著者

川村 慎一 木村 剛生 大森 修一 奈良林 直

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.15, no.1, pp.12-20, 2016 (Released:2016-02-15)

参考文献数

9

被引用文献数

4

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A filtered containment venting system was developed for nuclear power plants. In the Fukushima Dai-ichi Nuclear Accident, widespread land contamination was caused by cesium-137. This system was developed to filter aerosol particles and reduce the amount of radioactive particle release, while protecting the primary containment vessel from over pressure by venting gas from the vessel. Performance tests were conducted under various vent gas flow rate conditions to ascertain decontamination factors for aerosol particles with various diameters. It was observed through the tests that aerodynamic diameter was a good index for characterizing various aerosol particles for the filtered containment venting system. Test results showed that the decontamination factors were well over 1,000 for aerosol particles with aerodynamic diameters larger than 0.4 μm. For aerosol particles with aerodynamic diameters larger than 0.2 μm, the decontamination factors significantly increased with the diameter. This suggested that inertial deposition was the governing mechanism for filtering aerosols in this system. The decontamination factor of the water scrubber section of the filter increased with the increase in Stokes number.

著者

川村 慎一 大木 俊 奈良林 直

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

pp.J15.018, (Released:2016-03-15)

参考文献数

10

被引用文献数

1

---

Significant leakage of the primary containment vessel (PCV) occurred on March 15, 2011 at Unit 2 of Fukushima Dai-ichi Nuclear Power Station, causing land contamination over a large area. From the radiation dose rate map of Unit 2 and the temperature trend of the PCV, degradation of the PCV top head flange gasket was identified as the cause of the leakage. The design set point of the rapture disc and operability of the valves in the hardened containment venting system were further identified as factors contributing to the leakage. Based on the lessons from the leakage, the gasket material was improved to have greater heat resistance in a steam environment, the PCV cooling system was diversified to improve reliability, and the operability and operation methods of the PCV venting were improved for greater robustness of the PCV in severe accidents.

著者

藤原 了 橋本 紀彦 是永 眞理子 田宮 貴洋

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

pp.J14.025, (Released:2015-12-17)

参考文献数

32

被引用文献数

1 1

---

Since the 2011 Tohoku-Oki Earthquake, evaluations based on a tsunami simulation approach have had a very important role in promoting tsunami disaster prevention measures in the case of mega-thrust earthquakes. When considering tsunami disaster prevention measures based on the knowledge obtained from tsunami simulations, it is important to carefully examine the type of tsunami source model. In current tsunami simulations, there are various ways to set the tsunami source model, and a considerable difference in tsunami behavior can be expected among the tsunami source models. In this study, we carry out a tsunami simulation of the 2011 Tohoku-Oki Earthquake around Fukushima Daiichi (I) Nuclear Power Plant and Fukushima Daini (II) Nuclear Power Plant in Fukushima Prefecture, Japan, using several tsunami source models, and evaluate the difference in the tsunami behavior in the tsunami inundation process. The results show that for an incoming tsunami inundating an inland region, there are considerable relative differences in the maximum tsunami height and wave pressure. This suggests that there could be false information used in promoting tsunami disaster prevention measures in the case of mega-thrust earthquakes, depending on the tsunami source model.

著者

石川 奈緒 伊藤 歩 海田 輝之

出版者

一般社団法人 日本原子力学会

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.3, pp.87-93, 2014 (Released:2014-08-15)

参考文献数

26

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Radionuclide contamination from the nuclear accident at the Fukushima Daiichi Nuclear Power Plant has been found in sewage sludge ash produced in eastern Japan. When such contaminated waste contains less than 8,000 Bq/kg radiocesium, it is being disposed in controlled landfill sites. In order to assess the possible spread of the radionuclides by their leaching from the landfill sites, it is important to know the leaching behavior of the radionuclides from the sewage sludge ash and factors influencing the leaching behavior. In this study, leaching experiments using stable Cs and Sr were conducted for sewage sludge ash under several conditions to investigate effects of chemical composition of leachate, pH, and solid/liquid ratio on Cs and Sr leaching behaviors. In the pH range from 6 to 12, the leaching ratio of Cs or Sr was less than 5.2 or 0.21%, respectively. Additionally, the leaching ratio of Sr decreased with increasing pH of the leachate. In contrast, the higher the pH in the leachate was, the higher the leaching ratio of Cs was. Finally, possible radionuclide leaching from contaminated sewage sludge ash and then radionuclide concentrations in an actual landfill leachate were assessed. It could be suggested that 90Sr leaching from the landfill site had the least effect on the environment, whereas 134+137Cs leaching needed to be taken into account for spreading radioactive materials from the landfill site to the environment.

