Development and verification of a Monte Carlo two-step method for lead-based fast reactor neutronics analysis

Yiwei Wu,Qufei Song,Ruixiang Wang,Yao Xiao,Hanyang Gu,Hui Guo Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6

With the rise of economic and safety standards for nuclear reactors, new concepts of Gen-IV reactors and modular reactors showed more complex designs that challenge current tools for reactor physics analysis. A Monte Carlo (MC) two-step method was proposed in this work. This calculation scheme uses the continuous-energy MC method to generate multi-group cross-sections from heterogeneous models. The multi-group MC method, which can adapt locally-heterogeneous models, is used in the core calculation step. This calculation scheme is verified using a Gen-IV modular lead-based fast reactor (LFR) benchmark case. The influence of homogenized patterns, scatter approximations, flux separable approximation, and local heterogeneity in core calculation on simulation results are investigated. Results showed that the cross-sections generated using the 3D assembly model with a locally heterogeneous representation of control rods lead to an accurate estimation with less than 270 pcm bias in core reactivity, 0.5% bias in control rod worth, and 1.5% bias on power distribution. The study verified the applicability of multi-group cross-sections generated with the MC method for LFR analysis. The study also proved the feasibility of multi-group MC in core calculation with local heterogeneity, which saves 85% time compared to the continuous-energy MC.

Multigroup cross-sections generated using Monte-Carlo method with flux-moment homogenization technique for fast reactor analysis

Yiwei Wu,Qufei Song,Kuaiyuan Feng,Jean-Francois Vidal,Hanyang Gu,Hui Guo Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

The development of fast reactors with complex designs and operation status requires more accurate and effective simulation. The Monte-Carlo method can generate multi-group cross-sections in arbitrary geometry without approximation on resonances treatment and leads to good results in combination with diffusion codes. However, in previous studies, the coupling of Monte-Carlo generated multi-group cross-sections (MC-MGXS) and transport solvers has shown relatively large biases in fast reactor problems. In this paper, the main contribution to the biases is proved to be the neglect of the angle-dependence of the total cross-sections. The flux-moment homogenization technique (MHT) is proposed to take into account this dependence. In this method, the angular dependence is attributed to the transfer cross-sections, keeping an independent form for the total sections. For the MET-1000 benchmark, the multi-group transport simulation results with MC-MGXS generated with MHT are improved by 700 pcm and an additional 120 pcm with higher order scattering. The factors that cause the residual bias are discussed. The core power distribution bias is also significantly reduced when MHT is used. It proves that the MCMGXS with MHT can be applicable with transport solvers in fast reactor analysis.

Neutronics modelling of control rod compensation operation in small modular fast reactor using OpenMC

Hui Guo,Xingjie Peng,Yiwei Wu,Xin Jin,Kuaiyuan Feng,Hanyang Gu 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3

The small modular liquid-metal fast reactor (SMFR) is an important component of advanced nuclearsystems. SMFRs exhibit relatively low breeding capability and constraint space for control rod installation. Consequently, control rods are deeply inserted at beginning and are withdrawn gradually tocompensate for large burnup reactivity loss in a long lifetime. This paper is committed to investigatingthe impact of control rod compensation operation on core neutronics characteristics. This paper presentsa whole core fine depletion model of long lifetime SMFR using OpenMC and the influence of depletionchains is verified. Three control rod position schemes to simulate the compensation process arecompared. The results show that the fine simulation of the control rod compensation process impactssignificantly the fuel burnup distribution and absorber consumption. A control rod equivalent positionscheme proposed in this work is an optimal option in the trade-off between computation time andaccuracy. The control position is crucial for accurate power distribution and void feedback coefficients inSMFRs. The results in this paper also show that the pin level power distribution is important due to theheterogeneous distribution in SMFRs. The fuel burnup distribution at the end of core life impacts theworth of control rods.

MicroRNA-409-3p Inhibits Migration and Invasion of Bladder Cancer Cells via Targeting c-Met

Xin Xu,Liping Xie,Hong Chen,Yiwei Lin,Zhenghui Hu,Yeqing Mao,Jian Wu,Xianglai Xu,Yi Zhu,Shiqi Li,Xiangyi Zheng 한국분자세포생물학회 2013 Molecules and cells Vol.36 No.1

There is increasing evidence suggesting that dysregulation of certain microRNAs (miRNAs) may con-tribute to tumor progression and metastasis. Previous studies have shown that miR-409-3p is dysregulated in some malignancies, but its role in bladder cancer is still unknown. Here, we find that miR-409-3p is down-regulated in human bladder cancer tissues and cell lines. Enforced expression of miR-409-3p in bladder cancer cells significantly reduced their migration and invasion without affecting cell viability. Bioinformatics analysis identified the pro-metastatic gene c-Met as a potential miR-409-3p target. Further studies indicated that miR-409-3p suppressed the expression of c-Met by binding to its 3-untranslated region. Silencing of c-Met by small interfering RNAs phenocopied the effects of miR-409-3p overexpression, whereas restoration of c-Met in bladder cancer cells bladder cancer cells overexpressing miR-409-3p, partially reversed the suppressive effects of miR-409-3p. We further showed that MMP2 and MMP9 may be downstream effector proteins of miR-409-3p. These findings indicate that miR-409-3p could be a potential tumor suppressor in bladder cancer.

