著者

松村 宏 斎藤 究 石岡 純 上蓑 義朋

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.152-162, 2011 (Released:2011-07-29)

参考文献数

3

被引用文献数

18 18

---

In Fukushima and neighboring prefectures, the distributions of dose rate and γ-ray count rate of radionuclides from the Fukushima Daiichi Nuclear Power Station were measured on expressways on March 15, 16, 17, and April 8, 2011, using an NaI(Tl) detector and a LaBr3 detector. A radioactive plume that contained 133Xe, 132Te, 132I, 131I, 134Cs, and 136Cs was observed at Koriyama on the afternoon of March 15. The plume arrived in the Nakadori region of Fukushima prefecture, which is surrounded by two mountain ranges, and most of the radioactivity there was deposited by rainfall. Although the distributions of 132Te, 132I, 134Cs, 136Cs, and 137Cs were similar, the distribution of 131I was different from the others. The effective nuclides for the dose rate measurement were 132Te and 132I on March 15-17 and 134Cs and 137Cs on April 8. The initial distribution profile of the dose rate on March 15-17 was retained on April 8 because the deposited radioactive material was not moved from the initial location and there was no additional effective deposition of radioactivity.

著者

坂本 文徳 大貫 敏彦 香西 直文 五十嵐 翔祐 山崎 信哉 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

pp.1111290030, (Released:2011-11-30)

参考文献数

12

被引用文献数

8 10

---

The environmental behavior of radioactive Cs in the fallout from the accident of the Fukushima Daiichi Nuclear Power Plant has been studied by measuring its spatial distribution on/in trees, plants, and surface soil beneath the plants using autoradiography analysis. The results of autoradiography analysis showed that radioactive Cs was distributed on the branches and leaves of trees that were present during the accident and that only a small fraction of radioactive Cs was transported to new branches and leaves grown after the accident. Radioactive Cs was present on the grass and rice stubble on the soils, but not in the soils beneath the grass and rice stubble, indicating that the radioactive Cs was deposited on the grass and the rice plant. In addition, the ratio of the radioactive Cs that penetrated into the soil layer by weathering was very small two months after the accident. These results indicate that trees and other plants are the reservoir of the fallout Cs and function to retard the fallout Cs migration with rain water.

著者

西原 健司 山岸 功 安田 健一郎 石森 健一郎 田中 究 久野 剛彦 稲田 聡 後藤 雄一

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

pp.1202060058, (Released:2012-02-08)

参考文献数

15

被引用文献数

29 35

---

After the severe accident in the Fukushima-1 nuclear power plant, a large amount of contaminated stagnant water has been produced in turbine buildings and surrounding areas. This rapid communication reports the calculation of the radionuclide inventory in the core, the collection of the measured inventory in the stagnant water, and the estimation of the radionuclide release ratios from the core to the stagnant water. The present evaluation is based on data obtained before June 3, 2011. It was revealed that the release ratios of tritium, iodine and cesium were several tens of percent, while those of strontium and barium were smaller by one or two orders of magnitude. These release ratios of the Fukushima accident were equivalent to those of the TMI-2 accident.

著者

西原 健司 山岸 功 安田 健一郎 石森 健一郎 田中 究 久野 剛彦 稲田 聡 後藤 雄一

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.11, no.1, pp.13-19, 2012 (Released:2012-02-15)

参考文献数

15

被引用文献数

30 35

---

After the severe accident in the Fukushima-1 nuclear power plant, a large amount of contaminated stagnant water has been produced in turbine buildings and surrounding areas. This rapid communication reports the calculation of the radionuclide inventory in the core, the collection of the measured inventory in the stagnant water, and the estimation of the radionuclide release ratios from the core to the stagnant water. The present evaluation is based on data obtained before June 3, 2011. It was revealed that the release ratios of tritium, iodine and cesium were several tens of percent, while those of strontium and barium were smaller by one or two orders of magnitude. These release ratios of the Fukushima accident were equivalent to those of the TMI-2 accident.

