The institute did not indicate how many such facilities were located in the area.
But the industrial city of Mianyang
, where thousands were killed by the quake and more than 18,000 are believed trapped under rubble, is home to the headquarters of China
's nuclear weapons design industry.
The city of 700,000 people is on the edge of the disaster area in Sichuan province.
The French watchdog was more reassuring about China's four nuclear sites producing electricity because all are located more than 1,000km from the epicentre of the 7.9 quake.
The institute said it was waiting for Chinese inspections to confirm that the four electricity-producing sites in eastern China - Lingao, Daya Bay, Qinshan and Tianwan – were unharmed.
"It is probable that these reactors suffered no notable damage," it said.
China is expanding its nuclear energy production to reduce its reliance on greenhouse gas-producing coal, which presently accounts for 70 per cent of its massive energy needs.
It plans to increase the four per cent contribution from nuclear energy by building 30 new nuclear generators by 2020.