Cleaning the secondary circuit in nuclear power plants is an important process before the unit starting. Cleaning technologies for the secondary circuit of a pressurized water reactor(PWR) are relatively mature

but the ones for the secondary circuit in the high temperature gas-cooled reactor(HTGR) are lack of standards and processes. Thus

according to the system features and equipment materials of the secondary circuit in the HTGR

feasibility research on the cleaning process was conducted from the aspects of theory and engineering experience

by referring the cleaning processes for thermal power plant systems and PWR secondary circuits. Finally

a combined cleaning process was determined

which comprises cleaning installation

chemical cleaning and the secondary circuit overall water flushing. By comparing the feasibility of the three processes of manual cleaning

steam purging and chemical cleaning. Through comparing the feasibility of manual cleaning

steam blowing and chemical cleaning

it proved that the main steam pipe and high pressure side pipe cleaning process can only be realized by chemical cleaning process. After cleaning

the system should be washed with a large flow of water flushing using demineralized water(pH 9~10).