“It’s time to focus again on fast reactors: an innovative technology that extracts much more energy from uranium and recycles nuclear waste over and over again, helping to preserve natural resources while reducing the environmental impact of waste.” These words were spoken this year by IAEA Director General Rafael Mariano Grossi.

Grossi spoke at the opening of the fourth International Conference on Fast Reactors and Related Fuel Cycles: Sustainable Clean Energy for the Future.

Stressing the need to develop fast reactor technology Grossi said: “Besides being low carbon like all nuclear reactors, fast reactor systems tick key boxes when it comes to sustainability: they shrink the environmental footprint of the waste while extracting significantly more energy from the fuel. They can be a bridge to even safer and more efficient nuclear power, providing sustainable clean energy for generations.”

Early development of fast neutron reactors

Fast neutron reactors (FNRs) operate without a moderator such as water or graphite to sustain the fission chain reaction and can extract up to 70 times more energy from fuel than existing thermal reactor designs. Fast reactors can produce or ‘breed’ more fuel than they consume and can burn some of the waste contained in used fuel, greatly reducing the volume, toxicity and lifespan of the high-level waste (HLW). FNR systems also enable a fully closed nuclear fuel cycle, in which irradiated fuel is reprocessed and reused.

To date, liquid sodium has been the coolant of choice for FNRs. Sodium has a high boiling point and can extract more heat, allowing greater power density and higher temperatures. This enables smaller reactors to produce more energy and generate more electricity. Its disadvantage is its chemical reaction in contact with water and air. To overcome this, other liquid metal coolants are now being developed. Lead-Bismuth Eutectic (LBE) was used in Russian nuclear-submarines in the 1960s and is now being developed as another option for power reactors, along with lead. These coolants are chemically inert in contact with air and water, simplifying the heat transfer system. Moreover, liquid metals are not the only possible coolants under consideration. Gas coolants, such as helium, and molten salt mixtures are also being studied.

The first ever nuclear reactor to generate electricity was an FNR cooled by liquid sodium – the Experimental Breeder Reactor (EBR-I), at the US Idaho National Laboratory, which, in 1951, produced enough electricity to illuminate four 200-Watt light bulbs. The Dounreay Fast Reactor (DFR) in the UK in 1962 became the world’s first FNR to provide electricity to the national grid.

Enthusiasm for FNRs grew in the 1960s and 1970s in the US and Europe – in particular in the UK, France and Germany (See Table 1). However, things began to change in the late 1970s as concerns about scarce uranium resources waned and public opinion became increasingly hostile in the wake of the 1979 Three Mile Island accident in the USA and the Chernobyl disaster in 1986. By the early 1990s the US, the UK and Germany had closed down their FNR programmes. France continued with its Phénix and SuperPhénix projects for a few more years, despite sometimes violent public protest, finally closing SuperPhénix in 1998 and Phénix in 2009, Subsequently, in 2019, France also cancelled the Generation IV ASTRID sodium-cooled fast reactor demonstrator design project.

Co-operative efforts were made to save European FNR development. In 1984, France, the UK, Italy and Germany agreed to launch European Fast Reactor (EFR) studies and the EFR programme was initiated in 1985 between the UK, France, Belgium, Italy and Germany aiming to design a 1500 MW prototype reactor by 1993.

In 1988, the main design activities of France, Germany and the UK were merged and EFR Associates (EFR-A) was set up by Siemens, Novatome and NNC to design a new EFR, incorporating features from the three national projects.

The national R&D programmes were merged to support it. Utilities in Belgium, France, Germany, the UK, and Italy formed the European Fast Reactor Utilities’ Group (EFRUG) to act as the potential customer for an EFR. However, this came to nothing and the EFR project was cancelled in 1998.

Learning from experience

The troubled early years of development continued over the coming decades. Considerable experience was nevertheless gained and much was learned from the mistakes made during that time. In the US, for example, problems were experienced with the Experimental Breeder Reactor I (EBR-I) and with the Sodium Reactor Experiment (SRE). EBR-I, designed by Argonne National Laboratory was intended to validate nuclear physics theory indicating that a breeder reactor should be possible. In 1955, the reactor suffered a partial meltdown during a coolant flow test aimed at trying to determine the cause of unexpected reactor responses to changes in coolant flow. It was subsequently repaired for further experiments, which determined that thermal expansion of the fuel rods and the thick plates supporting the fuel rods was the cause of the unexpected reactor response.

