Superheated Water-Cooled Small Modular Underwater Reactor Concept

Koroush Shirvan,Mujid Kazimi 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.6

A novel fully passive small modular superheated water reactor (SWR) for underwater deployment is designed to produce 160 MWe with steam at 500ºC to increase the thermodynamic efficiency compared with standard light water reactors. The SWR design is based on a conceptual 400-MWe integral SWR using the internally and externally cooled annular fuel (IXAF). The coolant boils in the external channels throughout the core to approximately the same quality as a conventional boiling water reactor and then the steam, instead of exiting the reactor pressure vessel, turns around and flows downward in the central channel of some IXAF fuel rods within each assembly and then flows upward through the rest of the IXAF pins in the assembly and exits the reactor pressure vessel as superheated steam. In this study, new cladding material to withstand high temperature steam in addition to the fuel mechanical and safety behavior is investigated. The steam temperature was found to depend on the thermal and mechanical characteristics of the fuel. The SWR showed a very different transient behavior compared with a boiling water reactor. The inter-play between the inner and outer channels of the IXAF was mainly beneficial except in the case of sudden reactivity insertion transients where additional control consideration is required.

Design of an Organic Simplified Nuclear Reactor

Koroush Shirvan,Eric Forrest 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.4

Numerous advanced reactor concepts have been proposed to replace light water reactorsever since their establishment as the dominant technology for nuclear energy production. While most designs seek to improve cost competitiveness and safety, the implausibility ofdoing so with affordable materials or existing nuclear fuel infrastructure reduces thepossibility of near-term deployment, especially in developing countries. The organic nuclearconcept, first explored in the 1950s, offers an attractive alternative to advancedreactor designs being considered. The advent of high temperature fluids, along with advancesin hydrocracking and reforming technologies driven by the oil and gas industries,make the organic concept even more viable today. We present a simple, cost-effective, andsafe small modular nuclear reactor for offshore underwater deployment. The core ismoderated by graphite, zirconium hydride, and organic fluid while cooled by the organicfluid. The organic coolant enables operation near atmospheric pressure and use of plaincarbon steel for the reactor tank and primary coolant piping system. The core is designedto mitigate the coolant degradation seen in early organic reactors. Overall, the designprovides a power density of 40 kW/L, while reducing the reactor hull size by 40% comparedwith a pressurized water reactor while significantly reducing capital plant costs.

Technology Selection for Offshore Underwater Small Modular Reactors

Koroush Shirvan,Ronald Ballinger,Jacopo Buongiorno,Charles Forsberg,Mujid Kazimi,Neil Todreas 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.6

This work examines the most viable nuclear technology options for future underwaterdesigns that would meet high safety standards as well as good economic potential, forconstruction in the 2030-2040 timeframe. The top five concepts selected from a survey of 13 nuclear technologies were compared to a small modular pressurized water reactor(PWR) designed with a conventional layout. In order of smallest to largest primary systemsize where the reactor and all safety systems are contained, the top five designs were: (1) aleadebismuth fast reactor based on the Russian SVBR-100; (2) a novel organic cooledreactor; (3) an innovative superheated water reactor; (4) a boiling water reactor based onToshiba's LSBWR; and (5) an integral PWR featuring compact steam generators. A similarstudy on potential attractive power cycles was also performed. A condensing and recompressionsupercritical CO2 cycle and a compact steam Rankine cycle were designed. It wasfound that the hull size required by the reactor, safety systems and power cycle can besignificantly reduced (50-80%) with the top five designs compared to the conventionalPWR. Based on the qualitative economic consideration, the organic cooled reactor andboiling water reactor designs are expected to be the most cost effective options.

PESA: Prioritized experience replay for parallel hybrid evolutionary and swarm algorithms - Application to nuclear fuel

Radaideh Majdi I.,Shirvan Koroush 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10

We propose a new approach called PESA (Prioritized replay Evolutionary and Swarm Algorithms) combining prioritized replay of reinforcement learning with hybrid evolutionary algorithms. PESA hybridizes different evolutionary and swarm algorithms such as particle swarm optimization, evolution strategies, simulated annealing, and differential evolution, with a modular approach to account for other algorithms. PESA hybridizes three algorithms by storing their solutions in a shared replay memory, then applying prioritized replay to redistribute data between the integral algorithms in frequent form based on their fitness and priority values, which significantly enhances sample diversity and algorithm exploration. Additionally, greedy replay is used implicitly to improve PESA exploitation close to the end of evolution. PESA features in balancing exploration and exploitation during search and the parallel computing result in an agnostic excellent performance over a wide range of experiments and problems presented in this work. PESA also shows very good scalability with number of processors in solving an expensive problem of optimizing nuclear fuel in nuclear power plants. PESA's competitive performance and modularity over all experiments allow it to join the family of evolutionary algorithms as a new hybrid algorithm; unleashing the power of parallel computing for expensive optimization.

Measuring functional polycentricity developments using the flow of goods in Iran: a novel method at a regional scale

Hashem Dadashpoor,Sadegh Saeidi Shirvan 서울시립대학교 도시과학연구원 2019 도시과학국제저널 Vol.23 No.4

The debate concerning the polycentricity concept and its related methods has led to numerous studies. However, these studies have focused less on the analysis of polycentricity in developing countries, such as Iran, which is peculiar because of its various socioeconomic and political features. Also, while most of the current studies have measured the polycentricity at one time, only a limited number of them have paid attention to the longitudinal perspective. Thus, this paper intends to examine functional polycentricity developments by exploring a novel method on a regional scale. To do this, we have applied a dynamic method in the case of Iran to measure the polycentricity by using data concerning the flow of goods. Our findings indicate that the polycentricity index of the system raised from 0.24 to 0.81 over a 15-year period. Therefore, theoretically, the spatial system moved towards more polycentricity. The outcome of the socioeconomic flows in Iran was such that they continuously reduced the distance between centres and reproduced moves towards a more polycentric pattern.

Development of Cr cold spray – coated fuel cladding with enhanced accident tolerance

Martin Seve cek,Anil Gurgen,Arunkumar Seshadri,Yifeng Che,Malik Wagih,Bren Phillips,Victor Champagne,Koroush Shirvan 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.2

Accident-tolerant fuels (ATFs) are currently of high interest to researchers in the nuclear industry and ingovernmental and international organizations. One widely studied accident-tolerant fuel concept ismultilayer cladding (also known as coated cladding). This concept is based on a traditional Zr-based alloy(Zircaloy-4, M5, E110, ZIRLO etc.) serving as a substrate. Different protective materials are applied to thesubstrate surface by various techniques, thus enhancing the accident tolerance of the fuel. This studyfocuses on the results of testing of Zircaloy-4 coated with pure chromium metal using the cold spray (CS)technique. In comparison with other deposition methods, e.g., Physical vapor deposition (PVD), lasercoating, or Chemical vapor deposition techniques (CVD), the CS technique is more cost efficient due tolower energy consumption and high deposition rates, making it more suitable for industry-scale production. The Cr-coated samples were tested at different conditions (500 C steam, 1200 C steam, andPressurized water reactor (PWR) pressurization test) and were precharacterized and postcharacterizedby various techniques, such as scanning electron microscopy, Energy-dispersive X-ray spectroscopy(EDX), or nanoindentation; results are discussed. Results of the steady-state fuel performance simulationsusing the Bison code predicted the concept's feasibility. It is concluded that CS Cr coating has highpotential benefits but requires further optimization and out-of-pile and in-pile testing