PhD offer : Modelling of graphite bricks dynamic cracking

Engineering Doctorate : Modelling of graphite bricks dynamic cracking

• Eligibility : UK and EU candidates only.
• Start date : As soon as possible
• Sponsor : EDF Energy - EPSRC Nuclear EngD NE83
• Funding : Fees (£3,732) and stipend £13,590 (at 2011/12 rates)

Project details :
EDF Energy is considering the possibility to expend power plants life. Graphite moderator bricks are one of the main limiting components of the Advanced Gas-cooled Reactor’s (AGR) lifetime. The graphite bricks are subject to ageing and degradation due to both oxidation and irradiation effects. In their late lives, cracks are likely to occur on the keyway paths.
Understanding and evaluation of the crack’s initiation and propagation, and of the residual behaviour of cracked bricks, are key issues to underwrite whether a sufficient margin will still be preserved for the safe operation of the reactors, and how long this will be the case. Work is ongoing on the mechanical modelling of cracks initiation and propagation in graphite, and on the evaluation of the graphite strength in different loading and degradation conditions.

Experimental studies have shown that the fast fracture occurring on a keyway path of a brick may be the cause of an immediate crack on the opposite keyway. First numerical simulations have been performed in order to try to understand the dynamic behaviour and consequences of graphite bricks dynamic cracking. But the physical explanation of this phenomenon still has to be investigated, in order to know if and in which conditions bricks are likely to be singly or doubly cracked.
Methods to model graphite fast fracture are currently under development. The aim of this EngD is to investigate the capability of modelling techniques to take into account the dynamic effects of crack propagation on the stresses fields and on the integrity of uncracked parts of the brick, and to develop a modelling tool to be able to predict if a keyway cracking is likely to be the cause of further fragmentation of the brick.

Qualifications applicants should have/expected to receive :
The applicants should have a background in fracture mechanics, Finite Elements modelling, materials, physics and mathematics. Good organisation and communication skills are also expected.
The student will work through a partnership between EDF Energy Nuclear Generation, EDF Research & Development department and the Modelling and Simulation Centre of the School of Mechanical, Aerospace and Civil Engineering at the University of Manchester. The student will have the opportunity to develop his/her technical expertise and managerial skills by joining the teams of the different organisations involved. The student will also benefit from a number of industry-based technical training courses and from specific technical modules in Manchester.

If you are interested, please contact Laure Pellet (laure.pellet[at]manchester.ac.uk) and/or Prof. John yates (john.r.yates[at]manchester.ac.uk).