NEA Melt Coolability and Concrete Interaction Phase 2 (MCCI-2) Project

After successful completion of the MCCI Project at Argonne National Laboratory (ANL), a second project using the same ANL facilities was set-up. The MCCI‐2 program was carried out from 2006 to early 2010 to help bridge data gaps not fully covered in MCCI‐1. Testing falls into four categories:

Aside from these tests, a supporting analysis task was carried out to further develop/validate debris coolability models that form the basis for extrapolating the experiment findings to plant conditions. In total, 10 tests were conducted in this program (all successful).

Four category 1 tests were performed using the Small Scale Water Ingression and Crust Strength (SSWICS) apparatus. Tests were conducted to provide additional crust strength data to confirm the concept of a floating crust boundary condition at plant scale and to investigate the effect of gas sparging on water ingression cooling of corium. Crust strength tests (2) showed that the strength of un‐sectioned crust samples was consistent with that of the sectioned specimens tested in MCCI‐1. Gas sparging tests (2) showed that the presence of sparging significantly increases the cooling rate of a solidifying corium pool over that observed when sparging is absent.

Category 2 tests to examine the effectiveness of design features for augmenting coolability, i.e. melt stabilization concepts, were of two cooling types:

Category 3 tests were to provide additional 2‐D core-concrete interaction data. CCI tests in both the MCCI and French VULCANO facilities have shown a marked dependence of cavity erosion behaviour on concrete type. Tests with limestone/common sand (LCS) concrete generally exhibit a radial/axial power split of ~1; conversely, siliceous tests exhibit splits that are significantly greater than 1.  CCI‐4 conducted with LCS concrete, but with increased metal content (structural + cladding) to evaluate effect on cavity erosion behaviour. CCI‐5 conduced with siliceous concrete, but the apparatus was modified to increase lateral scale to diminish wall effects to the greatest extent possible. Test aspect ratio (cavity width/melt depth) increased from 1 to 3.7.

Category 4 was an integral test to validate severe accident codes. The large scale CCI‐6 test was conducted with early flooding to focus on debris coolability. Key features were:

Design incorporated an embedded array of water injection nozzles at a depth of 27.5 cm into the concrete. If debris did not quench, then a second test phase would be initiated to provide additional (Category 2) data on bottom water injection cooling. Results demonstrated that: i) early cavity flooding significantly enhances debris coolability, even for siliceous concrete, and ii) melt eruptions are a viable cooling mechanism for siliceous concrete. Test terminated on the basis of debris quench well before water injection nozzles were reached.

A concluding Seminar of the MCCI2 project was held in Cadarache, France, from 15 to 17 November 2010.

Project data

The data abstract is public.

Project participants

Belgium, Czech Republic, Finland, France, Germany, Hungary, Japan, Norway, Korea, Spain, Sweden, Switzerland and the United States.

Project period

April 2006 to December 2009


USD 1.1 million per year

Project Management

US Nuclear Regulatory Commission (USNRC)


A Summary of the CCI-4 Reactor Material Experiment Investigating the Effect of Metal Content on 2-D Cavity Erosion Behaviour – M. T. Farmer, S. Lomperski, R. W. Aeschliimann, and D. J. Kilsdonk – ANS Annual Meeting, Hollywood, Florida, June 26-30, 2011

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Last updated: 25 February 2014