The Nuclear Regulatory Commission (NRC) has approved the construction of four new nuclear reactors in the U.S., the first since 1978.
On February 9, Southern Co. won approval and an NRC construction permit to build two reactors at its Vogtle plant near Augusta, Georgia. The first unit is expected to be in service by 2016, and the second a year later. Then, on March 30, Scana won approval to build two units at its Virgil C. Summer plant in South Carolina.
These approvals are part of a worldwide trend showing what Industrial Info Resources says is a 10% growth in nuclear power generation in the U.S. by 2035. Richard Finlayson, Senior International Editor, says that despite natural gas-fed projects and renewable energy sources competing for larger stakes in the U.S energy mix, the Energy Information Administration (EIA) estimated that 15,800 (MW) of new nuclear capacity will be added between 2010 and 2035 from a mix of new plants and refurbished operating plants. But the nuclear contribution to the total energy mix of the U.S. will be reduced from 20% in 2010 to 18% by 2035.
While the approvals of these new reactors is a positive sign for the industry, there are still plenty of problems associated with older plants, including California’s San Onofre power plant. A report issued July 12 shows that what was originally thought to be an isolated problem of erosion on tubes that carry radioactive water is actually endemic to the reactor. More than 3,400 steam generator tubes in the new steam generators from Mitsubishi have been found to be damaged.
Problems such as these, coming on the heels of the Fukushima disaster, promoted NRC Chairman Gregory Jaczko to dissent against the new approvals, saying “I continue to believe that we should require that all Fukushima-related safety enhancements are implemented before these new reactors begin operating.”
While the NRC has appointed a special task force to identify improvements that can be made to US nuclear plants, its recommendations have not yet been approved. Nevertheless, the nuclear industry itself is already stepping up with improvements, including a plan to supply plants with portable back-up gear sufficient to survive a lengthy power failure. These first new reactors in a generation will incorporate safety features beyond any required before the Fukushima incident.
Scana and Southern both plan to build AP1000 reactors designed by Westinghouse Electric Co. In its approval, the NRC mandated inspection and testing of squib valves which are part of the passive safety features of the 1,100 MW Westinghouse AP1000 electric pressurized-water reactor. If a meltdown were to occur, the heat-sensitive valves would automatically open to release cooling water that sits above the reactor core.
Other passive design safety features considered for new plants include placing the reactor core at the lowest elevation in the plant. That allows the cooling water to drain into the core simply using gravity. No pumps or valves required.
U.S. nuclear utilities have also launched a program to stock portable reactor-cooling equipment at regional depots, and the NRC has also approved new mandates requiring operators to prepare for beyond design-basis events.
Experience is Key
The key to safety in nuclear plants is engineering. Some call it “elegant engineering”: getting physics to do the work rather than forcing, say, the movement of water against gravity. But this technology is only available in modern reactors like the AP1000 because of experience. Since the first electricity was generated by a nuclear reactor on December 20, 1951 in Idaho, safety engineering has been improving continually. While accidents like Three Mile Island, Chernobyl and Fukushima are hard lessons, the fact is, each of them provide opportunities for advancement and improvement in design.
As the U.S. cautiously moves forward with new nuclear power plants and new regulatory structures are put in place, decisions will have to be made about the costs and ultimate value of enhancements being mandated. For example, a potential requirement for some reactor containments to have “filtered” vents to prevent radiation leaks may not be as cost effective as additional pumps and safety valves.
As the recently approved projects get underway, the opportunities for valve, actuator and control manufacturers are great. With innovation and elegant engineering, these projects could hail the beginning of a new age of nuclear.