著者

野田 宏 奈良林 直 吉田 智朗 中村 誠 桐本 順広

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.7, no.4, pp.408-419, 2008 (Released:2012-03-02)

参考文献数

8

被引用文献数

1

---

Failures on demand of a reactor core isolation cooling (RCIC) system in BWRs are the most frequent events of limiting conditions for operation during 1982-2006 in Japan, according to data gathered in Nuclear Information Archives (NUCIA). In this work, probabilities of failures of the RCIC system are analyzed by using the hierarchical Bayes method. The failures on demand of the RCIC system are classified into two groups; one is related to the demand at a periodical inspection test, which is performed almost every 13 months at the end of the periodical inspection of the nuclear power plant, and the other is related to the monthly surveillance test during plant operation. The hierarchical Bayes analysis shows the characteristics of probabilities of failures of each Japanese plant and also that probabilities of failures at the periodical inspection test are quite different from those at the surveillance test, comparing Japanese nuclear power plants with American ones. This paper provides a new approach to analyzing sparse failure data taken from nuclear power plants in Japan.

著者

前田 茂貴 井口 哲夫

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.10, no.2, pp.63-75, 2011 (Released:2012-03-17)

参考文献数

59

被引用文献数

1 1

---

Neutron spectrum unfolding is a widely used technique for characterizing neutron fields for various types of reactor dosimetry, where the neutron spectrum is derived from integral measured data such as multiple-foil activation rates and moderated neutron detector counts. Many spectrum unfolding codes have been developed so far and their performances have been compared. However, a standardized metrology for neutron spectrum unfolding has not been satisfactorily established yet from the viewpoints of adequate selection and usage of unfolding codes, response function database and input data set preparation. This article reviews the present status of the neutron spectrum unfolding technique that is mainly related to reactor dosimetry with activation foils and discusses the validity of the solution spectra obtained from different unfolding codes under a typical fast reactor neutron field. The results show that the solution spectrum strongly depends on a priori (i.e., guess) spectrum required for the input data as well as the theoretical assumption in each unfolding code. The issues that must be resolved to improve the accuracy of reactor dosimetry are summarized for the a priori input spectrum, the nuclear database, and the standardization of the unfolding procedure.

著者

西山 祐一 片岡 隆浩 山岡 聖典

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.12, no.4, pp.267-276, 2013 (Released:2013-11-15)

参考文献数

54

被引用文献数

2 1

---

Radon therapy has long been performed for pain- and oxidative-stress-related diseases in Bad Gastein (Austria) and Misasa (Tottori). We carried out some animal experiments to clarify the mechanism underlying the effects of the therapy. The findings indicated that radon inhalation has antioxidative effects. For example, radon inhalation suppressed liver functional disorder and oxidative damage following carbon tetrachloride administration in mice. In addition, the anti-inflammatory effect through the enhancement of the antioxidative function, which suppresses inflammatory pain, was also obtained. From these findings, the possibility of health promotion by radon is suggested.

著者

沢 和弘 植田 祥平 相原 純 湊 和生 小川 徹

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.6, no.2, pp.113-125, 2007 (Released:2012-03-07)

参考文献数

55

被引用文献数

1

---

Interest in the future hydrogen economy has prompted the research and development of the Very High-Temperature Gas-Cooled Reactor (VHTR). To achieve the targeted outlet gas temperature exceeding 950°C, material problems have yet to be solved. The development of advanced coated particle fuel is also due in view of the vulnerability of the SiC layer of conventional TRISO-coated particle fuel at temperatures exceeding 1,600°C. The coated particle fuel employing ZrC instead of SiC has been developed in JAEA. Although the past irradiation tests on the ZrC-coated particle fuel were exclusively on samples from the laboratory scale production, the promising results have been obtained. The properties, fabrication and inspection techniques as well as the results of irradiation and post-irradiation tests are reviewed. The post-irradiation heating tests at accident temperatures above 1,600°C revealed the durability of the ZrC-layer, which maintained the tightness to noble-gas and volatile metal fission products. From 2004, JAEA started (1) ZrC-coating process development by large-scale coater, (2) inspection method development of ZrC coating and (3) irradiation test and post irradiation experiment of ZrC coated particles under contract research which is entrusted to the JAEA and MEXT.

