Conference Agenda

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Session Overview
13.01: Student Competition - Elevator Pitch Contest
Wednesday, 18/Mar/2020:
3:45pm - 5:00pm

Session Chair: Youssef A. Shatilla, Khalifa University, United Arab Emirates
Location: Main Auditorium

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The contribution has been accepted as Presentation Only.

5M-Micro Modular Mobile Multi-mission Molten salt reactor

Dong Hun Lee, In Cheol Bang

Ulsan National Institute of Science and Technology

Future types of nuclear reactors should focus more on miniaturization and multi-purpose with guaranteed efficiency and safety. Micro Modular Mobile Multi-Mission Molten Salt Reactor which is called 5M proposed in this paper is a very powerful design in terms of above-mentioned requirements. The concept of the 5M is a portable reactor that can be freely moved by truck with a molten salt reactor. Not only can energy transfer to the remote areas, but it can also be used for various purposes, such as hydrogen production using its high operating temperature (500 - 800°C), 5M design can be constructed with the size of a truck that is 12m long and 2.5m high.

Coupled with the good thermal-physical properties of molten salts and the innovative concept of using liquid fuel, unlike traditional reactor having solid-nuclear fuel, microreactors with high power density can be designed; i) the inherent characteristic of the molten salt itself is that the system constraints are not serious compared to conventional reactor due to the large heat margin and low vapor pressure, ii) the online refueling is possible due to the form of the fuel being molten in the coolant salt, iii) the pump is not required due to the low mass flow rate, and iv) highly resistant to nuclear proliferation. Thus, molten salt as liquid fuel can design the 5M as an extremely passive safe reactor and highly reduce the accident risk in mobile reactors. This reactor can be loaded into trucks, designed to generate hydrogen on one side, and a thermal-electric conversion device for generating power on the other side to complete a multi-purpose 5M. The choice of fuel options for a molten salt reactor is very flexible. In the case of 5M, fluoride-based molten salt is used as a coolant and liquid fuel like MSRE which is technically proven and highly feasible.

The concept of liquid fuel and molten salt is innovative and could be an ultimate solution for the challenges facing like the spent nuclear fuel and passive safety. Therefore, MSR can become a game-changer for the future energy system that is free from environmental pollution and is not dependent on geography.

The contribution has been accepted as Presentation Only.

EVRS-1: A compact high temperature gas reactor

W. Robb Stewart, Enrique Velez

Massachusetts Institute of Technology

Nuclear construction costs have escalated dramatically in recent years: from $3,000/kW in the 1990’s to over $7,000/kW in the West today. These megaprojects require thousands of workers and a decade of construction time. The average cost overrun for a nuclear project in the 21st century in the West is over 200%, burdening utilities, taxpayers, and ratepayers. Construction costs are the primary issue facing the nuclear industry, and they are strongly associated with the size of civil structures and complexity of construction, so we focus our innovative efforts on solving these challenges.

We propose a horizontally oriented, axially aligned high temperature gas reactor (HTGR). The reactor core and steam generator are mounted on rails and in-line with one another. The rail-mounted horizontal orientation simplifies installation and eliminates the need for an overhead crane. The horizontal orientation reduces the reactor building height enabling low-cost embedment, reducing overall construction cost. The reactor pressure vessel and steam generator are in-line to facilitate assembly and alignment as well as to eliminate complexity of supporting structures for addressing thermal expansion. Four modules are flanged and can slide together or separately along the rails: vessel head, reactor core, flow separation and shielding, and steam generator. The flanges facilitate refueling and maintenance. In sum, these changes reduce the reactor building size by 50%/kW relative to other HTGR designs, and the building power density is on par with a light water reactor – all with the inherent safety and simplicity of an HTGR.

Beyond building volume, preventing water ingress from the steam generator to the graphite core and radiation shielding challenge HTGR designers. Here, a series of dual-purpose flow separators and radiation shields both mitigates radiation leakage from the core to the steam generator and limits moisture flow from the steam generator to the core. These innovations allow for the close proximity of the steam generator and reactor core and the resulting building volume reduction.

