Advanced Modelling for Nuclear Fuel Route Thermal Hydraulics Analysis

Lead Research Organisation: University of Sheffield
Department Name: Mechanical Engineering

Abstract

The safety of NPP has attracted increasing scrutinies from the public domain. Advanced Gas-cooled Reactor (AGR) is a second generation of nuclear reactors that was designed to be safer and more efficient. In spite of the technological advancement, safety in operation is still constituted an absolute paramount criterion in its life-cycle, which requires a continuous risk assessment routine carried out by the operators. This proposal seeks to provide detailed analysis on the fluid structure and temperature distributions inside the core reactor of AGR's. The project hopes to develop better mythologies in using computational Fluid Dynamics (CFD) to simulate the flow physics and temperature distribution in more accurate and efficient ways. In particular, activities inside the pressurized vessel of the reactors involve complicated interactions with the boundary walls and the flow properties of coolant. Each component can withstand so much stress before developing deficiencies. Therefore, an accurate and detailed analysis on the thermal hydraulic properties of the coolant provides indispensable tool into designing a risk assessment plan and normal operation manual.

The physics associated with turbulent flow have not fully reached satisfactory agreement among fluid dynamicists. The perennial problem of effectively modelling such state of fluid flow has troubled even the brightest mind in the field. Yet, these states of flow are so important in the applications of mixing, heat dissipation and stress analysis. We can only take incremental steps towards achieving the ultimate goal of fully understanding the mathematical theory behind the innocent looking Navier-Stake's equations (N-S) or its derivatives. Whilst there are many literatures on the issues of solving Navier-Stoke's equations numerically, many of them did not provide any robust methodologies in tackling the problem effectively. The most recent numerical method is called the "one-step" or projection method, which introduces a virtue velocity field and the solution is projected to satisfy the mass conservation equation. However, the inherent low accuracy and the risks associated with not being able to satisfy the boundary conditions render the scheme difficult to implement. Therefore, we need more robust methodologies to discretise the N-S equations more effectively. In addition to provide information on the safety assessment on the operations of AGR's, this work has a wider aim of advancing the numerical techniques which could be implemented in other disciplines of science and engineering.

This proposal hopes to conclude in 3 years with the expected outcome of fully understanding the flow physics in each stage of the activities not limiting to the normal operation procedures but in exceptional circumstances where the components exhibit abnormal activities that could potentially damage the reactor cores due to accumulation of excess flow or thermal stress. This will be of interest to nuclear energy stakeholders and the scientific communities interested in the 3-dimensional flow physics, which are yet fully understood.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509735/1 01/10/2016 30/09/2021
1800030 Studentship EP/N509735/1 01/10/2016 30/09/2019 Ling Fang Cao