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

古野 朗子 茅野 政道 山澤 弘実

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.3, pp.229-240, 2006-09-25 (Released:2010-01-21)

参考文献数

20

被引用文献数

7 7

---

This paper describes a method of estimating source term, i.e., location, period and amount of atmospheric release of radioactive material in real-time during nuclear emergency. This method consists of: (1) trial simulations of atmospheric dispersions on the possible combinations of these parameters and (2) statistical comparison of model predictions with offsite measurements of air concentrations of radionuclides and/or air dose rates from monitoring stations, to find a set of release condition providing model prediction that fits best to the measurement. A parallel execution method for efficiently processing many possible initial conditions is also developed. The performance of this method is favorably evaluated by a verification study using the dataset from European Tracer Experiment.

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

中村 隆夫 中田 節也 岩田 吉左 小野 勤 濵﨑 史生

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.75-86, 2014 (Released:2014-08-15)

参考文献数

11

被引用文献数

2 4

---

Japan is one of the countries with abundant active volcanoes and has a long history of developing countermeasures to mitigate volcanic disasters. In the field of nuclear energy, it is also necessary to assess safety against volcanic hazards, and in 2009, a voluntary guideline was published as JEAG 4625 in order to set up requirements of site assessments and basic designs of nuclear power plants (NPPs). This guideline has been revised to satisfy the requirements for examining the necessity of considering volcanic phenomena and concrete countermeasures in detailed designs of NPPs. This paper focuses on the background and technical basis of this voluntary guideline and shows the basic policy to ensure the safety of NPPs and the requirements to prevent nuclear hazards due to volcanic phenomena based on the Defense in Depth Concept.

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

北田 淳子

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.12, no.3, pp.177-196, 2013 (Released:2013-08-15)

参考文献数

29

被引用文献数

3 9

---

In this study, the results of surveys conducted over the past 30 years were analyzed. The surveys include continuous opinion polls conducted by seven organizations, those conducted by eight news media one year after the Fukushima Daiichi accident, and those conducted by INSS fourteen times from 1993 to December 2011. The results were as follows: (1) Negative opinions toward nuclear power generation (NPG) suggesting “abolition or reduction”, which used to be 20-30% over the past 30 years, increased to 70% from four to six months after the accident, when there was also much news about renewable energy. (2) Even after the accident, 60% regarded NPG as “inevitable”, but many opposed future replacement or new construction of NPG facilities. (3) After the accident, recognition of the usefulness of NPG and concerns about electric power shortages in the near future remained unchanged, while anxiety and distrust toward NPG increased significantly. When considering power generation options, people now tend to focus on accident risks. (4) Nevertheless, people are neither aware of various possible problems caused by reducing NPG nor willing to accept a significant increase in electricity rate caused by the shift to renewable energy.

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

平山 英夫 松村 宏 波戸 芳仁 佐波 俊哉

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.14, no.1, pp.1-11, 2015 (Released:2015-02-15)

参考文献数

13

被引用文献数

2 9

---

Time histories of the I-131 concentration in air at monitoring posts in Fukushima prefecture in March 2011 were estimated using the pulse height distribution of a NaI(Tl) detector, which was opened to the public. Several corrections to the pulse height distribution were necessary owing to high count rates. The contribution to the count rates from I-131 accumulated around the monitoring post was estimated on the basis of the time history of the peak count rate by the method proposed by the authors. The concentrations of I-131 in air were converted from the peak count rates using the calculated response of the NaI(Tl) detector with egs5 for a model of a plume containing I-131 uniformly. The obtained time histories of the I-131 concentration in air at a fixed point in March 2011 were the first ones for Fukushima prefecture. The results at 3 monitoring posts, Naraha Town Shoukan, Hirono Town Futatunuma and Fukushima City Momijiyama, which can be analyzed during almost all of March, show that a plume including I-131 arrived after March 15. The results at other monitoring posts near Fukushima Daiichi Nuclear Power Station are used to characterize plume diffusion at the early period of the accident before March 15. The I-131 time-integrated concentrations in air at several monitoring posts were compared with those given in UNSCEAR 2013 ANNEX A, which were obtained using estimated time-dependent rates of release to the atmosphere. The agreement between the two results varies depending on the places compared, owing to the large uncertainties in the estimated release rate used in UNSCEAR. The results obtained in this study can be used to increase the accuracy of the time-dependent release rate estimation.

