| NPP containment sump strainer potential clogging has been one of widely focused safety issues by the nuclear industry. In traditional design, the hypothesis of 50% strainer clogging is not conservative and a huge nuclear safety risk exists.According to NRC technical guidelines, the accident scenario analysis is conducted to acquire the most conservative condition as the input for next analysis. After collecting design files, on-site walkdown is carried out to confirm the conformity between design status and installation status. Five types of LOCAs are selected based on the rules of maximum debris quantity or worst debris combinations transported to the strainer and debris generation analysis is conducted for the most conservative LOCA condition. For different types of insulations, the ZOI(Zone Of Influence) including its shape and size, is determined to acquire the spectrum of the debris generated post-accident.The debris transportation is conducted according to the NEI-04-07. The blowdown transport, wash-down transport, pool fill-up transport and recirculation transport should be considered in the analysis. The transported fraction is calculated by two ways, baseline and refined calculation. With the input form the NPP and two kinds of debris spectrum, the containment sump strainer sizing is performed and the qualification test is conducted. The qualification comprised a series of tests during normal temperature and a temperature corrected method is used to deduce the strainter pressure drop under post-accident circumstance.This paper summarizes the study on containment sump strainer potential clogging and implementary practice for CPR1000 NPP. Based on the existed research in United States and the NRC regulatory guidelines and technical report, a complete and systematic analysis is conducted and a proper resolution for containment sump strainer potential clogging is provided and implemented in CPR1000 nuclear power plant. |
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