著者

秋元 勇巳 植松 邦彦

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会誌 (ISSN:00047120)

巻号頁・発行日

vol.16, no.3, pp.128-136, 1974

---

A review is presented of the IAEA-IWGFR Specialists' Meeting on the "Development and Application of Absorber Materials for Fast Reactors" which was held at Dimitrovgrad, USSR, June 4-8, 1973. At the meeting, attention was given mainly to the choice of absorbing materials for the control elements of fast reactors, to the design of absorbing rods and tests of their performance.<BR>About two thirds of the sessions were devoted to the oldest established and the most promising absorber-B<SUB>4</SUB>C. The pre-irradiation properties of B<SUB>4</SUB>C are considered to be fairly thoroughly known already. Good agreement has been seen on the results of compatibility studies. On the other hand, the irradiation behavior of B<SUB>4</SUB>C-specially swelling and He release-stimulated brisk discussion among the participants in respect of the appreciable discrepancy discerned in the results obtained so far and the possible explanations given therefore. Development of the vented control rod is being actively undertaken in most of the countries.<BR>Tantalum and Eu<SUB>2</SUB>O<SUB>3</SUB> attracted attention as promissing alternatives to B<SUB>4</SUB>C. There arises problems, however, on the compatibility of these two materials in the presence of Na. Another difficulty foreseen in the use of Ta rods is cooling during reactor shut-off. For Eu<SUB>2</SUB>O<SUB>3</SUB>, phase stability should be an important problem for future study.

著者

田ノ岡 宏

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会誌 (ISSN:00047120)

巻号頁・発行日

vol.40, no.7, pp.542-543, 1998

著者

Yoichiro SHIMAZU

出版者

Atomic Energy Society of Japan

雑誌

Journal of Nuclear Science and Technology (ISSN:00223131)

巻号頁・発行日

vol.14, no.11, pp.805-810, 1977-11-25 (Released:2008-04-18)

参考文献数

6

---

An evaluation is made to estimate the transient xenon behavior in an MSBR for several representative patterns of operation. Such analysis is indispensable for detailed evaluation of reactivity balance under transient conditions. The results are compared with those of a typical PWR. The xenon behavior does not differ between the two types of reactor to the extent that might be expected from the fact that in the MSBR, xenon behavior is additionally conditioned by the processes of migration into the circulating bubbles and into the graphite, as well as by diffusion therein.It is shown that the reactivity transients due to xenon buildup can be held within the range of counteraction by control rod movement for any normal change of reactor output, so long as the reactor is not shut down. After a shutdown, insertion of the control rods will not suffice to override the xenon buildup, but then the fuel processing system could be conveniently utilized to increase the quantity of 233U contained in the fuel and regain required reactivity of the core.

著者

下浦 一邦 筒井 天尊

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会誌 (ISSN:00047120)

巻号頁・発行日

vol.12, no.10, pp.582-585, 1970

---

Volume reduction of radioactive sludge by de-watering is important in the chemical treatment of radioactive liquid wastes. The de-watering characteristics of super-decanter type centrifuge for ferric hydroxide sludge has been investigated experimentally. The results obtained include the relation of sludge removing efficiency to feed rate, the correlation of centrifugal force with volume reduction factor and with radioactivity eluted from the sludge.<BR>Addition of polymer as coagulating agent is effective in improving the treating capacity and in shortening the settling time after separation. Experiments were performed to determine the conditions for adding the polymer to obtain optimum coagulation of the sludge.

