CometPC: first results for a simplified cooling concept based on porous concrete = : CometPC: Erste Ergebnisse für ein vereinfachtes, auf porösem Beton basierendes Kühlungskonzept

In the modified CometPC cooling concept, the water is supplied to the bottom of the melt through a layer of porous concrete which is filled and pressurised with water from an elevated water reservoir. This layer of porous concrete replaces the array of sealed injection tubes which are used in the or... Full description

In the modified CometPC cooling concept, the water is supplied to the bottom of the melt through a layer of porous concrete which is filled and pressurised with water from an elevated water reservoir. This layer of porous concrete replaces the array of sealed injection tubes which are used in the original COMET concept. By supply of a certain coolant water flow, a reasonable fragmentation, cooling, and complete solidification of the melt are achieved. Five transient experiments with thermite melts are reported which were used to develop and test the required porous layers. It is found that the cooling process results in similar cooling and solidification rates of the melt as observed in the original concept. The porosity in the solidified melt is sufficiently high to safely maintain the heat removal. The first large scale test with sustained decay heat simulation in the melt resulted in lower, yet still sufficient flooding rates, as the concrete layers were fabricated in a slightly different way, and safe cooling and arrest of the melt were demonstrated over 1.6 hours. The experiments performed so far show that the use of porous concrete layers is an attractive and economic simplification of the bottom flooding cooling concept. Additionally, and increased resistance against downward penetration of the melt even under extreme conditions is expected. Future large scale tests will concentrate on the improvement and proper design of the porous layers to optimise the coolant flow with respect to the desired porosity of the solidified melt and its solidification rate.