The intrinsic relationship between color variation and performances of the deteriorated aviation lubrication oil

Jun Ma,Shaojun Ruan,Jianqiang Hu,Yuanbao Sun,Yiwei Fei,Xufeng Jiang,Shibao Dong,Teng Chen,Nan Wu 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-

Dose the blackened lubrication oil needs to be replaced forflying safety? Since there is very limited roomfor inaccurate assessment of oil quality due to strictflying safety standards, much aviation lubrication oilis disposed in advance long before their service life. More important, aircrafts still face the fatalchallenges from unpredictable lubrication oil deterioration. Color change is surely a significant signal to diagnose the quality of lubrication oils. Based on thecolorimeter, the color numbers of the testing lubrication oils are measured in this paper to identify thecolor variation degree of the oxidized lubrication oils. Then the molecular structures of the oxidizedlubrication oils are investigated tofind the intrinsic relationship between the oxidation products andcolor numbers. Based on key performances of the oxidized oil samples, the oil quality is undoubtfullydeteriorated which is coincident with the variation of color number. The color numbers of the usedaviation lubrication oils could provide an alternative way to readily and quickly measure the declinedegree and residual lifetime.

MicroRNA-576-3p Inhibits Proliferation in Bladder Cancer Cells by Targeting Cyclin D1

Liang, Zhen,Li, Shiqi,Xu, Xin,Xu, Xianglai,Wang, Xiao,Wu, Jian,Zhu, Yi,Hu, Zhenghui,Lin, Yiwei,Mao, Yeqing,Chen, Hong,Luo, Jindan,Liu, Ben,Zheng, Xiangyi,Xie, Liping Korean Society for Molecular and Cellular Biology 2015 Molecules and cells Vol.38 No.2

MicroRNAs (miRNAs) are small, endogenous RNAs that play important gene-regulatory roles by binding to the imperfectly complementary sequences at the 3'-UTR of mRNAs and directing their gene expression. Here, we first discovered that miR-576-3p was down-regulated in human bladder cancer cell lines compared with the non-malignant cell line. To better characterize the role of miR-576-3p in bladder cancer cells, we over-expressed or down-regulated miR-576-3p in bladder cancer cells by transfecting with chemically synthesized mimic or inhibitor. The overexpression of miR-576-3p remarkably inhibited cell proliferation via G1-phase arrest, and decreased both mRNA and protein levels of cyclin D1 which played a key role in G1/S phase transition. The knock-down of miR-576-3p significantly promoted the proliferation of bladder cancer cells by accelerating the progression of cell cycle and increased the expression of cyclin D1. Moreover, the dual-luciferase reporter assays indicated that miR-576-3p could directly target cyclin D1 through binding its 3'-UTR. All the results demonstrated that miR-576-3p might be a novel suppressor of bladder cancer cell proliferation through targeting cyclin D1.

MicroRNA-576-3p Inhibits Proliferation in Bladder Cancer Cells by Targeting Cyclin D1

Liping Xie,Zhen Liang,Shiqi Li,Xin Xu,Xianglai Xu,Xiao Wang,Jian Wu,Yi Zhu,Zhenghui Hu,Yiwei Lin,Yeqing Mao,Hong Chen,Jindan Luo,Ben Liu,Xiangyi Zheng 한국분자세포생물학회 2015 Molecules and cells Vol.38 No.2

MicroRNAs (miRNAs) are small, endogenous RNAs that play important gene-regulatory roles by binding to the imperfectly complementary sequences at the 3 -UTR of mRNAs and directing their gene expression. Here, we first discovered that miR-576-3p was down-regulated in human bladder cancer cell lines compared with the non-malignant cell line. To better characterize the role of miR-576-3p in bladder cancer cells, we over-expressed or down-regulated miR-576-3p in bladder cancer cells by transfecting with chemically synthesized mimic or inhibitor. The overexpression of miR-576-3p remarkably inhibited cell proliferation via G1-phase arrest, and decreased both mRNA and protein levels of cyclin D1 which played a key role in G1/S phase transition. The knock-down of miR-576-3p significantly promoted the proliferation of bladder cancer cells by accelerating the progression of cell cycle and increased the expression of cyclin D1. Moreover, the dual-luciferase reporter assays indicated that miR-576-3p could directly target cyclin D1 through binding its 3 -UTR. All the results demonstrated that miR-576-3p might be a novel suppressor of bladder cancer cell proliferation through targeting cyclin D1.