel, e.g., F82H, is the leading candidate structural material for fusion blanket. Of many blanket concepts, the water-cooled ceramic breeder blanket is an attractive concept because of its compactness and its compatibility with the technologies which using high-temperature water as coolant in conventional light water reactor. For tritium breeding, it is necessary to manage the corrosion of F82H by controlling not chemicals but hydrogen and oxygen in the cooling water. Understanding the effects of oxygen and hydrogen on corrosion property was therefore required for the blanket design. This work aims to investigate the corrosion behavior of F82H in high-temperature water with hydrogen added. Based on the results of the corrosion test, it is speculated that hydrogen addition expected no considerable change of the flow-accelerated corrosion (FAC). In contrast, it was found that the number of cycles to fracture was decreased in the high-temperature water in comparison to the fatigue test at room temperature in air.

Reduced activation ferritic/martensitic (RAFM) steel, e.g., F82H, is the leading candidate structural material for fusion blanket. Of many blanket concepts, the water-cooled ceramic breeder blanket is an attractive concept because of its compactness and its compatibility with the technologies which using high-temperature water as coolant in conventional light water reactor. For tritium breeding, it is necessary to manage the corrosion of F82H by controlling not chemicals but hydrogen and oxygen in the cooling water. Understanding the effects of oxygen and hydrogen on corrosion property was therefore required for the blanket design. This work aims to investigate the corrosion behavior of F82H in high-temperature water with hydrogen added. Based on the results of the corrosion test, it is speculated that hydrogen addition expected no considerable change of the flow-accelerated corrosion (FAC). In contrast, it was found that the number of cycles to fracture was decreased in the high-temperature water in comparison to the fatigue test at room temperature in air.

核融合炉開発において、エネルギーの取出しを担うブランケットは重要な開発項目である。日本は構造材料に低放射化フェライト鋼(F82H)を用いた水冷却ブランケットを第一案としており、ブランケットから炉外の冷却系統につながる配管にはオーステナイト系ステンレス鋼の使用が予定されている。二つの鋼材の配管に共通の冷却水が流れるために、双方の材料の健全性を維持可能な水化学条件を見出す必要がある。F82Hと高温高圧水との共存性評価データは少なく、応力負荷環境下での材料表面に形成される酸化皮膜の性状、応力腐食割れ感受性等のデータ、また水の放射線分解で生じる酸素の効果のデータを蓄積する必要がある。本研究は水の放射線分解で酸素が発生した環境を模擬した高温高圧水中にF82Hを浸漬し、負荷応力が及ぼす酸化皮膜の微細組織への影響評価、SCCき裂発生・進展挙動評価を行った。併せて、電気化学測定によるF82Hの腐食挙動評価の予備的検討を行った。, 2021 年度 日本金属学会・日本鉄鋼協会両北海道支部合同サマーセッション

A water-cooled ceramic breeder blanket system is the Japanese promising design, and the candidate structuralmaterial is a reduced activation ferritic/martensitic steel, F82H. On the other hands, the material of the pipes ofcooling system is planned to an austenitic stainless steel, SUS316 L. The cooling water will commonlyflow bothF82H cooling channels and SUS316 L cooling pipes. Appropriate water chemistry condition for each of them isdifferent, but it is necessary tofind out a reasonable and common water chemistry condition for both of them. Inthe fusion blanket, since the cooling water will be irradiated by neutrons and brought about the radiolysis ofwater, the dissolved oxygen concentration of the cooling water is considered to change by the radiolysis ofwater. This research provides the simultaneous effects of dissolved oxygen and applied stress on surface mor-phology of F82H and SUS316 L by the pressurized water immersion test in dissolved oxygen concentration up to100 ppb.

Reduced activation ferritic/martensitic (RAFM) steels are assumed as structural material of blanket design activities. Determining the design limit is essential for the RAFM steels to qualify their use in fusion blankets. This work investigates fatigue properties of a RAFM steel, F82H at elevated temperature up to 823 K in the air and vacuum condition. The tests were carried out with axial strain controlled condition using cylindrical specimen, and the results were summarized using the Manson’s modified universal slope method, which can describe fatigue lifetime as a function of tensile properties. Although fatigue lifetime of F82H decreased with temperature, the fatigue lifetime up to 723 K fell into factor of 2 of the lifetime at ambient temperature. The lifetime at vacuum condition was successfully described using universal slope method. On the other hand, the lifetime in the air was 1/3 or shorter than that in vacuum condition. It is notable that a heat of F82H prepared for IEA round robin tests demonstrated 1/5 of shorter lifetime than latest F82H. The difference is discussed with inclusion morphologies affected by steel manufacturing process and so on. This report has been prepared as an account of work assigned to the Japanese Implementing Agency within the ‘‘Broader Approach Agreement’’ between the Government of Japan and the European Atomic Energy Community.

