Bill McCollum, chief operating officer of TVA

The massive ash spill at the Kingston Fossil Plant in Kingston, Tenn., on Dec. 23, 2008, is shown the day following the spill. No one was physically hurt in the spill of coal ash from a Tennessee Valley Authority plant storage pond into the Emory River and across some 300 acres in the Swan Pond community about 35 miles west of Knoxville. But property owners in the area say they have been hurt financially.

TVA's chief operating officer and No. 2 man announced Wednesday that he will retire on June 30.

The retirement of William R. "Bill" McCollum Jr., 60, comes on the heels of a number of nuclear problems coming to light at all three of the utility's operating plants.

On Tuesday, TVA disclosed that the Nuclear Regulatory Commission has raised another safety flag on its nuclear plants -- a white finding, the lowest safety rating, at Watts Bar Nuclear Plant's security division.

Sequoyah Nuclear Plant outside Chattanooga received a white finding last month after having too many unplanned reactor shutdowns in less than a year, and since summer, Browns Ferry Nuclear Plant in Alabama has been under a red rating -- the NRC's worst rating before it shuts down a plant, something it has never done.

Under NRC's color-coded inspection findings, white is least serious, then yellow, then red. A plant operating with no safety problems is coded green.

But during a conference call Wednesday about his retirement, McCollum did not directly answer a question about whether those problems had any bearing on his early retirement. He said he will have reached five years with TVA in June and that is "an appropriate time" to retire.

"I'm making the decision for me as far as my retirement is concerned," he said in a telephone call with reporters.

He said the utility's nuclear performance "continues to improve every day."

In a prepared statement, TVA President and CEO Tom Kilgore praised McCollum's "focus" to TVA's power fleet, integrating "a 'one fleet' approach" and investing in the improvement of our people and processes."

Kilgore said McCollum has been instrumental in diversifying TVA's future energy mix and shaping its vision to "be a leader in nuclear energy, provide cleaner air with low rates and high reliability."

An electrical and nuclear engineer and a native of Rossville, Ga., McCollum joined the Tennessee Valley Authority in April 2007. He has had responsibility for all of TVA's power generation and transmission operations.

According to TVA's fiscal 2011 annual report, McCollum made more than $2.5 million in the year ending Sept. 30, an amount that includes salary, bonus, non-equity incentive plan payments, pension and other benefits.

During the six-month transition time between now and his last day, he will mainly work on TVA's capital project planning, he said.

Before joining TVA, McCollum worked for 33 years at Duke Energy, which is headquartered in Charlotte, N.C.