Severe accident in high-power light water reactors: Mitigating strategies, assessment methods and research opportunities

The advancement in innovative high-power reactors necessitates concurrent study on the core failure modes and severe accident scenarios, towards a better reactor design. This work presents a detailed review of severe accidents in high-power light water reactors. We highlight the new understanding of severe accident phenomena in light water reactors and present fresh perspectives on the adequacy or otherwise of the existing computational codes for severe accident analysis in such reactors. In addition, the application of existing low-power reactor models for severe accident assessment of high-power reactors, and the required additional consideration necessary to improve existing models are discussed. As major contributions, different severe accident scenarios, management guidelines, and mitigating strategies implementation are discussed. Further, recent knowledge not considered in the early assessments, and research opportunities required for a safer reactor core are presented. The systematic presentation of core coolability under different severe accident concepts aims to foster an in-depth understanding of severe accident progression, dominant phenomena, assessment methods, and the mitigating strategies, towards a better design and safer operation of high-power light water reactors.