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JAEA Reports

Fuel unloading work in decommissioning of the prototype fast breeder reactor Monju; First stage of Monju decommissioning project

Shiota, Yuki; Kudo, Junki; Tsuno, Hiromi; Takeuchi, Ryotaro; Ariyoshi, Hideo; Shiohama, Yasutaka; Hamano, Tomoharu; Takagi, Tsuyohiko; Nagaoki, Yoshihiro

JAEA-Technology 2023-002, 87 Pages, 2023/06

JAEA-Technology-2023-002.pdf:8.53MB

In the first stage of Monju decommissioning project, fuel unload work began to be carried out. There are two tasks in this work. One is Fuel Treatment and Storage work that gets rid of sodium on the fuel assemblies unloaded from Ex-Vessel fuel Storage Tank (EVST) and carries it in the storage pool, and the other is Fuel Unloading that the fuel assemblies in the reactor core is replaced with dummy fuels and stored in EVST. Fuel Treatment and Storage work and Fuel Unloading work are performed alternately, and 370 fuel assemblies in the core and 160 fuel assemblies in EVST are all carried to the storage pool. Monju had a large amount of sodium in the reactor vessel and EVST, and there was a residual risk of fuel failure due to the superposition of a large scale sodium fire. Therefore, in the first stage of the Monju decommissioning project, it was decided to take about 5.5 years to remove the residual risk by storing all the fuel rods in the fuel storage pool. There are few Fuel handling system of Sodium Fast Reactor in the world, so the driving record and experience are not enough. So, events that occur even if taken measure are assumed. The following three events apply to this; first, events that are difficult to prevent, events. Second, that are due to lack of experience, and final, events optimization of system is not enough. Plans were taken to suppress these events. This report summarizes the "Monju decommissioning project" work conducted so far in all four campaigns.

JAEA Reports

Fuel Unloading Operations -2019- in the decommissioning of prototype fast breeder reactor "Monju"

Yabe, Takanori; Murakami, Makio; Shiota, Yuki; Isobe, Yuta; Shiohama, Yasutaka; Hamano, Tomoharu; Takagi, Tsuyohiko; Nagaoki, Yoshihiro

JAEA-Technology 2022-002, 66 Pages, 2022/07

JAEA-Technology-2022-002.pdf:10.45MB

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 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 Ex-Vessel fuel Storage Tank. "Fuel Treatment and Storage" and "Fuel Unloading" are performed alternately until 370 fuel assemblies in the core and 160 fuel assemblies in the Ex-Vessel fuel Storage Tank are all transferred to the storage pool. In fiscal 2018, as "Fuel Treatment and Storage", 86 fuel assemblies were transferred to the storage pool. As "Fuel Unloading", 76 dummy fuel assemblies were stored in the Ex-Vessel fuel Storage Tank. In fiscal 2019, as "Fuel Unloading", 60 fuel assemblies and 40 blanket fuel assemblies were unloaded from the core. These assemblies were stored in the Ex-Vessel fuel Storage Tank, and dummy fuel assemblies were loaded into the core instead. During these operations, a total of 38 cases of alarming or equipment malfunctions classified into 24 types occurred. However, no significant events that menaces to safety have occurred. The operations were continued safely by removing the direct factors for the malfunctions in the equipment operation and performance.

JAEA Reports

Fuel unloading work in decommissioning of the prototype fast breeder reactor Monju; Fuel treatment and storage work in 2018 and 2019

Shiota, Yuki; Yabe, Takanori; Murakami, Makio; Isobe, Yuta; Sato, Masami; Hamano, Tomoharu; Takagi, Tsuyohiko; Nagaoki, Yoshihiro