We report on the detection of long-term X-ray periodicity from the Be/X-ray binary pulsar X Persei. Based on over 23 years of X-ray data observed using RXTE/ASM, Swift/BAT and MAXI/GSC, we confirmed that X Persei exhibits quasi-periodic X-ray flares with a period of ∼7 years. The recurrence timescale corresponds to approximately 10 times its binary orbital period of 250 days. Spectral and hardness ratio changes were not detected along with long-term periodic activity. If we interpret the observed 7 year periodicity of X-ray band flux as a superorbital modulation, then this would be the first observation among the Be/X-ray binaries.

In this study, creep-fatigue (CF) tests on F82H at 823 K were conducted according to the standard specimen and requirement of ASTM. Tension holding (TH) showed higher lifetime than compression holding (CH). Compared with 9Cr-1Mo-V steels, CF lifetime degradation was not observed at the holding time less than 0.05 h in case of CH and 0.17 h in case of TH. CF damages were summarized from the CF test results by Campbell method. The obtained damages distributed around CF damage envelope of Grade 91 in ASME NH. CF damage of cylindrical water-cooled ceramic breeder (WCCB) test blanket module (TBM) container at the zenith of hemisphere body under the ITER thermo-mechanical load was calculated. The calculated damage located within of the damage envelope of Grade 91. It was indicated that the present design of cylindrical WCCB TBM might resist CF interaction under the ITER thermo-mechanical load conditions.

The paper summarizes the current status of the materials property handbook for a structural design using Japanese reduced activation ferritic/martensitic steel F82H. Specifically, the key structural parameters, e.g., time-independent/dependent design stresses and fatigue design curves, were determined following the French structural design code RCC-MRx. Besides, under the Japan-U.S. collaboration, tensile data were newly added to the benchmark heavy irradiation data up to 80 dpa, as critical input information in the intermediate check and review in Japan. Furthermore, the status of structural material data and the near-term and long-term issues were clarified by the evaluation using the attribute guides. In parallel, the structural design approaches which were newly introduced and extended to cope with the structural design issues under the complex environmental conditions peculiar to the DEMO reactor were noted with the initial R&D results. Of many design issues, the multi-axial loading condition due to the complexity of the DEMO reactor as well as the coolant compatibility and the irradiation effect is mentioned. For example in the paper, the multi-axial fatigue-creep testing and evaluation using the modified universal slope method and the brittle/ductile fracture testing and evaluation by the local approach are explained toward DEMO.

核融合中性子源A-FNSの試験モジュールとして、中性子束計測モジュール(NFMM)、F82Hの核融合中性子照射下腐食データを取得する放射化腐食生成物試験モジュール(ACPM)、トリチウム増殖材・中性子増倍材微小球からのトリチウム放出 回収特性試験モジュール(TRTM)、ブランケット機能材料照射試験モジュール(BFMTM)に関する基本概念を検討した。MCNPによる核解析を実施し、試験モジュールの核特性を評価し照射条件等を確立したので報告する。, 2019年日本原子力学会春の年会

