Until now, all nuclear reactor technologies have been designed for large-scale facilities with production capacities in the GW range. However, new small-capacity reactors, in the 10-300MW range, are now being developed.
What are small modular reactors (SMRs)?
Small Modular Reactors (SMRs) are nuclear reactors that miniaturize existing technologies. The advantages of standardization are manifold:
- They can be built in dedicated factories, which speeds up and improves processes
- There is less need for skilled labor on site
- They can be built continuously, so installation itself is very quick.
SMRs can be built in three years, compared with 5 to 10 years for conventional power plants. Their price should be in the same range.
One advantage of the small format is that it would be easy to integrate them into production circuits. In particular, it would be easier to recover heat. This use is envisaged for high-temperature electrolysis, district heating networks and desalination. Shell and Nuscale are already planning to use SMRs for hydrogen production.
Finally, these reactors, like the Toshiba 4S, would be designed to require less supervision.
Note that this term defines a format, not a generation of nuclear reactor. In fact, SMRs using 2nd, 3rd or 4th generation reactor technologies are conceivable. At present, it’s the most mature technology, pressurized water reactors, that are being considered. However, several projects are considering fast neutron technology.
A Canadian report estimates that SMRs will be the cheapest source of energy, once the cost of electricity storage is taken into account.
Are SMRs as safe as conventional nuclear power plants?
The question is whether small modular reactors are as safe as conventional power plants. IRSN answered yes in a note dated October 2021:
On the contrary, IRSN considers that there is no reason to lower the safety requirements for SMRs, as simplification and the inherent safety features should benefit safety and the demonstration thereof through compliance with these requirements.
https://www.irsn.fr/FR/Actualites_presse/Actualites/Pages/20211008_NI_Small-Modular-Reactors.aspx#.Y587KX2ZOUl
SMR (Small Modular Reactor) projects worldwide
Very small reactors are already in use on a number of aircraft carriers, submarines and class breakers. There are many different reactor concepts. Here are a few examples I found noteworthy.
TerraPower
Terrapower is a Bill Gates-backed start-up and one of the leaders in nuclear innovation.
It is currently pursuing several projects:
- Natrium: a partnership with GE Hitachi Nuclear Energy to create a 345MW sodium fast neutron reactor. This project has received $80 million in 2020 from the US Department of Energy.
Nuward
Nuward is a major European project, led by EDF, Framatome, CEA, TechnicAtome and NavalGroup, which have experience in miniaturizing nuclear power. Announced in 2019, the first reactor design will be presented in April 2021. Its first reactors would have a power of 170MW and use pressurized water technology. They could be built in 40 months and would begin deployment in the early 2030s.
The target price would be between €50 and €80 per MWh of electrical power.
Nuscale
Nuscale is an Oregon-based company that pioneered the SMR concept. Its premises are based on research conducted by the US Department of Energy and several universities in the early 2000s. Although the grant ended in 2003, a group of researchers at the University of Oregon continued and inherited the technology in 2007, leading to the creation of Nuscale that same year. In 2011, Nuscale raised $35 million. It went public through a merger in May 2022, raising $380 million.
Their reactors would be presurized water reactors. One of its special features is that it can operate for 12 years without refueling, even though the renewal cycle is normally 2 years. The first step towards certification in the USA was taken with a press release dated July 29, 2022. Certification was granted on January 19, 2023, and came into force on February 21, 2023.
The “Nuscale Power Module” is tall and is expected to generate a maximum of 77MWe of electricity. They plan to market it in power plants containing 12, for a total of 924 MWe, called “VOYGR”. The final price (LCOE) would be between $40 and $65/MWh. The plants could be built in less than 3 years.
Moltex
Moltex is a rather original British company, developing a “stable salt” fast neutron reactor, as well as a process to recycle nuclear waste into fuel (WATSS) and another to store the reactor’s thermal energy. [rq: I have the impression they’re talking about used fuel rather than “nuclear waste” stricto sensu]
One of its features is that this reactor would be completely self-regulating: as the heat increases, the intensity of the reaction would decrease.
Holtec
Holtec is an American company developing a compact 160MWe pressurized steam reactor: the SMR-160 module. Its main advantage would be absolute safety.
Kairos Power
Kairos Power is a startup created in 2016 in California to develop a high-temperature molten-salt reactor generating between 100 and 400MW of heat. It has received €303 million in funding over 7 years to 2020, to build a prototype near Oak Bridge National Laboratory.
