While industry is confident that the overnight costs of today’s Gen III/III+ Light Water Reactors can be reduced significantly as series are being developed, there is some uncertainty as to whether these large reactors can compete in a cost-effective manner in future low carbon energy markets, with increasing shares of variable and distributed generation.

More disruptive innovations may be required for nuclear to secure its role as a flexible, reliable and dispatchable source of energy.

Three types of innovations are being pursued. The development of smaller reactors, which could have higher operational flexibility. The development of innovative fuels that could ensure higher performance at lower cost. And finally, the development of non-electric applications, such as process heat, hydrogen production and desalination, which could displace fossil-based processes.

Why is this gap important?

While there are several alternatives to decarbonise the power sector (renewables, CCS, nuclear), there are fewer to decarbonise applications for which fuel switching (electrification) is not possible or limited.

While nuclear energy is recognised as a proven technology to provide low-carbon electricity as well as grid services, its potential as a source of low-carbon heat is often neglected, even though there is proven industrial experience (nuclear district heating in Switzerland for over three decades; process heat in CANDU plants in Canada; nuclear desalination in Kazakhstan in the 1980s). Hence, demonstrating the coupling of advanced reactors with non-electric applications can provide policy makers with alternatives to decarbonise transport (carbon-free production of hydrogen using nuclear heat and electricity), process heat applications and other energy-intensive industries such as desalination plants.

Coupling nuclear reactors with non-electric applications can also provide energy system storage – i.e. storing energy in the form of heat or as an energy vector such as hydrogen. This is the basic concept of hybrid energy systems.

Furthermore, demonstrating the possibility of multiple revenue streams (sales of electricity as well as heat or hydrogen) can improve the case for investing in nuclear technology, which will remain a capital-intensive technology.

Technology solutions

Current status: TRL 4. SMRs for both electric and non-electric applications are being developed and are becoming an attractive technological alternative to fossil fuel usage. However, until industrial-scale demonstrations are in place, it will be difficult to attract investors.

Challenges to commercialising non-electric applications of nuclear energy include:

• The lack of a business model that clearly defines the roles and responsibilities of nuclear plant operators and of users of nuclear heat (steam) as well as revenue streams.
• Inappropriate valuation of low-carbon steam compared with fossil-generated heat.
• A lack of regulatory frameworks to oversee reactor operations (i.e. nuclear safety framework), operations of the industrial plants (which could be subject to chemical plant safety rules) and the coupling of nuclear and industrial plants.
• A lack of awareness among policy makers of the potential benefits of nuclear cogeneration, including energy storage through conversion of nuclear energy into heat or hydrogen.

What are the leading initiatives?

• NICE Future initiative under the Clean Energy Ministerial, which (among other objectives) aims to discuss the concept of nuclear hybrid energy systems.
• Nuclear hydrogen production by coupling an advanced reactor (Japan’s HTTR) with a hydrogen production plant using thermo-chemical cycles. Hydrogen production can also be achieved by coupling nuclear power production with high-temperature electrolysis.
• Feasibility study between Korea and Saudi Arabia to couple a SMR (SMART reactor) with a desalination plant.
• Project to couple a high-temperature reactor with an industrial process heat plant in Poland.
• Project to bring electricity and heat to the city of Pevesk (Siberia) with a floating nuclear power plant (Akademik Lomonosov, under commissioning).

Recommended actions over the next 5-10 years

• Governments and international organisations should: recognise the benefits of coupling a nuclear reactor with a non-electric application (to store energy or produce desalinated water or hydrogen); promote international co‑operation to develop and demonstrate such a coupling.
• Industry (nuclear and other) should develop and demonstrate coupling of an advanced reactor with a non-electric application.
• Regulators should develop regulations to oversee the coupling of a nuclear reactor with a non-electric application (which could be a chemical plant).

Why is this gap important?

Fuel design improvements can offer additional benefits such as enhanced performance and increased safety margins.

Innovative fuels may incorporate new materials and designs for cladding and fuel pellets. Testing in experimental reactors and validation in power reactors are needed before such fuels can be licensed.

Technology solutions

Current status: TRL 4. Efforts are under way in several countries (United States, Russia, China, France and other European countries) and within international research projects involving fuel vendors, utilities and research organisations, to advance the design and validation of innovative fuels, including accident-tolerant fuels (ATFs). The US DOE confirmed funding to develop and license efforts in this area, with the objective of having NRC approval for initial partial core loadings into commercial nuclear power plants in the mid-2020s.

