A paragliding Greenpeace activist who dropped a smoke bomb over a French nuclear reactor on Wednesday added a new element to the presidential race there -- and raised the question of whether the same, or worse, could happen at a U.S. nuclear reactor.
"At no moment was the safety of the installations at risk," said the plant's operator, French utility giant EDF, adding that the pilot was arrested by security staff at the Bugey nuclear plant in southeast France.
EDF acknowledged that a second activist was arrested at another nuclear site in southwest France after entering via a truck gate and hiding for an hour in brush within the "surveillance zone," Reuters reported.
Greenpeace said it was raising awareness of nuclear power issues ahead of France's presidential elections on Sunday.
It "illustrates the vulnerability of French nuclear to the threat of air attack," Greenpeace France spokeswoman Sophia Majnoni d'Intignano said in a statement. "While Germany took into account the aircraft crash in its safety testing, France still refuses to analyze this risk for our plants."
France, which gets 80 percent of its electricity from nuclear power, pledged special safety tests at its 58 reactors after Japan's Fukushima nuclear disaster in March 2011.
Those tests include standing up to floods, earthquakes, power outages and cooling system failures -- but not terrorist attacks or even a plane crash.
So could a paraglider attack happen in the U.S. -- or would it be shot down before even getting to a nuclear site?
"Completely speculative," Steve Kerekes, a spokesman for the Nuclear Energy Institute, told msnbc.com. "Our facilities are extremely well-defended. Let's leave it at that."
Over at the Union of Concerned Scientists, a group that says it's neither for nor against nuclear power, two nuclear experts said that while a reactor's containment dome would be hard to penetrate other targets are available.
The intake structure, where water is brought in to cool the reactor fuel, "is an easier target," Dave Lochbaum told msnbc.com. Without coolant, that fuel could cause a meltdown.
The aerial threat exists, added Edwin Lyman, because the Nuclear Regulatory Commission "decided in 2007 to exclude any kind of aerial attack from the 'design basis threat' -- that is, the set of attacks that reactor operators must provide protection to defend against.
"So the NRC doesn't require that nuclear plants have means to detect or defend against intrusions from the air," he added. "And the federal government also does not require 'no fly zones' around nuclear plants that could be enforced by the military."
Kerekes countered by noting that an independent study in 2002 found that U.S. nuclear containment structures can withstand even a crash from a commercial airliner.
As for paragliders, Lochbaum said a more likely scenario is where one or more are used at night in an attempt to get into a nuclear plant.
"While nuclear plant security perimeter fences are well lit, the lighting is to allow security officers to catch anyone trying to climb over, cut through, or tunnel under the fences," he said. "The lights and the camera angles might not readily show someone flying in. That someone could be carrying sufficient weapons to cause problems."
At that point, Lochbaum said, "it becomes a race -- can the intruder access area(s) needed to sabotage the plant before the security officers intervene?"
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Nuclear plants already test such scenarios, and Lochbaum said "the good guys sometimes lose the race" in testing -- even with the six weeks notice given by the Nuclear Regulatory Commission.
"Typically, the force-on-force tests are conducted once every three years at each U.S. nuclear plant," he said. "A test may consist of four exercises -- different entry points and different targets. It would be useful to periodically throw in a glider or parachute entry to make sure the security officers practice handling such threats, too."
Back in France, the stunt certainly got attention -- but not all of it flattering for Greenpeace.
"The main consequence of this stupid action will be to prevent any air recreation within more areas of France," posted one person on Greenpeace's main blog on the stunt.
An anonymous post on another Greenpeace blog criticized the stunt, saying a paraglider couldn't carry enough explosives to damage nuclear containment areas.
"You've also missed the point," the writer added, "that someone could cause far graver damage by carrying out a similar attack on the Olympic Stadium in London later in the year."
Reuters contributed to this report.
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