A system optimization model for low-level nuclear waste disposal

Abstract

The development of waste management systems for the disposal of low-level radioactive waste (LLW) is becoming an increasingly complex problem in decision-making. The complexity is the result of increasing considerations for the protection of water quality and remedial actions for system failures. The process becomes more complex as the points of regulatory compliance are moving closer to the disposal unit instead of the boundary of disposal site. This trend would result in every disposal unit being regulated as a discharge point, similar to the National Pollutant Discharge Elimination System (NPDES). The Oak Ridge Reservation (ORR) is in the process of developing a disposal complex for solid LLW. The complex will be a combination of disposal sites, disposal units, and disposal unit technology. Disposal unit technology includes the waste package (waste form and disposal container) and other engineered barriers added to the trench to prevent or control the transfer of radionuclides from the disposal unit into the environment. The combination of waste inventory and engineered barriers is called a waste facility. The waste facility is viewed as confinement systems and is the focal point in waste confinement studies. A disposal strategy has been developed as a framework for segregation of solid LLW according to the isotope and level of contamination in the waste. The objective of this framework is that different waste can be disposed of differently, according to the performance of the disposal site and disposal technology. A system optimization model has been developed as a portfolio of objective functions to provide insights into the implementation of the waste disposal strategy for the ORR complex. The model is aimed at making best use of the developable disposal capacities while providing for regulatory compliance, support operational continuity of the waste generators, and cost-effectiveness. This model is being designed to function as a strategic planning framework for the development of the specialized model system needed to provide the necessary data for decision making. This optimization model can be extended to the management of chemically hazardous and mixed (radioactive and chemically hazardous) waste.