They are aimed at either cleaning the water in the primary system, providing separate shutdown cooling functions, water chemistry, charging and volume control, makeup water.
它们的目标是清理主系统的水，提供分离的停止，冷却的功能，水化学，装料及容量控制，补充水。
2
When you have an event, the reactor is operating at full power, you blowdown the primary coolant which is hot, you start injecting emergency core coolingwater which is cold.
Then you have the reactor vessel and piping which is the primary boundary which has an eight to ten inch thick reactor vessel and three to four inch thick steel piping to contain the coolingwater.