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

pp.1109220007, (Released:2011-09-27)

参考文献数

7

被引用文献数

5 6

---

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

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

pp.1109220009, (Released:2011-09-27)

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

石川 奈緒 田上 恵子 内田 滋夫

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.8, no.4, pp.313-319, 2009 (Released:2012-02-22)

参考文献数

18

被引用文献数

2 1

---

Soil-to-plant transfer factor (TF) is one of the important parameters in radiation dose assessment models for the environmental transfer of radionuclides. Since TFs are affected by several factors, including radionuclides, plant species and soil properties, development of a method for estimation of TF using some soil and plant properties would be useful. In this study, we took a statistical approach to estimating the TF of stable strontium (TFSr) from selected soil properties and element concentrations in plants, which was used as an analogue of 90Sr. We collected the plant and soil samples used for the study from 142 agricultural fields throughout Japan. We applied a multiple linear regression analysis in order to get an empirical equation to estimate TFSr. TFSr could be estimated from the Sr concentration in soil (CSrsoil) and Ca concentration in crop (CCacrop) using the following equation: log TFSr=−0.88·log CSrsoil+0.93·log CCacrop −2.53. Then, we replaced our data with Ca concentrations in crops from a food composition database compiled by the Japanese government. Finally, we predicted TFSr using Sr concentration in soil from our data and Ca concentration in crops from the database of food composition.

著者

玉井 秀定 秋本 肇 高瀬 和之

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.11, no.1, pp.8-12, 2012 (Released:2012-02-15)

参考文献数

5

被引用文献数

1 1

---

The Fukushima Daiichi Nuclear Plant Unit 1 accident was investigated with the TRAC-BF1 code in order to confirm the effect of an isolation condenser (IC) on core cooling analytically. The analysis shows that the formation of two-phase natural-circulation flow is a key phenomenon for core cooling. Therefore, it is too late to cool fuel rods, once the core is heated up because of the lack of coolant. It also shows that the early start-up of the IC is essential for avoiding the core meltdown under station blackout conditions.

著者

玉井 秀定 秋本 肇 高瀬 和之

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.1201280043, (Released:2012-01-31)

参考文献数

5

被引用文献数

1 1

---

The Fukushima Daiichi Nuclear Plant Unit 1 accident was investigated with the TRAC-BF1 code in order to confirm the effect of an isolation condenser (IC) on core cooling analytically. The analysis shows that the formation of two-phase natural-circulation flow is a key phenomenon for core cooling. Therefore, it is too late to cool fuel rods, once the core is heated up because of the lack of coolant. It also shows that the early start-up of the IC is essential for avoiding the core meltdown under station blackout conditions.

著者

坂本 文徳 大貫 敏彦 香西 直文 五十嵐 翔祐 山崎 信哉 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.11, no.1, pp.1-7, 2012 (Released:2012-02-15)

参考文献数

12

被引用文献数

8 10

---

The environmental behavior of radioactive Cs in the fallout from the accident of the Fukushima Daiichi Nuclear Power Plant has been studied by measuring its spatial distribution on/in trees, plants, and surface soil beneath the plants using autoradiography analysis. The results of autoradiography analysis showed that radioactive Cs was distributed on the branches and leaves of trees that were present during the accident and that only a small fraction of radioactive Cs was transported to new branches and leaves grown after the accident. Radioactive Cs was present on the grass and rice stubble on the soils, but not in the soils beneath the grass and rice stubble, indicating that the radioactive Cs was deposited on the grass and the rice plant. In addition, the ratio of the radioactive Cs that penetrated into the soil layer by weathering was very small two months after the accident. These results indicate that trees and other plants are the reservoir of the fallout Cs and function to retard the fallout Cs migration with rain water.

著者

菅原 慎悦 城山 英明

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 = Transactions of the Atomic Energy Society of Japan (ISSN:13472879)

巻号頁・発行日

vol.9, no.4, pp.368-383, 2010-12-01

被引用文献数

1 2

---

In France, there exist organizations called "Commission Locale d'Information" (CLI) in all the siting areas where nuclear facilities located. Previously, the CLI organizations were established voluntarily by some local governments or nuclear utilities. Since 2006, however, the Nuclear Transparency and Safety Act has obliged the establishment of CLI in all the siting areas in conjunction with reforming the nuclear regulatory agencies. This means that the concerned local governments are officially part of nuclear safety regulation. In this study, we investigated present conditions of the CLI organizations through some interviews in France and consider their roles from the standpoint of nuclear regulatory governance. As a result, we found that the CLI plays the following roles: (1) medium of communication among concerned parties (not only between nuclear utilities and local habitants but also between the national nuclear regulatory agency and various local governments) and (2) implementing various activities in accordance with each local condition through the participation of local assembly members. In addition, we clarified that CLI's activities are supported by related institutional infrastructures, such as cost burden between central and local governments, and some other systems of citizen participation in building or expanding nuclear facilities.<br>

著者

山田 祥徳 酒井 幹夫 水谷 慎 越塚 誠一 大地 雅俊 室園 浩司

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.10, no.3, pp.185-193, 2011 (Released:2011-08-24)

参考文献数

21

被引用文献数

27 26

---

In nuclear engineering, fluid flows involving free surface were well studied, e.g., pipe thinning produced by liquid droplet impingement, and steam explosion triggered by molten metal immersed in water. The moving particle simulation (MPS) method was often used in past studies. In this method, the Poisson equation was solved to obtain the pressure field. Solving the Poisson equation becomes a dominant process. Reducing the time of calculation of the Poisson equation is important for using the CFD in the engineering fields. Thereat, we propose a new MPS method by which the pressure field is calculated explicitly. We call it the explicit (E-)MPS method. The E-MPS method was applied to a static water and dam break problem to show its adequacy. Besides, we compare the calculation time between the E-MPS method and traditional one.

