The Ringhals plant has four reactors and produces about 20 percent of all electricity used in Sweden.
“The Swedish Radiation Safety Authority (SSM) has observed a series of shortcomings since 2005. These involve weaknesses in management and governance, a lack of traceability of internal decisions, and failure to adhere to routines and instructions,” it said in a statement.
“But despite measures introduced by Ringhals the problems persist,” it added.
SSM ordered Ringhals to investigate why its routines were not respected and submit a report, and demanded that new security measures be put in place.
The Ringhals plant is owned 70 percent by Swedish state-owned group Vattenfall and 30 percent by German energy giant E.ON.
Another nuclear plant owned by Vattenfall, the Krümmel station near Hamburg, Germany, underwent an “emergency shutdown” at the weekend following a short circuit in one of the plant’s transformers.
That incident occurred only one week after the Krümmel plant reopened after two years of repairs. It will now remain offline until April or May 2010.
The Swedish energy and enterprise ministry on Wednesday demanded an explanation from Vattenfall following the two incidents.
The ministry “calls for a special report from the state owned company Vattenfall on how they work with nuclear safety,” it said in a statement.
The state “made it very clear during Vattenfall’s stakeholders’ annual meeting this spring that one of the most important expectations we have on the company now, is to improve the confidence in their company brand.”
“The incidents these last few days have unfortunately damaged the confidence in the company both in Sweden and Germany,” state secretary Ola Alterå said in the statement.
Sweden, which has 10 reactors at three power stations, announced earlier this year that it had reversed a decision to phase out nuclear power, saying the reactors could be replaced at the end of their life spans as part of an ambitious new climate programme.
Swedish news agency TT said Wednesday’s decision by SSM was only the third time such measures had been ordered against a nuclear plant in the country.