※ 半角英数字
 年 ~ 
検索結果: 13 件中 1件目~13件目を表示
  • 1


Initialising ...



Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...



Dynamic probabilistic risk assessment of nuclear power plants using multi-fidelity simulations

Zheng, X.; 玉置 等史; 杉山 智之; 丸山 結

Reliability Engineering & System Safety, 223, p.108503_1 - 108503_12, 2022/07

Dynamic probabilistic risk assessment (PRA) more explicitly treats timing issues and stochastic elements of risk models. It extensively resorts to iterative simulations of accident progressions for the quantification of risk triplets including accident scenarios, probabilities and consequences. Dynamic PRA leverages the level of detail for risk modeling while intricately increases computational complexities, which result in heavy computational cost. This paper proposes to apply multi-fidelity simulations for a cost- effective dynamic PRA. It applies and improves the multi-fidelity importance sampling (MFIS) algorithm to generate cost-effective samples of nuclear reactor accident sequences. Sampled accident sequences are paralleled simulated by using mechanistic codes, which is treated as a high-fidelity model. Adaptively trained by using the high-fidelity data, low-fidelity model is used to predicting simulation results. Interested predictions with reactor core damages are sorted out to build the density function of the biased distribution for importance sampling. After when collect enough number of high-fidelity data, risk triplets can be estimated. By solving a demonstration problem and a practical PRA problem by using MELCOR 2.2, the approach has been proven to be effective for risk assessment. Comparing with previous studies, the proposed multi-fidelity approach provides comparative estimation of risk triplets, while significantly reduces computational cost.


Predictive modeling of a simple field matrix diffusion experiment addressing radionuclide transport in fractured rock. Is it so straightforward?

Soler, J. M.*; Neretnieks, I.*; Moreno, L.*; Liu, L.*; Meng, S.*; Svensson, U.*; Iraola, A.*; Ebrahimi, K.*; Trinchero, P.*; Molinero, J.*; et al.

Nuclear Technology, 208(6), p.1059 - 1073, 2022/06



Evaluation report of Task 9B based on comparisons and analyses of modelling results for the $"A$sp$"o$ HRL LTDE-SD experiments

Soler, J. M.*; Meng, S.*; Moreno, L.*; Neretnieks, I.*; Liu, L.*; Kek$"a$l$"a$inen, P.*; Hokr, M.*; $v{R}$$'i$ha, J.*; Vete$v{s}$n$'i$k, A.*; Reimitz, D.*; et al.

SKB TR-20-17, 71 Pages, 2021/07

亀裂性岩石中の地下水流動と物質移行のモデル化に関するSKBタスクフォースにおけるTask 9Bは、スウェーデンのエスポ岩盤研究所で実施された原位置長期収着・拡散試験(LTDE-SD)の試験結果のモデル化に焦点をあてたものである。10のモデリングチームによって、異なるモデル概念やコードを用いたモデル化が実施された。モデル化のアプローチは、(1)拡散方程式の解析解、(2)連続多孔質媒体中の数値計算モデル、(3)微細な不均質性(鉱物粒界,微細亀裂の分布等)を考慮した微細構造モデルの大きく3種に分類できる。異なるチームによるモデル化結果から、岩石や亀裂の表面の擾乱影響を含む岩石特性の不均質な分布、微細な亀裂の効果など、様々な異なるモデル概念の比較・評価がなされた。


Simulation-based Level 2 multi-unit PRA using RAVEN and a simplified thermal-hydraulic code

Zheng, X.; Mandelli, D.*; Alfonsi, A.*; Smith, C.*; 杉山 智之

Proceedings of 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL 2020 and PSAM-15) (Internet), p.2176 - 2183, 2020/11

The paper introduces a simulation-based Level 2 probabilistic risk assessment (PRA) of a multi-unit nuclear power plant. We propose the methodology by quantifying risk for a station-blackout accident scenario, initialized by a loss-of-offsite-power event. Contrary to classical PRA that applies static models such as event-tree/fault-tree, the analysis is seamlessly integrated with mechanistic simulation and PRA models, including: (1) a simplified thermal-hydraulic code for simulating system behaviors; (2) a Markovian model for the failure mechanism of decay-heat-removal systems, to investigate the interaction between mechanistic simulation and reliability analysis; and (3) classical containment event trees for evaluating containment performances and hydrogen-explosion risk under severe accident conditions. All dynamic and static models, including plant dependencies, are unified within the RAVEN computational framework, applying RAVEN components, External Model, Ensemble Model, and PRA Plugins. The study demonstrates an integrated assessment of risks by considering accident progression and inter-unit system interactions, both time dependent. Statistical data analysis is used to quantifying risk metrics, including core damage frequencies, large early release frequencies and plant damage status. The methodology pertains to modern risk-analysis methodologies such as risk-informed safety margin characterization (RISMC) and dynamic PRA.


