Core Cooling Mechanism on Loss of Flow Accident of PWR Power Reactor

Loss of flow accident causes the flow rate of primary coolant on the reactor core decreases or even there is no flow and the heat produced in the reactor core can not removed adequately. The core temperature will increase and when reactor protection system and reactor safety system do not work soon, the core will be in dangerous condition and the fuel element will be damaged. The required protection is reactor trip and followed by the adequate core cooling to remove residual heat and decay heat. There is no safety injection system to function because the primary coolant pressure is still high. For this case the review is carried out with the purpose to analyze qualitatively the mechanism and capability of core cooling based on the several causes of loss of flow accident. The expected core cooling is by natural circulation on primary loop and the heat is removed through steam generator to secondary cooling system. By reviewing and based on the accident sequences as methodology used for problem description, it is obtained that the core cooling capability by natural circulation is adequate and the conclusion is that the core integrity is still assured. (author)