著者

Noboru KOBAYASHI Ichiro YAMAMOTO

出版者

Atomic Energy Society of Japan

雑誌

Journal of Nuclear Science and Technology (ISSN:00223131)

巻号頁・発行日

vol.34, no.3, pp.318-324, 1997-03-25 (Released:2008-04-18)

参考文献数

6

被引用文献数

1

---

By making use of the isotope approximation; neglecting squares of relative mass differences among the isotopes, the authors derived analytically approximations to ordinary diffusion coefficients in a 3- and 4- component isotope mixture. Moreover, approximations to multi-component diffusion coefficients were given on the analogy of those to the 3- and 4-component coefficients, and these approximations were verified to satisfy constrains on the exact ordinary diffusion coefficients. For 4-component mixture of uranium hexafluoride isotopes, 234UF6-235UF6-236UF6-236UF6, composition dependences of the approximation were equal to those of the exact diffusion coefficients. In addition, relative errors between the exact and the approximations were less than 0.2% for 5-component mixture of krypton 80-82-83-84-86 isotopes.

著者

竹上 弘彰 高松 邦吉 伊藤 主税 日野 竜太郎 鈴木 敬一 大沼 寛 奥村 忠彦

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.13, no.1, pp.7-16, 2014

---

One of the important problems in the control of the Fukushima Daiichi Nuclear Power Plant is the removal of fuel debris. As preparation, a nondestructive inspection method for identifying the position of fuel debris is required. Therefore, we focused on a nondestructive inspection method using cosmic-ray muons, which is utilized for ground investigation. In this study, the applicability of this method for internal visualization of the reactor was confirmed by a preliminary test of the internal visualization of the High-Temperature Engineering Test Reactor (HTTR) of Japan Atomic Energy Agency. By using cosmic-ray muons, main components in the HTTR reactor, such as concrete walls and the reactor core, can be observed from the outside of the containment vessel of the HTTR. From the results of the preliminary examination, it appears that the inspection method with muons is promising for searching for fuel debris in a reactor. Based on the results, we also proposed some improvements of this system for its application to inspection at the Fukushima Daiichi Nuclear Power Station.<br>

著者

芳原 新也 稲垣 昌代 小島 清 山西 弘城 若林 源一郎 杉山 亘 伊藤 哲夫

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.10, no.3, pp.145-148, 2011 (Released:2011-07-29)

参考文献数

14

被引用文献数

5 4

---

Radioactive materials were released to the general environment due to the accident at the Fukushima Daiichi nuclear power station. The released radioactive materials fell and contaminated the land mainly in the Tohoku and Kanto areas of Japan. We surveyed the air dose rate in relation to the pave condition of the land, and investigated the contamination level in some nonpaved areas at the center of Fukushima City, Koriyama City, and Nasushiobara City. From the survey results, the dose rates of the nonpaved areas were found to be higher than those of the paved areas, and the dose rates of the paved areas depend on the paving materials of the area. The contamination level of the nonpaved area in Nasushiobara City was below the regulation level of specific activities in a radiation-controlled area in Japan. However, the contamination levels in the nonpaved areas in Fukushima City and Koriyama City were above the regulation level.

著者

若林 二郎 森 寿久 住田 侑 石井 一典 川太 徳夫 飯島 隆

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会誌 (ISSN:00047120)

巻号頁・発行日

vol.28, no.10, pp.913-923, 1986

被引用文献数

2

---

原子力発電所の運転形態を従来の基底負荷運転から負荷追従運転も含んだ形に拡大していく必要が高まりつつある。電力系統の負荷は季節変化,日変化,さらにより小さな時間スケールの変動成分よりなる複雑な変化を示し,それに対応して原子力発電所を運転するには新しい制御方策の導入と複数種の制御手段の有機的な統合利用が必要となる。<BR>本稿では,現在盛んに開発が進められているこの種技術の実情について、BWR,PWR,ATRの各炉型ごとに要約して紹介する

著者

渡辺 正 石垣 将宏 佐藤 聡 中村 秀夫

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.10, no.4, pp.240-244, 2011 (Released:2011-11-30)

参考文献数

4

被引用文献数

2 2

---

The analysis of the long-term station blackout accident of BWR has been performed using the TRAC-BF1 code. The actuation of RCIC was assumed, and the results were compared with the data observed at the Fukushima Daiichi power plant unit 2 reactor. BWR-5 of 1,100 MW was analyzed, while the unit 2 reactor was BWR-4 of 780 MW. The reactor pressure and the core liquid level were, however, in good agreement with the observed data. It was confirmed that the quasi-steady state continued for a long time with the RCIC actuation. The timing of recovery action, which was composed of depressurization and coolant injection, necessary for the maximum clad temperature being less than 1,500 K was studied and compared with that of the unit 2 reactor.

