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Kazimi Mujid S. 한국원자력산업회의 2005 원자력산업 Vol.25 No.6

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.

Thermal Shock Fracture of Silicon Carbide and its Application to LWR Fuel Cladding Performance During Reflood

이유호,Thomas J. Mckrell,Mujid S. Kazimi 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.6

SiC has been under investigation as a potential cladding for LWR fuel, due to its high melting point and drasticallyreduced chemical reactivity with liquid water, and steam at high temperatures. As SiC is a brittle material its behavior duringthe reflood phase of a Loss of Coolant Accident (LOCA) is another important aspect of SiC that must be examined as part ofthe feasibility assessment for its application to LWR fuel rods. In this study, an experimental assessment of thermal shockperformance of a monolithic alpha phase SiC tube was conducted by quenching the material from high temperature (up to1200ºC) into room temperature water. Post-quenching assessment was carried out by a Scanning Electron Microscopy (SEM)image analysis to characterize fractures in the material. This paper assesses the effects of pre-existing pores on SiC claddingbrittle fracture and crack development/propagation during the reflood phase. Proper extension of these guidelines to anSiC/SiC ceramic matrix composite (CMC) cladding design is discussed.

THERMAL SHOCK FRACTURE OF SILICON CARBIDE AND ITS APPLICATION TO LWR FUEL CLADDING PERFORMANCE DURING REFLOOD

Lee, Youho,Mckrell, Thomas J.,Kazimi, Mujid S. Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.6

SiC has been under investigation as a potential cladding for LWR fuel, due to its high melting point and drastically reduced chemical reactivity with liquid water, and steam at high temperatures. As SiC is a brittle material its behavior during the reflood phase of a Loss of Coolant Accident (LOCA) is another important aspect of SiC that must be examined as part of the feasibility assessment for its application to LWR fuel rods. In this study, an experimental assessment of thermal shock performance of a monolithic alpha phase SiC tube was conducted by quenching the material from high temperature (up to $1200^{\circ}C$) into room temperature water. Post-quenching assessment was carried out by a Scanning Electron Microscopy (SEM) image analysis to characterize fractures in the material. This paper assesses the effects of pre-existing pores on SiC cladding brittle fracture and crack development/propagation during the reflood phase. Proper extension of these guidelines to an SiC/SiC ceramic matrix composite (CMC) cladding design is discussed.

Wafer-scale synthesis of monolayer two-dimensional porphyrin polymers for hybrid superlattices

Zhong, Yu,Cheng, Baorui,Park, Chibeom,Ray, Ariana,Brown, Sarah,Mujid, Fauzia,Lee, Jae-Ung,Zhou, Hua,Suh, Joonki,Lee, Kan-Heng,Mannix, Andrew J.,Kang, Kibum,Sibener, S. J.,Muller, David A.,Park, Jiwoon American Association for the Advancement of Scienc 2019 Science Vol.366 No.6471

<P><B>Single-layer porphyrin polymerization</B></P><P>Two-dimensional polymers can be made as monolayer sheets through controlled synthesis at an interface. However, it is often difficult to create intact sheets over large areas that can be transferred onto substrates. Zhong <I>et al.</I> polymerized derivatized porphyrin molecules during laminar flow at a sharp pentane-water interface to form sheets that are 5 centimeters in diameter (see the Perspective by MacLean and Rosei). The authors used electron microscopy and spectroscopy to confirm that they had produced intact monolayers. These films were then transferred onto monolayer sheets of molybdenum disulfide to form superlattices for use as capacitors.</P><P><I>Science</I>, this issue p. 1379; see also p. 1308</P><P>The large-scale synthesis of high-quality thin films with extensive tunability derived from molecular building blocks will advance the development of artificial solids with designed functionalities. We report the synthesis of two-dimensional (2D) porphyrin polymer films with wafer-scale homogeneity in the ultimate limit of monolayer thickness by growing films at a sharp pentane/water interface, which allows the fabrication of their hybrid superlattices. Laminar assembly polymerization of porphyrin monomers could form monolayers of metal-organic frameworks with Cu<SUP>2+</SUP> linkers or covalent organic frameworks with terephthalaldehyde linkers. Both the lattice structures and optical properties of these 2D films were directly controlled by the molecular monomers and polymerization chemistries. The 2D polymers were used to fabricate arrays of hybrid superlattices with molybdenum disulfide that could be used in electrical capacitors.</P>

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.

Capillary Origami with Atomically Thin Membranes

Reynolds, Michael F.,McGill, Kathryn L.,Wang, Maritha A.,Gao, Hui,Mujid, Fauzia,Kang, Kibum,Park, Jiwoong,Miskin, Marc Z.,Cohen, Itai,McEuen, Paul L. American Chemical Society 2019 NANO LETTERS Vol.19 No.9

<P>Small-scale optical and mechanical components and machines require control over three-dimensional structure at the microscale. Inspired by the analogy between paper and two-dimensional materials, origami-style folding of atomically thin materials offers a promising approach for making microscale structures from the thinnest possible sheets. In this Letter, we show that a monolayer of molybdenum disulfide (MoS<SUB>2</SUB>) can be folded into three-dimensional shapes by a technique called capillary origami, in which the surface tension of a droplet drives the folding of a thin sheet. We define shape nets by patterning rigid metal panels connected by MoS<SUB>2</SUB> hinges, allowing us to fold micron-scale polyhedrons. Finally, we demonstrate that these shapes can be folded in parallel without the use of micropipettes or microfluidics by means of a microemulsion of droplets that dissolves into the bulk solution to drive folding. These results demonstrate controllable folding of the thinnest possible materials using capillary origami and indicate a route forward for design and parallel fabrication of more complex three-dimensional micron-scale structures and machines.</P> [FIG OMISSION]</BR>