December 20, 2011
Development of a small modular reactor, or SMR, is a top internal priority at Westinghouse. The SMR would generate about 225 megawatts (MW), as compared to the 1100 MW generated by the company’s flagship AP1000. Four of the AP1000 units are currently under construction at two sites in Georgia and South Carolina. In contrast to the several years needed to construct the AP1000, the entire construction process for the SMR is expected to take about 18 months. The SMR breaks down into smaller components, so the entire plant can be transported piece by piece on rail cars. The reactor will be built underground in a hole that measures about 100 feet deep and 100 feet wide. All of the components – from the power-generating core to the coolant pumps filled with water – are housed in the 90-foot tall reactor vessel not visible to the casual observer. Several buildings are built above ground to house the plant, so all that’s obvious to the outside eye is a block of buildings that wouldn’t look out of place in any business park.
Among the markets for the SMR being considered by Westinghouse are parts of the Midwest that are dependent upon electricity from coal-fired plants in need of costly retrofits to meet EPA’s recently issued strict emissions requirements. A report issued earlier in December from the Energy Policy Institute at the University of Chicago concludes that small modular reactors may hold the key to the future of U.S. nuclear power generation. According to Robert Rosner, who led the research team at the University of Chicago, small modular reactors could be especially appealing for markets that could not easily accommodate gigawatt-scale plants, such as those currently served by aging, 200- to 400-megawatt coal plants, which are likely to be phased out during the next decade. The economic viability of the SMRs will depend partly on how quickly manufacturers can learn to build them efficiently. An important safety aspect of the SMRs is that they are designed to eliminate the need for human intervention during an emergency.
The development of SMRs could represent a turning point in the U.S. nuclear industry. The biggest obstacles are the costs and long lead times associated with the large-scale reactors, and the concerns about safety in light of the nuclear disaster at Fukushima. The SMRs offer the promise of factory construction efficiencies and a much shorter timeframe, thereby avoiding the seven to nine year construction times associated with building a large scale reactor. Most utilities simply cannot afford to wait up to nine years to see a return on the $10 billion investment that a large-scale nuclear plant would require. With respect to the safety issue, the University of Chicago study concludes that current SMR designs have three inherent advantages over the current class of large operating reactors: (1) the SMR designs mitigate and, potentially, eliminate the need for back-up or emergency electrical generators, relying exclusively on robust battery power to maintain minimal safety operations; (2) they improve seismic capability with the containment and reactor vessels in a pool of water underground; this dampens the effects of any earth movement and greatly enhances the ability of the system to withstand earthquakes; and (3) they provide large and robust underground pool storage for the spent fuel, drastically reducing the potential of uncovering of these pools.