This paper reports on the X-ray emission evolution of the ultra-luminous Galactic X-ray pulsar, Swift J0243.6+6124, during the 2017-2018 giant outburst observed by the MAXI GSC. The 2-30 keV light curve and the energy spectra confirm that the luminosity $L_\mathrm{X}$ reached $2.5\times 10^{39}$ erg s$^{-1}$, 10 times higher than the Eddington limit. When the source was luminous with $L_\mathrm{X}\gtrsim 0.9\times 10^{38}$ erg s$^{-1}$, it exhibited a negative correlation on a hardness-intensity diagram. However, two hardness ratios, a soft color ($=$ 4-10 keV / 2-4 keV) and a hard color ($=$ 10-20 keV / 4-10 keV), showed somewhat different behavior across a characteristic luminosity of $L_\mathrm{c}\simeq 5\times 10^{38}$ erg s$^{-1}$. The soft color changed more than the hard color when $L_\mathrm{X} < L_\mathrm{c}$, whereas the opposite was observed above $L_\mathrm{c}$. The spectral change above $L_\mathrm{c}$ was represented by a broad enhanced feature at $\sim 6$ keV. The pulse profiles made a transition from a single-peak to a double-peak one as the source brightened across $L_\mathrm{c}$. These spectral and pulse-shape properties can be interpreted by a scenario that the accretion columns on the neutron star surface, producing the Comptonized X-ray emission, gradually became taller as $L_\mathrm{X}$ increased. The broad 6 keV enhancement could be a result of cyclotron-resonance absorption at $\sim 10$ keV, corresponding to a surface magnetic field $B_\mathrm{s}\simeq 1.1\times 10^{12}$ G. The spin-frequency derivatives calculated with the Fermi GBM data showed a smooth correlation with $L_\mathrm{X}$ up to the outburst peak, and its linear coefficient is comparable to those of X-ray binary pulsars whose $B_\mathrm{s}$ are $(1-8)\times 10^{12}$ G. These results suggest that $B_\mathrm{s}$ of Swift J0243.6$+$6124 is a few times $10^{12}$ G., 19 pages, 13 figures, accepted for publication in ApJ

The accretion-induced pulse-period changes of the Be/X-ray binary pulsar X Persei were investigated over a period of 1996 January to 2017 September. This study utilized the monitoring data acquired with the RXTE/ASM in 1.5$-$12 keV and MAXI/GSC in 2$-$20 keV. The source intensity changed by a factor of 5$-$6 over this period. The pulsar was spinning down for 1996$-$2003, and has been spinning up since 2003, as already reported. The spin up/down rate and the 3$-$12 keV flux, determined every 250 d, showed a clear negative correlation, which can be successfully explained by the accretion torque model proposed by Ghosh & Lamb (1979). When the mass, radius and distance of the neutron star are allowed to vary over a range of 1.0$-$2.4 solar masses, 9.5$-$15 km, and 0.77$-$0.85 kpc, respectively, the magnetic field strength of $B=(4-25) \times10^{13}\ \rm G$ gave the best fits to the observation. In contrast, the observed results cannot be explained by the values of $B\sim10^{12}\ \rm G$ previously suggested for X Persei, as long as the mass, radius, and distance are required to take reasonable values. Assuming a distance of $0.81\pm0.04$ kpc as indicated by optical astrometry, the mass of the neutron star is estimated as $M=2.03\pm0.17$ solar masses., 11 pages, 9 figures, accepted for publication in PASJ

This work investigates mechanical properties of weld joints of a reduced activation ferritic/martensitic steel, F82H and effects of post weld heat treatment on the welds. Vickers hardness, tensile and Charpy impact tests were conducted on F82H weld joints prepared using tungsten-inert-gas and electron beam after various heat treatments. Although narrow groove tungsten-inert-gas welding reduced volume of weld bead, significant embrittlement was observed in a heat affected zone transformed due to heat input. Post weld heat treatment above 993 K successfully moderated the brittle transformed region. The hardness of the brittle region strongly depends on the heat treatment temperature. Meanwhile, strength of base metal was slightly reduced by the treatment at temperature ranging from 993 to 1053 K. Moreover, softening due to double welding was observed only in the weld metal, but negligible in base metal.

We report the MAXI observation of the gravitational-wave (GW) event GW170817 and the electromagnetic counterpart of GW170817. GW170817 is a binary neutron star coalescence candidate detected by the Advanced LIGO and Advanced Virgo detectors, and it is the first event for which the optical counterpart has been discovered. In the MAXI observation, the Gas Slit Camera (GSC) covered approximately 62% of the sky region of the GW event within 90% probability during the first 92 min of orbit after the trigger. No significant X-ray transient was detected in the error region, and the upper limit of the average flux with a significance of 3 $\sigma$ in the 2--10 keV band was 53/26 mCrab (one-orbit observation/one-day observation). In the optical counterpart of GW170817, the observational window of GSC at the position started at 20 s after the GW trigger, but the high voltage of GSC was unfortunately off at the time because the ISS was entering a high-particle-background region. The first observation of the position by GSC was eventually performed at 16797 sec (4.6 hours) since the GW trigger, yielding the 3 $\sigma$ upper limit of 8.60$\times$10$^{-9}$ erg cm$^{-2}$ s$^{-1}$ in the 2--10 keV band, though it was the earliest X-ray observation of the counterpart., Comment: 9 pages, 19 figures, Accepted to Publications of the Astronomical Society of Japan on May 29 2018