A later accident at SRE, built by Atomics International at the Santa Susana Field Laboratory near Simi Valley in California, was altogether more serious. In July 1959, the reactor experienced a partial meltdown when 13 of the reactor’s 43 fuel elements partially melted, resulting in a release of radioactive gas into the atmosphere. The reactor was repaired and operated from 1960 to 1964 with a new reactor core.

However, local communities continued to register concerns about possible health and environmental impacts of the incident, and in 2009, the Department of Energy (DOE) finally agreed to hold a community workshop to discuss the situation. As a result of the incident, key changes were made to SRE – the sodium system was modified, instrumentation was improved and the fuel-element geometry was modified.

In the UK, the Prototype Fast Reactor (PFR) at Dounreay, which achieved criticality in 1974 and began supplying electricity in 1975, faced many delays and reliability problems before reaching full power. These included problems with the three cooling circuits when leaks in the sodium/water steam generators shutdown one and then two of the cooling circuits in 1974 and 1975.

In France, Rapsodie, which operated for 15 years, suffered two leaks – a sodium micro leak in 1978 that was so small it was never found, and a nitrogen gas leak in 1982. Phénix ran without problems for two decades, but in the early 1990s exhibited a number of unexplained behaviours, including large power transients. As a result, it was repeatedly shut down, and mostly offline between 1991 and 1994. It was recertified and underwent a significant refurbishment between 1994 and 2002. SuperPhénix, intended as a commercial FNR, proved disappointing in terms of electricity output. Its liquid sodium cooling system also suffered from corrosion and leaks, although these problems were fixed by 1996, when it achieved 90% of nominal power. Nonetheless, during its 11 years of operation, the plant had only 53 months of normal operations (mostly at low power) due to technical problems and political and administrative issues.

In Russia, in 1973, the BN-350 experienced a major sodium fire when a steam generator failed as a result of poor welding. The reactor was shut down for repair for four months. In the early years of the BN-600 there were 27 sodium leaks and 12 steam generator leaks. The last one occurred in 1994. None resulted in an emergency or prevented the plant from restarting operation after repairs.

Japan’s Joyo and Monju FNRs have both suffered a number of incidents. In 2007 a test subassembly became jammed in the Joyo reactor vessel and special equipment had to be designed to retrieve it, which finally took place in 2014. Monju, which achieved criticality in 1994, was shut down in 1995 after a sodium coolant leak and fire. The reactor was restarted in 2010 but was shut down three months later after a fuel handling machine was accidentally dropped into the reactor during a refuelling outage.

In India, the Fast Breeder Test Reactor (FBTR) was shut down between 1987 and 1989 due to technical problems. There were two major incidents – a fuel handling incident in 1987 and a primary sodium leak from the purification cabin in 2002, as well as three reactivity incidents (in 1994, 1995 and 1999).

However, all these incidents contributed to the growing body of experience on FNR technology and operation. While FNR development had effectively ceased in Europe and the US by the 1990s, it continued apace in Russia, China and India, where there are now five FNRs in operation (See Table 2) and five more under development (See Table 3).

Russia presses ahead

Russia leads the field in fast reactor technology, and has also supported China in this area. In the USSR, fast reactor designs were drawn up in 1949 as a way of avoiding shortages of uranium and a fast reactor development programme was launched at the Institute of Physics and Power Engineering (IPPE) in Obninsk. In 1955 the BR-1 (Bystry Reactor-1) critical assembly was commissioned at IPPE, fuelled with metallic plutonium and without using a coolant. BR-2 began operation in 1956 with liquid mercury. However, the metal plutonium fuel was not stable under irradiation, even at low temperatures, and mercury leaked from pipe joints and corroded the steel cladding. BR-2 was replaced in 1959 with the BR-5 cooled with liquid sodium and fuelled with plutonium dioxide. Its power was increased to 10MWt in 1973 (BR-10) and in 1983 reconstruction and vessel replacement significantly improved its safety. It operated until 2004.

