Impact of Zr Metal and Coking Reactions on the Fission Product Aerosol Release During MCCI (Molten Core Concrete Interactions)

摘要

During a core meltdown accident in a light water reactor, molten core materials (corium) could leave the reactor vessel and interact with concrete. In this paper, the impact of the zirconium content of the corium pool and the coking reaction on the release of fission products during Molten Core Concrete Interactions (MCCI) are quantified using CORCON/MOD2 and VANESA computer codes. Detailed calculations show that the total aerosol generation is proportional to the zirconium content of the corium pool. Among the twelve fission product groups treated by the VANESA code, CsI, CsO sub 2 and Nb sub 2 O sub 5 are completely released over the course of the core/concrete interaction, while an insignificant quantity of Mo, Ru and ZrO sub 2 are predicted to be released. The release of BaO, SrO and CeO sub 2 increase with increased Zr content, while the releases of Te and La sub 2 O sub 3 are relatively unaffected by the Zr content of the corium pool. The impact of the coking reaction on the radiological releases is estimated to be significant; while the impact of the coking reaction on the aerosol production is insignificant. (ERA citation 12:038902)