Simulation of hydrogen distribution and effect of Engineering Safety Features (ESFs) on its mitigation in a WWER-1000 containment

In this study, thermal–hydraulic parameters inside the containment of aWWER-1000/v446 nuclear power plant are simulated in a double-ended cold leg accident for short and long times (by using CONTAIN 2.0 and MELCOR 1.8.6 codes), and the effect of the spray system as an engineering safety feature on parameters mitigation is analyzed with the former code. Along with the development of the accident from design basis accident to beyond design basis accident, the Zircaloy–steam reaction becomes the source of in-vessel hydrogen generation. Hydrogen distribution inside the containment is simulated for a long time (using CONTAIN and MELCOR), and the effect of recombiners on its mitigation is analyzed (using MELCOR). Thermal–hydraulic parameters and hydrogen distribution profiles are presented as the outcome of the investigation. By activating the spray system, the peak points of pressure and temperature occur in the short time and remain belowthe maximumdesign values along the accident time. It is also shown that recombiners have a reliable effect on reducing the hydrogen concentration below flame propagation limit in the accident localization area. The parameters predicted by CONTAIN and MELCOR are in good agreement with the final safety analysis report. The noted discrepancies are discussed and explained.

营卫失常与动脉粥样硬化相关性探讨

阐述营卫失调与动脉粥样硬化及其斑块形成的相关性。首先提出将动脉粥样硬化斑块的中医病名定为"脉积"。营卫功能与血脉紧密相关,营卫又与体质量、体脂、血糖、血压相关,营卫失常是肥胖、糖尿病、高血压、高脂血症的基本病机,因此,营卫失常与脉积密切相关。其中,营气失常,痰浊瘀血内结,成为脉积的基本成分;营阴亏虚,阴不制阳,火热内生,扰动气血,炙灼动脉,有形之邪稽留,发生脉积。卫气失常是脉积发病之关键。卫气有余,火热灼脉;卫气失常,腠理疏松,痰浊瘀血遁脉,久成脉积。总之,营卫失常,动脉损伤,发生脉积。因此,通调营卫是防治脉积的基本原则。