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20 | 9TH - 15TH SEPTEMBER 2016 | UTILITY WEEK Operations & Assets Analysis L arge-scale nuclear is having a difficult rebirth in the UK. The Hinkley Point saga was expected to end in July when EDF made its final investment decision. However, prime minister Theresa May had different ideas, calling for a review and delaying the project yet again. With the sheer scale of the nuclear power plant, and the massive amount of capi- tal required – £18 billion – it is no surprise that attention is turning to smaller, cheaper alternatives that could be quicker and easier to build. These alternatives include small modular reactors (SMRs). Proponents say these offer a form of secure, low-carbon energy, the cost of which is comparable to, if not lower than, larger reactors. They come with the bonuses of smaller up-front costs, shorter build times, the option to gradually scale up capacity and even to provide low-carbon heat. So enticing is this proposition that the government has now launched a compe- tition to find the best value small reactor technology. However, critics say it is a solution looking for a problem; an attempt to make nuclear seem relevant at a time when alternatives are looking more and more appealing. If SMRs are to find a future in the UK's energy mix, they will have to overturn one of the main principles that underpin reactor design – economies of scale. Building one 400MW reactor rather than two 200MW ones, goes the argument, will not require twice the amount of materials and land to build, or twice the number of staff to operate. The 3.2GW Hinkley Point C project is a product of this thought process, as are the other reactors proposed for development in Britain at Wylfa Newydd in North Wales and Moorside in Cumbria. Tony Roulstone, nuclear lecturer in the Department of Engineering at the University of Cambridge, says: "With smaller reactors you're going against that trend and against that principle." SMRs rely on a different form of scale eco- nomics to keep costs down – economies of mass production. The idea is that building them in large numbers in a controlled factory environment will avoid expensive on-site construction issues and enable suppliers to refine the manufacturing process. "If these small reactors were to try to make up for their losses of economies of scale through this kind of mass manufac- ture, they would have to be manufactured in the hundreds, if not the thousands," says MV Ramana an associate research scholar at the Princeton University Nuclear Futures Laboratory. "Are there hundreds of utilities looking to buy the reactors? The answer is no." According to Ramana, the idea of SMRs is appealing to utilities; particularly the short build times and lower up-front cost for each reactor. However, they are unlikely to be prepared to place an order until the reac- tors become cheap enough. That will require any developer to have a large enough order book to build the factories that will produce them. "There's a chicken and egg problem," he says. Another factor in favour of SMRs is the evidence that the theory of economies of scale does not seem to fully apply to large- scale reactors. Roulstone says: "Theoreti- cally it sounds very plausible – but there is almost no evidence of it working." He points Nuclear in small packages Ongoing uncertainty about the future of large-scale nuclear generation in the UK has put the spotlight on the role that smaller, cheaper reactors might play. Tom Grimwood reports. A NICHE FOR SMALL NUCLEAR IN THE UK? Waste heat rejected to the environment Baseload electricity Baseload electricity Electricity for grid balancing Heat recovery for district heating systems Turbine Turbine Containment structure Reactor vessel Control rods Steam generator Generator Condenser Containment structure Reactor vessel Control rods Steam generator Generator Condenser Single revenue stream Multiple revenue streams +