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Journal Articles

Difference in accumulation of plutonium and curium isotopes formed in americium targets irradiated in Joyo and JMTR

Onishi, Takashi; Koyama, Shinichi*; Yokoyama, Keisuke; Morishita, Kazuki; Watanabe, Masashi; Maeda, Shigetaka; Yano, Yasuhide; Oki, Shigeo

Nuclear Engineering and Design, 432, p.113755_1 - 113755_17, 2025/02

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

Evaluation of the production amount of $$^{225}$$Ac and its uncertainty through the $$^{226}$$Ra(n,2n) reaction in the experimental fast reactor Joyo

Sasaki, Yuto*; Sano, Aaru; Sasaki, Shinji; Iwamoto, Nobuyuki; Ouchi, Kazuki; Kitatsuji, Yoshihiro; Takaki, Naoyuki*; Maeda, Shigetaka

Journal of Nuclear Science and Technology, 61(4), p.509 - 520, 2024/04

 Times Cited Count:5 Percentile:73.39(Nuclear Science & Technology)

$$^{225}$$Ac is attracting attention as an alpha-emitting medical radioisotope. Since its demand is expected to increase, domestic production of $$^{225}$$Ac is required from the viewpoint of Japan's medical research and economic security. To establish the technical bases for the $$^{225}$$Ac production, JAEA has evaluated the radioactivity that can be produced in the experimental fast reactor Joyo and designed the concept that upgrades the existing facilities for transporting the irradiated target from Joyo to a neighboring PIE facility rapidly. Efficient $$^{225}$$Ac Separation from $$^{226}$$Ra irradiated in a fast reactor was studied. Ba and La were used as alternatives to Ra and Ac, respectively. By using DGA resin as an adsorbent, it can be expected that Ra and impurities generated by irradiation will be removed and Ac will be isolated. This study has revealed that Joyo can sufficiently produce $$^{225}$$Ac as a raw material for pharmaceuticals.

Journal Articles

Production of Ac-225 using the experimental fast reactor Joyo

Maeda, Shigetaka

Hoshasen Kagaku Furonteia, (5), P. 17, 2024/02

Regarding Actinium-225, which is one of the medical radioisotopes and has been attracting attention today, we will report on the domestic movement toward domestic production, the research and development plan and progress for production of Actinium-225 using the experimental fast reactor Joyo.

Journal Articles

Status of the $$^{226}$$Ra nuclear data library and its impact on the production amount of $$^{225}$$Ac via the $$^{226}$$Ra (n,2n) reaction

Sasaki, Yuto; Iwamoto, Nobuyuki; Takaki, Naoyuki*; Maeda, Shigetaka

Journal of Nuclear Science and Technology, 61(2), p.251 - 260, 2024/02

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

$$^{225}$$Ac is a promising alpha emitter for targeted alpha therapy. However, the current capability of $$^{225}$$Ac supply is limited to approximately 63 GBq/y, primarily relying on the natural source of $$^{229}$$Th stocked at a few institutes. Therefore, alternative $$^{225}$$Ac production methods are highly desired. The research and development of $$^{225}$$Ac and its parent nuclide production methods using accelerators and reactors to target $$^{226}$$Ra and $$^{232}$$Th are actively pursued worldwide. Hence, the authors focused on the $$^{226}$$Ra(n,2n) $$^{225}$$Ra method using fast neutron spectra as an application of the experimental fast reactor Joyo. This study investigated the status of nuclear data libraries for $$^{226}$$Ra, an essential target for $$^{225}$$Ac production, and evaluated the impact of different nuclear data libraries on the amount of $$^{225}$$Ac produced. Consequently, cross-sections with covariance data were stored in TENDL-2021, JEFF-3.3, and EAF-2010 but not in ENDF or JENDL, the major nuclear data libraries. Furthermore, no consistency occurred among the respective nuclear data, and the $$^{225}$$Ra production amount varied.

