Investigation of Disturbances Cause at the GA Siwabessy Secondary Cooling System

When the reactor is in shut down condition, secondary cooling system of the reactor is continuously operated by operating flooding pump. Objective to operate this pump is to avoid corrosion due reduction process. Disturbance of the secondary cooling system currently occur is inadvertently pressure drop when pressure in the secondary cooling is rose. This paper is a result of disturbances investigation occurred to this system. Investigation is performed through testing of various valves present at the secondary cooling system followed by determining corrective action and maintenance done to the system/components suspected as disturbance cause. From investigation result, it is found that closed position at the pressure isolation valve, butterfly model, is not correctly closed. Cause of this un-proper position is phosphate chemical compound layer unevenly patch at the inside part of the valve. It is then can be concluded that phosphate compound injection to the secondary cooling system should be monitor and controlled due to phosphate compound potentially may cause disturbance to the secondary cooling system components. (author)