A nuclear power plant about 50 miles outside Washington D.C. has allegedly been left virtually unguarded, according to an investigation by The Daily Caller. Standing on the western shore of the Chesapeake Bay, it's the kind of place that would be deemed vulnerable enough for a terrorist attack.

A disturbing video released by the website Tuesday features a reporter and videographer driving through the front gates of the Calvert Cliffs Nuclear Power Plant and parking not far from a nuclear reactor without coming in contact with any security.

The Nuclear Regulatory Commission, who sets security requirements for plants like Calvert Cliffs, is appointed by the president. In this case, the Obama administration has oversight of the physical protection of nuclear plants through the NRC.

The experiment was repeated again last Friday without anyone taking notice or stopping the reporters from accessing the power plant site.

On one visit, the reporter saw a lone marked security vehicle pass by, but the person inside failed to slow down or ask questions, Fox News reported. On a subsequent visit, a large civilian truck, like the type used in terrorist attacks, including at the Oklahoma City federal building in 1995, drove through the gates without being stopped.

The investigation began after someone visited the nuclear facility last month and noticed the apparent lack of security.

"That facility is the softest target I have ever seen in my life," the visitor recalled.

However, the padlocked guardhouse and lack of visible security teams at Calvert Cliffs were defended by a spokeswoman for the commission on Monday.

"Based on the security inspections we've conducted on an on-going basis, security at Calvert Cliffs is appropriate to protect the public health and safety," spokeswoman Diane Screnci said.

Kory Raftery, a spokesman for the plant's owner, Exelon Corporation, told the Ddaily Caller that manned checkpoints are "not required" at all nuclear power plants, adding that the corporation's nuclear power plants are "highly secure, virtually impenetrable facilities."

"The fences and checkpoints you see at Calvert Cliffs are only a small part of our defense in depth security strategy," he said. "In fact, much of our defense lies in the things you can't see."

When questioned about unmanned security checkpoints and empty guard booths, Raftery replied: "Nuclear security is always evolving. I can't get into too many details, but redeployment enhanced overall site security, increased safety for our officers and provided more effective use of resources."

Yet according to experts, a visible security presence is vital, because it may help deter terrorists from targeting a facility in the first place.

"Part of security is to have a visible defense so that it doesn't attract adversaries who might see this kind of weakness to exploit," said Edwin Lyman, an expert in nuclear terrorism at the Union of Concerned Scientists.

But recently, lack of adequate security at nuclear power plants around the country has become common, Lynn said in an interview on Monday.

"What I think has happened lately is the industry has really let those owner-controlled areas' protections just completely erode," Lyman said. "And so they're leaving the checkpoints unmanned all the time and not doing surveillance of the areas so people can enter the owner controlled area without any problem or detection. And I think that's a problem."

Asked about a hypothetical meltdown at Calvert Cliffs, Lyman said the Fukushima disaster showed that a reactor meltdown could warrant evacuations 25 or 35 miles away, and could threaten radiation exposure to people who live 50 miles or more away, which in this case would include the 3.6 million people who live in Washington, D.C. and surrounding suburbs, according to the DC.

"You could really damage, perhaps destroy, that reactor and the whole area surrounding it, including the nation's capital," Tucker Carlson, editor of the Daily Caller, said, calling the lack of security "bizarre."

Meanwhile, given the knowledge that 9-11 terrorists initially considered attacking a nuclear power reactor, and with recent reports that Islamic militants might have access to American passports, the threat against nuclear power plants is real.