著者

氏田 博士

出版者

一般社団法人 日本原子力学会

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.1, pp.1-11, 2011 (Released:2012-03-17)

参考文献数

24

被引用文献数

1 1

---

Energy security was a major concern for OECD governments in the early 1970s. Since then, successive oil crises, volatility of hydrocarbon prices, as well as terrorist risks and natural disasters, have brought the issue back to the centre stage of policy agendas. Here, an energy security concept has been proposed, which is defined by time frame and space frame as well. Wide-meaning energy security is divided broadly into two categories. One is short-term (∼10 y) energy crisis, which is narrow-meaning energy security. Short-term energy crisis is further divided into contingent crisis, such as energy supply chain (sealane) interruption due to conflict, accident, terrorism, etc., and structural crisis, such as price fluctuations, supply shortage, energy demand increase in Asia, technology development stagnation, etc. The other is long-term (∼100 y) energy crisis and global energy problems, such as fossil fuel exhaustion and global warming.

著者

田川 明広

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.11, no.2, pp.111-117, 2012 (Released:2012-05-15)

参考文献数

6

被引用文献数

2 3

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The Japan Atomic Energy Agency decontaminated schools, playgrounds, swimming pools, and houses in nonevacuated, less-contaminated areas in Fukushima for environmental restoration. A small, 150 m2 playground lot in the residential area was chosen for decontamination demonstration, which used routinely available tools and commodities to carry out the work. The surfaces of playground lot equipment, such as swings, slides, and horizontal iron bars, were completely decontaminated by brushing with water and/or detergent. Side gutters around the playground lot were cleaned by removing the mud and then brushed and washed with a high-pressure water jet (7 MPa). The air dose rate at the playground lot was dominated by radiation from the ground surface and adjacent surroundings, such as apartments and rice fields. Two or three centimeters of the surface soil contaminated with cesium was removed manually with shovels, hoes, and other gardening tools. This significantly reduced the average air dose rate of the entire playground lot from 1.5 μSv/h before decontamination to 0.6 μSv/h. These results showed that ground surface decontamination can contribute measurably to the reduction in air dose rate in relatively small areas in residential areas.

著者

長縄 弘親 熊沢 紀之 斉藤 浩 柳瀬 信之 三田村 久吉 永野 哲志 鹿嶋 薫 福田 達也 吉田 善行 田中 俊一

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.227-234, 2011 (Released:2011-11-30)

参考文献数

7

被引用文献数

4 6

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We tried the decontamination of surface soils for three types of agricultural land at Nagadoro district of Iitate-mura (village) in Fukushima Prefecture, which is highly contaminated by deposits of radionuclides from the plume released from the Fukushima Daiichi nuclear power plant. The decontamination method consisted of the peeling of surface soils solidified using a polyion complex, which was formed from a salt solution of polycations and polyanions. Two types of polyion complex solution were applied to an upland field in a plastic greenhouse, a pasture, and a paddy field. The decontamination efficiency of the surface soils reached 90%, and dust release was effectively suppressed during the removal of surface soils.

