22 Dec (NucNet): Deficiencies in OKG’s safety assessment of its Oskarshamn-2 nuclear reactor unit are serious enough for another assessment to be submitted by the end of 2017 instead of the scheduled 2020, the Radiation Safety Authority (SSM) said.
Every 10 years nuclear power station operators in Sweden make an overall assessment of their reactors, detailing how they meet safety requirements set down in law. The assessment must also cover the implementation of scientific and technological developments that result in safety being further increased.
SSM said it has reviewed OKG’s assessment and found “flaws” in it and in the plant’s operation methods.
Many of the shortcomings have already been made known within the framework of a back-fitting, life-extension and capacity increasing project that began in 2004.
In 2012, SSM imposed special conditions on OKG for operation of the boiling water reactor unit because the availability of emergency power-supply diesel generators was not ensured.
And in October 2014, SSM said OKG had violated regulations by failing to submit predicted collective dose information and radiation protection actions for renovation work at Oskarshamn-2. SSM also said OKG had begun the work without authorisation. All work where the total collective dose is expected to exceed 100 person-millisieverts must be reported in advance.
SSM has now said OKG had not performed the analyses and implemented the measures required to manage the plant’s transition to long-term operation. SSM said it saw no immediate risks with this, but OKG must “address the gaps”.
OKG has been asked to submit a new safety assessment by 31 December 2017 instead of the scheduled 31 December 2020.
Oskarshamn-2 has been offline for a major modernisation programme that began on 1 June 2013.
OKG said in June 2014 that it had extended the modernisation programme and the restart date for the unit was “uncertain”. It was initially planned to return the unit to operation in the spring of 2015, but OKG has said that could now be the summer of 2015.
OKG said after the modernisation project is completed, the plant will be able to deliver electricity for at least another 20 years. The project will be concluded with a power increase from 660 megawatts to 840 MW.
Oskarshamn-2 began commercial operation in 1975. There are two other commercially operational BWRs at the Oskarshamn station.