Past, present and future - The future is fast1 January 2003
Professor Yevgeny Adamov, director of the NIKIET research institute and former minister of atomic energy, is a keen advocate of the fast reactor. By Judith Perera
NEI: Ambitious plans to develop nuclear power as a large-scale energy source have not been realised globally. Does nuclear power have a future?
Adamov: Serious accidents at Windscale in the UK, Three Mile Island in the USA and at Chernobyl in the Ukraine revealed the unacceptable level of safety at first generation plants. Currently, the prospects of energy supply for sustainable development look precarious, and environmental problems are becoming increasingly alarming. While nuclear power has a good potential to meet these challenges, it has been held back by a number of problems. These include safety, non-proliferation of weapons technologies, and disposal of radioactive waste. It is only by resolving these problems and by gaining a firm economic edge over other energy technologies that nuclear power will be able to grow significantly. The public have become increasingly concerned about safety and aware of the problems posed by the build-up of spent fuel and radioactive waste.
NEI: Surely in the wake of the accidents you mentioned, most safety issues have now been addressed?
Adamov: Given the present scale of the nuclear power industry, contemporary reactors are relatively safe. It should be remembered that the industry has about 8000 reactor-years of operating experience, with some 5000 reactor-years since April 1986 being free of major accidents. This may be seen as a real success for nuclear technology. However, the philosophy of "engineered" safety, which has predominated, tolerated potentially hazardous design approaches and addressed the possible risks by developing safety systems and barriers, and by stepping up the requirements for equipment and personnel. This philosophy was responsible for nuclear losing its competitiveness. Reactors of the current generation rely mostly on increasing the number of various engineered safety features and activity confinement systems, and on introducing more and more stringent requirements for equipment and personnel. This inevitably adds to the complexity of nuclear plants and, hence, to their cost.
NEI: So what is the long-term future for nuclear power?
Adamov: Fast reactors with a liquid metal coolant have the greatest physical and technical potential for inherent safety. This gives them greater economic efficiency than the first generation of such reactors. Recent investigations point to the feasibility of creating a nuclear technology in a reasonable time which will be close to the ideal of inherent, natural safety, without going too far from the technical solutions and materials that are already mastered by peaceful and military nuclear engineering. It has been demonstrated that adopting a high-density heat-conducting fuel and a chemically inert high-boiling coolant with low neutron activation gives deterministic preclusion of prompt criticality excursions, loss-of-coolant accidents, fires and hydrogen explosions - with any human errors or equipment failures - as well as preventing radioactive emissions that would require evacuation of the population, even in the event of failure of containment or reactor vessel.
The high cost of the first fast reactors proved to be the main barrier to their wide application in the energy sector. It is imperative to reduce the cost of the next generation of nuclear power plants to make them competitive. This means that costs have to be reduced significantly, and this should be extended to all the main structures, systems and components. This can be achieved by applying the concept of natural safety. Its consistent implementation - starting with the basic technical approaches - affords greater simplicity in design, eases the requirements for basic and auxiliary components, plant structures and personnel, and makes it possible to dispense with additional safety systems - all resulting in cost reduction.
In addition, in Russia, there are possibilities for trimming the costs of nuclear power plants by improving design regulations as well as doing away with some expensive and unnecessarily cumbersome buildings, structures and infrastructure components.
NEI: Do you see any future for thermal reactors worldwide?
Adamov: The existing global - and Russian - reserves of natural uranium are not large enough to sustain long-term development of nuclear power based on thermal reactors. The potential resources of cheap uranium, estimated at just over 10 million tonnes, are smaller in terms of energy equivalence, than those of oil and gas, let alone coal.
At present, Russian nuclear power requires 2800 to 3300 tonnes of natural uranium a year, while the total annual demand, including nuclear fuel export, is 6000-7700 tonnes. With the available uranium resources (natural deposits, stockpiles at mining enterprises, highly enriched uranium inventories), the domestic nuclear power industry can function for 80-90 years, if its capacity remains at around 20GWe. By closing the fuel cycle for thermal reactors and by using energy-grade plutonium and regenerated uranium, this period can be extended by another 10-20 years, depending on the method of regenerated fuel production.
However, uranium can be burned almost completely in a fast reactor with a breeding ratio of unity or more. An increase in the energy yield of nuclear fuel by a factor of 200 compared with thermal reactors means that a fast reactor mix of 4000GWe may be provided with cheap uranium for 2500 years, with fuel making only a small contribution to the total cost. Fast reactors can be fed with uranium from low-grade deposits, where resources are hundreds or even thousands of times greater than cheap uranium reserves.
