Abstract
In order to evaluate evaporation heat fluxes from coolant water in a spent fuel pit of a nuclear power plant to ventilation air during a shutdown of water purification and cooling systems, empirical correlations were derived. To derive correlations, the evaporation heat transfer databases at Shinsyu University, which were obtained using test sections A and B with heat transfer lengths of 940mm and 300mm, were used. The temperatures of the hot water and air were 35-65°C and about 20°C, respectively, and air velocity was up to 2.08m/s. In this study, a correlation including length scale was derived using the database under the outlet relative humidity less than 100% (Xout < 1.0) in the test section B and the analogy between heat and mass transfers. The heat flux data with 100% relative humidity at the outlet (Xout = 1.0) in the test section A were corrected using the heat flux data with Xout < 1.0 in the test section B in order to obtain evaporation heat fluxes under 100% relative humidity (X = 1.0) conditions, which might be applied to a spent fuel pit with the length scale of about 10m. Then, another correlation without the length scale was introduced from the heat fluxes corrected for conditions of X = 1.0. The heat fluxes for the length scale of 10m calculated using the two correlations agreed each other.