In April 2019, the first complete ATF assemblies were installed for testing at the Vogtle 2 nuclear reactor in the United States. Plans are also under way to test ATFs in research reactors in Russia and China.

What are the leading initiatives?

• United States: the DOE is providing support to three fuel vendors, Framatome, Global Nuclear Fuel and Westinghouse, and current development is for both near- and long-term Accident Tolerant Fuels (ATF) solutions for all types of nuclear power plants.
• Russian Federation: testing of ATFs designed by the TVEL fuel company is being performed in the MBIR experimental reactor.
• China: irradiation testing of its own ATF technology has begun.

Recommended actions over the next 5-10 years

• Governments should: provide support for innovative fuel development; promote international R&D co‑operation to facilitate prototype testing.
• Vendors should complete testing in research reactors and power reactors.
• Regulators should work with industry to advance licensing of innovative fuels and ATFs.

Why is this gap important?

While nuclear development has focused on constructing larger reactors in recent decades (typically light-water reactors [LWRs] of 1 400 megawatts electrical [MWe] to 1 750 MWe) to meet growing power demand within large-scale electricity grids, it has been recognised that future energy systems will also require different technologies. Smaller – perhaps more flexible – reactors will be needed for niche markets (small grids, isolated communities, or grids with large shares of variable renewables), to replace fossil fuel-based power plants in the 300 MWe to 600 MWe range, or to provide (in addition to electricity) low-carbon heat that can substitute for fossil fuel uses (desalination, process steam for industry, hydrogen production) or to burn nuclear waste. Advancing the design, certification and demonstration of SMRs and other advanced reactors such as Gen IVs for electric and non-electric applications will offer clean, low-carbon energy generation technologies to complement renewables and CCS.

In addition, countries with long-term policies to close the nuclear fuel cycle loop by multi-recycling nuclear materials are also maintaining efforts to develop Gen-IV fast-reactor designs (particularly sodium fast reactors) and the associated nuclear fuel cycle facilities.

Finally, countries with long term policies to close the nuclear fuel cycle with the multi-recycling of nuclear materials are also maintaining efforts for the development of Gen-IV fast reactor designs (in particular Sodium Fast Reactors) and associated nuclear fuel cycle facilities.

Technology solutions

Most SMR designs of LWR technology use proven technologies, for which the supply chain can be easily adapted. The first examples of SMRs, such as the innovative NuScale design in the United States, the CAREM reactor in Argentina and the KLT‑40S floating nuclear power plant in Russia, are expected to begin operating in the 2020s (TRL 4-7).

Reactor technologies using other coolants (e.g. helium, sodium or molten salts), such as those developed within the Generation IV International Forum or by private companies, are being demonstrated with prototypes in operation or under construction in Russia and China (TRL 4-7).

Coupling to non-electric applications is being investigated (e.g. hydrogen production with Japan’s high-temperature test reactor) but more efforts are needed to demonstrate industrial-scale generation of electricity and process steam (TRL 3-4).

What are the leading initiatives?

• China: ACP100 SMR scheduled to start construction in 2019, with 125‑MWe capacity by 2025.
• China: helium-cooled high-temperature reactor HTR-PM (210 MWe), full power operation scheduled for 2020.
• China: sodium-cooled CFR600 reactor under construction.
• Canada: SMR roadmap released; CNSC reviewing ten designs, including water-cooled, helium-cooled and molten-salt-cooled technologies. Application for the first micro modular reactor (MMR) received (very small high temperature reactor).
• Russia: operation of the 800‑MW sodium-cooled BN800 reactor and design of the 1 200‑MW BN1200 reactor.
• United States: NuScale, a 60‑MWe 12-module LWR SMR plant under licensing by the NRC and planned to be operational in the mid-2020s.
• France: F-SMR, an innovative 175‑MWe LWR SMR that can be installed with plant configuration of two to six modules is under development by a French consortium.

Recommended actions over the next 5-10 years

• Governments should: promote technological neutrality across low-carbon technologies and, more generally, a level playing field in power markets; promote technology development through financing options and support; promote international R&D co‑operation to facilitate technology demonstration and licensing.
• Regulators should: complete design certification of the most mature designs; develop harmonised regulatory requirements for advanced reactor technology; develop factory inspection and testing of modules.
• Industry should: complete design and prototype testing; work with regulators to develop a licensing framework; develop supply chains and standardisation; demonstrate safety and reliability of factory-assembled components (compared with on-site).