Comparison of two-phase critical flow models for estimation of leak flow rate through cracks

渡辺 正*; 勝山 仁哉; 真野 晃宏

International Journal of Nuclear and Quantum Engineering (Internet), 13(11), p.516 - 519, 2019/10



CFD analysis of hydrogen flame acceleration with burning velocity models

茂木 孝介; Trianti, N.; 松本 俊慶; 杉山 智之; 丸山 結

Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.4324 - 4335, 2019/08

Hydrogen managements under severe accidents are one of the most crucial problems and have attracted a great deal of attention after the occurrence of hydrogen explosions in the accident at Fukushima Daiichi Nuclear Power Plant in March 2011. The primary purpose of our research is improvements in computational fluid dynamics techniques to simulate hydrogen combustion. Our target of analysis is ENACCEF2 hydrogen combustion benchmark test conducted in the framework of ETOSON-MITHYGENE project. Flame acceleration experiments of hydrogen premixed turbulent combustions were simulated by the Turbulent Flame Closure (TFC) model. We implemented several laminar flame speed correlations and turbulent flame speed models on XiFoam solver of OpenFOAM and compared the results to investigate the applicability of these correlation and model equations. We found that all the laminar flame speed correlations could predict qualitative behavior of the flame acceleration, but Ravi & Petersen laminar flame speed correlation that is originally implemented in OpenFOAM underestimated the maximum flame speed for the lean hydrogen concentration. Zimont model and G$"u$lder model of the turbulent flame speed could reasonably simulate the flame acceleration behavior and maximum pressure peaks. The flame velocities calculated with G$"u$lder model tend to be faster than that calculated with Zimont model.


Evaluation and modelling report of Task 9A based on comparisons and analyses of predictive modelling results for the REPRO WPDE experiments; Task 9 of SKB Task Force GWFTS - Increasing the realism in solute transport modelling based on the field experiments REPRO and LTDE-SD

Soler, J. M.*; Neretnieks, I.*; Moreno, L.*; Liu, L.*; Meng, S.*; Svensson, U.*; Trinchero, P.*; Iraola, A.*; Ebrahimi, H.*; Molinero, J.*; et al.

SKB R-17-10, 153 Pages, 2019/01



Multiple coulomb excitation experiment of $$^{68}$$Zn

小泉 光生; 関 暁之*; 藤 暢輔; 長 明彦; 宇都野 穣; 木村 敦; 大島 真澄; 早川 岳人; 初川 雄一; 片倉 純一; et al.

Nuclear Physics A, 730(1-2), p.46 - 58, 2004/01

 被引用回数:14 パーセンタイル:64.85(Physics, Nuclear)



Effect of interlaminar fracture on mechanical strength of C/C composites

小嶋 崇夫; 橘 幸男; 藤本 望; 石原 正博

Proceedings of 8th Annual International Conference on Composites Engineering (ICCE/8), p.479 - 480, 2001/00



Effects of baseline on uncertainty of radiation risk models

中山 晃志; 加藤 正平

Radiation Risk Assessment Workshop Proceedings, p.140 - 150, 2001/00



First-order transitions in an infinite-range spin-glass model

横田 光史

Journal of Physics; Condensed Matter, 4, p.2615 - 2622, 1992/00

 被引用回数:11 パーセンタイル:57.61(Physics, Condensed Matter)



Numerical study of the SK spin glass in a transverse field by the pair approximation

横田 光史

Journal of Physics; Condensed Matter, 3, p.7039 - 7046, 1991/00

 被引用回数:4 パーセンタイル:33.64(Physics, Condensed Matter)



SKB GWFTS task force; Predictive modeling of a matrix diffusion experiment in gneiss at ONKALO (Finland)

Soler, J. M.*; L$"o$fgren, M.*; Nilsson, K.*; Lanyon, G. W.*; Gylling, B.*; Vidstrand, P.*; Neretnieks, I.*; Moreno, L.*; Liu, L.*; Meng, S.*; et al.

no journal, , 


13 件中 1件目~13件目を表示
  • 1