Is small beautiful?

Since they made their first appearance over 60 years ago, there has been a continuing drive to increase the size of commercial nuclear reactors. Capacity has risen from the early 60MW reactors built in the 1950s to the giant 21st century 1600MW designs that we are so familiar with today.

Throughout this time small reactors - those up to 190MW - have been used to power nuclear submarines and for research purposes. But the last few years have seen a surge in interest in using small modular reactors (SMRs) for commercial nuclear power.

A 2015 World Nuclear Association report identified four key factors that make SMRs attractive. The compact size and modularity mean the reactors could be built in a controlled factory setting and installed module by module. Their small size and passive safety features make them suitable for countries with smaller grids and less experience of nuclear power. They have smaller capital costs than a larger plant and the potential for series production of specific SMR designs could further reduce costs. Subject to regulatory approvals, SMRs could be installed on the sites of decommissioned coal-fired plants using the using existing grid connection.

Russia (graphite moderated boiling water), China (PWR), Pakistan (PWR) and India (PHWR) all currently operate small reactors, but they are established designs rather than the latest technology. Currently China is building two 250MW high-temperature gas- cooled reactors.

UK & US

The UK and the US governments are interested in supporting the development of new SMR technology, for power generation and as an opportunity to regain a share of the commercial nuclear technology market. However the technology is not yet ready for the market and further funding is required for the development work needed to bring the reactors onto the market and complete regulatory assessment.

In January 2012 the US Department of Energy (DoE) called for applications from industry to support the development of one or two US light-water reactor designs. The DoE allocated $450 million over five years to be used in a five-year cost-share agreement with Babcock & Wilcox to develop its 180MW mPower design. In 2015 the funding was pulled as the company could find neither customers nor investors for the design.

The DoE has also funded Oregon-based NuScale Power to support design development and NRC certification and licensing of its 45MW reactor design. NuScale is a young company set up in 2007 when it was spun out of DoE-funded nuclear research at Oregon State University and the Idaho National Laboratory. Established nuclear engineer, procure, construct (EPC) company Fluor now holds a majority interest. NuScale says it is working towards a combined construction and operating licence application (COLA) for a development operated by Utah Associated Municipal Power Systems (UAMPS) as part of Utah's Carbon Free Power Project. The plan is to site the SMRs in the high desert within the boundaries of the Idaho National Laboratory site. UAMPS says the first NuScale SMR will be in commercial operation in 2024, with the full 12-module plant following within a year.

The UK government's growing interest in SMRs was first set out in the 2013 Nuclear Industrial Strategy. Advantages identified included the potential for shorter deployment times, reduced costs of nuclear power for energy consumers, and a possible high value opportunity for UK manufacturing industry. A feasibility study by the National Nuclear Laboratory to assess the technical, economic and commercial case for the UK deployment of SMRs was published in December 2014. It showed that some SMRs were potentially viable within a ten-year timeframe and that there was the potential for collaboration between vendors and UK industry.

Reactor designer Westinghouse slowed US work on its 225MW light water SMR in 2014, at that time saying there was little prospect for multiple deployment. In October 2015 the company approached the UK government with a scheme to partner in the deployment of SMR technology. This proposal outlined a shared design and development model under which Westinghouse would contribute its mature concept SMR design and work with UK government and industry to complete, license and deploy the design.

In November 2015 the British government announced a "major commitment to small modular nuclear reactors", including a competition to identify the best value SMR design for the UK. The first phase of that competition was launched in March 2016, with a call for expressions of interest. Dialogue to gauge market interest among technology developers, utilities, potential investors and funders in developing, commercialising and financing SMRs in the UK is due to take place in May 2016. The UK government confirmed its interest again when the UK Chancellor of the Exchequer made his annual budget announcement in March. Saying the competition will "generate a list of SMR developers that could deliver on the government's objectives" he also promised the government would publish an SMR delivery roadmap later this year and "allocate at least £30 million for an SMR-enabling advanced manufacturing R&D programme to develop nuclear skills capacity".

