The role of ex-vessel core retention in severe accident mitigation: Chapter 8

Ex-vessel core retention can reduce the risk of severe nuclear accidents by: 1. preventing early, above-ground containment failure for some accident sequences; 2. eliminating the continuous and long-term sources of fission products, aerosols, and combustible gases associated with debris/concrete interactions; and 3. preventing basemat penetration in those reactors, such as a floating nuclear plant, having major liquid pathways for fission product release given such penetration. These effects are discussed and quantified with examples using the CONTAIN code. Finally, an overview of core retention concepts and a summary of recent research is presented. The concepts include particle beds, refractory brick crucibles, and castable ceramic liners