Investigation of Control Characteristics for a Molten Salt Reactor Plant under Normal and Accident Conditions

Run Luo,Chunyu Liu,Rafael Macián-Juan

doi:10.3390/en14175279

Run Luo, Chunyu Liu + Show 1 more

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https://doi.org/10.3390/en14175279

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Abstract

A molten salt reactor (MSR) has unique safety and economic advantages due to the liquid fluoride salt adopted as the reactor fuel and heat carrier fluid. The operation scheme and control strategy of the MSR plant are significantly different from those of traditional solid-fuel reactors because of the delayed neutron precursors drift with the liquid-fuel flow. In this paper, a simulation platform of the MSR plant is developed to study the control characteristics under normal and accident conditions. A nonlinear dynamic model of the whole system is built in the platform consisting of a liquid-fuel reactor with a graphite moderator, an intermediate heat exchanger and a steam generator. A new control strategy is presented based on a feed-forward and feedback combined scheme, a power control system and a steam temperature control system are designed to regulate load changes of the plant. Three different types of operation conditions are simulated with the control systems, including transients of normal load-follow operation, a reactivity insertion accident and a loss of flow accident. The simulation results show that the developed control system not only has a fast load-follow capability during normal operation, but also has a good control performance under accident conditions.

Highlights

The initial concept design of the molten salt reactor (MSR) was developed by the Oak Ridge National Laboratory (ORNL) for the purpose of driving a nuclear powered aircraft, which adopted liquid uranium fluoride as both reactor fuel and coolant [1]
The nonlinear dynamic model of the whole system that was built in the platform consisted of a liquid-fuel reactor with a graphite moderator, an intermediate heat exchanger and a steam generator
In order to investigate the operation and control characteristics of the MSR plant, three different transients were simulated with the developed simulation platform, which include normal load-follow operation, reactivity insertion accident and loss of flow accident

Summary

Introduction

The initial concept design of the molten salt reactor (MSR) was developed by the Oak Ridge National Laboratory (ORNL) for the purpose of driving a nuclear powered aircraft, which adopted liquid uranium fluoride as both reactor fuel and coolant [1]. Due to high melting point and high viscosity of the fuel salt, its long-term operation may cause irradiation and corrosion of structural materials. Another difficulty is that the liquid fuel flowing from the reactor core needs to be purified quickly, which poses a challenge to the chemical treatment of nuclear fuel [5]. Because of its great safety and economic advantages compared with solid-fuel reactors, the MSR was chosen as one of the six reactor types by the international forum of Generation IV nuclear energy systems [7]

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