Sintering behavior analysis of compacted dry recycled UPuO powder using master sintering curve theory

Nakamichi, Shinya; Sunaoshi, Takeo*; Hirooka, Shun; Vauchy, R.; Murakami, Tatsutoshi

Journal of Nuclear Materials, 595, p.155072_1 - 155072_11, 2024/07

https://doi.org/10.1016/j.jnucmat.2024.155072

First demonstration of a single-end readout position-sensitive optical fiber radiation sensor inside the Fukushima Daiichi Nuclear Power Station based on wavelength-resolving analysis

Terasaka, Yuta; Sato, Yuki; Uritani, Akira*

Nuclear Instruments and Methods in Physics Research A, 1062, p.169227_1 - 169227_6, 2024/05

https://doi.org/10.1016/j.nima.2024.169227

Horonobe Underground Research Laboratory Project Investigation Report for the 2022 Fiscal Year

Nakayama, Masashi

JAEA-Review 2023-032, 159 Pages, 2024/02

JAEA-Review-2023-032.pdf:19.37MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2022, we continued R&D on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rock to natural perturbations". These are identified as key R&D on challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. Specifically, "full-scale engineered barrier system (EBS) performance experiment" and "solute transport experiment with model testing" were carried out as part of "Study on near- field system performance in geological environment". "Demonstration of engineering feasibility of repository technology" and "evaluation of EBS behaviour over 100C" were addressed for "Demonstration of repository design options". A study on "Understanding of buffering behaviour of sedimentary rock to natural perturbations" was also implemented in two areas, "evaluation of intrinsic buffering against endogenic and exogenic processes" and "development of techniques for evaluating excavation damaged zone (EDZ) self-sealing behaviour after backfilling". The Horonobe International Project (HIP) was initiated in February 2023 to promote research and development in collaboration with national and international organizations.

Development of rapid and sensitive radionuclide analysis method by simultaneous analysis of , , and X-rays (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Japan Chemical Analysis Center*

JAEA-Review 2023-022, 93 Pages, 2023/12

JAEA-Review-2023-022.pdf:4.7MB

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 FY2022. 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 FY2020, this report summarizes the research results of the "Development of rapid and sensitive radionuclide analysis method by simultaneous analysis of , , and X-rays" conducted from FY2020 to FY2022. The present study aims to enable rapid analysis of radionuclides in fuel debris and waste, we have established the latest measurement system, such as the multiple -ray detection methods, and the Spectral Determination Method (hereinafter referred to as "SDM") was developed. In the research in 2022, we developed a code that handles measurement data of LSC, singles Ge, and 2D spectra (multiple ). In addition, to develop an integrated database, spectral data of 40 nuclides were obtained by actual measurements and simulation calculations.

Horonobe Underground Research Laboratory Project; Investigation program for the 2023 fiscal year

Nakayama, Masashi

JAEA-Review 2023-019, 70 Pages, 2023/11

JAEA-Review-2023-019.pdf:6.83MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2023, we continue R&D on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rocks to natural perturbations". These are identified as key R&D challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. In the "Study on near-field system performance in geological environment", we conduct the coupled analysis on the full-scale engineered barrier system performance experiment and test the coupled simulation code through comparison with different simulation codes in the international DECOVALEX-2023 collaboration project. Borehole investigations are also carried out for solute transport experiments in the Koetoi Formation. As for "Demonstration of repository design concept", we carry out in situ experiments and data analysis on concrete deterioration under the subsurface conditions. Geophysical surveys are also carried out around an experimental tunnel to be newly excavated at the 350m gallery and characterise the initial conditions of the excavation damaged zone. For the "Understanding of buffering behaviour of sedimentary rocks to natural perturbations", we analyse the results of the hydraulic disturbance tests conducted in previous years and understand the relationship between rock stress / stress state and fault / fracture hydraulic connectivity. Concerning the construction and maintenance of the subsurface facilities, the 350 m gallery is extended and shafts are sank to a depth of 500 m.

