Browsing by Subject "Nuclear fuel cycle"
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Item Essential physics for fuel cycle modeling(2011-12) Scopatz, Anthony Michael; Schneider, Erich A.; Biegalski, Steven; Landsberger, Sheldon; Deinert, Mark; Yim, Man-SungNuclear fuel cycles (NFC) are the collection of interconnected processes which generate electricity through nuclear power. Due to the high degree of coupling between components even in the simplest cycles, the need for a dynamic fuel cycle simulator and analysis framework arises. The work presented herein develops essential physics models of nuclear power reactors and incorporate them into a NFC simulation framework. First, a one-energy group reactor model is demonstrated. This essential physics model is then to simulate a sampling fuel cycles which are perturbations of well known base-case cycles. Because the NFC may now be simulated quickly, stochastically modeling many fuel cycle realizations dramatically expands the parameter space which may be analyzed. Finally, a multigroup reactor model which incorporates spectral changes as a function of burnup is presented to increase the fidelity of the original one-group reactor. These methods form a suite of modeling technologies which reach from the lowest levels (individual components) to the highest (inter-cycle comparisons). Prior to the development of this model suite, such broad-ranging analysis had been unrealistic to perform. The work here thus presents a new, multi-scale approach to fuel cycle system design.Item Modeling energy consumption in the mining and milling of uranium(2010-12) Tavrides, Emily Loree; Schneider, Erich A.; Biegalski, SteveA family of top-down statistical models describing energy consumption in the mining, milling, and refining of uranium are formulated. The purpose of the models is to estimate the energy-to-grade dependence for uranium extraction, while defining a minimum grade that can be feasibly mined and produced. The results serve as a basis for understanding the factors governing energy consumption in the production of U3O8. The models are applied to a considerably larger data set of operating mines than in any previous effort. In addition, the validity of the modeling approach is established by modeling energy for two other commodities, gold and copper, thereby showing it can be applied to other metals. Statistical measures of explanatory power show that the models the energy-to-grade relationship is well-described for both uranium and gold. For copper, there was insufficient data over a broad range of ore grades to obtain a model that passed statistical confidence measures. The results show that mining of lower-grade deposits of uranium is likely to be less energy-intensive than previous investigators concluded. It is shown that the uncertainty in the results is dominated by the contribution of the grade-independent component of energy consumption.Item Novel methods for generalizing nuclear fuel cycle design, and fuel burnup modeling(2015-12) Flanagan, Robert Ryan; Schneider, Erich A.; Wilson, Paul; Livnat, Yarden; Landsberger, Sheldon; Biegalski, StevenThe large number of reactor designs and concepts in existence open up a vast array of nuclear fuel cycle strategies. u. These different reactor types require unique supporting systems from raw material extraction and handling to waste management. Any system designed to model nuclear energy should therefore have methods that are capability of representing a large number of unique fuel cycles. This work examines a user interface designed to generalize the design of nuclear fuel cycles. This software, known as CycIC, allows users to interact graphically with a fuel cycle simulator (Cyclus). In this work, the capabilities of CycIC were improved through two rounds of rigorous user experience testing. These tests were used as a basis for implementing improvements to the software. Two views inside the software were improved to allow for users to interact with the software more intuitively, and features that provide help to the users were added to improve understanding of fuel cycles and Cyclus. Additionally, this work expands the capabilities of a reactor modeling software (known as Bright-lite) which uses the fluence based neutron balance approach to determine burnup, criticality, and transmutation matrixes for nuclear reactors to augment its modeling of the broadest range of fuel cycle strategies. Specifically, a multi-dimensional interpolation method was implemented to enable reactors to be characterized by sets of cross section libraries which potentially depend on a large number of reactor characteristics. The accuracy of this interpolation method is demonstrated for a number of parameters for light water reactors, and techniques for using this interpolation method to automatically generate reactor libraries for Bright-lite are demonstrated. This research also generalizes the ability of the Bright-lite to blend multiple streams of nuclear fuel while still maintaining constraints. This system is demonstrated for continuous recycle nuclear fuel cycles utilizing light water and fast spectrum reactors. The results show that Bright-lite is capable of blending fuel to reach several targets using up to three different input streams.Item The effects of isotopic separation on closed nuclear fuel cycles(2012-05) Flanagan, Robert Ryan; Schneider, Erich A.; Deinert, MarkThis paper investigates the potential benefits to the fuel cycle outcomes of removing a single isotope during separation processes. Two strategies for managing the removed isotope are considered. The first strategy looks at removal of a short to intermediate lived isotope from a mass stream to be recycled and subsequently recycling its decay daughter in a transmuting reactor. The second investigates the effect of removing a long lived fission product from high level waste and recycling it into the transmuting reactor. This analysis shows that the removal of Cm-244 using the first strategy provides a marked benefit to several fuel cycle metrics. The second strategy benefits the long term radioactivity measured from the high level waste from isotopes including Zr-93 and Cs-137.