Sweden's Oskarshamn nuclear plant on Tuesday shut down one of its reactors because of a valve problem, Associated Press quoted a plant official as saying. Anders Osterberg, a spokesman for the OKG company running the Oskarshamn plant, said there were no safety concerns related to the problem and that the shutdown would only be temporary. «We think there is something faulty in the computer-controlled mechanism in the closing of the valve,» he said.