Journal Articles

Effect of $$^{226}$$Ra purity as a target for $$^{225}$$Ac production using a fast reactor

Sasaki, Yuto; Maeda, Shigetaka

Journal of Radioanalytical and Nuclear Chemistry, 333, p.5987 - 5996, 2024/02

 Times Cited Count:0 Percentile:0.00(Chemistry, Analytical)

Researchers are seeking alternative $$^{225}$$Ac production methods because of the scarcity of $$^{225}$$Ac for targeted alpha therapy. Although $$^{226}$$Ra from waste sources has been considered, obtaining $$^{226}$$Ra is challenging. Therefore, the authors focused on the contamination of minerals with $$^{232}$$Th-derived $$^{228}$$Ra while investigating methods to recover $$^{226}$$Ra from uranium ores. The effect of 228Ra contamination on $$^{225}$$Ac production by $$^{226}$$Ra transmutation using fast reactors was evaluated. Consequently, toxic $$^{228}$$Ac contaminates $$^{225}$$Ac. However, using the different half-lives of $$^{225}$$Ac and $$^{228}$$Ac, pure $$^{225}$$Ac can be obtained from the chemical separation of actinium after cooling for 5-8 days.

Journal Articles

JAEA's action on medical RI production using research reactor

Arai, Masaji; Maeda, Shigetaka

Rinsho Hoshasen, 68(10), p.963 - 970, 2023/10

Ac-225 is attracting attention as an alpha-emitting medical radioisotope. Since its demand is expected to increase, domestic production of Ac-225 is required from the viewpoint of Japan's medical research and economic security. To establish the technical bases for the Ac-225 production, JAEA has evaluated the radioactivity that can be produced in the experimental fast reactor Joyo and designed the concept that upgrades the existing facilities for transporting the irradiated target from Joyo to a neighboring PIE facility rapidly. Efficient Actinium-225 Separation from Ra-226 irradiated in a fast reactor was studied. This study has revealed that Joyo can sufficiently produce Ac-225 as a raw material for pharmaceuticals.

Journal Articles

Development and issues of fast reactor core materials

Kaito, Takeji; Otsuka, Satoshi; Yano, Yasuhide; Tanno, Takashi

Nuclear Materials Letters (Internet), p.29 - 43, 2022/12

no abstracts in English

Journal Articles

Production of $$^{225}$$Ac for Targeted Alpha Therapy (TAT) using the experimental fast reactor Joyo

Maeda, Shigetaka; Kitatsuji, Yoshihiro

Enerugi Rebyu, 42(10), p.19 - 22, 2022/09

Ac-225 is attracting attention as an alpha-emitting medical radioisotope. Since its demand is expected to increase, domestic production of Ac-225 is required from the viewpoint of Japan's medical research and economic security. To establish the technical bases for the Ac-225 production, JAEA has evaluated the radioactivity that can be produced in the experimental fast reactor Joyo and designed the concept that upgrades the existing facilities for transporting the irradiated target from Joyo to a neighboring PIE facility rapidly. Efficient Actinium-225 Separation from Ra-226 irradiated in a fast reactor was studied. Ba and La were used as alternatives to Ra and Ac, respectively. By using DGA resin as an adsorbent, it can be expected that Ra and impurities generated by irradiation will be removed and Ac will be isolated. This study has revealed that Joyo can sufficiently produce Ac-225 as a raw material for pharmaceuticals.

Journal Articles

Next generation reactor development and current status

Kamide, Hideki

Karyoku Genshiryoku Hatsuden, 71(11), p.638 - 648, 2020/11

Development status of next generation reactors is outlined mainly for sodium cooled fast reactor developed in Japan Atomic Energy Agency (JAEA). Development strategy in Japan, status of the advanced reactor developments including SMR over the world, and also results of research and development in JAEA are explained.

Journal Articles

Measurement of niobium reaction rate for material surveillance tests in fast reactors

Ito, Chikara; Maeda, Shigetaka; Inoue, Toshihiko; Tomita, Hideki*; Iguchi, Tetsuo*

