Tank 241-A-105 evaporation estimate, 1970 through 1978

Tank 241-A-105 was subjected to a severe steam explosion in January 1965 that caused the metal liner on the bottom to bulge upward approximately 8 feet above its concrete foundation. Shortly after this event, radiation was detected in drywells around the tank and it was declared a leaker. Sluicing operations to remove material from the tank began in August 1968 and continued through August 1970. After sluicing was completed, a significant amount of heat generating material still remained in the tank. To keep tank temperatures below operating limits, the water level in the tank was maintained at an approximate depth of 1.5 feet. This practice was continued until January 1979 when it was believed that the contents had decayed sufficiently to discontinue the water addition and put the tank on a portable exhauster system. Recent concern has focused on what portion of this cooling water added to Tank 241-A-105 actually evaporated and how much leaked into the soil during the nine year time period. This report presents the results of a study that estimates the amount of water evaporated from Tank 241-A-105 between 1970 and 1979. The problem was completed in two parts. The first part involved development of a three dimensional heat transfer model which was used to establish the tank heat load. The results of this model were validated against thermocouple data from Tank 241-A-105. The heat removed from the tank by the ventilation air was then used as input to a second computer code, which calculated the water evaporation. Based upon these two models, the amount of water evaporated from Tank 241-A-105, between 1970 and 1979, was between 378,000 and 410,000 gallons. 9 refs., 17 figs., 7 tabs