State-owned utility Santee Cooper approved the sale of nearly $575 million in revenue obligation bonds Thursday to help pay for its share of two new nuclear units being built north of Columbia with South Carolina Electric & Gas Co.

The bonds, which mature from 2013 through 2043, have an interest rate of about 4.3 percent.

The bond issue drew ratings of AA- from Fitch Ratings and Standard & Poor’s, and an Aa3 from Moody’s Investment Service.

The Nuclear Regulatory Commission approved the license last Friday for construction of the twin 1,100-megawatt nuclear reactors. The $10 billion reactors are due to come online in 2016 and 2019, respectively.