The system has several potential revenue streams: efficient (and flexible) electricity generation, district heating, hydrogen production, and water desalination. Unlike many Gen IV reactor concepts, the prismatic HTGR design is built on an existing body of research, development, and operational experience. The horizontal, inline HTGR is a near-term and low-cost future for nuclear power plants.

The contribution has been accepted as Presentation Only.

Innovative micro-reactor with passive heat transport devices application for extreme environments

Ye Yeong Park, In Cheol Bang

Ulsan National Institute of Science and Technology

Recently, interest and demand for the development of micro-reactors with low initial investment costs and easy construction have been increasing worldwide. Using heat pipe cooling system in micro-reactor has been considered as an attractive technique that allows simplified design by eliminating the pumps and exclude concerns of loss of coolant accident, core damage, or station blackout. The heat pipe is a passive heat transport device driven by capillary pumping and phase change of working fluid, which have higher thermal conductivity about 90 times than a copper bar with the same size. Several concepts of micro heat pipe cooled reactor were developed, for example, Kilopower, a kW scale fission power reactor, developing in NASA for space application. In this paper, the concept of micro-reactor with high stability and thermal efficiency applying heat pipe, and vapor chamber radiator is proposed as follows. The micro-reactor consists of the core, power conversion system, heat pipe which transports heat from core to power conversion system, and vapor chamber radiator to remove residual heat from the system to surroundings. The vapor chamber radiator, which is one of the types of heat pipe that spread heat to the surroundings, integrate the heat pipe and radiator in existed micro-reactor which can significantly reduce the volume, increase phase change heat transfer area, and reduce the thermal resistance compared to conventional heat pipe-metal plate radiator which results in compact reactor design. The enhanced thermal efficiency of the reactor can be achieved by optimizing the design of the heat pipe and vapor chamber radiator, which enable to have the compact reactor design for the same thermal output or higher power output with the same design which leads to the economic benefit. The heat pipe and vapor chamber radiator of the micro-reactor proposed in this paper is a novel design applying porous membrane that having mili-scale to nano-scale pores, inducing enhanced thermal efficiency compared to those of conventional micro heat pipe cooled reactor. The advantages of the heat pipe and the vapor chamber that operate without external power, or in micro/zero-gravity conditions, indicates the possibility to be used in extreme environments such as oceans and space, which broaden the utilization range of micro-reactor. This reactor will not only expand the scope of nuclear power use but also have a positive effect on improving the negative perception of nuclear power with enhanced stability and safety features.

The contribution has been accepted as Presentation Only.

Using Frequency Analysis to Evaluate Molten Salt Reactor Operation

Alexander Wheeler, Ondrej Chvala, Visura Pathirana, Belle Upadhyaya

University of Tennessee

Molten Salt Reactors (MSRs) will likely play a significant role in the future of energy supply. Passive safety high flexibility in MSR design promise new economic opportunities for nuclear heat as well as energy. However, there are apparent gaps in research and development, which need to be closed for the commercial viability of MSRs. The high temperature and radioactivity of the molten fuel make much of the current nuclear reactor instrumentation unsuitable for MSRs. Similarly, safeguarding regimes will need to be modified to fit MSRs. We have already shown that, when there is a diversion of plutonium in an MSR, the delayed neutron fraction will shift. This change in delayed neutron fraction is significant enough that, for some frequencies of sinusoidal reactivity insertions, there will be a dramatic and easily detectable discrepancy in reactor response. A rotating reflector/absorber disk can easily generate a reactivity sine wave at the most sensitive frequency. A small heatwave that travels out of the core and through the external pipe is created as an unintended byproduct. The magnitude of the perturbation is tuned to generate a detectable thermal response, small enough to prevent thermal stresses. A system of thermocouples in the external piping will track the migration of the heatwave and thus monitors the fuel flow rate. We intend to fully characterize the information that can be measured from reactor frequency analysis using existing MSR dynamic models. In doing so, we will provide novel instrumentation options for MSRs developers and vendors.

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