Materials for nuclear reactors

 The limiting factor for the safe operation of a nuclear reactor is the deterioration of the materials from which it is constructed. Radiation damage is an important source of this deterioration. The ability of a material to resist radiation damage is determined by how well the microstructure can remove vacancies and interstitial defects in equal numbers. However, the exact processes by which this happens are poorly understood, and the search for promising materials has been largely heuristic.

Diagram authored by Prof Graeme Ackland. © The University of Edinburgh

In addition to existing fission power, the possibility of building fusion power stations, producing energy in the form of vast numbers of energetic neutrons and alpha particles, is firmly back on the agenda. But a key problem remains: What will they be built of?

The majority of the world’s power is generated by heat energy.  Usually, the heat energy is used to convert water into steam which then drives massive turbine power generators to produce the electricity we use in our homes.  However, this process is quite inefficient – around 60-70% of the energy is lost during the conversion process.  Thermoelectric power generation offers a way to reduce this inefficiency.  Thermoelectric devices utilize the Seebeck effect: when a conducting material is placed in a temperature gradient a potential difference is setup along the gradient.  The sign of the gradient is related to the type of carrier, electrons (negative) or holes (positive).  Thus using these two types of materials in parallel creates an electric pump that converts heat energy directly to electricity with an efficiency of around 10% (see the figure below for a schematic of a thermoelectric power generator).  Hence any industrial or even commercial or domestic process that produces waste could be use this technology to ‘recoup’ the lost energy.

Photograph by Dr Rosalind Allen. © The University of Edinburgh

Microbial fuel cells are low-power devices that use microbes (single-celled living organisms) to convert wastewater into electricity. A huge range of organic compounds can be converted into carbon dioxide, water and energy by a population of bacteria each of which is roughly 1 micron in size. Consumption of these compounds is a normal part of the micro-organisms metabolism; in a microbial fuel cell part of the energy liberated is harvested in the form of electricity.

An extensive program of experimental work and metabolic modeling of microbial fuel cells has been established in Edinburgh University by Igor Goryanin, Slava Fedorovich, Hongwu Ma (Informatics) and Andrew Free, Bruce Ward (Biology).

This activity links closely to SUPA research in Physics and the Life Sciences (PaLS). Here there is fundamental interest in the collective behaviour and evolution of bacteria. In the area of microbial fuel cellls we are contributing by modeling the population dynamics of communities of bacteria:

There are many unconventional sources of energy which are currently receiving renewed attention. In some areas, physicists believe they may be able to make decisive improvements to device performance. In SUPA we are pursuing a number of these including:

Microbial fuel cells

Thermoelectric materials

Fusion is a potential source of abundant, zero-carbon-emission and low-waste energy, and a sustainable long-term solution to the world’s energy needs. There are significant challenges ahead to realise fusion as a commercial energy source and the timescales are uncertain. However, the global potential of fusion energy is motivating international projects in fusion energy research. Researchers at SUPA institutions are playing important roles in these research programmes.

Nuclear energy refers to the energy of an atomic nucleus that can be released by fission, fusion or radioactive decay.  Researchers within SUPA are working on aspects of all three of these nuclear energy processes.  At Strathclyde, advanced approaches to inertial confinement fusion are being developed and researchers are modelling atomic spectroscopy data for use in diagnostics of magnetic confinement fusion plasmas.  Research into plasma instabilities occurring in both types of fusion plasma is also undertaken.  Staff at Glasgow University are developing new approaches to radiograph nuclear waste produced in fission reactors, whilst at Heriot-Watt the materials used in fission and fusion reactors are investigated.

Links:

Fusion Energy Research

Reactor Materials

Radiograph waste

Nuclear Energy Research page under development

Links:

Fusion Energy

Fission Energy

Transmutation

Theme Leader: Lethy Krishnan Jagadamma (lkj2@st-andrews.ac.uk) , St Andrews

If civilisation continues at its current rate of fossil fuel usage, an energy crisis will ensue this century. In order to survive this crisis, new and innovative methods to extract energy from renewable sources, and to conserve our current resources will need to be developed.

At present, mainstream development and implementation of new generation and conservation technology is slow, but, public awareness and government pressures to deliver on agreed emission targets are rapidly changing this story.

SUPA is a collaboration that supports the physics community in Scotland.  The universities of Aberdeen, Dundee, Edinburgh, Glasgow, Heriot Watt, St Andrews, Strathclyde and West of Scotland are members.

There is huge worldwide interest in exploring and exploiting the quantum nature of light. Particular areas of opportunity include quantum information processing, unconditionally secure information transport via quantum cryptography, ultracold atom manipulation, Bose Einstein condensation and quantum metrology. Scottish excellence in this area is substantial, wide-ranging and complementary across departments, so that a tremendous opportunity exists for substantial added value via co-ordination and pooling of resources, aided by new SUPA-supported personnel with cross-institution interests .