Radiation Protection, 40(6), p.491 - 495, 2020/11

A highly accurate and precise technique for measurement of the $$^{93}$$Nb(n,n')$$^{93m}$$Nb reaction rate was established for the material surveillance tests, etc. in fast reactors. The self-absorption effect on the measurement of the characteristic X-rays emitted by $$^{93m}$$Nb was decreased by the solution and evaporation to dryness of niobium dosimeter. A highly precise count of the number of $$^{93}$$Nb atoms was obtained by measuring the niobium solution concentration using inductively coupled plasma mass spectrometry. X-rays of $$^{93m}$$Nb were measured accurately by means of comparing the X-ray intensity of irradiated niobium solution with that of the solution in which stable $$^{93}$$Nb was added. The difference between both intensities indicates the effect of $$^{182}$$Ta, which is generated from an impurity tantalum, and the intensity of X-rays from $$^{93m}$$Nb was evaluated. Measurement error of the $$^{93}$$Nb(n,n')$$^{93m}$$Nb reaction rate was reduced to be less than 4%, which was equivalent to the other reaction rate errors of dosimeters used for Joyo dosimetry. In addition, an advanced technique using Resonance Ionization Mass Spectrometry was proposed for the precise measurement of $$^{93m}$$Nb yield, and $$^{93m}$$Nb will be resonance-ionized selectively by discriminating the hyperfine splitting of the atomic energy levels between $$^{93}$$Nb and $$^{93m}$$Nb at high resolution.

Journal Articles

Now is the time of fast reactor

Negishi, Hitoshi; Kamide, Hideki; Maeda, Seiichiro; Nakamura, Hirofumi; Abe, Tomoyuki

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 62(8), p.438 - 441, 2020/08

Prototype Fast Breeder Reactor, Monju, was under decommission since April, 2018. It is the first time for Japan to make a sodium cooled reactor into decommission. It is significant work and will take 30 years. The Monju has provided wide spectrum and huge amount of findings and knowledge, e.g., design, R&D, manufacturing, construction, and operation up to 40% of full power over 50 years of development history. It is significant to utilize such findings and knowledge for the development and commercialization of a fast rector in Japan.

JAEA Reports

Prototype fast breeder reactor Monju; Its history and achievements

Tsuruga Comprehensive Research and Development Center

JAEA-Technology 2019-007, 159 Pages, 2019/07

JAEA-Technology-2019-007.pdf:19.09MB
JAEA-Technology-2019-007-high-resolution1.pdf:42.36MB
JAEA-Technology-2019-007-high-resolution2.pdf:33.56MB
JAEA-Technology-2019-007-high-resolution3.pdf:38.14MB
JAEA-Technology-2019-007-high-resolution4.pdf:48.82MB
JAEA-Technology-2019-007-high-resolution5.pdf:37.61MB

This report summarizes the history and achievements of the prototype fast breeder reactor Monju. The development of Monju started in 1968 as a prototype reactor following the experimental fast reactor Joyo. The development covers all the activity related to the fast reactor; plant design, mockup tests, construction, operation, and plant management. This report summarizes the history and achievements for 11 technical areas: history and principal achievements, design and construction, operation test, plant safety, core physics, fuel, plant system, sodium technology, materials and mechanical design, plant management, and trouble management.

Journal Articles

Development of remote sensing technique using radiation resistant optical fibers under high-radiation environment

Ito, Chikara; Naito, Hiroyuki; Ishikawa, Takashi; Ito, Keisuke; Wakaida, Ikuo

JPS Conference Proceedings (Internet), 24, p.011038_1 - 011038_6, 2019/01

A high-radiation resistant optical fiber has been developed in order to investigate the interiors of the reactor pressure vessels and the primary containment vessels at the Fukushima Daiichi Nuclear Power Station. The tentative dose rate in the reactor pressure vessels is assumed to be up to 1 kGy/h. We developed a radiation resistant optical fiber consisting of a 1000 ppm hydroxyl doped pure silica core and 4 % fluorine doped pure silica cladding. We attempted to apply the optical fiber to remote imaging technique by means of fiberscope. The number of core image fibers was increased from 2000 to 22000 for practical use. The transmissive rate of infrared images was not affected after irradiation of 1 MGy. No change in the spatial resolution of the view scope by means of image fiber was noted between pre- and post-irradiation. We confirmed the applicability of the probing system, which consists of a view scope using radiation-resistant optical fibers.

