PPL Susquehanna has turned off the unit 1 reactor at the Susquehanna nuclear power plant in northeastern Pennsylvania, US, on 31 March 2012.
The reactor was turned off after 282 days of consecutive operation to commence a planned refueling and maintenance outage.
Each of the two units at the plant is taken out of service for refueling and maintenance every two years., and about 40% of the uranium fuel will be replaced.
Unit 2 at the plant continues to operate at full power, the company said.
The Susquehanna plant is owned jointly by PPL Susquehanna and Allegheny Electric Cooperative and is operated by PPL Susquehanna.
PPL Susquehanna is a generating affiliate of US-based PPL Corp, which owns or controls about 19,000MW of generating capacity in the US, sells energy in key US markets, and delivers electricity and natural gas to about 10 million customers in the US and the UK.