Inter-codes and nuclear data comparison under collaboration works between IRSN and JAEA

Gunji, Satoshi; Araki, Shohei; Watanabe, Tomoaki; Fernex, F.*; Leclaire, N.*; Bardelay, A.*; Suyama, Kenya

Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 9 Pages, 2023/10

Institut de radioprotection et de sret nuclaire (IRSN) and Japan Atomic Energy Agency (JAEA) have a long-standing partnership in the field of criticality safety. In this collaboration, IRSN and JAEA are planning a joint experiment using the new STACY critical assembly, modified by JAEA. In order to compare the codes (MVP3, MORET6, etc.) and nuclear data (JENDL and JEFF) used by both institutes in the planning of the STACY experiment, benchmark calculations of the Apparatus B and TCA, which are critical assemblies once owned by both institutes, benchmarks from the ICSBEP handbook and the computational model of the new STACY were performed. Including the new STACY calculation model, the calculations include several different neutron moderation conditions and critical water heights. There were slight systematic differences in the calculation results, which may have originated from the processing and/or format of the nuclear data libraries. However, it was found that the calculated results, including the new codes and the new nuclear data, are in good agreement with the experimental values. Therefore, there are no issues to use them for the design of experiments for the new STACY. Furthermore, the impact of the new TSL data included in JENDL-5 on the effective multiplication factor was investigated. Experimental validation for them will be completed by critical experiments of the new STACY by both institutes.

Behavior of FeCrAl-ODS cladding tube under loss-of-coolant accident conditions

Narukawa, Takafumi; Kondo, Keietsu; Fujimura, Yuki; Kakiuchi, Kazuo; Udagawa, Yutaka; Nemoto, Yoshiyuki

Journal of Nuclear Materials, 582, p.154467_1 - 154467_12, 2023/08

https://doi.org/10.1016/j.jnucmat.2023.154467

Modelling heterogeneous hydration behaviour of bentonite by a FracMan-Thames coupling method for the Bentonite Rock Interaction Experiment (BRIE) at sp HRL

Sawada, Atsushi; Sakamoto, Kazuhiko*; Watahiki, Takanori*; Imai, Hisashi*

SKB P-17-06, 154 Pages, 2023/08

The Development of a Multiphysics Coupled Solver for Studying the Effect of Dynamic Heterogeneous Configuration on Particulate Debris Bed Criticality and Cooling Characteristics

Li, C.-Y.; Wang, K.*; Uchibori, Akihiro; Okano, Yasushi; Pellegrini, M.*; Erkan, N.*; Takata, Takashi*; Okamoto, Koji*

Applied Sciences (Internet), 13(13), p.7705_1 - 7705_29, 2023/07

https://doi.org/10.3390/app13137705

Status report of JAEA-AMS-TONO; Research and technical development in the last four years

Kokubu, Yoko; Fujita, Natsuko; Watanabe, Takahiro; Matsubara, Akihiro; Ishizaka, Chika; Miyake, Masayasu*; Nishio, Tomohiro*; Kato, Motohisa*; Ogawa, Yumi*; Ishii, Masahiro*; et al.

Nuclear Instruments and Methods in Physics Research B, 539, p.68 - 72, 2023/06

https://doi.org/10.1016/j.nimb.2023.03.005

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has an accelerator mass spectrometer (JAEA-AMS-TONO-5MV). The spectrometer enabled us to use a multi-nuclide AMS of carbon-14 (C), beryllium-10, aluminium-26 and iodine-129, and we have recently been proceeding test measurement of chlorine-36. In response to an increase of samples, we installed a state-of-the-art multi-nuclide AMS with a 300 kV Tandetron accelerator in 2020. Recently, we are driving the development of techniques of isobar separation in AMS and of sample preparation. Ion channeling is applied to remove isobaric interference and we are building a prototype AMS based on this technique for downsizing of AMS. The small sample graphitization for C has been attempted using an automated graphitization equipment equipped with an elemental analyzer.