Analysis

Rethinking nuclear - why modular reactors are the future

As more delays beset Hinckley C, Paul Willson, head of innovation for power generation at WSP | Parsons Brinckerhoff, looks at small modular nuclear reactors

The UK is en route to becoming a global leader in small modular reactors, after chancellor George Osborne announced support for the technology through a £250m research and development programme. A competition has since been launched by the Department for Energy & Climate Change to identify the best-value small modular reactor design for the UK.

Amber Rudd, the energy secretary, has that 38 companies had submitted expressions of interest to participate in the competition. They are being notified whther they have been approved for the next phase. Bidders are understood to include the American groups Westinghouse and Bechtel, as well as CNNC, a Chinese state-controlled company, and a Korean-led consortium linked to the Korea Atomic Energy Research Institute. Britain’s Rolls-Royce is also involved as part of NuScale Power, a US-led group headed by Fluor, another US engineering giant.

This scale of spending clearly demonstrates the government’s commitment to the British nuclear industry and will help secure the UK’s low-carbon energy supply. 

Small modular reactors (SMRs) can be scaled-down versions of conventional nuclear plants or completely new designs, with a generation capacity of under 300MW. They are modular, since larger capacity can be delivered by deploying many identical units, and also as prefabrication of major components into modules minimises costly work on site. 

The business case for SMRs is strong: they offer greater simplicity of design, economy through mass production and shorter construction programmes, leading to lower overall costs and risks. WSP | Parsons Brinckerhoff support

 DECC in preparing its evaluation of SMRs and has been involved in a number of related techno-economic and planning studies, which have contributed to this next exciting step.

Small enough for mass production

Large nuclear power plants have proven to be slow and costly to deliver, challenging the ability of even governments to finance. By contrast SMRs are estimated to have a unit capital cost below £1bn, well within reach of commercial funding. 

The vision is for small modular reactors to be produced in the UK in plants similar to aircraft or aero-engine factories, maintaining high quality standards and driving down production costs. We could even imagine an automated mass production line, with

 reactors being shipped out every week, to the UK and international customers. Series production offers major opportunities for design improvements and better methods of manufacture to be identified and incorporated, progressively reducing costs and risks.

Safety comes first

One of the key advantages of the smaller reactor is that the safety systems needed to cool it down after shutdown are much smaller and simpler than those needed for a large reactor. A key hazard for a nuclear reactor is loss of cooling, damaging core temperatures. SMRs are small enough to be cooled by natural air or water circulation, avoiding the need for power pumps or human intervention and minimising the risk of dangerous failures.

Anytime and anywhere

Their small capacity makes SMRs a good option for remote off-grid locations. At WSP | Parsons Brinckerhoff, we studied the potential of very small reactors, with capacities below 30MW. The great opportunities for cost reduction through

 open up different applications and markets. At the smallest scale, different issues of siting and security become important as sites could become widely distributed and minimally manned.

Low-carbon energy

Large-scale production of SMRs offers the potential to undercut the cost of power from large reactors. Alternative low-carbon resources, such as solar PV or offshore wind, could deliver all the energy we need, but not necessarily when we need it. Storage capacity to bridge this gap is far beyond our current capability. SMRs offer more nimble power production, enabling them to complement intermittent power from renewables. 

SMR technology also offers a potential source of heat for district heating networks or for industrial processes, although this is challenging, given current rules on siting nuclear power stations. The cost of heat would be likely to be competitive with current gas tariffs at the point of production, and siting potentially closer to consumers would minimise the additional heat network costs.

 Challenges and opportunities

The ambition is to re-establish the UK as an international centre of excellence for nuclear power. SMRs will be made in Britain, perhaps with a partner, but offering the prospect of UK design ownership and economic opportunities. 

The competition for the best-value SMR design is expected to attract companies from China, South Korea, the USA, the UK and beyond. While their designs generally use similar technology, they are at very different stages of readiness. They diverge in other ways too; capacities range from below 10MW to over 200MW, and while some use conventional above-ground arrangements, others locate the reactor in protective underground silos.

Making the winning design a reality will not be straightforward. A prototype design will need to be approved by the Office of Nuclear Regulation. Safety is a key condition. One of the significant benefits of SMRs is that a full-scale prototype reactor, with electrical heating elements instead of nuclear fuel, can be used to test behaviour directly under extreme conditions, rather than depending on computer tests. 

Once the design has been accepted by the ONR, a suitable site for the prototype must be approved. The subsequent steps of contracting for construction, funding, manufacture, installation and commissioning will test all the preparatory work.

Vital business step

Turning a prototype reactor into a viable business has often eluded reactor vendors. Success hinges on developing the reactor factory to drive costs down. 

Initially, this factory would resemble a final assembly shop. However, as production gears up it could be expected to become more like an aircraft production line, with areas of intensive automation and quality control. The facilities would also need to produce large prefabricated sections of civil works to reduce construction costs.The key challenge will be building the confidence that the scale of sales will justify the large upfront investment.

It is essential to get public support for SMRs if they are to be viable and widespread. SMRs offer greater safety and smaller construction footprints, opening the prospect of location on a much wider range of sites. Policy needs to be developed further on this point, as the previous strategic siting assessment only considered siting for reactors of 50MW or more, and one of the conditions was the ability of sites to support generation by 2025.

Alongside the challenges there is an undoubted reward: the opportunity for the UK to re-establish itself in the nuclear sector globally. Such a position at the forefront of innovation would offer considerable potential for the development of skills and employment.

There is a need for over 10GW of nuclear capacity in the UK. Even if half of this were supplied by large reactors, potential remains for a fleet of 25-200 SMR units. And with the right export partners a UK vendor could participate in producing hundreds more units.

Despite the very real challenges and difficulties, the economic justification for the SMR competition seems persuasive. The key is to ensure that all participants seize this opportunity.

 

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