In core downstream effect for CANDU

The containment building prohibits radioactive materials release and facilitates core cooling on the event of a postulated Loss of Coolant Accident(LOCA) in the Nuclear Power Plant(NPP). The process water discharged from the break and containment spray is collected to the sump area. The strainer with perforated screen is installed in sump area to prohibit the debris passing to downstream area and to protect the components of the Emergency Core Cooling System(ECCS) and the Containment Spray System (CSS). The strainer must supply sufficient net positive suction head(NPSH) to the ECCS pump and the CSS pump and prevent debris into the fuel regions in the recirculation mode. However, some fibrous material, particulates and some chemical products may be introduced into the ECCS and the reactor coolant system (RCS). This phenomenon could be harmful for long term core cooling (LTCC) when recirculating the cooling water(coolant) from the containment sump. During operation of ECCS to recirculate coolant from the containment sump, debris in the recirculating coolant may accumulate in the flow path within the fuel bundle causing resistance to flow for core cooling. The in core downstream effect test was performed to measures the debris effects of fuel regions when the ECCS is operated the recirculation mode in CANDU