Spring 2019 Honors Poster Presentation May 1, 2019 Department of Physics and Astronomy

1 2 1. Department of Physics and Astronomy, Iowa State University John Mobley IV , Gregory Maxwell 2. Department of Mechanical Engineering, Iowa State University

On the Development, Applicability, and Design Considerations of Generation IV Small Modular Reactors

BACKGROUND RESULTS CONCLUSIONS

Small modular reactors (SMRs) are a class of fission reactors with DEVELOPMENT DESIGN CONSIDERATIONS Incorporation of SMRs within existing power grids offers a scalable, power ratings between 10 to 300 MWe which can be utilized as Fission power systems from each reactor generation were isolated based upon A molten salt fast breeder small modular reactor (MSFBSMR) was devised on low initial investment energy solution to increase energy security and modules in the unit assembly of a nuclear steam supply system. The their significance and contributions to the development of current designs. the basis of long-term operation with high fuel utilization. independence. rapid development of SMRs has been spurred globally by two main

features: proliferation resistance/physical protection and economic Figure I: Timeline of Nuclear Reactor Generations Table I: Critical System Reactor Materials and Specifications ■ Maturity of nuclear energy technologies have facilitated an appeal. On the topic of proliferation resistance/physical protection, Material Classification Key Property Color environment of revolutionary reactor designs. SMRs require much less nuclear material which can be of lower 6 FLiBe coolant COLEX processed; Pr = 13.525 enrichment, thus the potential for application in weapon systems is ■ Evaluation of reactor generations through a simplified SA reveals 15Cr-15Ni Ti cladding7 austenitic (Mo 1.2%) stymied by quantity and quality of the fissile material. In conjunction, meaningful improvements in regards to the economic- and 7 on-site containment safeguards can be continually upgraded due to AISI 316LN reactor vessel austenitic (Mo 2.5%) environmental-based pillars of sustainability. the modular nature of SMRs1. Albeit the United States is the world’s Carbon Steel instrumentation electronics approximation* largest producer of nuclear power, U.S. capacity has remained ■ The molten salt SMR based upon FLIBe coolant is capable of UO fissile material ~16% U-235 effective (DB feedback) relatively constant at 100,000 megawatts since 1990 while global 2 breeding fissile material from a U-238 fertile blanket via fast 2 He conduction gas8 λ = ~3.42・105 W/(m・K) [1 bar] demand has steadily increased . To continue to increase energy neutrons (i.e. >1 MeV).

independence and therefore energy security, the development and N2 evacuation gas triple bond-induced low reactivity deployment of small modular reactors is crucial in solutions which 9 B C neutron absorber B-10: high σ FUTURE RESEARCH are compatible with a myriad of existing power grids3. 4 n capture, thermal EuB neutron absorber Eu-151: high σ 6 n capture, thermal ■ Refinement of SMR design to produce more uniform neutron flux

OBJECTIVES Gd2O3 burnable poison Gd-157: high σn capture, thermal across the core of the reactor.

■ Investigate the historical precedents that have contributed to the Zr3Si2 neutron reflector Zr: high σscatter, fast APPLICABILITY ■ Development of coolant and structural material properties for rapid development of SMRs. Be2C neutron reflector Be: high σscatter, thermal A simplified SA based upon the three pillars of sustainability—that being more precise operational modeling. *Denotes estimation of Neutron Monitoring System (NMS) devices ■ Determine the environmental and financial sustainability of these economic-, societal-, and environmental-based—was employed to analyze fission reactor systems as it relates to their applicability in both Generation III and Generation IV reactor systems. ■ Analysis of reactor thermal hydraulics and efficiency of primary Keff properties for three SMR system scenarios were quantified with respect to addressing energy concerns of modern society. heat transfer systems. Figure II: Sustainability Assessment Visualization the global unit control rod core insertion percentage.

■ Devise and model an SMR which employs design considerations Figure III: Effective Multiplication Factor Scenarios ■ Model MSFBSMR physics through TRITON (Transport Rigor from aspects of nuclear accidents and materials science to fortify Implemented with Time-dependent Operation for Neutronic energy security. depletion) to conduct continuous energy Monte Carlo depletion analysis. METHODS ACKNOWLEDGMENTS Implementing the historical method, the most significant reactors from each generation—as it relates to the development of nuclear This work used the SCALE Code System developed, maintained, energy and the final SMR design—were documented. tested, and managed by the Reactor and Nuclear Systems Division

(RNSD) of the Oak Ridge National Laboratory (ORNL) under the Modifying the criteria associated with the sustainability assessment4 U.S. Department of Energy contract DE-AC05-00OR22725. Sincere (SA) method to be relevant in evaluating reactor systems, a simplified gratitude is expressed to the LAS Honors Committee and the approach to qualitatively determining the applicability of reactor University Honors Program for support of this work. generations was adopted. Figure IV: Reactor Geometric Configuration and Flux Overlay REFERENCES Utilizing the SCALE 6.2.3 software package5 within the Fulcrum graphical user interface, two distinct classes of SMR simulations [1]. Bari, R. A. (2015). Proliferation resistance and physical protection (PR&PP) in small modular reactors (SMRs). In M. Carelli & D. Ingersoll (Eds.), Handbook of Small were conducted to achieve the third objective: Modular Nuclear Reactors (pp. 219-236). Cambridge, UK: Woodhead Publishing Limited. [2]. U.S. Department of Energy. (2017). Valuation of Energy Security for the United States. I. CSAS6 (keff) Report prepared by U.S. Department of Energy. ■ Analysis area: Criticality safety [3]. Todreas, N. (2015). Small modular reactors (SMRs) for producing nuclear energy: an introduction. In M. Carelli & D. Ingersoll (Eds.), Handbook of Small Modular Nuclear ■ Usage: Determination of critical system configurations Reactors (pp. 3-26). Cambridge, UK: Woodhead Publishing Limited. (a) (b) (c) [4]. Salaa, S., Ciuffob, B., & Nijkamp, P. (2015). A systemic framework for sustainability assessment. Ecological Economics, 119, 314-325. [5]. Rearden, B. T. & Jessee, M. A. (2018). SCALE Code System. ORNL/TM-2005/39, II. MAVRIC (휙) Version 6.2.3, Oak Ridge National Laboratory, Oak Ridge, Tennessee. Available from Radiation Safety Information Computational Center as CCC-834. ■ Analysis area: Radiation shielding [6]. Sohal, M. S., Ebner, M. A., Sabharwall, P., & Sharpe, P. (2010). Engineering Database ■ Usage: Visualization of core neutron flux of Liquid Salt Thermophysical and Thermochemical Properties. doi:10.2172/980801. [7]. Fazio, C. & Balbaud, F. (2017). Corrosion phenomena induced by liquid metals in Generation IV reactors. In P. Yvon (Ed.), Structural Materials for Generation IV Nuclear Reactors (pp. 23-74). Cambridge, UK: Woodhead Publishing Limited.

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