The present study reports the corrosion behavior of a reduced-activation ferritic martensitic steel F82H exposed to high temperature pressurized water for 28 and 100 h using a rotating disk apparatus at rotation speeds of 500 and 1000 rpm at a temperature of 573 K under a water pressure of 15 MPa with

Japan Atomic Energy Agency (JAEA) is performing the development of a Water Cooled Ceramic Breeder (WCCB) Test Blanket Module (TBM) as one of the most important steps toward DEMO blanket. Regarding the blanket module fabrication technology development using F82H, the fabrication of a real scale mockup of the back wall of TBM was completed. In the design activity of the TBM, electromagnetic analysis under plasma disruption events and thermo-mechanical analysis under steady state and transient state of tokamak operation have been performed and showed bright prospect toward design justification. Regarding the development of advanced breeder and multiplier pebbles for DEMO blanket, fabrication technology development of Li rich Li2TiO3 pebble and BeTi pebble was performed. Regarding the research activity on the evaluation of tritium generation performance, the evaluation of tritium production and recovery test using D-T neutron in the Fusion Neutronics Source (FNS) facility has been performed. This paper overviews the recent achievements of the development of the WCCB Blanket in JAEA.

To observationally study spin-period changes of accreting pulsars caused by the accretion torque, the present work analyzes X-ray light curves of 12 Be binary pulsars obtained by the MAXI/GSC all-sky survey and their pulse periods measured by the Fermi/GBM pulsar project, both covering more than 6 years from 2009 August to 2016 March. The 12 objects were selected because they are accompanied by clear optical identification, and accurate measurements of surface magnetic fields. The luminosity $L$ and the spin-frequency derivatives $\dot{\nu}$, measured during large outbursts with $L\gtrsim 1\times 10^{37}$ erg s$^{-1}$, were found to approximately follow the theoretical relations in the accretion torque models, represented by $\dot{\nu} \propto L^{\alpha}$ ($\alpha\simeq 1$), and the coefficient of proportionality between $\dot{\nu}$ and $L^{\alpha}$, agrees, within a factor of $\sim 3$, with that proposed by Ghosh & Lamb (1979). In the course of the present study, the orbital elements of several sources were refined., Comment: 21 pages, 9 figures, accepted for publication in PASJ

著者人数: 32名, Accepted: 2011-09-20, 資料番号: SA1003145000

著者人数: 37名, Accepted: 2011-07-20, 資料番号: SA1003146000

The Gas Slit Camera (GSC) is an X-ray instrument on the MAXI (Monitor of All-sky X-ray Image) mission on the International Space Station. It is designed to scan the entire sky every 92-minute orbital period in the 2--30 keV band and to achieve the highest sensitivity among the X-ray all-sky monitors ever flown so far. The GSC employs large-area position-sensitive proportional counters with the total detector area of 5350 cm$^2$. The on-board data processor has functions to format telemetry data as well as to control the high voltage of the proportional counters to protect them from the particle irradiation. The paper describes the instruments, on-board data processing, telemetry data formats, and performance specifications expected from the ground calibration tests., 12 pages, 18 figure-files, accepted for PASJ

The influence of hydrogen content in steel on atmospheric oxidation behavior of low carbon austenitic stainless steel SUSF316L was investigated for clarifying the mechanism of SCC initiation in a boiling water reactor environment, which is closely associated with the localized oxidation and its acceleration. The stainless steel was charged with hydrogen by the means of cathodic electrolysis followed by subjecting the hydrogen-charged steels to the atmospheric oxidation test at 300°C for 10 h. The oxide films that formed on the non-charged and hydrogen-charged specimens were analyzed by optical microscopy, scanning electron microscopy, laser Raman spectroscopy and glow discharge optical emission spectroscopy. Experimental results revealed that relatively thick oxide films were formed on the hydrogen-charged specimen resulting in the hydrogen accelerated oxidation (HAO), when the hydrogen content was 35 mass ppm. However, there was almost no difference between the non-charged and the hydrogen-charged from the viewpoint of oxidation behavior when the hydrogen content was 24 mass ppm. The spinel-type oxides such as Fe3O4 and FeCr2O4 were identified by laser Raman spectroscopy only on the specimen surface where the HAO occurred. In addition, the Cr concentration in the inner oxide layer of the oxidation-accelerated specimen was around 20% and was lower than that of the non-charged (30-35%). The HAO seemed to be closely associated with this decrease in Cr concentration in the inner oxide layer.

