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Department of Mechanical, Aerospace and Civil Engineering

Life extension for UK nuclear reactors

Independent advice and research from our nuclear graphite academics have aided the Office of Nuclear Regulation in making decisions that are likely to increase the lifespans of 14 UK nuclear reactors by several years.

Case study

Four years extension icon


A four-year extension was granted to Oldbury power station on the basis of our advice, generating £300 million in additional income and saving six million tonnes of carbon dioxide.

18% generated icon


The percentage of UK electricity generated by AGR and Magnox nuclear power stations.

Nearly one-fifth of UK electricity comes from 15 nuclear power stations. Fourteen of these reactors use graphite to moderate the nuclear fission taking place with the reactor core.

Researchers examined how radiation damages graphite on a microscopic scale; they then developed statistical models of reactor behaviour and methods to predict the failure of reactor core components.

Data and methodologies developed at MACE have been used to predict more accurately the lifespan of individual reactor components - and hence work out how to extend the lifespan of an existing nuclear plant.

Following our modelling and advice, Oldbury nuclear power station was granted an additional four years of operation beyond its scheduled closure in 2008. Between 2008 and 2012 the site generated an additional seven terawatt hours of electricity, worth £300 million to the taxpayer and saving around six million tonnes of carbon dioxide emissions.

The daily operational value of a nuclear reactor is estimated at about £0.5 million, so every additional year of operation is worth £2.5 billion for the full nuclear fleet.

Electricity generator EDF has calculated a wide range of benefits from plant life extension, including:

  • 30 million tonnes of carbon dioxide emissions saved every year;
  • downstream contracts, mostly to UK businesses, worth £650 million annually;
  • job protection for 2,000 people, rising to 6,000 during the peak of the extension programme.

Our research in this area has developed a global reputation. It is a major partner within international, sponsored programmes on the development of inherently safe high temperature gas-cooled reactor technology.

It is also involved in research to develop recommendations for dealing with the 200,000 tonnes of irradiated graphite waste that exists worldwide.

Research background

Constant irradiation slowly damages graphite within the core of a nuclear reactor and this deterioration changes the graphite's properties and performance.

£2.5 million income icon


The additional income for nuclear generators for every extra year of operation.

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Tonnes of carbon dioxide emissions saved for every extra year of operation.

Reactors are scheduled for decommissioning partly based on the anticipated safe operational lifespan of components in a graphite reactor core.

This research examined how irradiation changes the microstructure of graphite. They found no dramatic 'cliff edge' changes. Statistical and predictive modelling showed that many reactors could continue to work safely beyond their planned closures.

Key techniques used as part of this research include the following:

  • X-ray micro-tomography and strain mapping to provide novel insights into the development of damage;
  • high-resolution transmission electron microscopy (TEM) to show how irradiation and temperature cause defects;
  • predictive models of graphite failure;
  • statistical models of novel materials, using pattern recognition and data mining.

As a centre of expertise in nuclear graphite technology, our researchers have participated in international programmes with partners from the USA, France, China, Japan, South Africa and South Korea.

Between 2008 and 2013, our academics produced 25 reports for the Health and Safety Executive, the International Atomic Energy Authority and others, along with 15 technical reports for the Graphite Technical Advisory Committee of the Office for Nuclear Regulation.