Development of methodology combining chemical analysis technology with informatics technology to understand perspectives property of debris and tie-up style human resource development (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Fukushima University*

JAEA-Review 2023-024, 109 Pages, 2024/03

JAEA-Review-2023-024.pdf:5.42MB

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 FY2019, this report summarizes the research results of the "Development of methodology combining chemical analysis technology with informatics technology to understand perspectives property of debris and tie-up style human resource development" conducted in FY2022. The present study aims to goal of this study is to implement a research plan relate to a development of combinational technology of new chemical analysis with informatics, and the aim is to develop new system for whole image estimation system using small quantities of information.

Nuclear data as foundation of nuclear research and development

Fukahori, Tokio; Nakayama, Shinsuke; Katabuchi, Tatsuya*; Shigyo, Nobuhiro*

Nihon Genshiryoku Gakkai-Shi ATOMO, 65(12), p.726 - 727, 2023/12

https://doi.org/10.3327/jaesjb.65.12_726

The Investigative Committee on Nuclear Data investigates and observes global trends in nuclear research and development and conducts comprehensive examinations of Japanese nuclear data activities from a broader perspective, as well as cooperation with domestic and foreign academic institutions in a wide range of fields other than the Atomic Energy Society. We aim to establish a system for communication, information exchange, and interdisciplinary cooperation. In this report, we will report on three of the main activities for the 2021-2022 term: a request list site for nuclear data, human resource development, and roadmap production.

Dependency of the source term estimation method for radionuclides released into the atmosphere on the available environmental monitoring data and its applicability to real-time source term estimation

Terada, Hiroaki; Nagai, Haruyasu; Kadowaki, Masanao; Tsuzuki, Katsunori

Journal of Nuclear Science and Technology, 60(8), p.980 - 1001, 2023/08

https://doi.org/10.1080/00223131.2022.2162139

It is essential to establish a method for reconstructing the source term and spatiotemporal distribution of radionuclides released into the atmosphere due to a nuclear accident for emergency countermeasures. We examined the dependency of a source term estimation method based on Bayesian inference using atmospheric dispersion simulation and environmental monitoring data on the availability of various monitoring data. Additionally, we examined the applicability of this method to a real-time estimation conducted immediately after an accident. A sensitivity analysis of the estimated source term during the Fukushima Daiichi Nuclear Power Station (FDNPS) accident for combinations of various monitoring data indicated that using monitoring data with a high temporal and spatial resolution and the concurrent use of air concentration and surface deposition data is effective for accurate estimation. A real-time source term estimation experiment assuming the situation of monitoring data acquisition during the FDNPS accident revealed that this method could provide the necessary source term for grasping the overview of surface contamination in the early phase and evaluating the approximate accident scale. If the immediate online acquisition of monitoring data and regular operation of an atmospheric dispersion simulation are established, this method can provide the source term in near-real time.

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.

Development of methodology combining chemical analysis technology with informatics technology to understand perspectives property of debris and tie-up style human resource development (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Fukushima University*

JAEA-Review 2022-030, 94 Pages, 2022/12

JAEA-Review-2022-030.pdf:4.87MB

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, 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 "Development of methodology combining chemical analysis technology with informatics technology to understand perspectives property of debris and tie-up style human resource development" conducted in FY2021. The present study aims to Goal of this study is to implement a research plan relate to a development of combinational technology of new chemical analysis with informatics, and the aim is to develop new system for whole image estimation system using small quantities of information. Conducting the collaboration study with JAEA researchers (tie-up style) make connect to the development of human resource from master's course student to post-doctoral researchers who are progress …

Revolatilization of iodine by bubbly flow in the suppression pool during an accident

Nanjo, Kotaro; Ishikawa, Jun; Sugiyama, Tomoyuki; Pellegrini, M.*; Okamoto, Koji*

Journal of Nuclear Science and Technology, 59(11), p.1407 - 1416, 2022/11

https://doi.org/10.1080/00223131.2022.2062065

Technical note for the cavitation damage inspection for interior surface of the mercury target vessel, 1; Development of specimen cutting machine for remote handling

Naoe, Takashi; Kinoshita, Hidetaka; Wakui, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro

JAEA-Technology 2022-018, 43 Pages, 2022/08

JAEA-Technology-2022-018.pdf:7.84MB

In the liquid mercury target system for the pulsed spallation neutron source of Materials and Life science experimental Facility (MLF) at the Japan in the Japan Proton Accelerator Research Complex (J-PARC), cavitation that is generated by the high-energy proton beam-induced pressure waves, resulting severe erosion damage on the interior surface of the mercury target vessel. The erosion damage is increased with increasing the proton beam power, and has the possibility to cause the leakage of mercury by the penetrated damage and/or the fatigue failure originated from erosion pits during operation. To achieve the long term stable operation under high-power proton beam, the mitigation technologies for cavitation erosion consisting of surface modification on the vessel interior surface, helium gas microbubble injection, double-walled beam window structure has been applied. The damage on interior surface of the vessel is never observed during the beam operation. Therefore, after the target operation term ends, we have cut out specimen from the target nose of the target vessel to inspect damaged surface in detail for verification of the cavitation damage mitigation technologies and lifetime estimation. We have developed the techniques of specimen cutting out by remote handling under high-radiation environment. Cutting method was gradually updated based on experience in actual cutting for the used target vessel. In this report, techniques of specimen cutting out for the beam entrance portion of the target vessel in high-radiation environment and overview of the results of specimen cutting from actual target vessels are described.

Nuclear data as foundation of nuclear research and development

Fukahori, Tokio; Nakayama, Shinsuke; Katabuchi, Tatsuya*; Shigyo, Nobuhiro*

Nihon Genshiryoku Gakkai-Shi ATOMO, 64(7), p.413 - 414, 2022/07

https://doi.org/10.3327/jaesjb.64.7_413

The Investigation Advisory Committee on Nuclear Data monitors global nuclear research and development trends, and conducts collaborative nuclear data activities with domestic and foreign academic institutions in a wide range of fields. The aims are to contact, to exchange information, and to build an interdisciplinary cooperation system. Reported are the activities on the request list site, human resources development, and roadmap creation regarding nuclear data directly related to future nuclear data research activities, among the main activities in the 2019-2020 period.

Status of the uncertainty quantification for severe accident sequences of different NPP-designs in the frame of the H-2020 project MUSA

Brumm, S.*; Gabrielli, F.*; Sanchez-Espinoza, V.*; Groudev, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; Bocanegra, R.*; Herranz, L. E.*; Berda, M.*; et al.

Proceedings of 10th European Review Meeting on Severe Accident Research (ERMSAR 2022) (Internet), 13 Pages, 2022/05

Subcriticality determination methodology during fuel loading of accelerator-driven system

Katano, Ryota

Journal of Nuclear Science and Technology, 59(3), p.368 - 381, 2022/03

https://doi.org/10.1080/00223131.2021.1973609

We propose a subcriticality determination methodology to be applied during fuel loading of an accelerator-driven system (ADS). In this methodology, subcriticality is determined via the area ratio method (via the proton accelerator) in the first step and by the neutron source multiplication method (through the spontaneous fission neutrons of minor actinides) in subsequent steps; then, the number of fuel assemblies to be loaded in the next step is predicted. We performed a numerical simulation of the proposed methodology, and the estimated subcriticalities agreed well with those obtained by eigenvalue calculations. We also conducted an uncertainty assessment of the proposed methodology and deduced a value of 1000 pcm for the uncertainty. The proposed methodology can be a candidate for practical subcriticality monitoring for ADS.