Plant Vogtle Unit 4 reaches initial criticality

ATLANTA – The second of two additional nuclear reactors being built at Plant Vogtle has safely reached initial criticality, Georgia Power announced Wednesday.

Initial criticality is a key step during start-up testing that shows operators have safely started the Unit 4 reactor. Achieving initial criticality is necessary to continue the start-up of the unit.

Unit 3 at the plant south of Augusta entered commercial operation last summer. A malfunction within the cooling system in Unit 4 reported earlier this month has put back the in-service date for the second reactor from the first quarter of this year to the second quarter.

The new schedule isn’t expected to affect the total capital cost forecast for the project. However, any slippage in the timetable for completion beyond March 31 would reduce Georgia Power’s return on equity to zero, which would reduce earnings by about $30 million for each month until the work is finished.

The Georgia Public Service Commission voted in December to let the Atlanta-based utility pass on to customers almost $7.6 billion of its costs in building the two additional nuclear reactors at Plant Vogtle, the first built in the United States since the 1980s.

The project was originally expected to cost $14 billion when the PSC approved it in 2009 but has more than doubled due to a series of cost overruns and delays in the construction schedule. The project will increase the average monthly bill to residential customers by $8.95.

Now that Unit 4 has reached criticality, operators will continue raising power to support synchronizing the generator to the electric grid and begin producing electricity. Through multiple steps, power eventually will be raised to 100%.

When both reactors are operating, each will produce enough electricity to power an estimated 500,000 homes and businesses.