CORIUM COOLABILITY UNDER EX-VESSEL ACCIDENT CONDITIONS FOR LWRs

Late Containment Failure

“…The MACE Project was followed by the MCCI-1 and MCCI-2 Projects [3], also conducted at the Argonne National Laboratory from 2002 to 2010, under the auspices of the Nuclear Energy Agency (NEA) of the Organization for Economic Cooperation and Development (OECD). The objective of the MCCI-1 Project was to perform experiments at reasonable scale, employing prototypic melt material, to understand the physics of the different coolability mechanisms and to provide data for validation of the models developed for these mechanisms.…”

“…The data obtained in the MCCI-1 Project [3] showed that the addition of concrete to the melt reduced the rate of water ingression. The rate reached a plateau; perhaps a certain rate of water ingression will always occur in the melt pool crust, as long as the dry-out condition is not reached.…”

“…The cooling of integral corium concrete interaction (CCI) tests by water flooding was not successful, except for one case with the LCS concrete [3]. The concrete ablation continued, though at a somewhat lower rate, but the melt pool temperature under the top crust did not decrease below the concrete ablation temperature.…”

“…The MCCI-2 Project [3], also performed under the auspices of the OECD, was a continuation of the MCCI-1 Project. Its objectives with respect to melt coolability were to (1) to obtain more data on the water ingression mechanism, in particular with gas injection from the bottom to represent the gas generation that would occur with the ablation of concrete; (2) to perform tests incorporating methods to enhance coolability of the melt, for example, the COMET concept (described later in this section) and the cooling plate at the bottom face of the melt pool, as employed in the Gen. III plant: EPR and (3) to perform integral tests for validation of melt coolability models.…”

Development and verification of molten corium–concrete interaction code

“…Crust anchoring occurred in the prototypic experiments under the top flooding (Farmer et al, 2009) although it is expected impossible for the real plant scale. So crust anchoring has to be considered in this case rather than a simple floating crust treated in the dry cavity.…”