The Institute of Physics and Power Engineering (IPPE) at Obninsk is home to several fast research reactors. The BR-1 is a critical assembly commissioned in 1955, which was used to experimentally confirm plutonium breeding. It now serves as a testified neutron source for calibration of detectors, specimens, and instrumentation. An experimental mercury-cooled BR-2 began operating in 1956 but was closed down after a year. IPPE also has a fast critical facility, BFS-2, used for studying physical parameters of fast reactors including full-scale core simulation.
The BR-5 has been in operation at IPPE since 1959 and has made it possible to obtain the first basic data on the physics, radioactive sodium technology, fuel element endurance, and other parameters needed to design the first sodium-cooled fast reactors. After it was upgraded in 1973 its capacity increased to 8MWt and is now referred to as BR-10. In 1983, essential reconstruction and vessel replacement significantly improved its safety and today it is used to investigate fuel endurance, study materials, and produce isotopes for biological and medical purposes. Various technical solutions to improve the safety of power reactors are verified and tested on BR-10, including experimental study of fission-product yield from failed fuel elements and study of structural material creepability. The facility provides continuous fast neutron and gamma irradiation and is also used for radioisotope production and treatment of cancer patients. Reactor life is being extended to the end of 2002 and the reactor will be decommissioned in 2003.
The operating experience gained with BR-10 and other facilities at IPPE was used as the basis for designing the more powerful experimental BOR-60, now operating at the Research Institute of Atomic Reactors (RIAR) in Dimitrovgrad, as well as the BN-350 in Kazakhstan and the BN-600 at Beloyarsk in the Urals. Work is now continuing on the larger BN-800 which is already licensed for construction at Beloyarsk. All these units depend on liquid sodium for cooling.
The BOR-60, which went critical in 1969, is used for endurance tests of fuel, fuel subassemblies and new cores. It is also used for testing steam generators and mastering new technologies. The 20-year design life of BOR-60 expired in 1989 and a life extension programme is valid up to 2002. Further work for life extension to 2010 is in progress.
Power reactors
The world’s first power fast reactor, the BN-350 at Aktau in Kazakhstan’s Mangyshlak peninsula on the shore of the Caspian Sea, went critical in 1972. Before it closed down in 2000 it was an important power source for western Kazakhstan, providing desalinated water as well as electricity. By providing 8000 tonnes/day of fresh water and 130MW of electricity it made possible the development of the city of Aktau. It also functioned as an experimental basis for large-scale testing of sodium technology, tests of fuel subassemblies and other core elements, studies in physics, and equipment tests.
The BN-600 has been operating at Beloyarsk since 1980 and plays a key role in the Middle Ural power system. The 1470MWt/600MWe plant has an advanced integral design with a good safety record, high reliability and efficiency. The design life of BN-600 expires in 2010 and work is under way for life extension by 10 more years. Studies are continuing on a BN-600 hybrid core design for use of weapons grade plutonium.
Plans to build two larger 800MWe and 1600MWe fast reactors (BN-800 and BN-1600) were frozen for some years because of financial and political problems, but construction of the BN-800 is now to go ahead at Beloyarsk. The reactor was originally designed to use mixed oxide (MOX) fuel, burning both civil and weapons-grade plutonium, but research is now under way to upgrade the design to use mixed nitride (UN-PuN) fuel instead which will avoid the need for a uranium blanket thereby increasing reactor safety and proliferation resistance.
Nuclear operator Rosenergoatom has earmarked over R1 billion ($34 million) in 2002 for the project. R320 million ($11 million) were set aside in the federal budget for 2001. It was recently reported that $1.2 billion is to be spent on the BN-800 within the coming eight to nine years.
The Sverdlovsk region’s minister for construction and architecture, Alexander Karlov told representatives of the Sverdlovsk and Chelyabinsk regions that work could resume by the end of 2001. He said railways are to be restored; catering services, including a canteen for workers, are to be set up; and auxiliary premises, a reactor assembly workshop, warehouses and a garage are to be built. The power engineering construction plant Uralenergostroi has been chosen as general contractor. Because BN-800 construction was suspended ten years ago, he explained, some of the materials have become “outdated and rusty, so construction of the energy block may face some difficulty”. About 6000 workers will be required for the construction, which will be carried out in shifts by various local construction companies.
Development programme
According to the revised “Programme for Nuclear Power Development in the Russian Federation for 1998-2005, and the period until 2010”, the start-up of the BN-800 at Beloyarsk is scheduled for 2009. Further activities in fast reactor development include:
• Justification of a hybrid core design for the BN-600 to incinerate
weapons-grade plutonium.
• Justification of life extensions for BR-10, BOR-60 and BN-600.
• Review of the BN-800 reactor design to reduce construction costs.
Development of advanced fast reactor designs with enhanced safety (large sodium cooled fast reactor with mixed oxide fuel, and BREST-300 lead-cooled demonstration fast reactor with nitride fuel), including experimental support studies.
