Current status and future prospects of the Horonobe International Project (HIP), 4; Task C: Full-scale Engineering Barrier System (EBS) dismantling experiment

Ono, Hirokazu

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 31(2), p.140 - 143, 2024/12

https://nuce.aesj.or.jp/jnuce/vol31/jnuce-vol31-2-p140-143.pdf

In the geological disposal of high-level radioactive waste, after emplacement of an EBS, the near-field environment is affected by processes such as heat release from the waste, groundwater infiltration into the EBS, swelling and deformation of the buffer material, and chemical reactions between groundwater and minerals. It is crucial to develop simulation codes to evaluate such coupled thermal-hydraulic-stress-chemical (THMC) processes for safety assessment of geological disposal. The full-scale vertical-emplacement EBS experiment (Horonobe EBS experiment) has been undertaken in the 350 m gallery of the Horonobe Underground Research Laboratory (URL) with the Horonobe geological environment. In the Horonobe EBS experiment, various sensors were installed in the buffer and backfill material to obtain the data required to evaluate coupled THMC processes in near-field. In Task C of the Horonobe International Project (HIP), the dismantling experiment of the Horonobe EBS experiment will be carried out and the data obtained from this experiment will be used to understand the coupled processes and to evaluate the simulation code.

Development of the buckling evaluation method for large scale vessels in fast reactors made of grade 91 steel and austenitic stainless steel with large initial imperfections

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Watakabe, Tomoyoshi; Ando, Masanori; Miyazaki, Masashi

Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 8 Pages, 2024/07

We have developed the buckling strength equations of vessels for fast reactors with seismic isolation system. The applicability of the buckling equations was confirmed by a series of buckling tests and analyses under monotonic or cyclic axial compressive load accompanied with constant horizontal load in the previous reports. In this report, we proposed a correction factor to reduce the buckling strength calculated by the buckling equations for large initial imperfections. A series of elastic-plastic buckling analyses considering large displacement and large strain theories was conducted to Grade 91 steel and austenitic stainless steel vessels which has a wide range of dimensions, initial imperfection amplitude, and vertical/horizontal load ratio. The simulation results showed that the correction factor generally shows a reduction tendency of buckling strength corresponding to initial imperfection amplitude, and the modified buckling equations are applicable to the vessels in fast reactors even for large initial imperfection amplitude which exceeds half the wall thickness.

Impact of interatomic structural characteristics of aluminosilicate hydrate on the mechanical properties of metakaolin-based geopolymer

Kim, G.*; Cho, S.-M.*; Im, S.*; Suh, H.*; Morooka, Satoshi; Shobu, Takahisa; Kanematsu, Manabu*; Machida, Akihiko*; Bae, S.*

Construction and Building Materials, 411, p.134529_1 - 134529_18, 2024/01

https://doi.org/10.1016/j.conbuildmat.2023.134529

Multiphysics analysis of reactivity changes due to solution flow in the past criticality accident at Windscale Works in 1970

Fukuda, Kodai; Yamane, Yuichi

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

This study presents the results of multiphysics analysis, which investigates the change of reactivity caused by the motion of fluids, of Windscale Works criticality accident. The purpose of this study is to confirm previously reported trends of emulsion formation and increase in reactivity by the multi-physics analysis which takes the motion of fluids into account. Continuous energy Monte Carlo code MVP3 was used to calculate reactivity based on the material distribution obtained by CFD calculation using OpenFOAM. An interface program in python was developed to transfer data from OpenFOAM to MVP3. The change of reactivity caused by the motion of solutions was calculated without considering the generation of heat by fissions in a system that simulated the transfer vessel at Windscale Works. As a result, trends of emulsion formation and increase in reactivity were confirmed. The influence of the resolution of the calculation system on the results was also discussed.

Radio-tellurium released into the environment during the complete oxidation of fuel cladding, containment venting and reactor building failure of the Fukushima accident

Hidaka, Akihide; Kawashima, Shigeto*; Kajino, Mizuo*

Journal of Nuclear Science and Technology, 60(7), p.743 - 758, 2023/07

https://doi.org/10.1080/00223131.2022.2142311

An accurate estimation of radionuclides released during the Fukushima accident is essential. Therefore, authors investigated Te release using the Unit emission-regression estimation method, in which the deposition distribution is weighted based on the hourly deposition obtained from mesoscale meteorological model calculations assuming Unit emissions. The previous study focused on confirming the applicability of this method. Subsequent examination revealed that if any part of the time when a release have occurred is missing from the estimated release period, the entire source term calculation will be distorted. Therefore, this study performed the recalculation by extending the estimation period to cover all major releases. Consequently, unspecified release events were clarified, and their correspondence to in-core events was confirmed. The Te release caused by Zr cladding complete oxidation can explain the regional dependence of the Te/Cs ratio in the soil contamination map.