著者

大橋 弘史 佐藤 博之 國富 一彦 小川 益郎

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.13, no.1, pp.17-26, 2014 (Released:2014-02-15)

参考文献数

19

被引用文献数

1 5

---

A new safety concept in a high-temperature gas-cooled reactor (HTGR) was proposed to provide the most advanced nuclear reactor that exerts no harmful consequences on the people and the environment even if multiple failures in all safety systems occur. The proposed safety concept is that the consequence of the accidents is mitigated by the confinement of fission products employing not multiple physical barriers as in light water reactors, but only the cladding of fuel (i.e., the coating layers of the coated fuel particle). The progression of the events that lead to the loss or degradation of the confinement function of the coating layers (i.e., core heat up, oxidation of the coating layers, and explosion of carbon monoxide) is suppressed by only physical phenomena (i.e., the Doppler effect, thermal radiation and natural convection, formation of a protective oxide layer for coating layers of fuel, oxidation of carbon monoxide) that emerge deterministically as a cause of the events. The feasibility studies for severe events and related information revealed that the HTGR design based on this safety concept is technically feasible. This concept indicates the direction in which nuclear reactor research should be headed in terms of safety after the accident at the Fukushima Daiichi Nuclear Power Plant.

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

土田 辰郎 木村 浩

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.2, pp.132-143, 2011 (Released:2012-03-17)

参考文献数

21

---

Media coverage plays an important role in delivering information to the public in a rapid and easy-to-understand manner in terms of the subjects of nuclear energy. The mass media has so far covered nuclear accidents that occurred in nuclear facilities. The media coverage usually gains the attention of the public through the news media, such as TV and newspapers. In this study, three main cases of nuclear accidents were quantitatively examined by using the database of a newspaper. In addition, various comments of journalists whom the author interviewed were added for the evaluation of the three cases. As a result, it was revealed that the amount of media reporting commonly reached a maximum just after the nuclear accidents occurred. It became also clear that the smoothness of the information flow from the nuclear industry to the mass media affected the trend of the media coverage from the viewpoints of the duration and number of news reports. Most of the journalists considered that it was significant for the nuclear industry to strengthen the initial reaction on the occasion of nuclear accidents. The nuclear industry should understand the characteristics that are typical of the media coverage on nuclear accidents in the future.

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

平山 英夫 近藤 健次郎 海野 泰裕 松村 宏 岩瀬 広 柚木 彰 佐々木 慎一

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.J14.048, (Released:2015-06-30)

参考文献数

16

被引用文献数

1

---

A rapid and simple method to measure the concentration of 90Sr in water by measuring β-rays from 90Y was presented. Under the situation that 90Sr/90Y, 134Cs and 137Cs are the main radionuclides included in the water sample, only β-rays from 90Y can transmit through 1.5-mm-thick polyethylene. From this fact, it is possible to measure β-rays from 90Y using a β-ray detector, such as the GM-counter, set beneath the 1.5-mm-thick bottom of the water bottle containing the sample with 90Sr/90Y. The acrylic resin collimator having 0 cm, 1.00 cm, 1.50 cm or 3.00 cm diameter was made to detect β-rays at the fixed region of the GM-counter used. Contributions from bremsstrahlung produced by β-rays and γ-rays from radionuclides such as 134Cs and 137Cs/137mBa are removed by subtracting the count rate measured with a 1.00 cm acrylic resin collimator without a hole as the background count rate. The developed method was studied using the bottle routinely used at the Fukushima Daiichi Nuclear Power Station. It was confirmed that the developed method can be applied to measure the 90Sr concentration in water to the order of several Bq/cm3 if 134Cs and 137Cs concentrations are less than or equal to the 90Sr/90Y concentration.