JAEA-Technology 2022-001, 117 Pages, 2022/07

JAEA-Technology-2022-001.pdf:25.55MB

In the first stage of Monju decommissioning project, fuel unload work began to be carried out. There are two tasks in this work. One is fuel treatment and storage work that gets rid of sodium on the fuel assemblies unloaded from Ex-Vessel fuel Storage Tank (EVST) and carries it in the storage pool, and the other is fuel unloading that the fuel assemblies in the reactor core is replaced with dummy fuels and stored in EVST. Fuel treatment and storage work and fuel unloading work are performed alternately, and 370 bodies in the core and 160 pieces in EVST are all carried to the storage pool. 86 fuel assemblies was carried to the storage pool in fuel treatment and storage work in 2018 and 76 dummy fuels were stored in EVST for fuel unloading work. During the work, 86 types and 232 alarms / malfunctions occurred, but there was no impact on safety. There was one equipment's failure at gripper's claw open / close clutch of ex-vessel fuel transfer machine B, but it was repaired and restarted. Also it was eliminated the cause of problem or concession that the equipment failure due to the sticking of the sodium compound and continuous use of the equipment. Some problems related to system control occurred, but the work was done after checking the safety. With estimation of various troubles, reduction of frequency of trouble occurrence and minimization of impacts on schedule performed.

Journal Articles

Status of decommissioning for prototype ATR Fugen and FBR Monju

Ito, Kenji; Kondo, Tetsuo; Nakamura, Yasuyuki; Matsuno, Hiroki; Nagaoki, Yoshihiro; Sakuma, Yuichi

Dekomisshoningu Giho, (63), p.1 - 26, 2022/05

The prototype advanced thermal reactor Fugen entered into the decommissioning phases with the approval of the decommissioning plan in February 2008. The prototype fast breeder reactor Monju entered into the decommissioning stage with the approval of the decommissioning plan in March 2018. In April 2018, the head office of Tsuruga decommissioning demonstration was newly established to oversee the decommissioning operations in Tsuruga area, and decommissioning projects for two unique reactors have progressed safely and steadily.

Journal Articles

Overview of Fast Reactor Cycle System Technology Development Project (FaCT) phase 1 and future direction

Ieda, Yoshiaki; Ono, Kiyoshi; Negishi, Hitoshi; Shiotani, Hiroki; Nagaoki, Yoshihiro; Namba, Takashi

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 9 Pages, 2011/12

Since 1999, Japan Atomic Energy Agency (JAEA) has promoted R&D of the Fast Breeder Reactor Cycle in order to build the practical concepts and establish the technical systems, in cooperation with related entities. In the first 5-year of the Fast Reactor Cycle System Technology Development Project (FaCT), namely the FaCT phase1 (JFY2006-2010), the evaluation of the achievement degree to the performance target fixed by the Atomic Energy Commission and the adoption judgment of the innovative technology at present were carried out with "Sodium-cooled Fast Reactor with MOX fuel, advanced aqueous reprocessing process, and simplified MOX pellet fabrication process". FaCT phase1 moved forward almost smoothly and confirmed that the project will be able to enter the next phase to demonstrate the innovative technology by the engineering scale examination. The concrete results of the FaCT phase1 and future direction are introduced in the full paper.

Journal Articles

Status and prospects of the FaCT project

Nagaoki, Yoshihiro; Kikuchi, Shin; Ichimiya, Masakazu

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

"Fast Reactor Cycle Technology Development (FaCT)" project has been conducted since 2006. In this project, design study and research and development (R&D) on innovative technologies for fast reactor (FR) cycle system are implemented in order to present the conceptual designs of commercial and demonstration facilities by 2015 and start operating demonstration fast reactor in 2025. The R&Ds has been stepped forward into the development stage to establish the realization of innovative technologies which bring excellent performance to fast reactor cycle system. The purpose of R&D by 2010 is to decide weather innovative technologies shall be adopted. So promoting R&D of FR, the project governance was organized. Furthermore, several possible R&D have been effectively carried out within the frameworks of international cooperation, such as GNEP, GIF, and INPRO.

