Status and Future Direction of the MCCI Program

The first phase of the OECD-sponsored Melt Coolability and Concrete Interaction (MCCI) program has been successfully completed, and a follow-on MCCI-2 program has recently been initiated. Key elements of the first program included the conduct of reactor material experiments and associated analysis with the objectives of resolving the ex-vessel debris coolability issue, and addressing remaining uncertainties related to long-term, twodimensional molten core-concrete interaction under both wet and dry cavity conditions. During this first program, a total of eight separate effects tests were conducted to provide data on various core debris cooling mechanisms, and three large scale integral tests were conducted to provide data on long-term two-dimensional core-concrete interaction under both wet and dry cavity conditions. These tests provided a broad database to support the development and validation of models and codes that can be used to extrapolate to plant conditions. Based on these results, the follow-on program was devised to further broaden the scope of information gathered in the first program and also to pursue testing and analysis examining engineering features designed to increase coolability for advanced plant designs. This paper provides: i) an overview of results obtained during the first program, ii) an outline of key objectives and experiment approaches for the follow-on program, and iii) a summary of preliminary results from the first tests conducted as part of the follow-on program.