In 1969 the sodium-cooled BOR-60, with a power capacity of 60MWe, was commissioned at the Research Institute of Atomic Reactors (NIIAR) in Dimitrovgrad, near Ulyanovsk. Vibro-packed fuel and other fast reactor fuel has been tested in this reactor, which is still operating, and it has been widely used for international research projects on fuel and structural materials. It was originally designed for 20 years of operation but since 1988 its operating life has been extended several times – to 30, 40 and 45 years. It is soon to be replaced by the new Multipurpose Fast Breeder Research Reactor (Mnogotselevoy bystryy issledovatelskiy reactor – MBIR), already under construction at NNIAR, which will be the world’s largest fast neutron research reactor. MBIR will be capable of testing lead, lead-bismuth and gas coolants and is planned to be the base for an international research centre. Rosatom has scheduled the physical start-up of the facility for 2026, and the power plant for 2027– a year ahead of the original timeline – and says it will be available to international partners for research programmes in 2028.

Russia’s first fast neutron (bystryy neytron – BN) power reactor, the BN-350, started up in 1972 at Aktau in Kazakhstan. Many specialist organisations worked on the project with IPPE as scientific leader. Development Design Bureau of Machine Building (OKBM, Nizhny Novgorod) led construction of the reactor; Development Design Bureau Gidropress (OKB Gidropress, Podolsk) provided equipment; and the All-Russia Science Research and Design Institute of Power Engineering Technology (VNIPIET, St Petersburg) was general designer. About half of its 1,000MWt output was used for water desalination and it also produced 130MWe of electricity. It further functioned as an experimental base for large-scale testing of fast reactor technology and fuel. Its design life was 20 years and after 1993 it operated through annual licence renewal. After its operating licence expired in 1995 it continued to operate far below capacity until it closed in 1999.

Even before BN-350 began operating, plans were already in place for a more powerful reactor as a step toward FNR commercialisation. The BN-600, which was built at unit 3 of the Beloyarsk NPP, began operation in 1980 and in 1982 became the world’s first commercial fast neutron reactor. It has been regularly upgraded and its operating life was extended in 2010 until 2020 and then for an additional five years. A further extension is now in preparation. BN-600 has the best operating and production record of all Russia’s nuclear power units.

Plans for a larger commercial fast reactor, BN-800, were already in place, and construction started in 1984 at unit 4 of the Beloyarsk NPP, However, work was frozen after the 1986 Chernobyl accident and was further delayed by financial collapse following the break-up of the USSR in 1991. The design of the plant, which began in 1983, was completely revised in 1987 after Chernobyl, and again, to a lesser extent in 1993 to meet new safety guidelines. Construction resumed in 2006 and it finally began operation in 2016. Initially it used a hybrid fuel based on 80% uranium oxide and 20% mixed uranium-plutonium oxide (mox) – both pellet and vibro-packed types. The amount of mox was gradually increased and by 2022 comprised the entire core.

Unit 5 at Beloyarsk NPP is expected to host the even larger BN-1200 fast neutron reactor. It will incorporate many technological upgrades and is tentatively expected to begin operation in 2035. A final decision to proceed is expected by the end of 2022.

Meanwhile, construction began in July 2022 of the Brest-OD-300 reactor, which is seen as a possible successor to the BN fast reactor series. It has a capacity of 700MWt (300MWe) at 540°C, with lead as the primary coolant and supercritical steam generators. No weapons-grade plutonium can be produced because there is no uranium blanket and all the breeding occurs in the core. The initial cores will comprise plutonium and used fuel including radiologically ‘hot’ fission products. The NA Dollezhal Research and Development Institute of Power Engineering (Nikiet) completed the engineering design for the Brest reactor, with lead coolant, in September 2014. Rosatom said more than 25 divisions of Nikiet were involved in the technical design project along with 35 other nuclear industry organisations.

The Brest-OD-300 reactor is part of the pilot demonstration power complex (ODEK) being built at Russia’s Siberian Chemical Combine (SCC) in Seversk as part of the Proryv (Breakthrough) project.

Since 2011, SCC has been implementing the Proryv project to demonstrate closed fuel cycle technology. ODEK will include two other unique facilities: a module for fabrication and refabrication (MFR) of mixed dense uranium-plutonium nitride (MNUP) fuel and a module for reprocessing and recycling irradiated fuel. The MFR is the first of its type now nearing completion and is scheduled to start up in 2023. Construction of the fuel reprocessing module is scheduled to begin in 2024. The commissioning of all ODEK facilities is expected in 2029.

