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UTILITY WEEK | 9TH - 15TH SEPTEMBER 2016 | 21 Operations & Assets The SMR shortlist The government has named the organisations eligible for the first phase of its competition to find the "best value" small modular reactor (SMR) for the UK. Here are a few of the contenders: NuScale Power NuScale's plant design has up to a dozen 50MW power modules that can be combined to form a larger 600MW plant. The modules will be suspended in a below ground pool, and will each contain a passively cooled integral pressurised water reactor and a steam generator. The company has been awarded $217 million by the US Department of Energy to develop the design and has plans to install the first module in Idaho in 2024. Earlier this year it commissioned Sheffield Forgemasters to fashion a demo reactor vessel in Britain by the end of 2017. U-Battery U-Battery are going small, so small that they've dubbed their 4MW reactor design micro nuclear. The Urenco-led consortium says it will be ideal for a number of niche roles: providing combined heat and power (CHP) for heavy industrial users, powering remote towns and villages without grid access, replacing diesel plant as backup generation, and being deployed to power desalination plants. The design has been optimised for CHP generation, and the consortium says it could also be used to produce hydrogen as well, giving it a 'tri-gen' capability. It will be powered by TRISO fuel – small particles of uranium oxide coated in high-temperature ceramics. U-Battery says this will have significant safety advantages over traditional fuel and make a meltdown impossible. It is currently aiming to have a demonstration unit up and running by 2024. Moltex Energy Moltex's design is for a stable salt reactor in which the nuclear fuel – uranium or plutonium chlo- ride – is suspended in a molten salt coolant. The coolant will not be pressurised. The company says the by-products of fission will form stable compounds rather than gases, so the design will prevent the spread of radioactive material if the core is damaged. Also, there are no high-pressure systems and few moving parts, so it will be relatively simple to build. Tokamak Energy Perhaps the most ambitious entrant into the SMR competition, Tokamak Energy is hoping to crack fusion power; something that hasn't been done at any scale yet. The company is a spin-off from the Joint European Taurus reactor at the Culham Centre for Fusion Energy in Oxfordshire. The firm believes smaller reactors are the way to go for fusion, because they can achieve a "much higher plasma pressure for a given magnetic field than conventional tokamaks". Tokamak is planning to build five prototype reactors on the road to achieving fusion power. It has built two so far and has begun work on a third. SMR and district heating SMRs have the potential to help decarbonise the UK's heating systems. Although the technology has not been deployed in Britain so far, it has been used elsewhere, such as in the Refuna district in Swizterland. Heat from the Beznau nuclear power plant goes out into the countryside for tens of kilometres delivering heat to homes and businesses. Refuna district heating – facts and figures • Operational for 28 years. • More than 2 million MWh heat replaces approximately 200 million litres fuel oil. • 31 km backbone (high pressure system); 101 km distribution system. • Connected load 76 MWth (max.). • 142 GWh of heat sold per year Refuna – district heating system Heat supply (MWh) 2006/07 2005/06 Independent local networks 75,136 89,172 Customer distribution 33,578 37,634 Special contract customers 12,928 15,013 Total 121,642 141,819 out that studies from France, Japan, the UK, Canada and South Korea have all shown that these economies of scale are either small or completely absent. This is partly because of the escalation in construction costs, as cited in a report by Arnulf Grubler, programme director at the International Institute for Applied Systems Analysis. Academic research at the Department of Nuclear Engineering at Texas A&M Uni- versity estimated that each kilowatt-hour of electricity from an SMR would be at least 15 per cent and up to 70 per cent more expen- sive than a kilowatt-hour from a large-scale nuclear power station. To make them eco- nomically viable, SMRs would have to make up for their power shortfall by cutting manu- facturing costs. Whatever the case, one factor that the Energy Technologies Institute strategy manager Mike Middleton says is a "game changer" for the economics of SMRs is the potential to use them for district heating. "[SMRs] have got a more flexible approach to siting. You can find sites to put SMRs where you can't put big plants," says Middleton. Not only can SMRs be located closer to urban and developed areas, includ- ing industrial sites, "their thermal output is such that they're a much better match for the amount of heat that will be required by city- scale district heating systems". The ETI estimates that revenues from sell- ing heat could match those from power gen- eration for SMRs, and with a 20 to 30 per cent loss to electrical output taken into account, this represents a 40 to 60 per cent increase in overall revenues. One of the biggest challenges will be per- suading the public of the benefits of locat- ing reactors closer to population centres. Roulstone says: "I think that the public's not ready for it yet. It's quite a hill to get over." SMRs could present a viable future for new nuclear, and one that could comple- ment larger scale nuclear plants and other low-carbon technologies that are being developed. The main issue the technology faces revolve around finances and whether the savings promised by the theory of economies of mass production can be realised. This will only be known if and when mass orders for SMRs are placed. To achieve this, a long pipeline of orders is required, and this would stretch beyond the UK's national boundaries. As the govern- ment presses ahead with its competition to find the best value SMR design for the UK, it will have to work with other nations to crack the reactor riddle.