Journal Articles

Toward commercialization of FBR cycle, 1

Nagaoki, Yoshihiro; Nagura, Fuminori; Sakaguchi, Tomoyoshi; Kawasaki, Hirotsugu; Kikuchi, Shin

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 50(9), p.551 - 556, 2008/09

"Fast Reactor Cycle Technology Development (FaCT)" project has been conducted since 2006. In this project, design study and research and development (R&D) on innovative technologies for fast reactor (FR) cycle system are implemented in order to present the conceptual designs of commercial and demonstration facilities by 2015 and start operating demonstration fast reactor in 2025. The R&Ds has been stepped forward into the development stage to establish the realization of innovative technologies which bring excellent performance to fast reactor cycle system. The purpose of R&D by 2010 is to decide weather innovative technologies shall be adopted. So promoting R&D of FR, the project governance was organized. Furthermore, several possible R&D have been effectively carried out within the frameworks of international cooperation, such as GNEP, GIF, and INPRO.

Journal Articles

Celebration of 30th anniversary of the experimental fast reactor Joyo

Nakai, Satoru; Aoyama, Takafumi; Ito, Chikara; Yamamoto, Masaya; Iijima, Minoru; Nagaoki, Yoshihiro; Kobayashi, Atsuko; Onoda, Yuichi; Ohgama, Kazuya; Uwaba, Tomoyuki; et al.

Kosoku Jikkenro "Joyo" Rinkai 30-Shunen Kinen Hokokukai Oyobi Gijutsu Koenkai, 154 Pages, 2008/06

no abstracts in English

Journal Articles

Current status and prespective of FBR cycle development

Sagayama, Yutaka; Nagaoki, Yoshihiro

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 50(6), p.363 - 367, 2008/06

The Japan Atomic Energy Agency is developing the FBR Cycle that is the combination of a sodium cooled FBR (oxide fuel), an advanced aqueous reprocessing and a simplified pelletizing as "Key Technology of National Importance". From now on, the JAEA invests the development resource to a major concept intensively, and aims to put it to practical use by new project, "FaCT". With "FaCT" project, the adoption of innovative technology is going to be judged in 2010. The result of "Fact" are going to be presented in 2015 that is the systematized technologies based on R&D and the conceptual designs of demonstration facility and commercial facility. In order to start the demonstration reactor operation in 2025 by the result of "FaCT", the project is carried with international cooperation.

Journal Articles

History and current status regarding the research and development of minor actinide recycling

Nagaoki, Yoshihiro; Nakai, Ryodai

Genshiryoku eye, 53(1), p.58 - 61, 2007/01

The technology which separates the minor actinide from the high level radioactive waste and utilizes it as the nuclear fuel called "Minor Actinide (MA) Recycling." It explained that the significance of MA recycling, the history and current status of R&D and the major challenges. From the next time, the manufacturing technology development of MA content nuclear fuel, the irradiation test of MA content nuclear test fuel in the experimental reactor JOYO and the future program to strive to commercialization will be shown.

Journal Articles

None

Ono, Katsumi; masato, ando; Kotake, Shoji; Nagaoki, Yoshihiro; Namba, Takashi; Kato, Atsushi; Nakai, Ryodai; Negishi, Hitoshi

Nihon Genshiryoku Gakkai-Shi, 46(10), 685 Pages, 2004/10

A panoramic sensitivity analysis approach based on a statistic sampling method has been developed and applied for preliminary analysis on geological disposal of TRU waste considering variety of geological conditions and uncertainty. This approach can identify the parameters with the high importance for safety assessment and can extract the successful conditions for safety geological disposal.

Journal Articles

PROSPECTS AND PROGRESS STATUS OF THE ADVANCED FUEL CYCLE SYSTEM IN JAPAN

Namba, Takashi; Nagaoki, Yoshihiro; Sagayama, Yutaka

011-03, 0 Pages, 2004/06

Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.

