Energy Insight: Small modular reactors

The World Nuclear Association (WNA) defines small modular reactors (SMR) as ‘nuclear reactors with an electricity output of 300MW equivalent or less’. These advanced reactors are deployable either as a single or multiple modules, which can be built in factories, shipped to a site and assembled as demand arises.

As the name suggests, SMRs are much smaller than traditional nuclear reactors. For example, each reactor at the new Hinkley Point C power station (currently under construction in Somerset) has a planned gross output of 1720MWe. Based on the WNA size limit of 300 MWe, around 6 SMRs would be required to produce an equivalent amount of power. 

However, it is worth noting that Hinkley Point C is a huge project - construction costs are estimated at between £22bn and £23bn, and the total project time is set to be at least 10 years. The modular nature of SMRs is intended to be more economical and reduce construction times for new power stations.

Nuclear power is a significant source of low-carbon electricity. In 2018, over 10% of global electricity generation was from nuclear power plants. However, just a handful of these plants are SMRs. Why do proponents of SMRs believe the way forward is to shrink the size of reactors?

• Small physical footprint - SMRs take up much less space than traditional nuclear power plants, which also makes them easier to site. For example, SMRs could be constructed on brownfield sites, such as decommissioned coal-fired power stations.

• Easier to construct - the modular nature of SMRs means that they can be prefabricated in a factory, and then shipped to where they are needed. Additional modules can be added as required if the site grows. This makes for cheaper and easier construction and allows nuclear power to be deployed in more remote regions. A smaller geographic footprint also means they are also easier to protect from external threats. 

• Potential cost savings - a more modest sized power plant is cheaper to construct than a traditional nuclear project. SMRs require less capital expenditure, and investors may therefore view them as less risky to support.

• Safety and security - SMRs contain less nuclear fuel and produce less heat than their full-sized equivalents. This means that they are easier to inspect, regulate and shut down (if required). Many SMRs feature passive safety systems, which are designed to work even if the plant malfunctions or loses power. 

• Greater flexibility - individual modules could be placed on industrial sites for a specific task, such as to produce hydrogen or desalinate water.

• Nuclear waste - Just as with other nuclear power stations, SMRs produce nuclear waste, some of which is highly radioactive and must be contained and managed. The most dangerous waste needs to be permanently buried in a stable geological formation.

• Expensive form of energy - compared to other energy sources such as Combine Cycle Gas Turbine (CCGT) power plants, solar and onshore wind, nuclear power plants are expensive. In particular, new nuclear plants require a large capital expenditure (capex) as construction is the most expensive part of the project. For example, the US Energy Information Administration estimates that the levelized cost of electricity from a new nuclear plant commissioned in 2026 will be around $70 per MWh (compared to $33 per MWh for solar, $37 per MWh for CCGT). It is yet to be seen if SMRs can improve upon these costs estimates.

• Economies of scale required - nuclear projects are usually very large and complicated. SMRs aim to simplify construction and improve economies of scale, but these benefits may not be realised until large scale production of units is established. This is reflected in the cost predictions for a ‘first of a kind’ (FOAK) plant and an ‘nth of a kind’ (NOAK) plant; NOAK plants are cheaper to build as they are able to make use of the learnings and supply chain from previous projects.

• Low public confidence - In some countries, building any new nuclear power plants is unpopular and there may be strong political pressure against investment. For example, Germany and Switzerland opted to phase out all nuclear power plants in the years following the Fukushima-Daiichi disaster.

In the UK, surveys by BEIS suggest that a third of the public are supportive of nuclear power, with 23% opposed and 41% indifferent. Even when the public as a whole are supportive, local opposition to new nuclear can be substantial.

• Many competing designs - according to the IAEA, there are around 50 SMR designs under development for various purposes and applications. Getting a new nuclear design licensed is a long, complicated and expensive process, so a lack of international coordination on new designs slows the potential rollout of SMR units.

(2014) Energy and Climate Change Committee, Inquiry on small nuclear power.

This inquiry looked at the potential role of small nuclear power in the UK, including the barriers to deployment as well as potential risks and opportunities. 

(March 2015) Small nuclear power - Energy and Climate Change Committee, Government Response.  

(March 2015) Department of Energy and Climate Change (DECC): Research Services Small Modular Reactor Techno-Economic Assessment

To procure contractors to undertake a detailed techno-economic assessment into Small Modular Reactor designs and specific supporting studies. The techno-economic assessment will deliver the necessary evidence base to inform a policy decision on whether the Government should support the development and deployment of SMRs within the UK

(2020) A consortium led by Rolls Royce (includes Atkins, Laing O’Rourke and the National Nuclear Laboratory) aim to build up to 16 SMRs in the UK. Each power station would have an output of 440MWe and is estimated to cost around £2bn. Rolls Royce have received £18mn of funding from the UK Government to work on designs.

