Challenge of novel hybrid-waste-solidification of mobile nuclei generated in Fukushima Nuclear Power Station and establishment of rational disposal concept and its safety assessment (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*

JAEA-Review 2022-072, 116 Pages, 2023/03

JAEA-Review-2022-072.pdf:6.32MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2021, this report summarizes the research results of the "Challenge of novel hybrid-waste-solidification of mobile nuclei generated in Fukushima Nuclear Power Station and establishment of rational disposal concept and its safety assessment" conducted in FY2021. The present study aims to establish the rational waste disposal concept of a variety of wastes generated in 1F by the novel hybrid-waste-solidification. The phosphate form of ALPS sediment wastes containing Eu, Ce, Sr and Cs were synthesized as well as radioactive Sr, Cs and I which are both emitters, AREVA sludge and Iodine Calcium apatite were synthesized, and they were processed to the stabilization treatment such as sintering and Spark Plasma ...

Study on the relation between the crystal structure and thermal stability of FeUO and CrUO

Akiyama, Daisuke*; Kusaka, Ryoji; Kumagai, Yuta; Nakada, Masami; Watanabe, Masayuki; Okamoto, Yoshihiro; Nagai, Takayuki; Sato, Nobuaki*; Kirishima, Akira*

Journal of Nuclear Materials, 568, p.153847_1 - 153847_10, 2022/09

https://doi.org/10.1016/j.jnucmat.2022.153847

FeUO, CrUO, and FeCrUO are monouranates containing pentavalent U. Even though these compounds have similar crystal structures, their formation conditions and thermal stability are significantly different. To determine the factors causing the difference in thermal stability between FeUO and CrUO, their crystal structures were evaluated in detail. A Raman band was observed at 700 cm in all the samples. This Raman band was derived from the stretching vibration of the O-U-O axis band, indicating that FeCrUO was composed of a uranyl-like structure in its lattice regardless of its "x"' value. Mssbauer measurements indicated that the Fe in FeUO and FeCrUO were trivalent. Furthermore, FeCrUO lost its symmetry around Fe with increasing electron densities around Fe, as the abundance of Cr increased. These results suggested no significant structural differences between FeUO and CrUO. Thermogravimetric measurements for UO, FeUO, and CrUO showed that the temperature at which FeUO decomposed under an oxidizing condition (approximately 800 C) was significantly lower than the temperature at which the decomposition of CrUO started (approximately 1250 C). Based on these results, we concluded that the decomposition of FeUO was triggered by an "in-crystal" redox reaction, i.e., Fe U Fe U, which would not occur in the CrUO lattice because Cr could never be reduced under the investigated condition. Finally, the existence of Cr in FexCrUO effectively suppressed the decomposition of the FeCrUO crystal, even at a very low Cr content.

High-temperature gaseous reaction of cesium with siliceous thermal insulation; The Potential implication to the provenance of enigmatic Fukushima cesium-bearing material

Rizaal, M.; Nakajima, Kunihisa; Saito, Takumi*; Osaka, Masahiko; Okamoto, Koji*

ACS Omega (Internet), 7(33), p.29326 - 29336, 2022/08

https://doi.org/10.1021/acsomega.2c03525

Revealing the ion dynamics in LiGePS by quasi-elastic neutron scattering measurements

Hori, Satoshi*; Kanno, Ryoji*; Kwon, O.*; Kato, Yuki*; Yamada, Takeshi*; Matsuura, Masato*; Yonemura, Masao*; Kamiyama, Takashi*; Shibata, Kaoru; Kawakita, Yukinobu

Journal of Physical Chemistry C, 126(22), p.9518 - 9527, 2022/06

https://doi.org/10.1021/acs.jpcc.2c01748

Synthesis of a Si-Al gel as a starting material of aluminosilicate solids

Sato, Junya; Shiota, Kenji*; Takaoka, Masaki*

Zairyo, 70(5), p.406 - 411, 2021/05

https://doi.org/10.2472/jsms.70.406

An aluminosilicate solid is an inorganic material that has the property of immobilizing heavy metals or radionuclides in the matrix. In this study, aluminosilicates with a Si/Al molar ratio of 0.5 was synthesized from a chemical reagent in order to produce aluminosilicate solids with a low Si/Al molar ratio, which were expected to improve the immobilization of heavy metals and radionuclides contained in the matrix. The synthesized Si-Al gel with a Si/Al molar ratio of 0.5 had little impurity content and was in an amorphous phase. In addition, the compressive strength of the aluminosilicate solid produced by the synthesized Si-Al gel showed a 5 MPa or more, confirming that it can be used as a raw material for aluminosilicate solids. The aluminosilicate solid with a Si/Al molar ratio of 1.25 had a dense surface structure from the result of BSE images and had the highest compressive strength among all samples.

