51315-5432-Effect of Metallurgical Factors and Waste Chemistry on Corrosion and SCC of Hanford Radioactive Waste

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Product Number: 51315-5432-SG

ISBN: 5432 2015 CP

Author: Narasi Sridhar

Publication Date: 2015

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The Hanford site contains approximately 55 million gallons of radioactive and chemically hazardous wastes arising from weapons production beginning with World War II and continuing through the Cold War. The wastes are stored in 177 underground storage tanks of which 149 are single-shell tanks (SSTs) and the remaining tanks are double-shell tanks (DSTs). The U.S. Department of Energy Office of River Protection is responsible for retrieving the tank wastes treating them in order to encapsulate them in glass logs and then permanently close the tanks and associated facilities. Current plans call for transferring the wastes from the SSTs into the DSTs over the next 25 years or so retrieving wastes from the DSTs and vitrifying them and closing all tanks by approximately 2048. Such a time line places a great emphasis on maintaining the integrity of both types of tanks. Some of the SST’s were confirmed to have leaked as early as 1956 within about 6-10 years after first receiving wastes. Management of the DSTs will have an impact on the timely retrieval of wastes from SST’s and eventual transfer of all wastes. Recently one of the oldest DSS has been suspected to leak radioactive waste into the annular space between the inner and outer shell. This paper will present the results of ongoing studies into the effect of various waste chemistries on corrosion and SCC of the shell tank. The chemistries of the waste in the annular space have been simulated using various scenarios of evaporation and equilibration with atmosphere. Additionally the metallurgical treatments undergone by the tank during its installation have been simulated. The resultant simulant chemistries and thermal treatments are used in localized corrosion and SCC tests. The accelerated test results are used to determine the potential for future leaks from the tanks. Corrosion potentials of the tank are being monitored using probes inserted into the tank center. A finite element analysis model will be presented to determine potential distribution within the tank.