OECD MCCI-2 Project. Final Report

Enhanced Ex-Vessel Analysis for Fukushima Daiichi Unit 1: Melt Spreading and Core-Concrete Interaction Analyses with MELTSPREAD & CORQUENCH

“…Like all siliceous concretes, the basaltic concrete, does not release much gas upon decomposition in comparison to limestone-limestone or limestonecommon sand concretes. The reduction in melt eruption activity for low gas containing concretes is consistent with experiment observations [65]. Furthermore, the cavity pressure for these scenarios was quite high (7.5 MPa), which further reduced the melt sparging rate and, thereby, the potential for melt eruptions to occur.…”

“…Finally, only tests that ran for a fairly significant length of time (or ablation depth) were calculated so that the ability of the code to predict longer-term behavior could be assessed. In terms of dry cavity experiments, the matrix includes five tests conducted as part of the ACE/MCCI test series [62][63] at Argonne National Laboratory, two tests conducted as part of the SURC test series carried at Sandia National Laboratory [64], and finally two tests conducted as part of the OECD/MCCI-2 program [65] at Argonne. In terms of wet cavity tests, the matrix includes four tests conducted as part of the MACE program [60][61] at Argonne National Laboratory, two tests conducted as part of the OECD/MCCI-1 program [66][67][68], and finally a single large scale integral test featuring early cavity flooding that was carried out as part of the OECD/MCCI-2 program [65].…”

“…Water ingression was calculated using the Lomperski-Farmer correlation developed as part of the OECD/MCCI program [54]. The empirical constant C in this model was set to 9.0 based on previous code validation work [76]. The crust anchoring modeling option was disabled.…”

A Case Study on Severe Accident Water Addition and Water Management for a MARK I Containment

“…Transient concrete heatup and decomposition was modelled using the approach originally developed by Corradini [19]. The heat transfer between the corium and concrete was modeled using the Bradley correlation [16] with the radial/axial power split multipliers set to 1.0; testing has shown [20] that this is valid for limestone-common sand concrete. In terms of melt eruption modeling, the melt entrainment coefficient was conservatively set at 0.02%, which is at the lower end of reported values measured for this concrete type [20].…”

“…The heat transfer between the corium and concrete was modeled using the Bradley correlation [16] with the radial/axial power split multipliers set to 1.0; testing has shown [20] that this is valid for limestone-common sand concrete. In terms of melt eruption modeling, the melt entrainment coefficient was conservatively set at 0.02%, which is at the lower end of reported values measured for this concrete type [20]. The particle beds formed by eruptions were assumed to have a porosity and average particle diameter of 40 % and 2.8 mm, respectively; these values are based on posttest examination results reported as part of the MACE program [21].…”