Safe, efficient cementation of challenging radioactive wastes using alkali activated materials with high-flowability and high-anion retention capacity (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Hokkaido University*

JAEA-Review 2020-054, 72 Pages, 2021/01

JAEA-Review-2020-054.pdf:5.62MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Safe, efficient cementation of challenging radioactive wastes using alkali activated materials with high-flowability and high-anion retention capacity". The purpose of this study is to find safe, efficient cementation of challenging radioactive wastes using alkali activated materials with high-flowability and high-anion retention capacity, and to propose the concept of a manufacturing apparatus that is established as an actual plant. As a result of study in this year, it was revealed that the K-based alkali activated material has high-flowability and quick curing, and that high-iodine retention capacity is achieved by incorporating silver ions during manufacturing of solidified waste.

Development of HCl-free solid phase extraction combined with ICP-MS/MS for rapid assessment of difficult-to-measure radionuclides, 1; Selective measurement of Zr and Mo in concrete rubble

Do, V. K.; Furuse, Takahiro; Murakami, Erina; Aita, Rena; Ota, Yuki; Sato, Soichi

Journal of Radioanalytical and Nuclear Chemistry, 327(1), p.543 - 553, 2021/01

https://doi.org/10.1007/s10967-020-07503-z

A new HCl-free chromatographic separation procedure has been developed for sequential separation of Zr and Mo from concrete matrices. Accordingly, Zr and Mo could be sensitively and selectively measured by ICP-MS/MS using ammonia reaction gas. The recoveries of greater than 90% for Zr and Mo from concretes could be achieved. The measurement condition was optimized for complete suppression of interferences from Nb and peak tailing from abundant isotopes of Zr and Mo in concrete matrices. The removal of interferences was verified by measurement of radio-contamination-free concretes used as a sample matrix blank. Method detection limits of 1.7 mBq g and 0.2 Bq g were achieved for Zr and Mo, respectively, in the concrete matrices. The interference removal factor for Nb (equivalent to the decontamination factor in radiochemical separation) was of the order of 10, and the abundance sensitivity was of the order of 10, indicating that the developed method is reliable for verifying the presence of ultralow concentrations of Zr and Mo. The present method is suitable for the rapid assessment of Zr and Mo for radioactivity inventory of concrete rubble.

Frontline of R&D for decommissioning and waste disposal, 1; R&D for processing and disposal of low-level radioactive waste and closure of uranium mine

Tsuji, Tomoyuki; Sugitsue, Noritake; Sato, Fuminori; Matsushima, Ryotatsu; Kataoka, Shoji; Okada, Shota; Sasaki, Toshiki; Inoue, Junya

Nihon Genshiryoku Gakkai-Shi ATOMO, 62(11), p.658 - 663, 2020/11

no abstracts in English

Development of the sintering solidification method for spent zeolite to long-term stabilization (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

Collaborative Laboratories for Advanced Decommissioning Science; Shibaura Institute of Technology*

JAEA-Review 2019-028, 71 Pages, 2020/03

JAEA-Review-2019-028.pdf:6.46MB

JAEA/CLADS, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of the Sintering Solidification Method for Spent Zeolite to Long-term Stabilization". The present study aims to develop the sintering solidification method for zeolites (spent zeolites) that adsorbs continuously generated radionuclides such as cesium. The sintering solidification method is able to stabilize adsorbed radionuclides such as cesium in zeolites by adding a glass as a binder to spent zeolite and sintered it. It is expected that the sintering solidification method is significantly reduce the volume of the solidified body compare with the glass solidification method and to form a stable solidified body equivalent to the calcination solidification method. In this project, we planned to select a glass suitable for the sintering solidification method and optimize the sintering temperature, etc. using non-radioactive nuclides (cold tests), and verify it by using radioactive nuclides (hot tests). In FY2018, we investigated the thermal properties of candidate glasses for binder and the effect of heating atmosphere on the sintering solidification method. Irradiated fuel for preparing simulated contaminated water containing radionuclides was selected and the condition of it was observed. In addition, we surveyed existing research results and latest research trends about solidification of zeolite, calcination solidification and so on.

Unique anion-exchange properties of 3,3'-diaminobenzidine resulting in high selectivity for rhodium(III) over palladium(II) and platinum(IV) in a concentrated hydrochloric acid solution

Suzuki, Tomoya*; Ogata, Takeshi*; Tanaka, Mikiya*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi; Narita, Hirokazu*

Analytical Sciences, 35(12), p.1353 - 1360, 2019/12

https://doi.org/10.2116/analsci.19P204

no abstracts in English