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

玉田 正男 瀬古 典明 笠井 昇 清水 隆夫

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.4, pp.358-363, 2006-12-25 (Released:2010-01-21)

参考文献数

12

被引用文献数

51 54

---

Uranium cost in the annual collection of 1, 200t-U from seawater was evaluated by using the recovery system of braid type adsorbents synthesized by radiation-induced graft polymerization. The total cost was calculated by summating those in the processes of adsorbent production, uranium recovery, and elution and purification. When the adsorbent performance increased from 2g-U/kg-adsorbent (ad) to 6g-U/kg-ad, the cost of each process decreased in the same way. The increment of adsorbent durability of 6 times to 60 times reduced the process cost of adsorbent production especially. In the current state of 2g-U/kg-ad and 6 times usage of adsorbent, the uranium from seawater cost 90, 000yen/kg-U. The uranium cost becomes 25, 000yen/kg-U in the promising performance of 4g-U/kg-ad and 18 times usage of adsorbent.

著者

町田 昌彦 岩田 亜矢子 山田 進 乙坂 重嘉 小林 卓也 船坂 英之 森田 貴己

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.33-49, 2022 (Released:2022-02-15)

参考文献数

53

被引用文献数

4

---

We estimate the monthly discharge inventory of tritium from the port of Fukushima Daiichi Nuclear Power Plant (1F) from Jun. 2013 to Mar. 2020 using the Voronoi tessellation scheme, following the tritium monitoring inside the port that started in Jun. 2013. As for the missing period from the initial month, Apr. 2011 to May 2013, we calculate the tritium discharge by utilizing the ratio of tritium concentration to 137Cs concentration in stagnant contaminant water during the initial direct run-off period to Jun. 2011 and the discharge inventory correlation between tritium and 137Cs for the next-unknown continuous-discharge period up to May 2013. From all the estimated results over 9 years, we found that the monthly discharge inventory sharply dropped immediately after closing the seaside impermeable wall in Oct. 2015 and subsequently coincided well with the sum of those of drainage and subdrain etc. By comparing the estimated results with those in the normal operation period before the accident, we point out that the discharge inventory from the 1F port after the accident is not very large. Even the estimation for the year 2011 is found to be comparable to the maximum of operating pressurized water reactors releasing relatively large inventories in the number of digits. In the national level, the total domestic release inventory in Japan significantly decreased after the accident owing to the operational shutdown of most plants. Furthermore, 1F and even the total Japanese discharge inventory are found to be minor compared with those of nuclear reprocessing plants and heavy-water reactors on a worldwide level. From the above, we suggest that various scenarios can be openly discussed regarding the management of tritium stored inside 1F with the help of the present estimated data and its comparison with the past discharge inventory.

著者

平山 英夫 松村 宏 波戸 芳仁 佐波 俊哉

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.1, pp.1-14, 2017 (Released:2017-02-15)

参考文献数

11

被引用文献数

3 5

---

The Xe-135, I-131, I-132, I-133 and Te-132 concentrations in plumes at the monitoring posts in Fukushima prefecture in March 2011 were estimated using the pulse height distribution obtained from a NaI(Tl) detector, which were available to the public. Several corrections to the pulse height distribution were necessary owing to high count rates. The contribution to the count rates from each radionuclide except Xe-135 accumulated around each monitoring post was estimated using a method based on the time history of the peak count rate proposed by the authors. The concentration of each radionuclide in the plume was converted from the peak count rate using the response of the NaI(Tl) detector calculated with the egs5 code for a model of a plume containing a uniform distribution of radionuclides. The obtained time histories of Xe-135, I-131, I-132, I-133 and Te-132 concentrations in air at a fixed point in March 2011 were the first ones for Fukushima prefecture. The results at five monitoring posts near Fukushima Daiichi Nuclear Power Station were used to characterize radionuclides in the plume before March 15, soon after the accident. The results at three monitoring posts, Naraha-town Shoukan, Hirono-town Futatsunuma and Fukushima-city Momijiyama, which were analyzed during almost all of March, were used to characterize radionuclides in the plume in the period after March 14. It was fourd that Xe-135 was dominant on March 12 and Te-132 increased from March 13. For the radionuclides of iodine, I-131, I-132 and I-133 were detected with almost the same concentration for the first few days after the reactor shutdown.