Nuclear Reactors Starting Back Up

Wednesday, February 23, 2011 @ 07:02 PM gHale

Three different nuclear reactors are back on line for three distinct reasons.

Dominion Virginia Power is restarting its nuclear reactor at its Surry County power station after the unit remained idled for more than two weeks for repairs.

Surry’s Unit 2, which automatically shut down Feb. 2 because of a coolant-flow problem, was operating at 59 percent of capacity after its start up, according to the U.S. Nuclear Regulatory Commission (NRC).

Dominion told the NRC the Unit 2 reactor tripped when a valve in the reactor coolant system closed inadvertently and reduced the flow in the cooling system. There was no radiation release.

Unit 1, the other reactor at Surry, has remained in full operation.

Meanwhile, the San Onofre Nuclear Generating Station, Southern California’s largest power plant, returned to full power following a huge retrofit that involved cutting holes in its twin containment domes.

The southern reactor, Unit 3, resumed making electricity at 2:56 a.m. after an outage that involved refueling and replacing its biggest component, a pair of steam generators drive the 1,100 megawatt steam turbine.

The amount of power that initially came online was relatively small, about 55 megawatts, said spokesman Gil Alexander. Output will increase about 3 percent an hour. At peak capacity, each of San Onofre’s two reactors make enough power for 715,000 homes.

The northern reactor, Unit 2, returned to power last year after a similar retrofit.

The steam generators allow the plant to run its electric turbines without using radioactive steam.

The replacement of the four steam generators cost $671 million, said Southern California Edison spokesman Gil Alexander.

They needed the replacement because pipes in the original steam generators, installed when the two reactors were built 28 years ago, were getting plugged, and producing less steam.

In Massachusetts, following a three-day shutdown to repair a leak in a cooling system, the Pilgrim nuclear power plant in Plymouth should be up an running Thursday.

Operators started a controlled shutdown of the 685-megawatt plant early Sunday and notified the NRC.

Officials shut down the plant after monitors detected a leak in a tube that carries salt water used in a cooling system, said spokesman David Tarantino. The plant is next to the ocean and uses sea water to cool the steaming hot fresh water that turns the plant’s electricity-generating turbines.

The state’s only nuclear plant was operating at 100 percent capacity when the shutdown occurred. It had been on line for 634 consecutive days, “a record for us,” Tarantino said.

Entergy Corp., which operates the facility, said “this event had no impact on the health and/or safety of the public.”

The report said a section of a reactor building was “declared inoperable” Feb. 18 and could they could not repair it within 72 hours, prompting the shutdown at 12:01 a.m. Sunday.

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