著者

池田 佳隆 岡野 文範 逆井 章 花田 磨砂也 秋野 昇 市毛 尚志 神永 敦嗣 清野 公広 久保 博孝 小林 和容 笹島 唯之 助川 篤彦 千葉 真一 西山 友和 三代 康彦 柳生 純一 横倉 賢治 JT-60 チーム

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.13, no.4, pp.167-178, 2014 (Released:2014-11-15)

参考文献数

14

---

The upgrade of JT-60U to the superconducting tokamak “JT-60SA” has been carried out as a combined project of JAEA's program for national use and the Satellite Tokamak Program in collaboration with EU and Japan fusion communities. The JT-60U torus was dismantled so as to install the new JT-60SA torus at the same position in the torus hall. JT-60U used deuterium for 18 years, so the neutron yield reached about 1.5×1020 (n) in total. The dismantling project of JT-60U was the first decommissioning experience of a fusion device with radioactivity in Japan. The project was intended to demonstrate decommissioning technologies and work activities, and to acquire experience and data on the technologies as well as to implement the dismantling project safely. Moreover, all disassembled components were stored with the data such as dose rate, weight and kind of material being recorded, so as to apply the clearance level regulation in the future. The lessons learned from the dismantling project indicated that the cutting technologies and storage management of disassembled components were the key factors in conducting the dismantling project efficiently. After completing the dismantling project, efforts have been made to analyze the data for characterizing disassembling activities, so as to contribute to the estimation of manpower needs and the radioactivity of the disassembled components from other fusion devices.

著者

坂場 成昭 大橋 弘史 佐藤 博之 原 輝夫 加藤 竜馬 國富 一彦

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.7, no.3, pp.242-256, 2008 (Released:2012-03-02)

参考文献数

30

被引用文献数

6 6

---

Nuclear hydrogen production is necessary in an anticipated hydrogen society that demands a massive quantity of hydrogen without economic disadvantage. Japan Atomic Energy Agency (JAEA) has launched the conceptual design study of a hydrogen production system with a near-term plan to connect it to Japan's first high-temperature gas-cooled reactor HTTR. The candidate hydrogen production system is based on the thermochemical water-splitting iodine sulphur (IS) process. The heat of 10 MWth at approximately 900°C, which can be provided by the secondary helium from the intermediate heat exchanger of the HTTR, is the energy input to the hydrogen production system. In this paper, we describe the recent progresses made in the conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system. A new concept of sulphuric acid decomposer is proposed. This involves the integration of three separate functions of sulphuric acid decomposer, sulphur trioxide decomposer, and process heat exchanger. A new mixer-settler type of Bunsen reactor is also designed. This integrates three separate functions of Bunsen reactor, phase separator, and pump. The new concepts are expected to result in improved economics through construction and operation cost reductions because the number of process equipment and complicated connections between the equipment has been substantially reduced.

著者

皆月 功 溝上 頼賢

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.6, no.3, pp.276-288, 2007 (Released:2012-03-07)

参考文献数

13

被引用文献数

2 2

---

The design studies on High Temperature Gas Cooled Reactor with Gas Turbine (HTGR-GT) have been performed, which were mainly promoted by Japan Atomic Energy Agency (JAEA) and supported by fabricators in Japan. HTGR-GT plant feature is almost determined by selection of power conversion system concepts. Therefore, plant design philosophy is observed characteristically in selection of them.   This paper describes the evaluation and analysis of the essential concepts of the HTGR-GT power conversion system through the investigations based on our experiences and engineering knowledge as a fabricator. As a result, the following concepts were evaluated that have advantages against other competitive one, such as the horizontal turbo machine rotor, the turbo machine in an individual vessel, the turbo machine with single shaft, the generator inside the power conversion vessel, and the power conversion system cycle with an intercooler. The results of the study can contribute as reference data when the concepts will be selected.   Furthermore, we addressed reasonableness about the concept selection of the Gas Turbine High Temperature Reactor GTHTR300 power conversion system, which has been promoted by JAEA. As a conclusion, we recognized the GTHTR300 would be one of the most promising concepts for commercialization in near future.