JAEA Reports

Evaluation of decay heat used for effectiveness evaluations of countermeasures against severe accidents in the prototype FBR Monju

Usami, Shin; Kishimoto, Yasufumi*; Taninaka, Hiroshi; Maeda, Shigetaka

JAEA-Technology 2018-003, 97 Pages, 2018/07

JAEA-Technology-2018-003.pdf:12.54MB

The decay heat used for effectiveness evaluation of the prevention measures against severe accidents in the prototype fast breeder reactor Monju was evaluated by applying the updated nuclear data libraries based on JENDL-4.0, reflecting the realistic core operation pattern, and setting the rational extent of uncertainty. The decay heats of fission products, the actinide nuclides such as Cm-242, and radioactive structural materials were calculated by FPGS code. The decay heat of U-239 and Np-239 was evaluated based on ANSI/ANS-5.1-1994. The calculation uncertainty of each decay heat was evaluated based on summation of uncertainty factors, C/E values of reaction rates obtained in Monju system startup test, and so on. Furthermore, the decay heat evaluation method based on the FPGS90 was verified by the comparison of the results of the decay heat measurement of the two spent MOX fuel subassemblies in the experimental fast reactor Joyo MK-II core.

JAEA Reports

Measurement and analysis of in-vessel component activation and gamma dose rate distribution in Joyo, 2

Yamamoto, Takahiro; Ito, Chikara; Maeda, Shigetaka; Ito, Hideaki; Sekine, Takashi

JAEA-Technology 2017-036, 41 Pages, 2018/02

JAEA-Technology-2017-036.pdf:7.86MB

In the experimental fast reactor Joyo, the damaged upper core structure (UCS) was retrieved into the cask in May 2014 The dose rate on UCS surface was quite high due to the activation for over 30 years operation. In order to attain the optimum safety design, manufacture and operation of equipment for UCS replacement, the method to evaluate UCS surface dose rate was developed on the basis of C/E obtained by the in-vessel dose rate measurement in Joyo. In order to verify the evaluation method, the axial gamma-ray distribution measurement on the surface of the cask, which contained UCS, was conducted using a plastic scintillating optical fiber (PSF) detector. This paper describes the comparison results between calculation and measurement as follows. (1) The measured axial gamma-ray distribution on the cask surface had a peak on proper location with considering the cask shielding structure and agree well with the calculated distribution. (2) The C/E of axial gamma-ray distribution on the cask surface was ranged from 1.1 to 1.7. It was confirmed that the calculation for UCS replacement equipment design had a margin conservatively. Then, the results showed that the developed evaluation method for UCS replacement equipment design was sufficiently reliable.

JAEA Reports

Inspection and repair techniques in reactor vessel of the experimental fast reactor JOYO; Development of devices for retrieving bent MARICO-2 subassembly and completion of retrieval work

Ashida, Takashi; Nakamura, Toshiyuki*; Ito, Hideaki

JAEA-Technology 2017-024, 198 Pages, 2017/11

JAEA-Technology-2017-024.pdf:55.8MB
JAEA-Technology-2017-024-appendix(CD-ROM)-1.zip:298.09MB
JAEA-Technology-2017-024-appendix(CD-ROM)-2.zip:210.77MB

In the experimental fast reactor Joyo, the disconnecting of an irradiation test subassembly MARICO-2 (Material Testing Irradiation Rig with Temperature Control) from its holding mechanism was conducted in May 2007. After the operation, the rotating plug was rotated despite the fact that the test subassembly was not disconnected completely. Consequently, top of wrapper tube of the MARICO-2 subassembly was bent onto the in-vessel storage rack. Since the overhanging part of the subassembly was in the height in which contacts with the upper core structure, it had damaged the bottom surface of the upper core structure. As the result, it was necessary to replace the damaged upper core structure and to retrieve the bent MARICO-2 subassembly for Joyo restart. Retrieval devices for MARICO-2 subassembly consist of a gripper mechanism to lift subassembly together with transfer pot, a guide tube built-in a pantograph mechanism to adjust lifting axis and safety mechanisms to prevent or mitigate falling of MARICO-2 subassembly, a retrieval cask and so on. Design of the retrieval devices have been verified in ex-vessel partial or full-scale mock-up tests and in-vessel function tests. In 2014, MARICO-2 subassembly was successfully retrieved from the reactor vessel by applying these retrieval devices. Then, retrieved subassembly was transported to a hot-cell facility for post-irradiation examinations. Devices have demonstrated expected performance under the actual environmental conditions of a sodium cooled fast reactor. This is a synthetic report about the retrieval work of the deformed and irradiated test subassembly in Joyo. This report includes the detail design and fabrication of the special retrieval device, results of tests for confirmation including the mock-up tests in manufacturer's factory, and results of MARICO-2 retrieval work from the reactor vessel.

