INTERVIEW - No additional safety build-up needed to extend Bulgarian NPP's lifespan – regulator

Launching a formal procedure for giving an additional lease of life to the two Soviet-made reactors of 1,000 megawatts each is required by their design documentation which sets specific time limits for the operation of the basic equipment, including the reactor vessels, the chairman of the Nuclear Regulatory Agency, Sergei Tsochev, told SeeNews in a recent interview.

"The modernisation of Units 5 and 6 was completed with the implementation of the modernisation programme in 2008. This programme included 212 technical measures aimed at achieving a high level of safety for both units in line with current international norms and standards and increasing the units' operational reliability and efficiency," he said.

By the end of next year, the Bulgarian government should submit to the nuclear regulator a programme for extending the lifespan of Kozloduy’s Unit 5 based on a comprehensive survey of its systems and components. For Unit 6 the deadline for submitting such a programme is the end of 2015.

The issue of extending the lifespan of the two reactors was brought into the spotlight again at the beginning of this year after the government decided to abandon the project for building a second nuclear power plant in Belene, on the Danube river, arguing that Bulgaria does not have the financial resources needed to implement it and no strategic investor has turned up since Germany's RWE withdrew from the project in 2009. Besides, the government has taken steps to install in Kozloduy a 1,000-megawatt reactor commissioned to a Russian manufacturer and initially intended for the Belene nuclear power plant.

In this context Bulgaria kickstarted the first phase of a procedure for extending the lifespan of Kozloduy's two operating reactors by 20 years. Their project lifetime will expire in 2017 and 2021, respectively, said Tsochev.

"The expiry of their lifetime does not necessarily mean the units should be shut down. It is possible that their use be continued," he added.

The conditions for doing so are set out in the licenses for the operation of the two units. They include conducting a comprehensive survey of the actual status of the two units, defining the residual lifetime of the structures, systems and components that will remain in operation and identifying those which must be replaced with new ones.

In April Bulgaria signed a contract for a study of the actual status and assessment of the residual resource of the equipment and facilities of Units 5 and 6 in Kozloduy with a consortium of Russia's Rosenergoatom and Electricite de France (REA-EDF).

The comprehensive survey should employ a methodology consistent with the high level of expertise expected from a European Union member state, by a contractor having the experience from similar projects already implemented in the EU to make sure the arguments in favour of extending the lifespan of Units 5 and 6 will be undisputable, said Tsochev.

Bulgaria closed down Kozloduy's four older Soviet-made units of 440 MW each prior to its accession to the EU in 2007 to address nuclear safety concerns of the bloc.