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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:4 Percentile:75.44(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

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

Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

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.

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.

Journal Articles

A Simple method to create gamma-ray-source spectrum for passive gamma technique

Shiba, Tomooki; Maeda, Shigetaka; Sagara, Hiroshi*; Ishimi, Akihiro; Tomikawa, Hirofumi

Energy Procedia, 131, p.250 - 257, 2017/12

 Times Cited Count:0 Percentile:0.00(Energy & Fuels)

In the present paper, the $$gamma$$ ray source data was developed for the debris composition based on "best estimates", and the subsequent photon transportation calculation was performed to evaluate the leakage $$gamma$$ ray spectra according to the fuel debris. Since the creation of the line spectrum source requires a great deal, we have developed the relatively simple but accurate enough method to build up $$gamma$$ ray source, coupling of baseline spectra evaluated by ORIGEN2 code and several line spectra of interest. One of the advantages of the method is taking bremsstrahlung X rays into consideration by utilizing the bremsstrahlung libraries of ORIGEN2. The new $$gamma$$ ray source was used to calculate the detector response of HPGe detector and the results was compared as a benchmark with experimental measurement results of irradiated fuel pins. As the result, the simulated $$gamma$$ ray spectrum shape agreed well with the shape of $$gamma$$ ray spectrum obtained by the experiment.

Journal Articles

Validation of decay heat evaluation method based on FPGS cord for fast reactor spent MOX fuels

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

Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.3263 - 3274, 2016/05

The present paper describes the validation of the new decay heat evaluation method using FPGS90 code with both the updated nuclear data library and the rational extent of uncertainty, by comparing the results of the decay heat measurement of the spent fuel subassemblies in Joyo MK-II core and by comparing with the calculation results of ORIGEN2.2 code. The calculated values of decay heat (C) by FPGS90 based on the JENDL-4.0 library were coincident with the measured ones (E) within the calculation uncertainties, and the C/E ranged from 1.01 to 0.93. FPGS90 evaluated the decay heat almost 3% larger than ORIGEN2.2, and it improved the C/E in comparison with the ORIGEN2.2 code. Furthermore, The C/E by FPGS90 based on the JENDL-4.0 library was improved than that based on the JENDL-3.2 library, and the contribution of the revision of reaction cross section library to the improvement was dominant rather than that of the decay data and fission yield data libraries.

Journal Articles

2016 Professional Engineer (PE) test preparation course "Nuclear and Radiation Technical Disciplines"

Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.

Nihon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00

no abstracts in English

JAEA Reports

Design and manufacture of Joyo upper core structure for replacement

Ota, Katsu; Ushiki, Hiroshi*; Maeda, Shigetaka; Kawahara, Hirotaka; Takamatsu, Misao; Kobayashi, Tetsuhiko; Kikuchi, Yuki; Tobita, Shigeharu; Nagai, Akinori

JAEA-Technology 2015-026, 180 Pages, 2015/11

JAEA-Technology-2015-026.pdf:79.87MB

In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of "MARICO-2" (material testing rig with temperature control) had bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). The replacement of the UCS was conducted from May to December 2014. The design and manufacture of UCS was started from 2008, and the installation of UCS was completed successfully in November 21th 2014. The major results gained during the design and manufacture of UCS is as follows.

Journal Articles

Problem on MATXS files with multiple temperature cross section data

Konno, Chikara; Maeda, Shigetaka; Kosako, Kazuaki*

Energy Procedia, 71, p.213 - 218, 2015/05

 Times Cited Count:0 Percentile:0.00(Energy & Fuels)

We report a problem on multigroup cross section data MATXS files with multiple temperatures. This problem was newly found out through neutron and $$gamma$$ flux calculations in a simple model of experimental fast reactor Joyo with DORT and MATXSLIB-J40, which is a multigroup cross section data file (300, 600, 900, 1200, 1800 K) of the latest Japanese Nuclear Data Library version 4.0 (JENDL-4.0) processed with the NJOY99 code. The calculated total neutron fluxes were almost the same both in 300 K and 600 K, while the total $$gamma$$ fluxes in 600 K were by 10% higher those that in 300 K. Through our detailed investigation, it was found out that the MATXS data format processed with NJOY was not consistent to that assumed in TRANSX for $$gamma$$ production data. In order to solve this problem, we made a simple program for modifying MATXS files to ones suitable to TRANSX. MATXSLIB-J40 will be revised with this program.