Journal Articles

Current status of the next generation fast reactor core & fuel design and related R&Ds in Japan

Maeda, Seiichiro; Oki, Shigeo; Otsuka, Satoshi; Morimoto, Kyoichi; Ozawa, Takayuki; Kamide, Hideki

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Next Generation Nuclear Systems for Sustainable Development (FR-17) (USB Flash Drive), 10 Pages, 2017/06

The next generation fast reactor is being investigated in Japan, aiming at several targets such as "safety", "reduction of environmental burden" and "economic competitiveness". As for the safety aspect, FAIDUS concept is adopted to avoid re-criticality in core destructive accidents. The uranium-plutonium mixed oxide fuel, in which minor actinide elements are included, will be applied to reduce the amount and potential radio-toxicity of radioactive wastes. The high burn-up fuel is pursued to reduce fuel cycle cost. The candidate concept of the core and fuel design, which could satisfy various design criteria by design devisals, has been established. In addition, JAEA is investigating material properties and irradiation behavior of MA-MOX fuel. JAEA is developing the fuel design code especially for the fuel pin with annular pellets of MA-bearing MOX. Furthermore, JAEA is developing oxide dispersion strengthened (ODS) ferritic steel cladding for the high burnup fuel.

Journal Articles

Development of inspection and repair techniques in reactor vessel of experimental fast reactor "Joyo"; Retrieval of the bent test subassembly

Ashida, Takashi; Ito, Hideaki; Miyamoto, Kazuyuki*; Nakamura, Toshiyuki; Koga, Kazuhiro*; Ohara, Norikazu*; Ino, Hiroichi*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(4), p.210 - 222, 2016/12

In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of material testing rig named "MARICO-2" had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). As the result, for Joyo restart, it was necessary to replace the damaged UCS and to retrieve the bent sub-assembly. This paper describes in-vessel repair techniques performed in the retrieval work of the obstacle inside of the reactor vessel. The devices which were prepared for this work demonstrated expected performance under the environmental conditions of an SFR such as high temperature and radiation dose, and the work was completed in 2014. The successful operation of this retrieval work of the damaged component inside of a reactor vessel will contribute to the development of in-service inspections and repair technics in an SFR.

JAEA Reports

Inspection and repair techniques in the reactor vessel of the experimental fast reactor Joyo; Observation technical development in a reactor vessel of the fast reactor, 3

Okuda, Eiji; Sasaki, Jun; Suzuki, Nobuhiro; Takamatsu, Misao; Nagai, Akinori

JAEA-Technology 2016-017, 20 Pages, 2016/07

JAEA-Technology-2016-017.pdf:5.75MB

In-Vessel Observation (IVO) techniques for Sodium Cooled Fast Reactors (SFRs) in service are important for confirming their safety and integrity. Since IVO equipment for an SFR has to be designed to tolerate the severe conditions (high temperature, high radiation dose and limited access route), fiberscopes used to be used in previous IVO for SFRs. However, in order to attain an IVO with higher quality and resolution, IVO using a radiation resistant camera was conducted in the fast experimental reactor Joyo and obtained some results. The demonstration results provided valuable insights for use in further improving and verifying IVO techniques in SFRs.

JAEA Reports

Inspection and repair techniques in the reactor vessel of the experimental fast reactor Joyo; Replacement of upper core structure

Ito, Hiromichi*; Ota, Katsu; Kawahara, Hirotaka; Kobayashi, Tetsuhiko; Takamatsu, Misao; Nagai, Akinori

JAEA-Technology 2016-008, 87 Pages, 2016/05

JAEA-Technology-2016-008.pdf:18.11MB

In the experimental fast reactor Joyo, as a part of the restoration work of a partial dysfunction of fuel handling, the replacement of the upper core structure (UCS) was started from March 2014, and was completed in December 2014. In the jack-up test, the UCS was jacked-up to 1000 mm without significant sodium shearing resistance and interference. In the replacement of the UCS, a procedure was prepared with the use of wire-jack equipment assuming the interference. As a result, with the procedure and wire-jack were effectively functioned, the work was successfully completed.

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