The bus stops before a barbed wire gate at Surry Power Station, less than a mile from the James River.

Inside the fence, on a concrete pad the size of a football field, is nearly 1.9 million pounds of radioactive nuclear waste.

Encased in concrete casks and no immediate public health threat, the waste is a by-product of nearly four decades of atomic energy-making at Virginia's oldest nuclear power plant.

It should not be there.

The Department of Energy agreed decades ago to build a permanent nuclear waste repository. It hasn't. As a result, roughly 138 million pounds of spent commercial nuclear fuel sits at temporary sites — such as Surry — across the nation, according to the Nuclear Energy Institute.

The growing stockpile is alarming to environmental advocates who worry about long-term management of the waste and its potential ill effects. Some view it as a threat to national security. And it concerns nuclear power enthusiasts, who say a permanent storage site is needed to build new power plants.

"If you don't have that, you don't have a nuclear industry," Gov. Bob McDonnell said last month during an energy conference in Richmond.

DOE is required under the Nuclear Waste Policy Act of 1982 to build a permanent storage site for spent nuclear fuel and other radioactive waste. In 1987, Congress designated a site: Yucca Mountain, Nevada.

The plan was to begin transporting waste there in 1998. That never happened. Instead, Nevada officials fought the move and, in 2009, President Barack Obama eliminated funding for the project.

Obama, who supports the expansion of nuclear power, created a blue-ribbon panel to develop alternatives to Yucca Mountain. The panel is scheduled to issue a report in 2012.

Utilities, meanwhile, are required under the 1982 legislation to continue storing nuclear waste on-site.

In Virginia, that duty falls largely to Dominion Resources, which owns the Surry plant and a majority of state's other nuclear plant, North Anna Power Station, located roughly 45 miles northwest of Richmond.

Together, Surry and North Anna hold more than 5.2 million pounds of spent uranium. Most of the fuel is stored in 16-foot tall concrete casks that stand upright and weigh more than 262,000 pounds when full.

At Surry, the casks are surrounded by Hog Island State Waterfowl Refuge. They have little noticeable effect on the environment, which, on a recent October morning, included a bald eagle on a treetop.

"You can stand by one of those casks for an hour and get a low dose of radiation — something comparable to a dental X-ray," Dominion spokesman Richard Zuercher said.

At each plant Dominion also stores waste in steel-lined, concrete pools that are filled with water and kept indoors.

Edwin Lyman, a physicist and nuclear proliferation expert with the Union of Concerned Scientists in Washington, D.C., said both methods work temporarily, if properly monitored.

There are a handful of scenarios, such as an earthquake or terrorist attack, that could cause the casks or pools to leak, he said. Also, spent nuclear fuel remains radioactive for thousands of years — it could cause the concrete and other materials to erode, Lyman said.

"You can't isolate it forever from the groundwater," he said.

Case in point: Dominion officials last month reported abnormally high amounts of tritium, the radioactive isotope of hydrogen, in groundwater outside North Anna. While not a health hazard, Dominion officials have not pinpointed its source.

Rep. Robert C. "Bobby" Scott, D- Newport News, whose district includes Surry, said while on-site storage is not ideal, it's the best option until the nation opens a permanent storage facility.

Obama administration officials said salt domes, whose geology hasn't changed in millions of years, could be a better alternative to Yucca Mountain. A 1998 DOE study identified 16 states — Virginia isn't one of them — as having "major" salt deposits.

Others, including Scott, said Nevada's emerging political clout — not science — took Yucca Mountain off the table.

"I knew we were going to have trouble once it became an early primary state," he said alluding to Obama's campaign trail promise to Nevadans to halt work on the project.

Scott sits on a House committee that was told in July by Energy Department officials that the federal government could be liable for up to $13.1 billion by 2020 if it doesn't build a repository. Utilities already have filed more than 70 lawsuits against DOE — Dominion was awarded $112 million, but the ruling is under appeal.

Maureen Matsen, deputy secretary for natural resources in Virginia, said while McDonnell prefers to store waste elsewhere, the lack of a national repository should not prevent utilities from expanding.

A generation removed from accidents at Three Mile Island and Chernobyl, McDonnell supports Dominion's effort to build a third reactor at North Anna. The governor last month called on the federal government to expand loan guarantees to the nuclear industry.

Dominion is searching for a partner to help pay for the reactor, which is expected to cost billions of dollars.

"The financial folks on Wall Street still view new nuclear as a high risk investment," Matsen said.

The hesitance is playing out locally; French company AREVA announced in August it would delay building a plant in Newport News that would manufacture nuclear power plant components.

Still, regional transmission organization PJM Interconnection expects electricity demand in Virginia to grow by 5,600 megawatts — more than what the state's four reactors combined produce — by 2019.

Dominion officials hinted they may mothball the North Anna project and instead a build natural gas plant to take advantage of previously unavailable deposits being unearthed by hydraulic-fracturing, or fracking.

Regardless of what happens, Surry is licensed to operate until 2033 and North Anna until 2040. Each facility has the capability to store nuclear waste generated between now and then, Zuercher said.

Matsen said Congress could overturn a 1977 ban on reprocessing, or recycling, spent nuclear fuel. Other nations, such as France, allow the practice but it remains mired in debate in the U.S. because reprocessing produces plutonium, which can be used to make bombs.

Dominion, meanwhile, is now stacking its waste-filled concrete casks horizontally — not upright — at Surry. The change, Zuercher said, will make it easier to transport the waste, whenever the day may come.