Nuclear

Vogtle Unit 3 generates electricity and connects to the grid

The milestone followed initial criticality when operators started the nuclear reaction inside the reactor.
Vogtle Unit 3 generates electricity and connects to the grid
(Vogtle Unit 3 control room. Credit: Southern Nuclear)

Georgia Power said the generator at its Vogtle Unit 3 nuclear facility generated electricity for the first time on April 1, and the unit successfully synchronized and connected to the electric grid. 

At Vogtle Unit 4, nuclear operators began hot functional testing in March. 

Connecting to the electric grid is part of ongoing startup testing for Vogtle Unit 3. The utility said that operators would continue to raise reactor power for electricity generation while performing tests at various power levels.

The milestone followed initial criticality, reached on March 6, when operators started the nuclear reaction inside the reactor, generating heat to produce steam. Once all startup testing is successfully completed and the unit is available for dispatch, the unit will enter commercial operation.

On March 15 with Unit 3 in Mode 1 at 18%, the reactor automatically tripped due to the loss of two reactor coolant pumps when their electrical buses failed to transfer after a main generator excitation protective relay tripped. The incident was reported to the Nuclear Regulatory Commission.

Operators responded and stabilized the plant by engaging relief valves that removed decay heat. Units 1, 2, and 4 were not affected.

Georgia Power said that hot functional testing at Unit 4 marks the last series of major tests ahead of initial fuel load. The testing is being conducted to verify the successful operation of reactor components and systems together and confirm the reactor is ready for fuel load. 

As part of the testing, the site team will run Unit 4 plant systems and move through the testing process toward reaching normal operating pressure and temperature. Heat generated by the unit’s four reactor coolant pumps will be used to raise the temperature and pressure of plant systems to normal operating levels.

Once normal operating temperature and pressure levels are achieved and sustained, the unit’s main turbine will be raised to normal operating speed using steam from the plant. During these tests, nuclear operators will be able to validate procedures as required ahead of fuel load. 

The in-service date for Unit 3 is projected during May or June. Unit 4 is projected to enter service in late fourth quarter 2023 or first quarter 2024.

In an unrelated incident at a Georgia nuclear power plant, the reactor of the 2,800 MW Hatch Unit 2 was manually tripped on March 31 due to a loss of both recirculation pumps. Cause of the recirculation pump trips was under investigation. The incident was reported to the NRC.

Additionally, closure of CIVs in multiple systems occurred during the trip as a result of reaching the as-designed actuation setpoint on reactor water level. The trip was described as being “not complex”, with all systems reported to be responding normally post-trip.

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