UPGRADING PRAIRIE ISLAND

1973: Prairie Island Nuclear Unit 1 begins operating.

1974: Unit 2 begins operating.

2009: Minnesota Public Utilities Commission concludes that a proposed 12 percent power boost at Prairie Island nuclear plant is a good deal for customers.*

2011: U.S. Nuclear Regulatory Commission renews reactors' licenses for another 20 years.

2012: Plant owner Xcel Energy Inc. warns that the proposed power upgrade needs a fresh look in light of changed circumstances, including slack electric demand. Utility's application for federal safety review of the project is postponed.

2017-2018: Latest estimate of when plant modifications might take place for power upgrade.

2033-2034: Plant's operating license expires as each unit reaches 60 years old.

*Xcel separately plans to increase output at its other nuclear reactor in Monticello, Minn. The matter is pending before the Nuclear Regulatory Commission.

Sources: Xcel Energy Inc., Minnesota Public Utilities Commission