Regulator clearance in Sweden is required every ten years for the two reactors, Forsmark 1 and Forsmark 2, which are operated by Swedish company Vattenfall.
"Anyone who is authorized to hold or operate a nuclear facility must make an overall assessment of the plant's radiation safety at least every ten years according to legal requirements," the authority said in a written statement.
The Swedish authority said that Vattenfall has been given the all clear to operate the plants in a radiation-safe manner up until the next comprehensive assessment in 2028.
The two reactors have a total capacity of 2 gigawatts, equating to approximately one sixth of Sweden's total electrical energy consumption.
Forsmark 1 was commissioned in 1980 and Forsmark 2 in 1981.
"Until the next comprehensive assessment, Forsmark 1 and Forsmark 2 will pass the originally analyzed operating time of 40 years," it noted.
On June 20, International Atomic Energy Agency completed a review of long-term operational safety at Forsmark, which was then followed by the announcement from the Swedish Radiation Safety Authority.
(Anadolu Agency)