Background radiation monitoring via manned helicopter for application of technique of nuclear emergency response in the fiscal year 2021 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Sasaki, Miyuki; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Haginoya, Masashi*; Matsunaga, Yuki*; Akutsu, Yuichiro*; Hokama, Tomonori; et al.

JAEA-Technology 2022-028, 127 Pages, 2023/02

JAEA-Technology-2022-028.pdf:15.21MB

A large amount of radioactive material was released by the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company, caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011. After the nuclear disaster, airborne radiation monitoring via manned helicopter has been utilized to grasp rapidly and widely the distribution of the radioactive materials surrounding FDNPS. We prepare the data of background radiation dose, geomorphic characteristics and the controlled airspace surrounding nuclear facilities of the whole country in order to make effective use of the monitoring technique as a way of emergency radiation monitoring and supply the results during an accident of a facility. This report has summarized the knowledge noted above achieved by the aerial radiation monitoring around Ohi and Takahama nuclear power stations. In addition, the examination's progress aimed at introducing airborne radiation monitoring via an unmanned plane during a nuclear disaster and the technical issues are summarized in this report.

Fuel unloading operations -2020- in the decommissioning of the prototype fast breeder reactor "Monju"

Shiota, Yuki; Ariyoshi, Hideo; Shiohama, Yasutaka; Isobe, Yuta; Takeuchi, Ryotaro; Kudo, Junki; Hanaki, Shotaro; Hamano, Tomoharu; Takagi, Tsuyohiko

JAEA-Technology 2022-019, 95 Pages, 2022/09

JAEA-Technology-2022-019.pdf:7.59MB

In the first stage of "Monju" decommissioning project, "Fuel Unloading Operations" have been carrying out. The operations consists of two processes. The first process is "Fuel Treatment and Storage" is that the fuel assemblies unloaded from the Ex-Vessel fuel Storage Tank (EVST) are canned after sodium cleaning, and then transferred to the storage pool. The second process is "Fuel Unloading" that the fuel assemblies in the reactor core are replaced with dummy fuel assemblies and stored in the EVST. "Fuel Treatment and Storage" and "Fuel Unloading" are performed alternately until 370 fuel assemblies in the core and 160 fuel assemblies in the EVST are all transferred to the storage pool. This is a summary of "Fuel Unloading" in the third quarter of "Fuel Unloading Operation". In fiscal 2020, as "Fuel Unloading", 72 fuel assemblies and 74 blanket fuel assemblies were unloaded from the core, and stored in the EVST. From the EVST, 145 dummy fuel assemblies and 1 fixed absorber were loaded in the core instead. During these operations, a total of 36 cases alarming or equipment malfunctions classified into 4 types occurred. However, these events were estimated in advance, there were no significant events that menaces to safety of fuel assemblies and equipment. Therefore, there were no serious problem like fall of fuel assemblies and events that may affect schedule of the project like stick of gripper of ex-vessel fuel transfer machine. When equipment's work or performance fail, the operation continued with safety by elimination of causes of problem. Fuel handling system of Monju has function that is endemic to sodium cooling fast breeding reactor. Because continuous operations of fuel handling system with actual fuel assemblies start recently, we don't have as much experience as PWR and BWR. With estimation of various troubles, reduction of frequency of trouble occurrence and minimization of impacts on schedule performed.

Distinct variation of electronic states due to annealing in -type LaEuCuO and NdCuO

Asano, Shun*; Ishii, Kenji*; Matsumura, Daiju; Tsuji, Takuya; Kudo, Kota*; Taniguchi, Takanori*; Saito, Shin*; Sunohara, Toshiki*; Kawamata, Takayuki*; Koike, Yoji*; et al.

Physical Review B, 104(21), p.214504_1 - 214504_7, 2021/12

https://doi.org/10.1103/PhysRevB.104.214504

Background radiation monitoring using manned helicopter for application of technique of nuclear emergency response in the fiscal year 2019 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Sato, Kazuhiko*; Haginoya, Masashi*; Matsunaga, Yuki*; Kikuchi, Hikaru*; Ishizaki, Azusa; et al.

