Generation III and III+ reactors have significant improvements over Generation II designs in areas such as, fuel technology, thermal efficiency, modular construction, safety systems, and standardized design. They are designed for 60+ year operational life spans. Examples of Gen III reactors are all essentially advanced versions of Gen II reactors: Enhanced CANDU 6, Advanced Boiling Water Reactor (ABWR), and AP-600. The AP-600 in particular utilizes passive safety features to cool the core in the event of an emergency (rather than the mostly active features of Gen II). Passive safety features do not require external power sources to be effective. Also, their modular construction and standardized design significantly reduces cost and time of construction; having a noteworthy impact on the economics of nuclear energy. There are no Generation III reactors operating in the United States. [1].
Generation III+ reactors are essentially further improvements on Generation III designs. They make further efforts at implementing passive safety features that do not require operator intervention to take effect. Notable examples include the Westinghouse AP-1000 (a more advanced and powerful version of the AP-600) and the European Pressurized Reactor (EPR). These reactors are expected to achieve higher fuel burnup than their predecessors (resulting in less fuel consumption and waste production). (see nuclear cycle for more info)There are currently plans for the construction of 2 dozen Gen III+ reactors in the United States. [1].
When attacking nuclear power based on its technical design, most anti-nuclear organizations focus on concerns of meltdown, terrorist attack, and waste. A meltdown is exactly what it sounds like: the solid fuel in a reactor gets too hot (either from a run-away reaction or lack of cooling) and liquefies. For typical second generation designs, this means the reactor is much more difficult to control (as the fuel flows out of the fuel assembly), radioactive gases can build up putting pressure on the structure and other chemical reactions can cause explosions. A full or partial meltdown was responsible for the three largest nuclear disasters in history: Three Mile Island, Chernobyl, and Fukushima. Third generation designs, such as the Westinghouse AP1000, address this by providing complete passive cooling of the containment and in-vessel retention of core damage, which is significant because any partial meltdown of the core will be contained. This also means that in the event of a natural disaster (such as the earthquake that precipitated the meltdown in Japan) where the plant lost all backup power sources for cooling pumps, the AP1000 would (theoretically) still manage to cool itself by natural convection and prevent any disaster occurring from decay heat (heat from spent fuel). [3]. This newer, more flexible design has the potential to prevent future disasters like Fukushima from occurring.
http://www.climateandfuel.com/gifs/ap1000.jpg
Despite these significant improvements on second generation technology, anti-nuclear activists attack the AP1000 from a second generation perspective. In an article from Nuclear Watch South, an activist organization based in Georgia near the proposed locations of AP1000 construction, the group claims that regulators overlooked the possibility of a containment breach with which the passive cooling system would eject radioactive gases into the atmosphere [2]. Their efforts, along with those of similar groups, have led the Nuclear Regulatory Commission (NRC) to delay the approval of an amendment to the AP1000’s design this fall (2011) despite the fact that the NRC had previously approved the overall design in 2005 [4]. The containment is a shell surrounding the reactor chamber composed of several feet of concrete and steel, designed as a redundancy measure to prevent any radioactive material potentially released into the reactor chamber from reaching the outside atmosphere. They are required at all U.S. reactors and have been for decades. The latest containment designs such as the one in an AP1000 reactor have been calculated to withstand several consecutive commercial airplane impacts (a requirement since September 11th). Though this group appears to base its argument on engineering concerns, it is really just using it as a guise to voice its political agenda. If this is an engineering concern, it is not enough to merely say that the containment could rust through, they should give some sort of analysis of what it would take to rust through and if this is in the realm of possibility (their argument is purely qualitative).
Regardless, the nuclear regulatory commission (the agency responsible for conducting these kinds of analyses) should not be so easily swayed by political lobbying. Their sole focus should be on engineering and technical concerns of new reactor designs. If the AP1000 is too dangerous, the NRC should find this on its own; it should not need the intervention of a political activist group to carry out effective safety review.
[1] Goldberg, Stephen M. and Rosner, Robert. “Nuclear Reactors: Generation to Generation.” American Academy of Arts and Sciences. 2011 <http://www.amacad.org/pdfs/nuclearReactors.pdf>.
[2] Nuclear Watch South. ” Groups Urge Feds to Suspend Nuclear Licensing; Westinghouse AP1000 Reactor Defect Was Missed by Regulators.” 21 April 2010. <http://www.nonukesyall.org/AP1000.html>.
[3] World Nuclear Association. “Advanced Nuclear Power Reactors.” October 2011. <http://www.world-nuclear.org/info/inf08.html>.
[4] Yurman, Dan. “NRC Tying AP1000 Up in Knots.” The Energy Collective. Social Media Today LLC. Jul 5, 2011 <http://theenergycollective.com/dan-yurman/60750/tying-ap1000-knots-nrc>
New Nuclear Energy 
