The Mühleberg power station near Bern has been restarted after three months of annual checks and safety improvements.
The Federal Nuclear Safety Inspectorate gave the go-ahead at the weekend for the plant to continue operations.
The operator BKW Energy company said the checks on the plant – one of the oldest in Switzerland – had guaranteed its safety and “long-term use”.
High-tech analyses were done on cracks in the shell of the reactor core and deemed them safe, the company said. The technology used enabled a closer inspection of the cracks, determining their length and depth. The company said the tests confirmed the tendency of cracks to stabilise.
Alarm systems, turbines, alternators and electrical protection systems were also tested. In addition, the operators had to confirm that the plant could cope with severe flooding. The time needed for all of this work required a two-month shutdown, which cost nearly SFr28 million ($31 million).
Anti-nuclear protestors say the shell cracks are a security risk. They have criticised the authorities for not having an emergency evacuation plan in the event of a disaster at the controversial plant, which has been on the electricity grid since 1972.
Following the disaster at the Japanese nuclear power station at Fukushima earlier this year, the government announced in May that it planned to decommission Switzerland’s five nuclear power reactors by 2034, once they reach the end of their lifespan. The plans still need the approval of the Senate.
swissinfo.ch and agencies