22 Oct (NucNet): A routine annual refueling and inspection outage at the Oskarshamn-3 boiling water reactor (BWR) unit in Sweden is being extended after problems were discovered with a control rod.

During the annual outage one control rod was found to have fissures in its shaft. The problem was discovered during a random sample inspection of a control rod extension. On 17 October 2008 plant operator OKG decided to extend the outage so a full inspection could be carried out.

The company said it had also found problems with other control rods at unit 3. The complete results of these inspections are expected by 23 October 2008, when inspectors from Sweden�s Radiation Safety Authority (SSM) are due to visit the plant. SSM was established on 1 July 2008 under the Ministry of Environment when it took over the responsibilities and the 250 staff of the Swedish Radiation Protection Institute and the Swedish Nuclear Power Inspectorate.

Units 1 and 2 at Oskarshamn do not have the same type of control rods as unit 3, but were also inspected as a precaution. These inspections did not find anything unexpected and the two units are operating as normal, OKG said.

SSM has asked OKG to report its findings in connection with the control rod problems. The authority has also asked the operators of Sweden�s two other nuclear power plants, Ringhals and Forsmark, to prepare safety reports on their BWRs.

The Forsmark plant has three BWR units. There are four units at the Ringhals plant, but only unit 1, which entered commercial operation in 1976, is a BWR.

Officials at Forsmark said they had already shut down unit 3 because it was equipped with the same type of control rods as the Oskarshamn reactor with the control rod problem. They said units 2 and 3 have a different control rod design and that �based on present information�, there were no indications of faults in these control rods.

>>Related reports in the NucNet database (available to subscribers)

New CEO To Take Over At Oskarshamn (World Nuclear Review No. 38, 21 September 2007)

Swedish Poll Shows Increasing Support For Nuclear (News No. 51, 269 June 2008)

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