NUCLEAR ENERGY Voyage into a (semi) virtual future
What are the technological prospects which provide a basis for the pursuit and relaunch of a European strategy for the nuclear energy sector? Nuclear physicists and engineers are currently exploring ideas, some still in their infancy but others nearer fruition.
They had been given approximately 25-30 years. But most of the 150 or so nuclear plants still operating in the Union are ageing less quickly than expected. The timetable for decommissioning is therefore set to be extended, stretching from 2010 to 2020. But what could be available to replace them by then? The development of any technological renewal must respect the constraints of maximum risk control and therefore takes time.
The EPR option
Plan for a prototype third-generation EPR plant: increased safety levels; substantial improvements in performance permitting an almost 10% reduction in the kilowatt-hour; nominal power increased to almost 1.5Gwe (a generating capacity unmatched to date); increased recycling and thus reduced waste; and a life expectancy of at least 50 years.
Two ‘realistic’ developments can be envisaged. Given their different time-scales for implementation, one does not rule out the other. In terms of investment, however, they could prove to be rivals. The 'quickest' solution is the third-generation reactor which would represent a transitional stage. This involves improving the safety and productivity parameters of the pressurised water reactors which make up the greater part of Europe's present nuclear energy capability.
This project is known by the acronym EPR – European Pressurised Water Reactor. It was proposed back in 1992 by the two major European players in the nuclear sector at the time: Framatome of France and Siemens of Germany (today merged under Framatome ANP). Apart from a rethought and reinforced conception of safety – based in particular on standards rendering impossible the kind of failures recorded at the time of the 'reference accidents' of the past – the EPR seeks to boost the performance of this 'traditional' design substantially. Its nominal power would be increased to almost 1.5 GWe, giving it an electricity generating capacity which is unequalled today.
This increased efficiency would mean a reduction of almost 10% in the kilowatt-hour produced. The reactor's life expectancy would be 50 years or more. Finally, the EPR project is designed to consume a very large proportion of MOX fuels, re-using much of the plutonium which results from the fission by combining it with uranium.
Controversial debate In October 2003, French Industry Minister Nicole Fontaine announced that her government was tending towards a positive decision for the EPR solution. Supporters of the project took the view that this switch to the third-generation reactor would meet an anticipated demand for the renewal and extension of the nuclear market in the short term, in emerging countries (such as China) as well as Europe. At the end of 2003, the Finnish operator TPO – mandated by its government which is currently the only one in the Union to have decided to increase its present capacity of four reactors – came out clearly in favour of the EPR and placed a first firm order worth € 3 billion with the Arena(1)-Siemens consortium.
However, France itself has not yet made the final decision on implementing the EPR, which remains a subject of controversy. Apart from the expected opposition from the anti-nuclear campaigners, there is also some criticism from industrialists and supporters of nuclear energy who would like to see more innovative reactors. Its detractors see the thinking behind the EPR (conceived a decade ago) as simply a continuation of existing technologies. Although improved, they would be insufficiently revised, in their view, in particular in terms of reduced waste production.
The fourth generation looms Other innovative alternatives are, in fact, already beginning to take shape. This brings us to the world of the fourth generation and a vast field of research aimed at developing, within the next 15 to 20 years, radically new concepts which would correct the weak points of present reactors – notably in terms of a better use of fuel and a reduction in waste – while offering increased safety and lower production costs.
Research undertaken so far in this field has focused on improving the fission process itself, in particular its use of 'rapid neutrons' which had been abandoned (see box). Work is also continuing on fuel composition, by including a maximum proportion of fuel recycled at the production site. Another focus of research is the transport of the energy produced by new coolants – gases, liquid metal and molten salts rather than water. A gas coolant makes it possible to use the direct cycle (electricity generation without passing through a secondary circuit) which increases output.
Fourth-generation systems also promise a substantial increase in operating temperatures, from the present 300°C in pressurised water reactors to 850°C. In thermodynamic terms, this temperature increase would make it possible to achieve a 50% yield in the conversion of heat into electricity.
At these levels, nuclear power plants can become sources of co-generation. The associated heat production would then be used in industrial processes. It is also believed that the heat produced by coastal power plants could be used for the large-scale development of sea-water desalination. If temperatures could climb to 900°C, for example, the heat recovered would be able to produce large quantities of hydrogen by means of the thermochemical cracking of the water. Hydrogen is particularly interesting for generating energy using fuel cells with zero greenhouse gas emissions.
Europe between fission… Where does Europe lie in this nuclear future? Time and competing technologies are both determining factors.
With a solid base after almost 50 years of activity, the electronuclear sector must compete with other energies. It is therefore up to the industry itself to manage its continued activity autonomously in the short term of around 30 years. European support for research is limited to a shared interest, first in the issue of waste management and, to a lesser extent, in the monitoring of satisfactory and coordinated safety measures.