Russia works closely with the IAEA’s Technical Working Group on Fast Reactors (TWG-FR), formerly International Working Group on Fast Reactors, which is the only global forum for the review and discussion of liquid metal fast reactor (LMFR) programmes. The TWG-FR has mostly focused on experimental and theoretical aspects of fast reactor technology and safety. A co-ordinated research project was conducted to apply acoustic signal processing for the detection of boiling or sodium/water reactions in LMFRs. Benchmark analyses addressed accident behaviour and design improvements of the BN-800 reactor as part of a collaborative project between the IAEA and the European Community. The IAEA also helped with development of an effective decommissioning programme for the BN-350 in Kazakhstan.
Closed fuel cycle
Despite the success of Russia’s sodium-cooled fast reactors, research is now centred on new fast reactor designs with inherent safety and alternative liquid metal cooling. Such reactors are the basis of Russia’s long-term plans to develop its nuclear sector based on a closed fuel cycle. Former Nuclear Power Minister Yevgeny Adamov, an ardent advocate of this plan, argued that fast reactor physics has inherent properties – such as its unique neutron excess – that allow for reproducing fuel, attaining high safety and economic efficiency, and solving the problems of radioactive waste and non-proliferation. His views however are broadly shared within Russia’s nuclear sector and were detailed in 2001 in a paper “Fulfilling ‘Fermi’s dream’ and solving cardinal problems of the 21st century”, written jointly with his predecessor at the Ministry, Victor Mikhailov, and his successor Alexander Rumyantsev.
The paper points out that the large quantities of plutonium accumulated by thermal reactors and the expected much lower rates of global energy production growth, compared with the post-war decades, eliminate the need for high breeding rates and high power density. As a result, the use of liquid-metal fast reactors within a closed fuel cycle is consistent with the safety and economy requirements of a large-scale power industry and can be developed and demonstrated within a reasonable time and at moderate cost. According to the paper: “Demonstration of a safe and economical fast reactor with a liquid metal coolant would make it possible to stop feeling dazzled by the variety of nuclear power development options proposed today and to focus on a course chosen by the industry founders, with E Fermi among them.”
Nuclear power could be deployed on a large scale (thousands of GW) using fast reactors of moderate power density without surplus plutonium breeding. The sodium coolant, always considered a fire risk, could then be replaced by a heavy, chemically inert, high-boiling lead, based on 40 years of experience of using lead-bismuth in Russian submarines. It would also be possible to do away with the uranium blanket for reasons of safety, non-proliferation and economy provided mixed nitride fuel were used instead of MOX.
The scientific and technical principles underlying this plan are outlined in “The strategy of nuclear power development in Russia in the first half of the 21st century” which was adopted by Minatom in December of 1999 and endorsed by the Russian Government in May of 2000. The long-term aim of the strategy is to move on the present limited use of nuclear power using thermal reactors to a large-scale industry based on fast reactors and closed cycle technology. Minatom and various institutes are currently finalising the engineering design of a plant with a demonstration inherently safe 300MWe fast reactor BREST-OD-300 and an on-site closed fuel cycle. Feasibility studies are also under way for a commercial plant with two 1200MWe BREST reactors.
Computational and design studies have been supplemented with experiments on the key problems of the BREST technology. Critical assemblies were used to study uranium-plutonium-lead reactor physics. Other studies include the thermal hydraulics of lead coolant technology, and steel corrosion in lead circulation loops, with specimens exposed to lead for over 10,000 hours at BREST operating temperatures of 420 to 650ºC. An experimental UN-PuN fuel assembly and a channel-loop with a pump are being tested in the BOR-60 reactor.
For Russia, closing of the nuclear fuel cycle is a strategic goal intended to ensure much more efficient use of natural fuel and the fissile materials generated during reactor operation. It should also minimise the radwaste from spent fuel reprocessing and establish, as far as practicable, a radiation equivalence between buried waste and mined ore.
Over 50 years, a 1000MWe LWR uses around 104 tonnes of natural uranium, Adamov and his colleagues pointed out in the paper. Assuming potential resources of cheap uranium, estimated at about 10 million tonnes, up to 1000 such units could be put on line. In terms of power output, 350GWe is already in place and the remaining 650GWe could be brought in within the 21st century. In this case, the generating capacity of thermal reactors could double by mid-century, allowing for decommissioning. However, this would not prevent the nuclear contribution to energy production from declining and stopping in the second half of the century as the world’s resources of natural uranium are not enough to provide long-term sustained development of nuclear power based on thermal reactors.
The use of fast reactors, with a breeding ratio of around 1, would mean a 200-fold increase of the energy yield from nuclear fuel. This would make possible a 4000GWe fast reactor mix with cheap fuel for 2500 years by using plutonium from the reprocessed spent fuel of LWRs (10,000t) and unburned U-235 (15,000t). Fast reactors can also use uranium from poor quality deposits.
The use of weapons plutonium in mixed uranium-plutonium fuel of fast reactors is regarded as a first step in developing the technology of the future closed fuel cycle. The law dealing with the import of foreign spent fuel which was passed by the State Duma and signed by the Russian President in July 2001, provides a legal basis for building a closed nuclear fuel cycle which could make use of foreign irradiated fuel resources.
TablesRussia’s fast reactors