The instrumented indentation test was applied to the interrupted creep specimens of turbine rotor steel (Fe-10Cr-1Mo-1W-VNbN) to investigate the changes in contributions of matrix and block boundary strengths to macroscopic hardness during creep. The indentation tests were performed under the loads of 1 and 10 mN to determine the matrix strength and the block boundary strength, respectively. The matrix strength of the grip portion decreased gradually with increasing life fraction and, for the gauge portion, the decrease was more pronounced, particularly, at the latter half of the life. On the other hand, the experimental results revealed that the block boundary strength decreased significantly at the early stage of the creep life, but this decrease was no longer pronounced when the creep life fraction exceeded 20%. Additionally, there was a good correlation between the block boundary strength and the width of block boundary carbide and the carbide coarsening was considered to be closely associated with the decrease in block boundary strength.

Outstanding strength performance of high Cr ferritic steels is attributable to the combined strengthening mechanisms of matrix and various grain boundaries. However, it is by no means easy to separate the contributions of such strengthening factors and quantitatively understand them because of extremely fine and complicated microstructures. In this study, the instrumented indentation test was carried out to clarify the change in contribution of “block” during creep. The materials used in this study were turbine rotor steel (Fe–10Cr–1Mo–1W–VNbN). The indentation test was applied to the as-tempered and creep damaged specimens under the maximum loads ranging from 1 to 1000 mN. The test results revealed that the decrease in contribution of block was the predominant factor controlling the material deterioration, namely, softening at the early stage of the creep life. This decrease in block's contribution was caused by the decrease in resistance of the block boundary to deformation.

著者人数: 12名, Accepted: 2007-09-04, 資料番号: SA1000314000

Reduced activation ferritic/martensitic steels (RAFs) have a complex and fine lath martensitic structure consisting of several kinds of microstructural units, namely, lath, block, packet and prior austenite grain. However, it is by no means easy to distinguish the contributions of such units to the strengthening mechanism. In this study, the instrumented indentation test was carried out under a wide range of maximum indentation loads using the crept specimens of the RAFs, JLF-1, in order to clarify the contribution of each grain boundary to it's strength and degradation. Experimental results revealed that the block boundary was the most effective boundary and at least seven block grains were necessary for reflecting fully the effect of block boundary in the macroscopic hardness. In addition, it was also revealed that the decrease in matrix strength of block grain was predominant factor of the reduction in macroscopic hardness due to creep. The retardation of the decrease in block boundary strength restrained the significant reduction in macroscopic hardness in JLF-1.

Since the typical magnetic field strengths of neutron stars reach 10 12 Gauss, the cyclotron resonance produced by a transition between Landau levels appears in the X-ray band. Systematic measurements of cyclotron absorption features in bright sources have been carried out extensively with Ginga, RXTE, BeppoSAX , and INTEGRAL . The cyclotron resonance phenomena can now be studied with a higher sensitivity over a wider hard X-ray band than before, thanks to the Hard X-ray Detector onboard the fifth Japanese X-ray satellite, Suzaku , launched in July, 2005. Suzaku observed Hercules X-1 mainly for calibration purposes, and successfully confirmed its well-known cyclotron absorption feature. Furthermore, the transient pulsar A0535+262 was observed with Suzaku on 14 September, 2005, in the decay phase of its minor outburst (Finger, M.F. Renewed Activity from A0535+26. The Astronomer’s Telegram, vol. 595, 2005). The cyclotron resonance of A0535+262 was successfully detected in absorption at about 45 keV (Inoue, H., Kunieda, H., White, N., Kelley, R., Mihara, T., Terada, Y., Takahashi, H., Kokubun, M., Makishima, K. Suzaku detection of cyclotron line near 50 keV for A0535+26. The Astronomer’s Telegram vol. 595, 2005; Terada, Y., Mihara, T., Nakajima, M., et al. Cyclotron resonance energies at a low X-ray luminosity: A0535+262 observed with Suzaku. ApJL 648, L139–L142, 2006), even though the object was as dim as 30 mCrab at 20 keV. Compared with previous measurements of the same feature achieved at much brighter phases (e.g., Kretschmar, P., Kreykenbohm, I., Pottschmidt, et al. Integral observes possible cyclotron line at 47 keV for 1A0535+262. The Astronomer’s Telegram, vol. 601, 2005; Wilson, C.A., Finger, M.H. RXTE confirms cyclotron line near 50 keV for A0535+26. The Astronomer’s Telegram 605, 2005), the Suzaku results give a new constraint to luminosity-related changes in the resonance energy that are observed in other binary pulsars (Nakajima, M., Mihara, T., Makishima, K., Niko, H. A further study of the luminosity-dependent cyclotron resonance energies of the binary X-ray pulsar 4U 0115+63 with the Rossi X-ray timing explorer. ApJ 646, 1125–1138, 2006).