On the other hand, Europe is involved in certain projects with a view to the 'fourth-generation' technology. Euratom, under the Fifth Framework Programme 1998-2002, lent its support to the Michelangelo(2) thematic network. Launched in 2001, this brings together a major group of industrialists and scientists and has set itself the mission of defining a strategy for keeping open the option of fission nuclear energy in 21st century Europe.
Research activities are also supported in the framework of four of the concepts adopted by the Generation IV Forum (see box): the HTR (High-Temperature Reactor), the fast gas-cooled reactor, the super-critical water reactor and the molten salt reactor). Another project is looking at seawater desalination. Calls for proposals for research on fourth generation reactors are continuing under the Sixth Framework Programme (FP6) 2002-2006.
…and fusion The much longer-term prospect – at least 50 years ahead – offered by thermonuclear fusion, is very different.
Control of this means of energy production, which involves harnessing the high-energy reactions at work within the sun and other active stars, would bring an unprecedented revolution in the history of mankind and remove any doubts about future energy supplies.
In the last few decades, the Commission has already invested several billion euro of EU funds – € 750 million under FP6 – with a view to the long-term realisation of this ambitious and strategic project. It is also the subject of active international co-operation by the United States, Japan, Russia, China and Korea.
Thanks to these efforts, Europe is today a leading partner in this joint research that is now entering a crucial stage: the construction, now firmly approved, of the first demonstration reactor, known as ITER. After a lengthy selection process, in November 2003 the Union chose to submit as sole European candidate the research centre at Cadarache, in France, as home for the ITER. The participants met in Washington a month later but did not manage to make a final choice between the Union site and the only other remaining candidate, the RokkashoMure site in Japan. The decision is expected in February 2004.
(1) Framatome subsidiary. (2) Michelangelo Network - Competitiveness and sustainability of nuclear energy in the EU.
Nuclear technologies generally use uranium 238 (described as fertile) as fuel. This is collected in the natural state and then pre-enriched with isotope 235. It is this isotope, representing about 3% of the content, which produces the fission ...
The International Generation IV Forum
Founded on the initiative of the US Department of Energy (DoE), this forum for research and reflection includes ten member countries – Argentina, Brazil, Canada, France, Japan, South Korea, South Africa, Switzerland, the United Kingdom, the United ...
Nuclear technologies generally use uranium 238 (described as fertile) as fuel. This is collected in the natural state and then pre-enriched with isotope 235. It is this isotope, representing about 3% of the content, which produces the fission reactions when bombarded with thermal neutrons, so-called slow neutrons. Approximately 1% of uranium 238 captures neutrons to produce plutonium 239, which is also a fissile material (see diagram). When it leaves the power plants, the spent fuel therefore contains a large part of uranium and about 1% plutonium.
During reprocessing, the uranium and the plutonium can be industrially separated from the spent fuel and reused to form a fissile mixture known as MOX. However, in thermal neutron plants, the MOX can only be recycled two or three times. Consequently, in this type of reactor it is only possible to use a small part of the nuclear fuels involved.
Bombarding fissile materials with higher energy neutrons, known as fast neutrons, is an alternative. This permits better fission of the plutonium and increases the capture of neutrons by the fertile uranium 238 present in the fuel to convert it into plutonium 239.
The 1970s brought a major development in fast neutron technology, with the concept of breeder reactor. These were presented as machines which produced more fuel than they used. Nevertheless, the development of this technology has encountered fierce opposition as plutonium 239 is also one of the raw materials used for nuclear weapons.
The breeder reactor built at Kalkar (Germany) has never been used. Apart from the experimental Phénix reactor at Marcoule, that is still suitable for service, France tried to make large-scale use of its Superphénix reactor at Creys-Malville. The experience did not produce convincing results and the reactor was shut down after two decades in 1997.
Following a radical reappraisal, fast neutron technology, which is very interesting in terms of minimising waste, could again find favour in the context of fourth-generation reactors.
The International Generation IV Forum
Founded on the initiative of the US Department of Energy (DoE), this forum for research and reflection includes ten member countries – Argentina, Brazil, Canada, France, Japan, South Korea, South Africa, Switzerland, the United Kingdom, the United States – plus the European Commission. Its aim is to explore the possible future of the electronuclear sector through to 2030. Initial research has identified six systems(1) which meet the stated requirements in terms of sustainability (especially the drastic reduction of waste), economy, safety and security (non-proliferation and protection against terrorism).
Research and development in these new fields is consequently at the start-up stage. A co-operative effort is now required to coordinate the work of the partners and to specify the conditions for the sharing of information and intellectual property. For its part, the Commission is supporting a number of research projects and a European exploratory network.
(1) SFR: sodium-cooled fast reactor; LFR: lead-cooled fast reactor; VHTR: very high temperature gas-cooled thermal reactor; GFR: gas-cooled fast reactor; SCWR: supercritical water-cooled reactor; MSR: molten salt reactor.