Newcleo
Newcleo is an Italian start-up launched by an Italian physicist, Stefano Buono, who raised 118 million euros in two months, rising to 300 million euros in June 2022. Its concept is a fast neutron reactor (RNR) using liquid lead. The target size is 200MW. It is working with ENEA (= Italy’s CEA).
Naaera
Naaera is a French start-up developing molten-salt fast neutron reactors. The idea is to use spent nuclear fuel from French power plants. They are targeting the genset market, with capacities ranging from 1 to 40MW. The reactor would be called XSMR.
It is notably financed by Paris Mouratoglou (founder of EDF Energies nouvelles and Eren Groupe) and a cooperation agreement has been signed with Assystem, an engineering group, which would provide project management and support in obtaining permits, integration and engineering services.
Rolls-Royce
Rolls Royce has developed a concept for a 470MW electric SMR and has initiated the regulatory approval process for its concept. The project had received £210m of development funding, and the first reactor could be in production by 2029. Operating costs would be $68/MWh.
Toshiba 4S
The Toshiba 4S is a concept developed by Toshiba and Japan’s Central Research Institute of Electrical Industries (CRIEPI). It would be a 4th-generation molten-salt fast-neutron reactor.
It is very special: designed to deliver 10MW, it is to be buried 30m underground. It was proposed in Alaska, in Fairbanks, in 2011.
PRM installations around the world
There are already a number of installation projects. Here are a few examples.
- China.
- In June 2021, China approved the construction of a power plant demonstrator using ACP100, a 125MW electric SMR-type pressurized water reactor. It had been approved by the International Atomic Energy Agency in 2016. Construction began in July 2021 on the island of Hainan, with a target power output of 125MW. The reactor, ACP100, is a pressurized water reactor.
- France.
- There had already been projects for small nuclear reactors for naval applications (CAS2G and CAS3G) and a 100 MW thermal reactor (Thermos) to supply a heating network, which was abandoned in 1977, revived and then abandoned again in 1981. There was also Flexblue, a project created in 2011 and abandoned.
- Romania.
- Nuscale, E-Infra and Nuclearelectrica signed a memorandum of understanding in 2022 to build a power plant in Doicesti.
- Russia.
- In December 2019, a floating nuclear power plant “Akademik Lomonosov” with 2 PWR 35MW reactors was commissioned.
- Czech Republic.
- An SMR could be built in Temelin in 2032 at the“South Bohemia Nuclear Park“.
SMR: the regulatory challenge
In the nuclear industry, regulation is crucial. In most countries, however, regulations are adapted to large-scale structures. Each country will therefore have to develop new laws to govern this new format. By way of example, the NRC (the US nuclear agency) authorization validating the design of Nuscale technology took 4 years and required the expenditure of 500 million dollars.
More problematically, the rules change from country to country. However, their modularity means that they can be exported and standardized. Developing common standards will be one of the challenges for the development of this sector. This is all the more complicated as safety authorities are often highly independent.
References
- J. Richards and C. Mabry, “Power When You Need It: The Case for Small Nuclear Reactors”, C.D. Howe Institute, November 15, 2022
- Testoni R., Bersano A., Segantin S., “Review of nuclear microreactors: Status, potentialities and challenges”, Progress in Nuclear Energy, Volume 138, August 2021, 103822, https://doi.org/10.1016/j.pnucene.2021.103822
Further information
- OECD, Small Modular Reactors: Challenges and Opportunities, 2022
- SFEN, 1/7 – SMR, an engineer’s paradise, https://www.sfen.org/rgn/1-7-smr-paradis-ingenieurs/
- An article on SMR competition in the UK: https://www.telegraph.co.uk/business/2022/12/12/rolls-royce-rivals-gear-mini-nuke-race-power-system-creaks/
- 3 extremely informative Twitter threads:
- Laydgeur, an engineer, delving into Nuward in particular: https://twitter.com/laydgeur/status/1450549562050060294
- On the history of SMRs by Michael Mangeon: https://twitter.com/Mangeon4/status/1448527841658904579
- De Buchebuche, another engineer
- https://twitter.com/buchebuche561/status/1174424956094078977
- On FR projects: https://twitter.com/buchebuche561/status/1468584730530562056