Design and Performance Verification of Passive Core Cooling System Strainer in Advanced Nuclear Power Plants of China

Abstract Once a loss-of-coolant accident (LOCA) occurs in the containment, various materials such as insulation and coating will be damaged by high-energy jet, and the ECCS strainer is used to filter the debris to avoid clogging of downstream equipment. A new advanced nuclear power plant in China equipped with a Passive Core Cooling system (PSI), which relies on the natural circulation driven by the water head difference between sump and core to achieve long-term core cooling after a LOCA. Some pipe break may locate under the sump flood-up elevation, resulting in most of the debris directly entering the core through the break instead of being filtered through the strainer. So a series of debris sources prevention criteria is specified to strictly minimized debris load to avoid clogging the fuel assembly flow path. An ECCS strainer with W-shaped bending filter screen is designed and a strainer module is used as the test prototype to evaluate head loss. According to the test results, 120m2 is selected as the suitable screen area; the chemical precipitate would cause a sharp head loss increase and thus the use of exposed aluminum material should be strictly restricted.