An Object-oriented Systems Engineering Model Development for Improving Design Factors of the Spent Fuel Extraction Process

The United States is embarking on a national program to develop accelerator transmutation of high-level radioactive waste (ATW) as part of the Transmutation Research Program (TRP) project at its national laboratories. Through the TRP, the U.S. joins international efforts to evaluate the potential of partitioning and transmutation along with advanced nuclear fuel cycles. The TRP is aiming to develop technology for the transmutation of nuclear waste to address major long-term disposal issues. The Argonne National Laboratory (ANL) researchers have been working on development of the chemical separations scheme as an integral part of the TRP program. The development of the fuel cycle scheme requires the consideration of complicate process from transuranic elements and long-lived fission products derived by Light Water Reactor (LWR) spent fuel to separation processes involving intermediate critical reactor steps. Any proposed modification to the process can have impacts on the fuel design, amount of waste generated by the process, number of cycles through the reactor, etc. In a nuclear growth scenario, the introduction of advanced thermal reactor designs will almost certainly result in changes in separations system requirements that must be met with optimized systems. Systems engineering model is a powerful tool for enhancing the ability to improve such tedious refinement process. The separation process, as a model, can be systematically identified into groups of blocks that have specific separation functions. One block’s effluent flows into another block as input. Each block has its process target. For a complex process like chemical separation process, the use of modularized systems engineering model approach can speedup the design and process refinement. Under the guidance from the Chemical Engineering Division, Argonne National Laboratories (ANL), the Nevada Center for Advanced Computational Methods (NCACM) at University of Nevada-Las Vegas (UNLV) is developing a systems engineering model that provides process optimization tool through the automatic adjusted input parameters, such as feed compositions, stage numbers and flow rates, to improve the countercurrent solvent-extraction process on treating high-level liquid waste, such as U and Tc. Major objectives of the paper are to introduce the design concepts of the systems engineering model and to demonstrate the completed multiple-run module. WM’05 Conference, February 27March 3, 2004, Tucson, AZ INTRODUCTION The United States is embarking on a national program to develop accelerator transmutation of high-level radioactive waste (ATW) as part of the Transmutation Research Program (TRP) project at its national laboratories. Through the Program, the U.S. joins international efforts to evaluate the potential of partitioning and transmutation along with advanced nuclear fuel cycles. Transmutation means nuclear transformation that changes the contents of the nucleus. The TRP is a developing technology for the transmutation of nuclear waste to address many of the longterm disposal issues. An integral part of this program is the proposed chemical separations scheme. Figure 1 shows a block diagram of the current process as envisioned by Argonne National Laboratory (ANL) researchers [1], [2], [3]. Nearly all issues related to risks to future generations arising from long-term disposal of such spent nuclear fuel are attributable to ~1% of its content that includes plutonium, neptunium, americium, and curium (the transuranic elements) and long-lived isotopes of iodine and technetium. While removing transuranics from discharged fuel destined for disposal, the toxic nature of the spent fuel drops below that of natural uranium ore within a timeframe of several hundred years. Figure 1 depicts the fuel cycle scheme in which the transuranic elements and long-lived fission products from Light Water Reactor (LWR) spent fuel are sent directly to an accelerator-driven sub-critical reactor for transmutation. Other schemes under consideration involve intermediate critical reactor steps; this would result in major changes in the design, development and analysis of separations systems. Systems engineering would enhance the ability to respond with such changes. The complete process considers existing LWR spent fuel, separation processes, fuel fabrication, transmutation, disposal as a low-level waste (LLW), and the reprocessing of fuel after transmutation. This is an involved process that can be varied in a number of ways. Any proposed change to the process can have impacts on the fuel design, amount of waste generated by the process, number of cycles through the reactor, etc. In a nuclear growth scenario, the introduction of advanced thermal reactor designs will almost certainly result in changes in separations system requirements that must be met with optimized systems. As indicated in Figure 1, the separation process can be systematically identified as a group of blocks that have specific separation functions and parameters. One block’s effluent flows into another block as input. Each block has its process target. For a complex process like chemical separation process, constructing a systems engineering model is critical for design optimization and process refinement. The objective of this research to develop a systems engineering model software that integrates existing separation modules from various agencies for analyzing and improving chemical separation process in a systematic and optimized ways. Due to the availability of the process modules, this research only demonstrates the systems engineering model using Argonne Model for Universal Solvent Extraction (AMUSE) module from Uranium Extraction (UREX) process. The system design concept and developed interface will be discussed in the paper. WM’05 Conference, February 27March 3, 2004, Tucson, AZ