Estimation of influence of implicit effect due to multi-group cross-section perturbations on uncertainty analysis in PWR-UO and -MOX lattice calculations

Fujita, Tatsuya

Journal of Nuclear Science and Technology, 62(8), p.731 - 739, 2025/08

https://doi.org/10.1080/00223131.2025.2470234

This study estimated the influence of implicit effect on the k-infinity uncertainty in the PWR-UO and -MOX fuel lattice geometries. Firstly, the preliminary investigation was performed, where the influence of implicit effect was roughly estimated based on the sandwich formula using the cross-section (XS) covariance matrix and the sensitivity coefficient. It was confirmed that the influence of implicit effect became large in the fission and (n,) reactions of heavy nuclides and the change of this dependence was small for the burnup of UO and MOX fuel assemblies. Then, focussing on the heavy nuclides, the influence of implicit effect was compared under several energy group conditions of the XS covariance matrix and neutron transport calculation. For Pu and Pu, the noticeable influence of implicit effect was observed in MOX fuel pin-cell geometry. However, increasing the number of energy groups for neutron transport calculations and that of the XS covariance matrix can reduce the influence of implicit effect. Consequently, by appropriately setting the number of energy groups for neutron transport calculations and that of the XS covariance matrix, it became practically possible not to explicitly consider the implicit effect during the random sampling.

Establishing a new evaluation system to characterize radiation carcinogenesis by stem cell dynamics (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; National Institutes for Quantum Science and Technology*

JAEA-Review 2022-051, 78 Pages, 2023/01

JAEA-Review-2022-051.pdf:7.12MB

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 "Establishing a new evaluation system to characterize radiation carcinogenesis by stem cell dynamics" conducted from FY2019 to FY2021. Since the final year of this proposal was FY2021, the results for three fiscal years were summarized. In this study, we will use cell lineage tracing technology that can permanently label stem cells and their progenies to capture and mathematically model the long-term clonal proliferation of cells in mammary tissue after high to low dose radiation exposure to determine the origin of radiation carcinogenesis, the stem cells. The objective is to characterize radiation-induced breast cancer by its dynamics.

Establishing a new evaluation system to characterize radiation carcinogenesis by stem cell dynamics (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; National Institutes for Quantum Science and Technology*

JAEA-Review 2021-052, 52 Pages, 2022/01

JAEA-Review-2021-052.pdf:2.63MB

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 FY2020. 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 "Establishing a new evaluation system to characterize radiation carcinogenesis by stem cell dynamics" conducted in FY2020. In this study, the long-term clonal expansion of mammary stem cells after high- to low-dose radiation exposure was investigated using stem-cell lineage tracing technology that can permanently label stem cells and their progenies. The purpose of this study is to characterize radiation-induced breast cancer based on the dynamics of radiation-exposed stem cells by capturing proliferation and analyzing it using a mathematical model.

On the mathematical model with morphological change of tumorigenesis in view

Ouchi, Noriyuki

Hoken Butsuri, 40(2), p.166 - 169, 2005/06

https://doi.org/10.5453/jhps.40.166

Development of the new mathematical model of the carcinogenesis in a low dose in mind is reported. The new model which describes from cell canceration to the tumorigenesis in consideration of the physical dynamics of a cell level was built. In a cell group level, it has both intra-cellular dynamics, such as mutation, cell division, and cell death, and physical dynamics such as, adhesion between cells, modification, and movement, and a model can investigate with time that tumor is formed.

Evolution of porewater in a Neogene sedimentary formation in the Horonobe area, Hokkaido, Japan; Modeling of burial diagenesis

Miyakawa, Kazuya; Kashiwaya, Koki*; Komura, Yuto*; Nakata, Kotaro*

no journal, , 

In the thick marine sediments, groundwater altered from seawater during the burial diagenesis may exist. Such altered ancient seawater will be called fossil seawater. In such a field, groundwater flow is considered extremely slow because it is not affected by the seepage of meteoric water even after the uplift. During diagenesis, dehydration from silicates causes changes such as a decrease in the salinity of the porewater. However, dehydration reactions alone cannot quantitatively explain water chemistry changes. In this study, we developed an analytical model that considers the dehydration reaction from silicates during the burial process and the upward migration of porewater due to compaction and examined the possible evolution of porewater chemistry. The results showed that the water chemistry, which was strongly influenced by the dehydration reaction from opal-A to quartz and from smectite, was similar to the observations from boring surveys. The results suggest that the fossil seawater formed during the diagenesis may have been preserved since the uplift and strongly supports the slow groundwater flow in the area where the fossil seawater exists.

A Novel bacterium, sp. strain Z1-71, isolated from the terrestrial subsurface environment and its co-cultivation within a methanogenic archaeon

Ueno, Akio*; Tamazawa, Satoshi*; Tamamura, Shuji*; Murakami, Takuma*; Inomata, Hidenori*; Amano, Yuki; Miyakawa, Kazuya; Naganuma, Takeshi*; Igarashi, Toshifumi*

no journal, , 

no abstracts in English

Prediction of sub-channel-wise coolant void fraction and temperature distributions by deep neural network for boiling water reactor pin bundle

Liong, C.*; Yamamoto, Akio*; Endo, Tomohiro*; Tada, Kenichi

no journal, , 

The DNN model to predict coolant void and temperature in each pin-wise subchannel on a simplified BWR fuel assembly for coupled neutronics and thermal hydraulics simulation was developed. The calculation results are obtained from the coupling calculation with or without control blade, which serves as the training data for the DNN model. In the DNN model, we employed the pin-wise coolant void fraction and temperature distribution at the lower axial mesh and the pin-power radial distribution at the current axial mesh to predict the coolant void fraction and temperature distribution at the current axial mesh. The DNN model makes accurate predictions for without the control blade case, while slight biases are observed with the control blade case.