It is calling on operators to examine their current safety analyses of plants’ resistance to the impact caused by a commercial jet deliberately crashing, the Swiss news agency SDA reported.
Operators have been told to check the limits of tolerance using a simulator.
Since the last report on aircraft crash resistance 10 years ago, new, heavier airliners such as the Airbus A380 have come into operation.
Aircraft navigation technology has also been further developed, SDA said, quoting ENSI.
The previous safety report was compiled following the September 11, 2001 terrorist attacks in the United States.
It concluded at the time that Swiss atomic power stations were adequately protected against a deliberate aircraft impact.
The probability of radiation being released into the atmosphere following an aircraft strike was low, the report said.
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The ENSI decision to recheck resistance at the Swiss nuclear plants is partly based on research projects and partly on the findings of foreign supervisory bodies, SDA said.
Operators will have to check the upper speed limit reactors can tolerate when struck by an airliner.