著者

熊谷 友多 永石 隆二 木村 敦 田口 光正 西原 健司 山岸 功 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

pp.1109220008, (Released:2011-09-27)

参考文献数

15

被引用文献数

3 3

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Zeolite is used for decontamination of radioactive water containing salts from seawater in the Fukushima Dai-ichi Nuclear Power Station. Evaluation of hydrogen production by water radiolysis during the process is important for a safe operation. Thus, hydrogen production from the mixture of zeolite and seawater was studied by γ-radiolysis experiment, and the hydrogen production during the process was evaluated. The measured yield of hydrogen from seawater was comparable to the primary yield in the γ-radiolysis of water. This result indicates that oxidation of hydrogen by radical products of water radiolysis is not effective in seawater. The measured yield from the mixture decreased at a high weight fraction of zeolite. However, the measured yield was higher than that expected from the direct radiolysis of water in the mixture, which would decrease proportionally to the weight fraction of water. This result suggests that the radiation energy deposited on zeolite is involved in hydrogen formation. From the measured yields, the hydrogen production rate was evaluated to be 3.6 mL/h per ton of radioactive water before the process and 1.5 L/h per ton of the waste adsorbent after the process.

著者

尾方 義人 川崎 和男

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.5, no.1, pp.76-80, 2006-03-25 (Released:2010-03-08)

参考文献数

19

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The expected nuclear powered battery is the isotope battery, which applies photoconduction or radiant rays, in other words, releases electron. Because of its lightweight and constant stability and 80 years long (=half time of radiant rays energy) running span, this battery is very effective for artificial satellites, desert island, and artificial hears. For this small battery, production method, waste disposal method, and emergency risk management need to be designed as international standards. To make that possible, design of the battery should achieve universal consensus with its form and shape. True meaning of peace could be shared worldwide, this isotope battery will be international standard.And, On this research as Design Development of Thermoelectric Generator by Design Engineering, we used a "Design Activities Theory" in which the activities involved in Knowledge Management and Project Management aimed at ensuring the efficiency of that Knowledge Management function as a single system.

著者

石川 浩康 宮原 信哉 吉澤 善男

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.452-461, 2008 (Released:2012-03-02)

参考文献数

7

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Supercritical carbon dioxide (CO2) is being investigated as a material for a secondary cooling system of sodium (Na)-cooled fast reactor to avoid Na/water reaction. In this type of reactor, however, it is necessary to consider the consequences of Na/CO2 reaction, which might occur in the case of tube rupture in a heat exchanger between primary and secondary systems. Experiments were carried out with test equipment for the Na/CO2 reaction, which can handle 1-5 g order of Na and measure temperatures using thermocouples. The solid products of the Na/CO2 reaction sampled from the equipment were analyzed by X-ray diffraction (XRD) and chemical analysis. The parts of exhaust gases were analyzed by gas chromatography. From these experimental results, we proved that the reaction proceeded between liquid Na and CO2. The Na/CO2 reaction stopped only the pool surface reaction with a small quantity of aerosol emission when the initial temperature of Na was lower than 570°C. On the other hand, the reaction continuously proceeded with an orange-colored flame and aerosol release when the Na initial temperature was higher than 580°C, and the reaction products expanded to the margin of the Na pool tray.

著者

木村 謙仁 柴田 智文 松尾 雄司 村上 朋子

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.21, no.1, pp.15-26, 2022 (Released:2022-02-15)

参考文献数

20

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In this study, we perform model analyses assuming the Japanese power supply portfolio in 2050 to evaluate the economic efficiency of nuclear power generation under mass introduction of variable renewable energy (VRE) ― such as solar PV and wind ― and of hydrogen power generation in 2050. As a result, this study shows that even if the unit cost of VRE falls significantly by 2050, not only existing nuclear power plants, but also new construction, will have economic efficiency. Its benefit would become much larger when 100% carbon-free generation is mandated, but in that case, the role of nuclear energy as the base load power generation would be changed. On the other hand, in the case where hydrogen power generation will be deployed, the nuclear energy would be smaller than those in other 100% carbon-free cases, but its base load operation would be maintained.

著者

吉田 昌弘 遠藤 章 佐藤 滋朗 大畑 勉 渡辺 正敏 大山 柳太郎 古屋 廣高

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.4, no.3, pp.213-218, 2005-09-25 (Released:2009-04-21)

参考文献数

16

被引用文献数

1 1

---

A number of consumer's goods which contain natural uranium and thorium are circulated in the familiar living environment. Based on various kinds of information sources, 20 kinds of these consumer's goods were collected and their radioactive concentrations were measured by using ICP-MS and Ge semiconductor detector. As this result, it was found that the concentrations of uranium and thorium in the consumer's goods used at home and industries were below 34Bq/g and below 270Bq/g, respectively. Next, the concentrations of daughter nuclides were not so different from the ones of uranium or thorium, which showed that the secular radioactive equilibrium held between both concentrations.In addition, the radiation exposures for public consumer were evaluated when four kinds of typical consumer's goods frequently used in daily life are utilized. The results computed by MCNP-4C code were below 250μSv/y.