Journal Articles

Gamma heating rate evaluation for material irradiation test in the Joyo experimental fast reactor

Maeda, Shigetaka; Naito, Hiroyuki; Soga, Tomonori; Aoyama, Takafumi

Nuclear Data Sheets, 118, p.494 - 497, 2014/04

 Times Cited Count:4 Percentile:31.51(Physics, Nuclear)

The evaluation of the spatial distribution of $$gamma$$ heating in fast reactors requires consideration of all the $$gamma$$ intensity components. However, the delayed $$gamma$$ ray yield data of all actinides are not prepared in evaluated nuclear data files such as ENDF or JEDNL. In this study, new neutron/$$gamma$$ cross section constants based on JENDL-3.2 and -4 were developed. The delayed $$gamma$$ yields were added to JENDL-3.2 and JENDL-4. Based on these modified JENDL-3.2 and -4, MATXSLIB-type library for conventional discrete ordinate multi-group transport code were generated. Neutron and $$gamma$$ ray coupling calculations for the experimental fast reactor Joyo core, based on transport theory as a fixed source problem, revealed that the $$gamma$$ flux increased by approximately 40% when the delayed $$gamma$$ intensity in both JENDL-3.2 and -4 were considered. The calculated $$gamma$$ heat rates were verified by comparison with the measured data obtained by on-line irradiation rigs. It was confirmed that the calculated $$gamma$$ heat rates agreed with the measurements within 3-12%.

Journal Articles

Development of neutron spectrum unfolding method for advanced nuclear emulsion

Maeda, Shigetaka; Ito, Chikara; Ishihara, Kohei*; Takagi, Keisuke*; Minato, Haruna*; Sakai, Yosuke*; Kawarabayashi, Jun*; Tomita, Hideki*; Iguchi, Tetsuo*

Progress in Nuclear Science and Technology (Internet), 4, p.665 - 669, 2014/04

In order to realize neutron spectroscopy in high-intensity $$gamma$$ ray fields, an advanced nuclear emulsion based on a non-sensitized OPERA film with AgBr grain sizes of 60 nm has been developed together with a neutron spectrum unfolding method. The response functions were evaluated in the neutron energy range between 0.1 and 4.5 MeV by Monte Carlo calculations. To realize a highly reliable unfolding method that does not require an initial guess spectrum, an algorithm was formulized based on the maximum entropy principle and the maximum likelihood method, and the new unfolding code MEALU was developed. Through analyses of mock-up data, its performance was checked. The neutron spectrum from fresh fuel from the experimental fast reactor Joyo was estimated and track lengths were simulated using the calculated response function and the estimated spectrum. Comparison between the assumed neutron spectrum and the unfolded one confirmed the effectiveness of the proposed technique.

Journal Articles

Investigation of development condition with new nuclear emulsion for neutron measurement under high gamma-ray background

Ishihara, Kohei*; Kawarabayashi, Jun*; Tomita, Hideki*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakamura, Mitsuhiro*; Maeda, Shigetaka; Iguchi, Tetsuo*

Progress in Nuclear Science and Technology (Internet), 4, p.661 - 664, 2014/04

Spent fuel emits not only neutrons but also lots of $$gamma$$-rays by its included fission products (for example, neutron/$$gamma$$ ratio is in the order of 10$$^{-8}$$). For its safety handling, it is important to investigate the neutron characteristics such as an emission rate, emission profile and energy spectrum. But it is difficult to measure the neutron characteristics with high precision because of lots of $$gamma$$-rays. So the neutron characteristics are estimated by an evaluation based on its burning history. It is necessary to measure them for estimate of adequacy of the simulated result. Also, a direct measurement of the neutron characteristics is essential in the case that each spent fuel has different burning history and is mixed (for example the accident of the Fukushima Dai-ichi Nuclear Power Plant). Therefore, we develop a new nuclear emulsion in order to measure neutrons under high $$gamma$$-rays field in our study.

Journal Articles

Fast neutron detection under intense $$gamma$$-ray fields with novel nuclear emulsion technique

Ishihara, Kohei*; Takagi, Keisuke*; Minato, Haruna*; Kawarabayashi, Jun*; Tomita, Hideki*; Maeda, Shigetaka; Naka, Tatsuhiro*; Morishima, Kunihiro*; Nakano, Toshiyuki*; Nakamura, Mitsuhiro*; et al.

Radiation Measurements, 55, p.79 - 82, 2013/08

 Times Cited Count:2 Percentile:10.07(Nuclear Science & Technology)

In order to measure the neutron under a condition of high intensity of $$gamma$$-ray background, we made new nuclear emulsion based on non-sensitized OPERA emulsion which had small AgBr grain size (AgBr grain size of 60, 90 and 160 nm). The sensitivity of this new emulsion, which was a correlation between stopping power and grain density, was estimated experimentally by irradiating neutrons with several energies. We also simulated the response to $$gamma$$-ray induced electrons and compared with some experimental results by using $$^{60}$$Co $$gamma$$ source. The results showed that there might be a threshold energy deposited in one AgBr grain under which it was impossible to develop. We estimated efficiency to the $$gamma$$-ray and the neutron with this obtained response of the new emulsion.

148 (Records 1-20 displayed on this page)