A combined peridynamics and FE modelling approach to nuclear power plant materials

The UK government made it clear in a recent white paper of 2008 that nuclear energy was a vital part of the UKs energy mix to ensure both security of supply and a commitment to reduction in CO2 emissions. The recent Office of Nuclear Regulation Weightman report on the Fukushima accident has confirmed that Fukushima showed no reason to curtail nuclear operation or nuclear new build in the UK and in 2012 it is expected that EDF will start work on the first new nuclear power station at Hinkley Point. Perhaps one key issue/lesson learnt from the Fukushima accident, especially in Japan, was the need for continued research into nuclear safety to support existing and new build nuclear power plant programmes. Until recently there has been relatively little UK research into nuclear power and as such there are also relatively few young academics truly in the field. There is also a growing need to train new young talented engineers and physicists in nuclear engineering disciplines if the new build programme is to be successful and to help rebuild the UKs reputation as a world leader in this field.
This proposal is made to try to address some of these issues and at the same time explore a new growing area of modelling, known as peridynamics, with great potential for modelling many problems within the nuclear engineering materials area.
The project aims to investigate two nuclear fuel problems thus far difficult to model: pellet-cladding interactions (PCI) in nuclear fuels and oxide phase change/spallation on zirconium alloy cladding of water-cooled reactors. These problems are ideal for a mixed finite element (FE) -peridynamics modelling approach.
Both PCI and oxide growth and spallation require a model that is able to deal with a ductile material (cladding) bonded to a brittle material (UO2 ceramic fuel) under complex stress states, geometries and incorporating heat transfer and material heterogeneity. The peridynamics approach is able to model material with defects without some of the numerical issues inherent within the FE approach. However, combining the two modelling techniques can bring the advantages of both techniques together.
This project will develop a peridynamics implementation into the finite element code Abaqus. The models will then be developed further to model the specific problems of PCI and oxide spallation problems described. The project will also develop a new young post doctoral researcher and a early career academic in the field of nuclear fuel modelling.

The principal beneficiary of the research will be the nuclear power industry and in particular EDF Energy. The research work is aimed at providing detailed modelling of nuclear fuel performance for both advanced gas-cooled reactor (AGR) and pressurised water reactor (PWR) systems and better ways of managing fuel. Good quality information obtained by a combined finite element and peridynamics modelling approach to the problem of pellet-cladding interactions (PCI) will support decision making as to the optimum operating regime for the fuel. Current models of AGR PCI are largely empirical and are not capable of accurately determining the relative merits of alternative modes of reactor operation. EDF Energy is the only operator of AGRs in the world and cannot use analysis or experience from other operators. Improved analytical tools are therefore potentially of significant benefit in terms of nuclear safety, operational flexibility and financial performance.
The benefit to the public of the work is ultimately due to the fact that better fuel performance leads to safe, cost-effective, low carbon emission electricity.
Support to the PI who specialises in nuclear engineering and nuclear engineering materials in particular will also benefit the nuclear industry more generally through development of a post-doctoral researcher and more generally through graduates and MSc students under the PIs supervision.
Other nuclear industry companies in the UK will also benefit from the research by virtue of meetings the investigator will have with them through membership of expert groups on nuclear fuel and at conferences. This work will be disseminated into the whole nuclear power industry.