著者

山崎 正俊 宇根崎 博信

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.9, no.3, pp.243-251, 2010 (Released:2012-02-08)

参考文献数

8

被引用文献数

1 1

---

For the sake of more efficient operation of nuclear power plants and to reduce the number of spent nuclear fuel assemblies, increasing uranium enrichment is one of the rational options. However, current uranium enrichment for the whole fuel cycle infrastructure is limited to no greater than 5 wt% from the view point of criticality safety. In this review, three main topics are discussed: 1) the necessity of increasing the uranium enrichment above 5 wt%; 2) current status and challenges to go over 5 wt% enrichment; and 3) proposal of the “Erbia Credit Super High Burnup Fuel” as a measure to break the “5 wt% enrichment barrier.” The third topic is further elaborated on by discussing the introduction scenarios before concluding with a mention of the necessity of a best-mix analysis for this concept in the fuel cycle supply chain.

著者

Shigeru IKUTA Kenji YOSHIHARA Takanobu SHIOKAWA

出版者

Atomic Energy Society of Japan

雑誌

Journal of Nuclear Science and Technology (ISSN:00223131)

巻号頁・発行日

vol.14, no.9, pp.661-663, 1977-09-25 (Released:2008-04-18)

参考文献数

8

被引用文献数

1

---

The behaviors of CH3He+ and C2H5He+ formed by the decay of CH3T and C2H5T were studied theoretically using the STO-3G molecular orbital method and was compared with that of HHe+ in the decay of HT. It was clearly shown that the ground state daughter ions CH3He+ and C2H5He>+ dissociate instantly to give CH3+ and C2H5+ because their poten-tial energy curves are repulsive, whereas the daughter ion HHe+ in the ground state does not dissociate. The transition probability to the ground state ions of CH3He+ and of C2H5He+ are computed to be 66.5 and 64.8%, respectively. These values are in fairly good accordance with those obtained experimentally.

著者

福村 卓也 福谷 耕司 有岡 孝司

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.9, no.3, pp.318-329, 2010 (Released:2012-02-08)

参考文献数

12

被引用文献数

2 2

---

Some pressurized water reactor (PWR) plants have switched secondary system feed water treatment to ethanol-amine (ETA) injection from all-volatile treatment (AVT) to reduce iron transfer in the steam generator (SG). However, the effect of ETA injection on FAC rate has not been studied systematically. To assess the effect of ETA injection on FAC rate, the water chemistries in secondary systems were calculated by considering the thermal decomposition of hydrazine in SG and the vapor/liquid partition of ammonia, ETA, and hydrazine in SG and in a moisture-separator-and-reheater (MSR). Then, we measured the FAC rate experimentally by rotation tests to examine the effect of ETA injection. The high pH condition of ETA injection reduced the FAC rate more than the low pH condition of AVT. No chemical effect on the FAC rate was observed between ETA injection and AVT at 180°C. We also evaluated the FAC rate using magnetite solubility with and without ETA injection. The evaluation showed that ETA injection reduces the FAC rate of the secondary system.

著者

Katsuhiko SAGAE Akira SUZUOKI

出版者

Atomic Energy Society of Japan

雑誌

Journal of Nuclear Science and Technology (ISSN:00223131)

巻号頁・発行日

vol.22, no.11, pp.870-880, 1985-11-25 (Released:2008-04-18)

参考文献数

7

被引用文献数

2

---

An analytical model for sodium pool combustion has been developed and verified by ex-periments. The model can be used to analyze sodium fire accidents in LMFBRs. It features a layer of sodium vapor between the flame and the sodium pool surface which functions to resist heat transfer. Results obtained with the model show : combustion rate increases with oxygen concentration, sodium pool temperature and gas pressure, but it decreases with in-creases in gas temperature. Calculated combustion rates agree within 15% of the experi-mental results.