长期低功率运行(Extended Low Power Operation,ELPO)在压水堆(Pressurized Water Reactor,PWR)中具有广泛的实践经验,随着国内核电装机容量增加,为满足电网负荷不断变化的需求,越来越多的核电机组需面对日负荷跟踪或ELPO。大部分在运...长期低功率运行(Extended Low Power Operation,ELPO)在压水堆(Pressurized Water Reactor,PWR)中具有广泛的实践经验,随着国内核电装机容量增加,为满足电网负荷不断变化的需求,越来越多的核电机组需面对日负荷跟踪或ELPO。大部分在运机组通过调整硼浓度来实现ELPO运行,ELPO期间主流体硼浓度升高、堆芯功率降低,这些变化会影响硼在燃料表面污垢(Chalk Rivers Unidentified Deposit,CRUD)中的析出,改变垢致轴向功率偏移(Crud Induced Power Shift,CIPS)程度。本文揭示了CIPS的根本原因,并采用子通道程序和污垢分析程序评估了某百万千瓦级PWR采用ELPO模式后的CIPS风险。计算结果表明,将堆芯功率下降至75%,CIPS风险降低;继续将堆芯功率下降至50%,CIPS风险略有升高,但仍低于满功率运行工况。研究结果为评估ELPO对CIPS的影响提供了数据支撑,同时也为控制CIPS风险提供了新的思路。展开更多
The study examined the impact of using power tiller as a means of mechanizing lowland rice production in Nigeria. The study was carried out in Bida area, Niger State, where the sawah rice production was disseminated b...The study examined the impact of using power tiller as a means of mechanizing lowland rice production in Nigeria. The study was carried out in Bida area, Niger State, where the sawah rice production was disseminated by Watershed Initiative in Nigeria （WIN）. And in Ajase Ipo of Kwara State, some of the parameters assessed during the study included average speed of operation, average wheel slip/travel reduction, average draught of implement, and fuel consumption. The cost of operation and yield over five years of usage at Niger State and two years in Kwara State was determined and it was therefore concluded that the power tiller is the most appropriate field machinery for tillage operations such as puddling, leveling on lowland rice production in Nigeria.展开更多
文摘长期低功率运行(Extended Low Power Operation,ELPO)在压水堆(Pressurized Water Reactor,PWR)中具有广泛的实践经验,随着国内核电装机容量增加,为满足电网负荷不断变化的需求,越来越多的核电机组需面对日负荷跟踪或ELPO。大部分在运机组通过调整硼浓度来实现ELPO运行,ELPO期间主流体硼浓度升高、堆芯功率降低,这些变化会影响硼在燃料表面污垢(Chalk Rivers Unidentified Deposit,CRUD)中的析出,改变垢致轴向功率偏移(Crud Induced Power Shift,CIPS)程度。本文揭示了CIPS的根本原因,并采用子通道程序和污垢分析程序评估了某百万千瓦级PWR采用ELPO模式后的CIPS风险。计算结果表明,将堆芯功率下降至75%,CIPS风险降低;继续将堆芯功率下降至50%,CIPS风险略有升高,但仍低于满功率运行工况。研究结果为评估ELPO对CIPS的影响提供了数据支撑,同时也为控制CIPS风险提供了新的思路。
文摘The study examined the impact of using power tiller as a means of mechanizing lowland rice production in Nigeria. The study was carried out in Bida area, Niger State, where the sawah rice production was disseminated by Watershed Initiative in Nigeria （WIN）. And in Ajase Ipo of Kwara State, some of the parameters assessed during the study included average speed of operation, average wheel slip/travel reduction, average draught of implement, and fuel consumption. The cost of operation and yield over five years of usage at Niger State and two years in Kwara State was determined and it was therefore concluded that the power tiller is the most appropriate field machinery for tillage operations such as puddling, leveling on lowland rice production in Nigeria.
