The Combined Construction and Operating License (Regulatory Guide 1.206, COL) replaced the previous Draft Regulatory Guide 1145 as the licensing process for new nuclear power plants in the United States. It is a part of a new "streamlined" process that is hoped to prevent delays in operation that contributed to the mothballing of many plants since the 1980s.
Previously, the licensing process had two steps, construction and operation, each of which required a different license to be issued. Oppositions raised before a plant started operation versus before it started construction could thus be extremely financially damaging to a utility. A COL alone, however, is still not enough to construct a nuclear plant, an Early Site Permit (ESP) application must also be filed. The ESP addresses the site that plant will be built on while the COL addresses the reactor design and construction. The COL and the ESP can happen simultaneously.
Two COL applications have been filed as of November 2007. Three ESP applications have been filed by Dominion, Entergy, and Exelon.