我々は，化審法における生分解性予測に新たな視点を加えるため，その変化物生成の主たる要因の一つである加水分解予測に，量子化学計算による反応解析から得られる活性化エネルギーを判断指標の一つとして用いることを検討している。この過程において，MOPACベースでの平易な活性化エネルギーの算出を可能とするインタフェースとして，加水分解予測システムを開発した。このシステムでは，遷移状態付近の構造探索を効率的に行うために，過去の計算結果を利用する置換基法を，加水分解反応に特化して応用しシステム化した。その結果，エステル酸加水分解反応について，市販の量子化学計算ソフトウェアのみを用いた反応解析に比べ，大幅に計算時間を短縮しつつ，MOPACベースでの活性化エネルギー計算結果が得られることが判明した。今後，DFT計算やab initio MO計算といった上位の計算手法との併用も視野に入れ，生分解性予測へ活用することを検討している。

Suzaku has observed some cyclotron X-ray pulsars in the SWG (Science working group) phase. Suzaku detected the cyclotron feature in the lowest luminosity from A0535+26. In Her X-1, Suzaku measured new data points in the year-long trend of cyclotron resonance energy, and searched for the second harmonic structure. The RXTE observations of X0331+53 gave the second example on changing the resonance energy and indicated that the energy ratio of the 2nd and 1st cyclotron energies is apart from two.

A report is made on the luminosity and pulse-period evolution of the Be binary X-ray pulsar, GX 304$-$1, during a series of outbursts from 2009 to 2013 observed by MAXI/GSC, RXTE/PCA, and Fermi/GBM. In total, twelve outbursts repeated by $\sim$ 132.2 days were observed, which is consistent with the X-ray periodicity of this object observed in the 1970s. These 12 outbursts, together with those in the 1970s, were found to all recur with a well defined period of 132.189$\pm$0.02 d, which can be identified with the orbital period. The pulse period at $\sim 275$ s, obtained from the RXTE/PCA and Fermi/GBM data, apparently exhibited a periodic modulation synchronized with the outburst period, suggesting the pulsar orbital motion, which is superposed on a secular spin-up trend throughout the entire active phase. The observed pulse-period changes were successfully represented by a model composed of the binary orbital modulation and pulsar spin up caused by mass accretion through an accretion disk. The orbital elements obtained from the best-fit model, including the projected orbital semi-major axis $a_{\rm x}\sin i \simeq 500-600$ light-s and an eccentricity $e \simeq 0.5$, are typical of Be binary X-ray pulsars., 10 pages, 6 figures, accepted for publication in PASJ

著者人数: 31名, Accepted: 2006-07-28, 資料番号: SA1000375000

The present paper reports on the RXTE observations of the binary X-ray pulsar 4U0115+63, covering an outburst in 1999 March-April with 44 pointings. The 3-30 keV PCA spectra and the 15-50 keV HEXTE spectra were analyzed jointly for the cyclotron resonance features. When the 3-50 keV luminosity at an assumed distance of 7 kpc was in the range (5-13)x10^{37} erg s^{-1}, harmonic double cyclotron features were observed in absorption at ~11 and ~22 keV, as was measured previously during typical outbursts. As the luminosity decreased below \~5x10^{37} erg s^{-1}, the second resonance disappeared, and the fundamental resonance energy gradually increased, up to $\sim$16 keV at 0.16x10^{37} erg s^{-1}. These results reconfirm the report by Mihara et al. (2004) using Ginga, who observed a single absorption at ~16 keV in a minor (~10^{37} erg s^{-1}) outburst of this object. The luminosity-dependent cyclotron resonance energy may be understood as a result of a decrease in the accretion column height, in response to a decrease in the mass accretion rate.