著者

飯島 亨 安部 浩 鈴木 謙一

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.7, no.2, pp.99-111, 2008 (Released:2012-03-02)

参考文献数

9

---

The seismic probabilistic safety assessment (PSA) is an available method for evaluating the residual risk of nuclear plants, which are designed under definitive seismic design conditions. Our preliminary seismic PSA analysis has indicated that the malfunction of electric panels would have a significant influence on the core damage frequency (CDF). In recent years, there has been a growing desire to raise the reliability of the seismic PSA; thus, a higher seismic capacity of the electric panels is necessary. The Japan Nuclear Energy Safety Organization (JNES) tested eight kinds of main electric panels and thirty kinds of main electric parts at high acceleration, which considerably exceeds the design level. From the test results, JNES obtained precise seismic capacity data of the electric panels that have a significant effect on CDF. JNES also proposed a method of evaluating seismic capacity. The method can use the seismic capacity data of electric parts and the acceleration amplification ratios calculated from the FEM analysis. JNES expects that the seismic capacity data obtained from this study will increase the reliability of the seismic PSA.

著者

佐波 俊哉 佐々木 慎一 飯島 和彦 岸本 祐二 齋藤 究

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.163-169, 2011 (Released:2011-07-29)

参考文献数

6

被引用文献数

11 12

---

The time variations in the dose rate and γ spectrum of radio nuclides originating from the accident of Fukushima Daiichi Nuclear Power Station were measured at Tsukuba City, Ibaraki, during the period from 15th March to 9th April 2011. The radiation dose peaked three times during the period from 15th to 16th March (1.27 μSv/h at maximum). The contribution of Xe-133 to the dose rate was observed from the γ spectrum obtained from the 5 h measurement during the peaks on 15th and 16th March, indicating that radioactive plume passed through Tsukuba City at that time. After the peaks, a dose rate increase with rainfall was observed on 21th March, dominating the integral dose rate measured at Tsukuba City. The dose after the rainfall comes from I-131, Cs-134, and Cs-137 that can be observed as peaks in the spectra.

著者

加藤 和明

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.23, no.2, pp.111-115, 1981

---

An accidental loss of an RI radiation source, a sealed <SUP>90</SUP>Sr of 1mCi, which occurred at KEK in March, 1980, is reported. Actual dealing with it and lessons learned from it are also stated. In addition, problems in radiation control works at a public research laboratory for universities such as KEK are discussed.

著者

中田 翔治 高嶋 隆太 長野 浩司 木村 浩 班目 春樹

出版者

Atomic Energy Society of Japan

雑誌

日本原子力学会和文論文誌 = Transactions of the Atomic Energy Society of Japan (ISSN:13472879)

巻号頁・発行日

vol.9, no.3, pp.252-270, 2010-09-01

被引用文献数

3

---

Replacement of nuclear power plants has the possibility of affecting the management of electric power suppliers. Therefore, in the nuclear policy, a depreciation method as an equalization method, which means that part of the investment cost is accumulated as an allowance, and after the start of operation, the depreciation cost in the replacement project is equalized, has been introduced in Japan. In this paper, we evaluate the replacement of nuclear power plants by taking into account the uncertainty of operating costs and the depreciation cost in order to examine the effect of the depreciation method on the decision criteria of the replacement. We found that the equalization method is effective for inducing the acceleration of the replacement. Furthermore, we show the relationship between the uncertainty and the depreciation method. It turns out that as uncertainty increases, the difference in investment threshold between the equalization method and the existing depreciation method decreases, and that in option value increases.<br>

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

---

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

---

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

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

---

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

渡利 一夫 星野 忠也 木下 睦 岩島 清 本田 嘉秀

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.18, no.6, pp.336-345, 1976

---

原子力開発,それに伴う核燃料再処理工場の稼動,そして低レベル放射性廃液の海洋放出による環境汚染等の問題から放射性Ruの重要性が認識されている。本稿は,放射化学,核燃料再処理,保健物理あるいは海洋放射生態学等の分野における放射性Ruの研究の実情を,それぞれの観点からまとめたものである。