NUCLEAR power plants are more vulnerable to a 9/11-style attack than officials think, a study says.
Scientists say testing of reinforced concrete walls focused on smaller planes, rather than passenger jets.
In a trial 30 years ago, an F-4 Phantom flown into the walls used at power plants at 500mph was totally destroyed.
But Dr Topi Sikanen, of the Technical Research Centre of Finland, said a bigger commercial plane could penetrate the 4ft to 7ft thick walls: "Following the September 11 terrorist attacks in 2001, these analyses have been extended to assume the impact of a large commercial aircraft.
"Such an aircraft can damage safety-related structures and components through mechanical impact and fire."
According to Dr Sikanen, a larger plane could set off large internal fires that would be able to burn through the walls of the plant: "Initially, a large fireball is created by the fuel cloud erupting from the breaking fuel tanks.
"Only a fraction of the fuel carried by the plane will burn in the initial fireball.
"The remaining part of the fuel will accumulate and burn in pools near the aircraft impact position."
MOST READ IN UK NEWS
Eventually, he says the plane's fuel would make its way into the plant and cause additional fires: "Even if the amount of penetrated fuel is small it can cause a rapid ignition of existing fire loads and result in internal fires."
Dr Sikanen wants power plants to boost safety standards to withstand such attacks.
"Each portion of the problem touches on a widely researched problem in fire safety science: pool fires, fireballs and spray flames," he said.