China develops FNRs with Russian support

China’s research and development on fast neutron reactors started in 1964, supported by Russia. The objective of building an FNR was first included in China’s state programme on high-tech development in 1987, and the China Institute of Atomic Energy (CIEA), near Beijing, was appointed as lead organisation. To minimise costs, China decided to involve foreign parties, and cooperation with Russia on the project began in 1992. In 1995, Russia’s Ministry of Atomic Energy (Minatom) signed an Inter-Agency Agreement for Cooperation in the Field of Developing the Experimental Sodium-Cooled Fast Reactor with the China Nuclear Energy Industry Corporation (CNEIC).

First concrete for the Chinese Experimental Fast Reactor (CEFR) was poured in May 2000 and in 2002 a formal intergovernmental agreement was signed by Russia and China for cooperation its construction and operation. Russia’s OKBM Afrikantov built the CEFR in collaboration with OKB Gidropress, Nikiet and the Kurchatov Institute. In 2010, the 20MWe/65MWt CEFR achieved first criticality and was connected to the grid in 2011. CEFR operating personnel were trained using test facilities at OKBM, IPPE, and at NIIAR using the BOR-60.

Operation of the CEFR has paved the way for larger fast reactors. A 600MWe unit is now under construction and is to be followed by a 1000MWe plant. The pouring of first concrete for the 600MWe (1500MWt) demonstration CFR-600 took place at Xiapu, in Fujian province in December 2017. ZiO-Podolsk is supplying heat exchange modules for steam generators. Rosatom’s fuel company TVEL and the Chinese company CNLY (part of China National Nuclear Corporation) signed a contract for the supply of nuclear fuel for the CFR-600 reactor in 2018. To fulfil the contract, Russia’s Mashinostroitelny Zavod (MSZ) in Elektrostal upgraded its fast reactor fuel production facilities in 2021, and a new production site was commissioned for the serial production of CFR-600 fuel.

India commits to FNR development

In India, the Department of Atomic Energy’s (DAE’s) interest in FNRs began to the 1950s, when a three-phase strategy was proposed to expand nuclear energy given India’s limited reserves of uranium. However, it did have large reserves of thorium, and a phased programme involving uranium and thorium was adopted using different reactor types. DAE started a fast reactor programme in 1965, based at the Bhabha Atomic Research Centre (BARC). India then decided to collaborate with a country experienced in FNR technology. France offered its support and a bilateral agreement was signed in 1969. The design for a fast breeder test reactor (FBTR) was largely based on France’s Rapsodie, with some modifications. DAE approved a budget in 1971 and construction of FBTR started in 1972 at the Indira Gandhi Centre for Atomic Research (IGCAR) at Kalpakkam. All the components except grid plate, one control rod drive mechanism and one primary sodium pump were manufactured indigenously.

FBTR, jointly designed, constructed, and operated by BARC and IGCAR, was commissioned in 1985. The reactor was designed to produce 40MWt and 13.2MWe using mixed plutonium-uranium carbide as a driver fuel. Its operation was interrupted by several accidents causing long delays. It rarely operated at designed capacity and was shut down between 1987 and 1989 due to technical problems. From 1989 to 1992, it operated at 1MWt. In 1993, the power level was raised to 10.5MWt. In 2005, the fuel cycle for the FBTR was closed with an end to the reprocessing of its fuel and power was gradually increased to a maximum of 32 MWt which it reached in 2018. In March 2022 it reached its full 40 MWt design power level for the first time following replacement of its core. In 2011 it was announced that FBTR was to undergo a 20-year lifetime extension, to 2030.

India is also completing a 500MWe sodium-cooled prototype fast breeder reactor (PFBR) at IGCAR. Construction began in 2004 by Bhavini, a special purpose vehicle set up by DAE to realise the project and oversee the construction and operation of future FNRs in India. IGCAR and Bhavini are now developing detailed engineering studies for a new 600MWe commercial fast reactor (CFBR) design.

To prepare for the construction of the two commercial FBRs, a site assembly workshop and electrical substation are being built at IGCAR. DAE also intends to develop four more FNRs at a different site and has set up a ‘site-selection committee’.

Renewed interest in Europe and the USA

Interest in FNRs is now reviving in Europe and the USA both through collaborative projects and government support for private company initiatives but it remains at the design phase. R&D on six reactor concepts is being coordinated at the international level through initiatives such as the Generation IV International Forum (GIF). It brings together 13 countries (Argentina, Australia, Brazil, Canada, China, France, Japan, Korea, Russia, South Africa, Switzerland, the UK and the USA), as well as Euratom – representing the 27 European Union members. GIF’s selected reactor technologies for further R&D include three FNR types – the gas-cooled fast reactor (GFR), the lead-cooled fast reactor (LFR), and the sodium-cooled fast reactor (SFR).

