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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.
Yano, Yasuhide; Uwaba, Tomoyuki; Tanno, Takashi; Yoshitake, Tsunemitsu; Otsuka, Satoshi; Kaito, Takeji
Journal of Nuclear Science and Technology, 9 Pages, 2023/00
Times Cited Count：1 Percentile：68.31(Nuclear Science & Technology)The effects of fast neutron irradiation on tensile properties of modified 316 stainless steel (PNC316) claddings and wrappers for fast reactors were investigated. PNC316 claddings and wrappers were irradiated in the experimental fast reactor Joyo at irradiation temperatures between 400 and 735 
C to fast neutron doses ranging from 21 to 125 dpa. The post-irradiation tensile tests were carried out at room and irradiation temperatures. Elongations of PNC316 measured by the tensile tests were maintained at an engineering level, although the material incurred significant irradiation hardening and softening. The maximum swelling of PNC316 wrappers was about 2.5 vol.% at irradiation temperature between 400 and 500C up to 110 dpa. Japanese 20% cold-worked austenitic steels, PNC316 and 15Cr-20Ni, had sufficient ductility and work-hardenability even after above 10 vol.% swelling, while they had very weak plastic instabilities.
Ashida, Takashi; Takamatsu, Misao; Ito, Hideaki; Okawa, Toshikatsu; Yoshihara, Shizuya
no journal, ,
In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly (S/A) of MARICO-2 (material testing rig with temperature control) had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). This incident necessitated the replacement of the UCS and the retrieval of the MARICO-2 sub-assembly for Joyo restoration. This paper describes the summary of Joyo restoration works. In-vessel repair techniques for sodium cooled fast reactors (SFRs) are important in confirming safety and integrity of SFRs. However, the demonstrated techniques under the actual reactor environment with high temperature, high radiation dose and remaining sodium are not enough to secure the reliability of these techniques. The experience and knowledge accumulated in the UCS replacement provides valuable insights into further improvements for in-vessel repair techniques in SFRs.
Itagaki, Wataru; Saito, Hiroto; Yamamoto, Masaya; Takamatsu, Misao; Maeda, Shigetaka
no journal, ,
JAEA applied for inspections of Joyo under the new regulation on March 30, 2017. It is undergoing NRA's safety review against core modification to MK-IV 100 MW irradiation core, measurement to natural disaster and BDBAs. The MK-IV core will have the maximum fast neutron flux (E 
0.1 MeV) of 10
n/cm
s. This is a high-level fast neutron flux of the irradiation test facilities in the world. Joyo can further enhance its capabilities by tailoring neutron spectrum, decreasing or increasing the irradiation temperature. For an experiment, it is important to evaluate neutron flux, dpa and temperature. Joyo provides accurate evaluation of irradiation conditions based on calculations verified by previous characterization tests and measurement using dosimetry technique. In this presentation, measure to new regulation, schedule for restart and irradiation capability of Joyo are introduced.
Yano, Yasuhide; Toyama, Takeshi*; Tanno, Takashi; Otsuka, Satoshi; Mitsuhara, Masatoshi*; Nakashima, Hideharu*; Onuma, Masato*; Kaito, Takeji
no journal, ,
no abstracts in English
Maeda, Shigetaka
no journal, ,
The objectives of this study are a production of Actinium-225 in Japan, and the use of the experimental fast reactor, Joyo. In this concept study, the technical bases of the production should be established. This concept study shows that the experimental fast reactor Joyo can produce a sufficient amount of Ac-225. This has been confirmed by calculation. The existing refueling and PIE transfer systems with some modifications can quickly transfer irradiated Ra-226 to the neighboring PIE facility. We have completed the concept design for the modifications. Issues and challenges are procuration of Ra-226, Joyo restart, for which we need take measures to meet the new regulations of NRA, Japan, licensing for RI use, production, and disposal, and, demonstration of Ac-225 production in Joyo.
Maeda, Shigetaka
no journal, ,
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.
Iwahashi, Daiki*; Sasaki, Yuto*; Maeda, Shigetaka; Takaki, Naoyuki*
no journal, ,
Ac-225 is attracting attention as a radioisotope for targeted 
-therapy (TAT) used for the treatment of prostate cancer and the like. Therefore, we investigated a method of loading Ra-226 into the fast reactor Joyo and producing Ac-225 by transmutation. Ac-225 production can be expected by the (n,2n) reaction using fast neutrons in the center of the core and the (3n,
) reaction using thermalized neutrons in the reflector region.
Sasaki, Yuto*; Iwahashi, Daiki*; Maeda, Shigetaka; Takaki, Naoyuki*
no journal, ,
Mo-99 (half-life: 66 hours) / Tc-99m (half-life: 6 hours), which is the most sought after RI for diagnosis, is 100% dependent on imports. Therefore, domestic production is expected due to the instability of supply due to the deterioration of overseas manufacturing reactors and transportation troubles caused by natural disasters, and discussions are becoming active in the RI expert subcommittee. In this study, we investigated a method for efficiently producing Mo-99 by the neutron capture reaction of Mo-98 utilizing the neutron deceleration field around the core of the high-speed experimental reactor "Joyo". Specifically, a parameter survey was conducted on the core configuration, target loading position, deceleration aggregate material and its filling ratio, etc., and the most efficient core configuration was clarified.
Takaki, Naoyuki*; Iwahashi, Daiki*; Sasaki, Yuto*; Maeda, Shigetaka
no journal, ,
We compared the production characteristics of Tc-99m and Ac-225 in the fast experimental reactor "Joyo" and commercial PWR, summarized the characteristics of each, and showed the possibility of domestic production of medical RI using domestic infrastructure.
Ac production rate and its uncertainty in the experimental fast reactor Joyo utilizing the total Monte Carlo methodSasaki, Yuto; Iwahashi, Daiki*; Maeda, Shigetaka; Takaki, Naoyuki*
no journal, ,
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 medical research and economic security of Japan. To establish the technical bases for the Ac-225 production, JAEA has evaluated the radioactivity 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. This study has revealed that Joyo can sufficiently produce Ac-225 as a raw material for pharmaceuticals.
Sasaki, Yuto; Sano, Aaru; Itagaki, Wataru; Maeda, Shigetaka; Takaki, Naoyuki*
no journal, ,
no abstracts in English
Maeda, Shigetaka
no journal, ,
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.
