Water and gas release from heated concrete

A methematical model for predicting water and gas release from heated concrete is described. The heating conditions of interest are those associated with postulated accidents in LMFBR plants. The scope of the program includes development of a mechanistic model of moisture and gas transport in heated concrete, experimental measurements on concrete to provide needed transport coefficients, and overall substantiation of the model. Work completed to date indicates that the dominant mechanism for water and gas transport in heated concrete is a pressure-driven flow of fluid through concrete pores. Water may exist as vapor, as liquid, and as a sorbed phase. All three forms, and interchange between the three forms, must be recognized in a satisfactory model. Finite difference equations were written for a model in which water moves between concrete nodes as a result of pressure and concentration gradients.