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

谷村 嘉彦 平山 英夫 近藤 健次郎 永田 寛 岩永 宏平 鈴木 征四郎

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.15, no.3, pp.129-132, 2016 (Released:2016-08-15)

参考文献数

6

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Photon energy spectra were measured above the operating floor of unit 3 reactor at the Fukushima Daiichi Nuclear Power Station by using a CdZnTe semiconductor spectrometer. The spectrometer was installed in a lead collimator to measure the photons from the area directly below the detector. The collimator and spectrometer were lifted up by a huge crane and set above the operating floor. The photon spectra were derived by unfolding the pulse height spectra measured using the spectrometer. The response function of the spectrometer was calculated with the MCNP-4C code and was used as an input parameter of the unfolding code MAXED. It was found from the photon energy spectra that low-energy photons with energy below 0.4 MeV were dominant above the operating floor. These spectra are fundamental data for evaluating the dose reduction effect by setting up shields on the operating floor.

著者

酒谷 圭一 中谷 隆良 船橋 英之

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.18, no.1, pp.43, 2019-03-01 (Released:2019-01-30)

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理由:日本原子力学会和文論文誌 Vol.14, No.4, p.261-267 (2015)掲載論文に用いた腐食速度の算出にかかる水素発生データについては,データ取得の信頼性について問題があることが判明したため本誌より撤回する。一般社団法人 日本原子力学会編集委員会論文誌編集長 矢野豊彦

著者

安藤 真樹 松田 規宏 斎藤 公明

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.16, no.2, pp.63-80, 2017 (Released:2017-05-15)

参考文献数

29

被引用文献数

21

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In order to determine the contribution of radioactive cesium due to the Fukushima Daiichi nuclear power plant accident to the ambient dose equivalent rates measured by car-borne surveys, natural background radiation was evaluated for eastern Japan as municipality-averaged values. The window count method for the distinction between natural and artificial radioactive nuclides was applied to car-borne surveys using KURAMA–II. The distribution of the evaluated natural background radiation reflected geological features, and it was found that the radiation measured along paved roads reflected the distribution of terrestrial gamma rays. The contribution of the radioactive cesium as of 2014 for the municipalities designated as the Intensive Contamination Survey Area was beyond the uncertainty of the natural background radiation. That for the other municipalities, however, was found to be almost negligible.

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

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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

牟田 仁 古屋 治 村松 健

出版者

一般社団法人 日本原子力学会

雑誌

日本原子力学会和文論文誌 (ISSN:13472879)

巻号頁・発行日

vol.15, no.2, pp.70-83, 2016 (Released:2016-05-15)

参考文献数

15

被引用文献数

2

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One of the most important issues of the current PRA methodology is the precise modeling of dynamic changes such as state transitions among several states including fault(s) or maintenance of the nuclear facility, safety-related systems or components by fault-tree analysis and event-tree analysis. Moreover, though safety-related systems are usually in the stand-by state during normal operating conditions of a nuclear power plant, modeling of the dynamic changes in safety functions, along with changes in component failure rates due to the aging effect in the stand-by state or continuous/intermittent effects originating from external hazards, is also carried out under the same situation. On the basis of the background described above, the authors proposed a reliability analysis methodology of using the Markov state transition model applied to the digital reactor protection system of an ABWR plant, and demonstrated the applicability of the developed methodology using the component failure modes discussed in DIGREL, the task group of WGRisk belonging to OECD/NEA/CSNI. These studies showed that the PRA methodology including the state transition model can consider state transitions of components and time-dependent changes in component failure rates, and the relationship between this methodology and minimal cut sets for calculating the core damage frequency was also clarified.