In Europe, the Sustainable Nuclear Energy Technology Platform (SNETP) has defined its own strategy and priorities for the FNRs that are the most likely to meet Europe’s energy needs in the long term in terms of security of supply, safety, sustainability and economic competitiveness.

Like GIF, these are the SFR, LFR, and GFR. In addition, the European sodium fast reactor – safety measures assessment and research tools (ESFR-SMART) project (2017-2021) is the latest incarnation of previous European SFR concepts – the EFR (1990-2000) and CP-ESFR – Collaborative Project on European Sodium Fast Reactor (2008-2012). It considers
the safety objectives envisaged for generation IV reactors, taking into account the lessons learned from the Fukushima accident, and guidelines have been defined to drive ESFR-SMART developments.

As to the USA, the DOE says its fast reactor programme is “focused on science-based research that supports increasing the performance and economic competitiveness of fast reactor technology and providing validated experimental and operational data supporting fast reactor licensing cases”.

A key component of the US fast reactor programme is the Mechanisms Engineering Test Loop Facility (METL) at the Argonne National Laboratory – an intermediate-scale liquid metal experimental facility. Since 2018, DOE has used METL to test industry identified fast reactor components and will continue to “perform experiments that will yield results that can be useful to multiple fast reactor developers”. DOE says the USA “has been engaged in many code validation and verification tasks via participation in numerous national and international benchmark projects”. It “is developing several advanced fast reactor fuel forms and the tools and methodologies to accelerate the qualification of these fuels for use in advanced reactor designs”.

The DOE says the Versatile Test Reactor (VTR) “is an important piece of infrastructure to work in harmony with demonstration reactors to help us discover, test, and advance the innovative nuclear energy technologies that we need to help our planet achieve zero carbon emissions”.

In July 2022, the DOE issued a record of decision (ROD) to build a sodium-cooled fast test reactor at Idaho National Laboratory (INL). “If appropriated by Congress, the Versatile Test Reactor (VTR) would be the first fast spectrum test reactor to operate in the USA in nearly three decades,” the DOE noted. “Bringing a fast neutron test source back to the US is an investment in our transition to a future carbon-free economy,” said Assistant Secretary for Nuclear Energy Dr Kathryn Huff. “Now that we have completed this important step in the decision-making process, I look forward to working with Congress to obtain the funding needed to someday make VTR a reality.”

Although Congress did not provide Fiscal Year 2022 funding for VTR, the DOE has requested FY 2023 funding to help move the project forward toward the design phase. The DOE established the VTR programme in 2018. The team includes experts from six national laboratories, 19 universities, and nine industry partners. “Once built, VTR will generate higher neutron fluxes to test nuclear materials up to 10 times faster than what is currently capable in the United States. This testing capability only exists in Russia today,” the DOE noted.

Today, the IAEA plays a key role in supporting fast reactor development and deployment through sharing information and experience, coordinated research projects, technical publications, technical working groups and international conferences. Its International Project on Innovative Reactors and Fuel Cycles (INPRO) also helps catalyse fast reactor development and deployment and related fuel cycles by supporting countries in planning and collaboration.

While there are signs of renewed interest in FNRs in Europe and the USA, so far this is limited to discussions of designs, as in GIF, SNETP and the US VTR, or is being left to private company initiatives backed by limited government finance. In a world, which is increasingly concerned about limited energy supplies, global warming and environmental issues, the advantages of FNRs are clear. They offer the prospect of multiple re-use of fuel and a way to burn dangerous high-level wastes, while also producing clean electricity.

Russia’s BN reactors have already proved the commercial viability of sodium-cooled FNRs, while its lead-cooled Brest reactor and associated ODEK project are on track to demonstrate the feasibility of a completely closed fuel cycle based on FNRs in which specially developed fuel can be recycled and wastes reprocessed at a single site.

However, further FNR development, like the development of nuclear power in general, cannot be left to private initiative and will require serious governmental commitment. It is no coincidence that the only real advances in FNR technology and deployment over the last three decades have taken place in India, China and especially Russia, where state support for such ambitious programmes has been consistent.

Author: Judith Perera is Contributing Editor, Nuclear Engineering International