Two reactors at the Forsmark power station, north of Stockholm, were shut after a problem was detected in a rubber seal on the outer wall of one of the reactors.
One of the reactors at the Ringhals nuclear station was closed down a week ago after a problem with its cooling system, and another reactor at the installation was shut down last week to check instruments after anomalous readings.
Last week the Swedish Nuclear Power Inspectorate filed a police complaint against the Forsmark station over the handling of an emergency shutdown last July. The inspectorate says the current closedown at Forsmark is not serious, however.
Nuclear power accounts for about one-half of Sweden’s energy needs.