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Xiaoyu Zheng,Jun Ishikawa,Tomoyuki Sugiyama,YU MARUYAMA 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.2
Containment venting is one of several essential measures to protect the integrity of thefinal barrier of a nuclear reactor during severe accidents, by which the uncontrollablerelease of fission products can be avoided. The authors seek to develop an optimizationapproach to venting operations, from a simulation-based perspective, using an integratedsevere accident code, THALES2/KICHE. The effectiveness of the containment-ventingstrategies needs to be verified via numerical simulations based on various settings of theventing conditions. The number of iterations, however, needs to be controlled to avoidcumbersome computational burden of integrated codes. Bayesian optimization is an efficientglobal optimization approach. By using a Gaussian process regression, a surrogatemodel of the “black-box” code is constructed. It can be updated simultaneously whenevernew simulation results are acquired. With predictions via the surrogate model, upcominglocations of the most probable optimum can be revealed. The sampling procedure isadaptive. Compared with the case of pure random searches, the number of code queries islargely reduced for the optimum finding. One typical severe accident scenario of a boilingwater reactor is chosen as an example. The research demonstrates the applicability of theBayesian optimization approach to the design and establishment of containment-ventingstrategies during severe accidents.
OVERVIEW OF RECENT EFFORTS THROUGH ROSA/LSTF EXPERIMENTS
HIDEO NAKAMURA,TADASHI WATANABE,TAKESHI TAKEDA,YU MARUYAMA,MITSUHIRO SUZUKI 한국원자력학회 2009 Nuclear Engineering and Technology Vol.41 No.6
JAEA started the LSTF experiments in 1985 for the fourth stage of the ROSA Program (ROSA-IV) for the LWR thermal-hydraulic safety research to identify and investigate the thermal-hydraulic phenomena and to confirm the effectiveness of ECCS during small-break LOCAs and operational transients. The LSTF experiments are underway for the ROSA-V Program and the OECD/NEA ROSA Project that intends to resolve issues in thermal-hydraulic analyses relevant to LWR safety. Six types of the LSTF experiments have been done for both the system integral and separate-effect experiments among international members from 14 countries. Results of four experiments for the ROSA Project are briefly presented with analysis by a best-estimate (BE) code and a computational fluid dynamics (CFD) code to illustrate the capability of the LSTF and codes to simulate the thermal-hydraulic phenomena that may appear during SBLOCAs and transients. The thermal-hydraulic phenomena dealt with are coolant mixing and temperature stratification, water hammer up to high system pressure, natural circulation under high core power condition, and non-condensable gas effect during asymmetric SG depressurization as an AM action.
OVERVIEW OF RECENT EFFORTS THROUGH ROSA/LSTF EXPERIMENTS
Nakamura, Hideo,Watanabe, Tadashi,Takeda, Takeshi,Maruyama, Yu,Suzuki, Mitsuhiro Korean Nuclear Society 2009 Nuclear Engineering and Technology Vol.41 No.6
JAEA started the LSTF experiments in 1985 for the fourth stage of the ROSA Program (ROSA-IV) for the LWR thermal-hydraulic safety research to identify and investigate the thermal-hydraulic phenomena and to confirm the effectiveness of ECCS during small-break LOCAs and operational transients. The LSTF experiments are underway for the ROSA-V Program and the OECD/NEA ROSA Project that intends to resolve issues in thermal-hydraulic analyses relevant to LWR safety. Six types of the LSTF experiments have been done for both the system integral and separate-effect experiments among international members from 14 countries. Results of four experiments for the ROSA Project are briefly presented with analysis by a best-estimate (BE) code and a computational fluid dynamics (CFD) code to illustrate the capability of the LSTF and codes to simulate the thermal-hydraulic phenomena that may appear during SBLOCAs and transients. The thermal-hydraulic phenomena dealt with are coolant mixing and temperature stratification, water hammer up to high system pressure, natural circulation under high core power condition, and non-condensable gas effect during asymmetric SG depressurization as an AM action.
Jung, K. J.,Lee, E. K.,Kim, S. J.,Song, C. W.,Maruyama, N.,Ishigami, A.,Kim, N. D.,Im, D. S.,Yu, B. P.,Chung, H. Y. Springer Science + Business Media 2015 Journal of molecular medicine Vol.93 No.3
<P>Recent studies on senescence marker protein-30 (SMP30) have shown that it has an important functional role in the aging process, but its precise participation in cellular works has not been fully determined. We hypothesize that SMP30 plays crucial roles in signaling processes by modulating the balance of protein tyrosine kinase (PTK)/protein tyrosine phosphatase (PTP) and in activating proinflammatory NF-kappa B. An experimental paradigm of gain and loss of SMP30 function was established using SMP30-overexpressed YPEN-1 cells (herein referred to as 'SMP30(+) cells') and SMP30 (Y/-) knockout mouse kidneys. The resulting data show that SMP30 expression suppressed oxidative stress-induced PTK/PTP dysregulation and PP1/2A inactivation in SMP30(+) cells, leading to the suppression of NF-kappa B activation. In the kidneys of SMP30 (Y/-) mice, SMP30 deficiency was found to induce NF-kappa B activation via the upstream signaling of NIK/IKK and MAPKs and to upregulate downstream NF-kappa B-responsive gene expression. In this study, we also demonstrate for the first time that SMP30 deficiency induced PTK activity in SMP30 (Y/-) kidneys, thereby significantly increasing the tyrosine phosphorylation of a catalytic subunit of PP2A (PP2Ac-Tyr307). Based on these findings, we propose that SMP30 involves NF-kappa B regulation through the PTK/PTP balance and that the age-related decrease of SMP30 causes NF-kappa B activation, which contributes to an exacerbation of the inflammatory process during aging. Key message SMP30-deficient mice induced a shorter lifespan and redox changes. Overexpression of SMP30 prevented oxidative stress insults. The depletion of SMP30 increased redox-related PTK/PTP imbalance and PP1/PP2A inactivation. The depletion of SMP30 caused an elevation of NF-kappa B-responsive inflammatory markers. SMP30 may be a potent inhibitory protein against oxidative stress and chronic inflammation.</P>