Ever since a reactor meltdown at Three Mile Island terrified the U.S. in 1979, the Nuclear Regulatory Commission hasn't approved the construction of any new facilities. But the de facto nuclear freeze is thawing, thanks to rising demand for low-carbon-emission energy sources. Public utilities are taking advantage of a 2005 law that offers annual tax credits and risk insurance to companies that build nuclear plants, and the rush is on. The N.R.C. expects to receive applications for 32 new reactors by 2010. But buying a reactor isn't like buying a car. The base price for a reactor is around $2 billion. Plus, there are only five models to choose from. But among those five, there's bound to be a nuclear reactor for every need (and budget).

Illustrations by Bryan Christie

Mitsubishi Heavy Industries

Estimated cost: $2.7 billion

Reach: 1.3 million households

Pending applications: Two, from Luminant Power

Mitsubishi's reactor demands less downtime for refueling—which happens just once every 24 months (as opposed to a more typical 18). The design is last in line for N.R.C. approval, so any utility that chooses this model will be stalled until at least 2011.

Areva NP

Estimated cost: $4.8 billion

Reach: 1.2 million households

Pending applications: Seven, from Amarillo Power, UniStar Nuclear Energy, and others

Areva, jointly owned by Germany's Siemens and the French government, is positioning itself as a one-stop-shopping destination—it sells the reactor and the fuel.

G.E. Hitachi

Estimated cost: $3 billion

Reach: 1 million households

Pending applications: Two, from NRG Energy

Unlike most of the competition, this type of reactor is already approved for construction in the U.S. Its internal pumps are designed to reduce operating costs and radiation. Like Westinghouse's A.P. 1000 (see below), it can be built cost-effectively from prefabricated modules.

G.E. Hitachi

Estimated cost: $2 billion to $2.5 billion

Reach: 1.1 million households

Pending applications: Four, from Exelon, Entergy, and Dominion Resources

This reactor's control room is built belowground, and its safety system uses water flowing from pools into the core to cool the reactor during a shutdown.

Westinghouse Electric

Estimated cost: $2.5 billion to $3.5 billion

Reach: 814,000 households

Pending applications: Fourteen, from Progress Energy, Duke Power, Florida Power & Light, the Tennessee Valley Authority, and others

The grande dame of reactor builders, Westinghouse designed its first U.S. facility in 1957. This reactor can be built relatively quickly, but it generates less energy than its rivals, and some critics say it isn't designed to withstand an aerial attack.

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