Westinghouse, NuScale and Rolls Royce have expressed interest in the competition, and are exploring options for potential UK manufacture of their designs. NuScale Power was quick to confirm that it will put its SMR forward as part of the UK's competition. It said that talks with potential developers interested in deploying the technology in the UK in the late 2020s are advancing, as are plans to "put British nuclear engineering and advanced manufacturing at the forefront of that deployment".

Rolls Royce's reactor expertise comes producing power plants for the Royal Navy's submarines. It has submitted detailed designs to the government for 220MW SMRs that could be doubled up to 440MW. The company says that with financial backing from government to seed development and political and regulatory support, it could have the first SMR generating power in ten years for £1.25 billion.

Westinghouse & the UK

Reactor designer Westinghouse, now owned by Toshiba, has a long track record in the UK nuclear industry. The UK's only PWR reactor at Sizewell B is a Westinghouse design. NuGen, a joint venture between Toshiba and Engie (formerly GDF Suez) is working on plans to build three of Westinghouse's Generation III AP1000 nuclear power plants at the Moorside site adjoining Sellafield in Cumbria. The reactor design is currently in the closing stages of Generic Design Assessment by the UK nuclear regulators.

Simon Marshall, who is leading Westinghouse's UK SMR project, talked to NEI about the company's SMR design. He says the design is a 225MW reactor "providing maximum power from the smallest volume". Work on the reactor design started after construction of the first AP1000 was underway at Sanmen in China and it draws upon the passive safety functions developed for the large reactor. In addition, the nuclear island is partially underground, providing further security. A compact stand-alone SMR is designed to fit into a 15-acre site.

Westinghouse announced earlier this year it is working with the UK's Nuclear Advanced Manufacturing Research Centre (Nuclear AMRC) to explore the most effective way to manufacture reactor pressure vessels for the SMR in the UK. This key component is one of the largest and most demanding parts of any reactor. Identifying suitable UK manufacturing capability will be a key to fulfilling the ambition of enabling the UK to be the centre of production globally.

Springfields gearing up to fuel SMRs

Westinghouse also operates the nuclear fuel manufacturing plant at Springfields in Lancashire, which has been producing fuel for nearly 70 years. It was initially established on a Ministry of Supply munitions site, and after operating as part of the UK Atomic Energy Authprity (1954-1971) and British Nuclear Fuels (BNFL, 1971-2005) it is now operated by Westinghouse. It was the first plant in the world to make nuclear fuel for commercial power stations and has produced several million fuel elements over its lifetime. The facility made all the fuel for the UK's AGR and Magnox reactors. It is now focused on oxide fuels for advanced gas-cooled and light water reactors, as well as intermediate fuel products, such as powders, granules and pellets.

Westinghouse is gearing up to produce SMR fuel in the UK. Earlier this year the Springfields plant completed a readiness assessment on its ability to produce SMR fuel in the UK. Work on the fuel design for the Westinghouse SMR was carried out in the US several years ago and proprietary SMR fuel assemblies were manufactured at its Columbia manufacturing plant.

Based on the US fabrication data, Springfields is confident that UK fuel manufacturing can manufacture SMR fuel in the UK. Brian Nixon, Westinghouse head of Oxide Fuels Business at Springfields, told NEI the company is confident that making minor modifications to existing plant will enable the site to produce SMR fuel. On the Technology Readiness Level (TRL), Westinghouse fuel manufacture in the UK ranks around eight – meaning the actual system has been completed and qualified through test and demonstration. The reactor systems TRLs range from six to nine, which equates from having been demonstrated in a prototype demonstration to full operational experience

After decades of striving to make bigger reactors, designers are taking a fresh look at the economics and logistics of new nuclear power plant. The SMR represents a promising opportunity for speedy development and deployment of a powerful pint-sized iteration of modern reactor design. Time will tell if this will enable either or both of the US and the UK to establish themselves as the manufacturing powerhouse for this new development of the technology.