JAEA-Technology 2020-019, 128 Pages, 2021/02

JAEA-Technology-2020-019.pdf:15.75MB

A large amount of radioactive material was released by the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company, caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011. After the nuclear disaster, airborne radiation monitoring using manned helicopter has been utilized to grasp rapidly and widely the distribution of the radioactive materials around FDNPS. We prepare the data of background radiation dose, geomorphic characteristics and the controlled airspace around nuclear facilities of the whole country in order to make effective use of the monitoring technique as a way of emergency radiation monitoring and supply the results during accidents of the facilities. Furthermore, the airborne radiation monitoring has been conducted in Integrated Nuclear Emergency Response Drill to increase effectiveness of the monitoring. This report is summarized that the knowledge as noted above achieved by the aerial radiation monitoring around Higashidori nuclear power station, the nuclear fuel reprocessing plant in Rokkasho village and Shika nuclear power station, the full details of the aerial radiation monitoring in Integrated Nuclear Emergency Response Drill in the fiscal 2019. In addition, examination's progress aimed at introduction of airborne radiation monitoring using unmanned helicopter during nuclear disaster and the technical issues are summarized in this report.

Water distribution in Nafion thin films on hydrophilic and hydrophobic carbon substrates

Ito, Kanae; Harada, Masashi*; Yamada, Norifumi*; Kudo, Kenji*; Aoki, Hiroyuki; Kanaya, Toshiji*

Langmuir, 36(43), p.12830 - 12837, 2020/11

https://doi.org/10.1021/acs.langmuir.0c01917

Development of the residual sodium quantification method for a fuel pin bundle of SFRs before and after dry cleaning

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Kato, Atsushi; Otaka, Masahiko; Ide, Akihiro*

Journal of Nuclear Science and Technology, 57(4), p.408 - 420, 2020/04

https://doi.org/10.1080/00223131.2019.1691069

In a fuel handling system of sodium-cooled fast reactors (SFRs), it is necessary to remove the sodium remaining on spent fuel assemblies (FAs) before storing them in a spent fuel water pool (SFP) in order to minimize plant operating loads. A next-generation SFR in Japan has adopted an advanced dry cleaning process which consists of the following steps, argon gas blowing to remove the metallic residual sodium on the FA, moist argon gas blowing to deactivate the residual sodium, and direct storage in the SFP. This three-step process increases economic competitiveness and reduces waste products thanks to a waterless process. In this R&D work, performance of the dry cleaning process has been investigated.

Background radiation monitoring using manned helicopter for application of technique of nuclear emergency response in the fiscal year 2018 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Komiya, Tomokazu; Iwai, Takeyuki*; Seguchi, Eisaku*; Matsunaga, Yuki*; Kawabata, Tomoki*; Haginoya, Masashi*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.

JAEA-Technology 2019-017, 95 Pages, 2019/11

JAEA-Technology-2019-017.pdf:12.09MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the FDNPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background radiation monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in the aerial monitoring around FDNPS against nuclear emergency response. The results of monitoring around Shimane and Hamaoka Nuclear Power Stations in the fiscal 2018 were summarized in this report. In addition, technical issues were described.

Dry cleaning process test for fuel assembly of fast reactor plant system, 1; Pilot scale test for fuel pin bundle

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Kato, Atsushi; Ishikawa, Nobuyuki; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki; Ide, Akihiro*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 10 Pages, 2019/05

A next generation SFR in Japan has adopted an advanced dry cleaning system which consists of the argon gas blowing process to reduce the amount of metallic residual sodium remaining on spent fuel assemblies. This paper describes experimental and analytical work focusing on the amount of residual sodium remaining on a fuel pin bundle before and after the argon gas blowing process. The experiments were conducted using a sodium test loop and a short specimen consisting of a 7 pin bundle. The effects of the blowing gas velocity and the blowing time were quantitatively analyzed in the experiments. On the basis of these experimental results, evaluation models predicting the amount of the residual sodium were constructed.

Background radiation monitoring using manned helicopter for establishment of technique of nuclear emergency response in the fiscal year 2017 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Iwai, Takeyuki*; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.

JAEA-Technology 2018-016, 98 Pages, 2019/02

JAEA-Technology-2018-016.pdf:18.64MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in Fukushima against nuclear emergency response. The results of monitoring around Tomari, Kashiwazaki-Kariwa and Genkai Nuclear Power Station in the fiscal 2017 were summarized in this report. In addition, technical issues were described.

Background radiation monitoring using manned helicopter for establishment of technique of nuclear emergency response in the fiscal year 2016 (Contract research)

Sanada, Yukihisa; Mori, Airi; Iwai, Takeyuki; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo; Sato, Yoshiharu; et al.

JAEA-Technology 2017-035, 69 Pages, 2018/02

JAEA-Technology-2017-035.pdf:32.92MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We carried out the background monitoring around the nuclear power stations of the whole country to apply a technique of the airborne radiation monitoring that is cultivated in Fukushima as a technology of nuclear emergency response. This result of the aerial radiation monitoring using the manned helicopter around Ooi, Takahama and Ikata Nuclear Power Station and in the fiscal 2016 were summarized in the report. In addition, technical issues were described.