Journal Articles

Prospects and Progress Status of the Advanced Fuel Cycle System in Japan

Namba, Takashi; Funasaka, Hideyuki; Nagaoki, Yoshihiro; Sagayama, Yutaka

Proceedings of International Conference ATALANTE 2004 Advances for Future Nuclear Fuel Cycles (CD-ROM), 0 Pages, 2004/00

Experimental Study on Temperature Fluctuation Phenomena at T-pipe Junction(6)

Journal Articles

Present Status and Prospects in the FR Fuel Cycle System in Japan

Nakajima, Yasuo; Funasaka, Hideyuki; ; Nagaoki, Yoshihiro

Proceedings of 11th International Conference on Nuclear Engineering (ICONE-11) (CD-ROM), 0 Pages, 2003/00

Journal Articles

Nuclear Proliferation Resistance on Future FBR Cycle System

Ojima, Hisao; Nagaoki, Yoshihiro

INMM/ESARDA Workshop, 0 Pages, 2000/00

None

JAEA Reports

Burn-up reactivity measurements of the Joyo MK-II core

; Nagaoki, Yoshihiro

PNC TN9410 97-022, 34 Pages, 1997/02

PNC-TN9410-97-022.pdf:1.05MB

The core averaged burn-up reactivity has been measured and calculated for the Joyo MK-II core. In order to evaluate the relationship between the calculational error of burn-up reactivity and the nuclear data or calculated neutron flux, the burn-up reactivity for an individual fuel subassembly(S/A) must be measured. So the burn-up reactivity measurement test was conducted on the MK-II core. The burn-up reactivity for a driver fuel S/A was measured as a substitution reactivity worth between two S/As at different burn-ups. In the test a fuel S/A with a burn-up of 1 GWd/t was substituted by two S/As with 37 and 62 GWd/t, respectively. The substitutions were carried out at the core center(row 0), middle of the fuel region(row 2)and the border region of the fuel and reflector(row 4). The calculated burn-up reactivity worth performed by the core management code system "MAGI" was compared with the measured value. The results obtained were as follows: (1)Measured substitution reactivity worth(at row 0) between 1 and 37 GWd/t fuel S/A was -0.19%$$Delta$$k/kk' and that between 1 and 62 GWd/t was -0.28%$$delta$$k/kk'. (2)Relative distribution of the reactivity worth between 1 and 37 GWd/t agreed with that between 1 and 62 GWd/t. The relative value normalized at core center was 0.67 for the row 2 and 0.28 for the row 4. (3)The C/E value was 1.03$$sim$$1.05 for the substitution between 1 and 37 GWd/t and 0.94$$sim$$0.95 between 1 and 62 GWd/t at the row 0 and 2. It was clear that the C/E values at the row 4 are higher than those at the row 0 and 2 by 5$$sim$$7%. An analysis of the burn-up dependency on the C/E value of the burn-up reactivity worth is being performed in detail. Presents, the PIE of the fuel S/A used for the measurement is under way.

Oral presentation

Preparation for dismantling Monju

Nagaoki, Yoshihiro

no journal, , 

The Japanese government decided to decommission Monju on December, 2016.

Oral presentation

Current status of Monju decommissioning

Nagaoki, Yoshihiro

no journal, , 

no abstracts in English

Oral presentation

Consultancy Meeting on preparation for the International Workshop on policy and strategy for decommissioning of research reactors & fast reactors and management of spent fuel

Nagaoki, Yoshihiro; Sekine, Takashi

no journal, , 

According to the Backend Roadmap, JAEA is proceeding with the decommissioning of research facilities. Monju is proceeding with defueling work, and Joyo is preparing to restart. Thought Japan is promoting the nuclear fuel cycle, the future power supply has uncertain. Therefore, it is necessary to strategically manage the spent fuel of the fast reactor.

Oral presentation

Sodium extraction and transport

Nakashita, Tomohiro; Tanigaki, Takanori; Nagaoki, Yoshihiro; Matsui, Kazuaki; Hayashi, Takehiro; Sato, Takeshi

no journal, , 

no abstracts in English

22 (Records 1-20 displayed on this page)