(July 2020) Phase 2 of the Advanced Modular Reactor (AMR) Feasibility and Development project.

Tokamak Energy (nuclear fusion), Westinghouse (lead-cooled fast reactor) and U-Battery (modular reactors) received funding in phase 2

(November 2020) Prime Minster Boris Johnson’s 10 point plan for a green industrial revolution

Point 3 of the plan is dedicated to ‘delivering new and advanced nuclear power’. The Government has set a target of deploying SMRs in the UK by the early 2030s and is set to invest up to £215mn  in development, matched by £300mn in private sector funding. 

NuScale are the first company to have an SMR designed approved by the Nuclear Regulatory Commission. The Dept. of Energy (DoE) has invested over $300mn into research and development of their project, and the company will build their first SMR at the DoE’s National Laboratory in Idaho. Other US companies working on SMRs include Westinghouse, Hitachi and Holtec.

The Canadian Government released an SMR roadmap in 2018. Ontario Power Generation announced in 2020 that it was looking at SMRs from Hitachi, Terrestrial Energy and X-energy, all of which are currently going through the design review process. Other projects in development include the Moltex SSR-W reactor, which is planned for construction in Saint John . 

Russia is the only country in the world with floating SMRs and a nuclear-powered container ship. At the Bilibino plant in Siberia, SMRs have been used since the 1970s to provide district heating and electricity in an extremely remote location. Rosatom subsidiary OKBM is working on the VBER-300 reactor, again designed for remote locations.

There is lots of activity around SMRs in China, with companies such as NPIC, CNNC and CGN all working on advanced development of projects. The high-temperature pebble bed reactor (HTR-PB) under construction in China represents a new type of SMR design. Rather than emulating traditional PWRs which use fuel rods, the HTR uses a number of tiny ‘pebbles’, each with a small amount of nuclear fuel inside. The HTR design aims to prevent potential meltdown, as the chain reaction stops working at higher temperatures. 

A selection of the developers working on deployment of SMRs includes:

• NuScale Power (USA) 

• GE Hitachi (USA)

• OKBM (Russia) - subsidiary of Rosatom

• Korea Atomic Energy Research Institute (South Korea)

• Westinghouse (USA)

• Rolls Royce (UK)

• China General Nuclear Power Group (PR China)

• China National Nuclear Corporation (PR China)

Safety and Licensing Requirements for Small Modular Reactors: IAEA Hosts First Workshop for Regulators IAEA 9 March 2016
A new generation of advanced, prefab nuclear power reactors called small modular reactors (SMRs) could be licensed and hit the market as early as 2020, and the IAEA is helping regulators prepare for their debut. 

Office for nuclear regulation (ONR)   
The Office for Nuclear Regulation's mission is to provide efficient and effective regulation of the nuclear industry, holding it to account on behalf of the public.

New nuclear power: assessing power station designs 

Before a new nuclear power station can be built and operated in the UK, in addition to the reactor design going through the Generic Design Assessment (GDA) process, the proposed operator must obtain permission from regulators and Government in the form of:

• Site licence and relevant consent to begin nuclear-related construction from ONR;

• Environmental permits from Environment Agency or Natural Resources Wales (NRW);

• Planning permission from the Department for Business, Energy and Industrial Strategy (BEIS).

American Nuclear Society
The ANS aims to “Advance, foster, and spur the development and application of nuclear science, engineering, and technology to benefit society”.

IAEA International Atomic Energy Agency  
The IAEA is widely known as the world's "Atoms for Peace" organization within the United Nations family. 
Nuclear Energy Agency  
The Nuclear Energy Agency (NEA) is an intergovernmental agency that facilitates cooperation among countries with advanced nuclear technology infrastructures to seek excellence in nuclear safety, technology, science, environment, and law. 

Nuclear Energy Institute
The Nuclear Energy Institute is the policy organization of the nuclear technologies industry, based in Washington, D.C. Membership comprises 350 companies in 17 countries concerned in all aspects of the nuclear industry.

Nuclear Industry Association    
The NIA is the trade association for the UK’s civil nuclear industry representing more than 260 member companies across the supply chain.

Nuclear Institute  
The Nuclear Institute is the UK membership organisation for Nuclear Professionals.

World Nuclear Association      
The World Nuclear Association is the international organization that represents the global nuclear industry. Its membership comprises companies and research and development organisations concerned with all aspects of the nuclear industries.