Fault Tolerant Control for Increased Safety and Security of Nuclear Power Plants

Funding

This project is funded by the EPSRC UK-India Civil Nuclear Energy Programme, Phase 4, under grants EP/R022062/1 (grant value £292,834, hosted at the University of Portsmouth) and EP/R021961/1 (grant value: £236,149, hosted at Leeds-Beckett University). The Indian collaborators are funded by the Department of Atomic Energy.

The project period is 1 December 2018 to 31 July 2021.

Project team

• Professor Victor Becerra, Project Coordinator and Principal Investigator for the University of Portsmouth, UK
• Dr Nils Baush, Co-Investigator for the University of Portsmouth, UK
• Proessor Jiamei Deng, Principal Investigator for Leeds-Beckett University, UK
• Professor C. Pattinson (Co-Investigator for Leeds-Beckett University, UK
• Dr Vineet Vajpayee, Senior Research Associate, University of Portsmouth, UK
• Dr Shohan Banerjee, Senior Research Associate for Leeds Becket University, UK
• Dr S.R. Shimjith, Team leader for Bhabha Atomic Research Centre, Mumbai, India
• Dr John Arul, Team Leader for the Indira Gandhi Centre for Atomic Research, Chennai, India

Project summary

In safety-critical systems, such as nuclear power plants, the demand for reliability, safety and fault tolerance is high. Faults compromise plant safety, cause inefficiencies in the operation of industrial processes and reduce component life. In such safety-critical systems, it is useful to design control systems which are capable of tolerating potential faults to improve the reliability and availability while providing a desirable performance. A control system which can automatically tolerate component malfunctions, while maintaining desirable performance and stability properties is said to be a fault-tolerant control system.

Fault tolerant control approaches allow control systems to operate under fault conditions with minimal degradation of performance and stability, preventing localised, random, or intentional faults from developing into catastrophic system failures leading to accidents that may have severe consequences to human life, equipment, infrastructure, or the environment. Fault tolerance helps to reduce the damaging effects that faults can have while remedial action is taken to repair or eliminate the fault.

The project is developing a hierarchical fault-tolerant control scheme for PWR nuclear power plants which will be defined over three levels: execution, coordination and management levels. The execution level, which includes the reactor, steam generator and turbine, implements the control actions generated by the higher levels through actuators, senses relevant plant variables, and passes this information to the higher levels. The middle level acts as a coordinator between the plant manager level and the execution level.

To maximise its capabilities, the coordination level will include a bank of four different controllers that will be designed to tolerate faults of different severity, and there will be a mechanism to select the most appropriate controller given the circumstances of the plant as required by the management level. The coordination level also contains a diagnostic and prognostic system, which will the plant data and knowledge about the useful life of components to detect and characterise sensor related and other plant faults. The top level manages plant performance monitoring, plant condition evaluation, and passes commands to the coordination level. In addition, the management level transmits operational data to and receives instructions from a central command, control, and communication system which interfaces with human operators.

The project also involves the development of a nuclear plant simulator which will be used to test in real-time the hierarchical fault tolerant control scheme to be developed and implemented, to generate data about the behaviour of the plant under normal and fault conditions, and to generate simplified models of the plant, or parts of the plant, to be used for the purposes of controller design. The real-time tests will permit to assess the developments in a computational environment that is close to what would be encountered on a real plant, hence ensuring that the control methods to be developed are as realistic as possible.

The work is being carried out in collaboration with Bhabha Atomic Research Centre, and the Indira Ghandi Centre for Atomic Energy, both Indian research institutions that specialise in nuclear energy.

Project objectives

The main research aim of this project is to develop and test a hierarchical integrated fault-tolerant control architecture for PWR nuclear power plants. Specific objectives include:

a) Develop and test a nonlinear dynamic model of a typical PWR system using the MATLAB-SIMULINK platform, with specific adaptations to make it suitable for control design.

b) Design a robust multivariable controller for the PWR system using linear control theory.

c) Develop and test data-driven methods for fault diagnosis for nuclear power plants, incorporating component prognosis (remaining useful life models) to enhance diagnosis, as well as methods for automatic sensor calibration and validation. The model from objective (a) will be used as a test platform.

d) Develop and test in real time a fault-tolerant model-predictive controller, resilient and LQG reliable controllers for the PWR nuclear power plant.

e) Create a hierarchical integrated fault tolerant control system for PWR nuclear power plants using the methods from objectives (b), (c), and (d), and evaluate it in real-time using the model of objective (a).

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