Evaluation of AP1000 reactor vessel non-metallic insulation impact on reactor core long-term recirculation cooling

To enhance the insulation ability, non-metallic insulation material was adopted in the AP1000 reactor vessel metallic insulation design. The introduction of these materials increases the production probability of impingement fibrous debris and chemical precipitates, and may impact long-term recirculation through sump screen. Adopting the alternate analysis method, this paper draws the conclusion that no impingement fibrous debris will be generated based on the Region I and Region II analysis on the pipe break scenario of RCS cold leg, hot leg and DVI. Submerge test results were input to the AP1000 chemical model, and the quantity of chemical precipitates were obtained with the total amount still below the licensing basis. Therefore, the adoption of the non-metallic insulation will not pose adverse impact on the containment sump screen under LOCA situation, and bring about bad influence on the core long-term recirculation. (author)