Preliminary analysis of randomized configuration patterns in modified STACY core

Shiba, Shigeki*; Iwahashi, Daiki*; Okawa, Tsuyoshi*; Gunji, Satoshi; Izawa, Kazuhiko; Suyama, Kenya

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05

The Nuclear Regulation Authority (NRA) has tackled the experimental approach for determining the criticality of pseudo-fuel debris plausibly simulating actual fuel debris since 2014, collaborating with the Japan Atomic Energy Agency. To elucidate the characteristics of the pseudo-fuel debris, the Japan Atomic Energy Agency modified the STACY (STAtic experiment Critical facilitY) to conduct critical experiments simulating fuel debris. Thus, we proposed three types of modified STACY core configurations. In critical experiments in the modified STACY core, it is important to judge whether the proposed modified STACY core configurations are representative of molten core-concrete interaction debris or not. In this study, we built pseudo-fuel debris models considering a volume ratio of pseudo-fuel debris to moderation (V/V) and calculated uncertainty-based similarity values (C) between the modified STACY core configurations and pseudo-fuel debris models using Tools for Sensitivity and Uncertainty Analysis Methodology Implementation-Indices and Parameters (TSUNAMI-IP) in SCALE 6.2. Consequently, the modified STACY core configuration loading structure rods we proposed completely resulted in high similarity to the pseudo-fuel debris models through V/V values. The main contributions to C values were U , U , and Fe (n,), except for the pseudo-fuel debris model, including extremely high concrete components.

Statistical optimization of nZVI chemical synthesis approach towards P and NO removal from aqueous solutions; Cost-effectiveness & parametric effects

Maamoun, I.; Eljamal, R.*; Eljamal, O.*

Chemosphere, 312, Part 1, p.137176_1 - 137176_11, 2023/01

https://doi.org/10.1016/j.chemosphere.2022.137176

Chloramphenicol removal from water by various precursors to enhance graphene oxide-iron nanocomposites

Idham, M. F.*; Falyouna, O.*; Eljamal, R.*; Maamoun, I.; Eljamal, O.*

Journal of Water Process Engineering (Internet), 50, p.103289_1 - 103289_16, 2022/12

https://doi.org/10.1016/j.jwpe.2022.103289

Assessment report of research on development activities in FY 2021 Activity; "Computational Science and Technology Research" (Result and in-advance evaluation)

Center for Computational Science & e-Systems

JAEA-Evaluation 2022-003, 61 Pages, 2022/11

JAEA-Evaluation-2022-003.pdf:1.42MB
JAEA-Evaluation-2022-003-appendix(CD-ROM).zip:6.16MB

Japan Atomic Energy Agency (hereinafter referred to as "JAEA") consults an assessment committee, "Evaluation Committee of Research Activities for Computational Science and Technology Research" (hereinafter referred to as "Committee") for result and in-advance evaluation of "Computational Science and Technology Research", in accordance with "General Guideline for the Evaluation of Government Research and Development (R&D) Activities" by Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology" and "Regulation on Conduct for Evaluation of R&D Activities" by the JAEA. In response to the JAEA's request, the Committee assessed the research program of the Center for Computational Science and e-Systems (hereinafter referred to as "CCSE"). The Committee evaluated the management and research activities of the CCSE based on explanatory documents prepared by the CCSE, and oral presentations with questions-and answers.

Development of timing read-back system for stable operation of J-PARC

Yang, M.*; Kamikubota, Norihiko*; Sato, Kenichi*; Kikuzawa, Nobuhiro; Tajima, Yuto*

Proceedings of 18th International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS 2021) (Internet), p.927 - 930, 2022/02

https://doi.org/10.18429/JACoW-ICALEPCS2021-THPV029

Since 2006, the Japan Proton Accelerator Research Complex (J-PARC) timing system has been operated successfully. However, there were some unexpected trigger-failure events, typically missing trigger events, during the operation over 15 years. When a trigger-failure event occurred, it was often tough to find the one with the fault among many suspected modules. To solve the problem more easily, a unique device, triggered scaler, was developed for reading back accelerator signals. The performance of the module has been evaluated in 2018. In 2021, we measured and observed an LLRF signal as the first signal of the read-back system for beam operation. After firmware upgrades of the module, some customized timing read-back systems were developed, and successfully demonstrated as coping strategies for past trigger-failure events. In addition, a future plan to apply the read-back system to other facilities is discussed. More details are given in the paper.