NEI: What about the problems of radioactive waste disposal?
Adamov: Closing of the fuel cycle is a strategic goal in developing Russian nuclear power. The aim is to ensure much more efficient use of natural fuel and fissile materials generated during reactor operation, to minimise the radwaste from spent fuel reprocessing, and to establish, as far as practicable, a radiation equivalence between buried waste and mined ore.
The safety of radwaste burial over thousands of years is in doubt because of the questionable reliability of such long-range predictions. However, establishing a balance between the buried waste and the uranium produced from the earth in terms of radiation and biological hazards (radiation-equivalent waste disposal with intermediate regional concentration for cooling), can make a strong case in demonstrating the safety of radwaste management.
A surplus of neutrons and the energy spectrum affording fission of all actinides are factors that enable fast reactors to burn effectively the most hazardous and long-lived radionuclides from the fuel cycle wastes. This paves the way for a radiation balance between buried waste and mined uranium, without the need for special "burner" reactors.
The quantities of spent fuel are quite large, with 40,000t in Russia alone and 250,000t accumulated worldwide up to 2000, while its total radioactivity amounts to 5 billion Ci.
Fuel unloaded from nuclear power facilities is mostly in storage, as reprocessing takes place on a relatively small scale in Russia. However, storage is quickly becoming a real challenge. With increasing quantities of radwaste being unloaded from decommissioned power plants, transport (in particular submarines) and research reactors, existing storage facilities could be full by 2007.
We should also consider that current procedures for fuel storage in water over several decades is not entirely consistent with safety requirements, and that the fuel reprocessing facility which has been in operation at Mayak since 1977 needs to be upgraded.
It makes sense to postpone reprocessing of the bulk of spent fuel until new generation fast reactors are in serial construction. This would also prevent further accumulation of plutonium in stockpiles, in line with non-proliferation considerations.
NEI: How would a system based on fast reactors help to prevent weapons proliferation?
Adamov: The Non-Proliferation Treaty, which has been in force since 1970, failed to prevent new states from acquiring nuclear weapons. Concerns about proliferation prompted the USA and Western European countries to terminate development of fast reactors and a closed nuclear fuel cycle. However, today it is possible to dispense with the uranium blanket in fast reactors so that they no longer breed plutonium. By changing to fuel of equilibrium composition in fast reactors with core breeding ratio equal to approximately 1, and by phasing-out uranium enrichment technologies, we can provide technological support to the non-proliferation regime.
Using naturally safe fast reactors appears to be the most cost-effective way to safely dispose of plutonium accumulated in the spent fuel of modern power reactors. It would no longer be kept in spent fuel ponds, but would be either in reactors or well-protected fuel cycle facilities. The fuel cycle arrangement on the plant site allowing refuelling in a quasi-continuous mode means that the fuel would be kept in in-pile storage for 3 to 12 months and then passed on directly for reprocessing and refabrication on site. Thus,
no fresh or irradiated fuel would be stored outside of the reactor, long-range shipments would be unnecessary, and the risk of theft practically ruled out.
However, reprocessing of spent fuel from light water reactors involving plutonium separation and fabrication of the first cores for the fast reactors will be necessary and should take place at existing facilities or at specially built nuclear technology centres under international jurisdiction. In addition, fuel reprocessing technology should be modified to rule out its application for separation of Pu, U-235 or U-233. Removal of fission products would still be required, but should leave a residue of 1-10%. National capabilities (such as satellites) should be provided to monitor the configuration of buildings and structures designed for nuclear fuel reprocessing.
Needless to say, no new fuel cycle technology is capable of preventing illicit use of existing processes for plutonium separation, for example from LWR fuel, and for uranium enrichment to obtain weapons-grade materials. However, the proposed system sets technological barriers to proliferation by divorcing the fuel cycle from weapons production processes.
NEI: What do you see as the best solution for disposal of weapons-grade Pu?
Adamov: In Russia, the disposition of surplus weapons plutonium as well as of plutonium separated from irradiated fuel will be affected primarily by use of mixed uranium-plutonium fuel in fast reactors. Use of weapons plutonium will become technologically and economically feasible when our BN-800 and BREST-1200 plants are built. Limited quantities of weapons plutonium may be used in thermal reactors, if required by political agreements, but it should be borne in mind that, under today's conditions in Russia - with availability of relatively inexpensive uranium in sufficient quantities, in the absence of facilities for production of plutonium-containing fuel (MOX) and of nuclear reactors licensed to use such fuel - efforts to bring plutonium into the nuclear fuel cycle would entail substantial extra expenses.