Romania’s Cernavoda NPP is to be closed for three weeks, according to nuclear operator Nuclearelectrica. Unit 2 was automatically disconnected from the grid on 4 May due to a technical malfunction while unit 1 closed for scheduled maintenance on 10 May. Unit 2 will remain out of service for an extended period to allow for repair work, including replacing the transformer with a backup unit.
The automatic disconnection of unit 2, produced was caused by a failure in a power drain transformer insulator. Although it was initially hoped that the fault could be rectified quickly, the final technical decision was to completely replace the equipment with a backup transformer. The process is extremely complex, involving the relocation of massive components and rigorous leak-proofness and calibration tests, ruling out an immediate restart.
The 706 MWe Candu reactors supply around 15-20% of Romania’s electricity. Unit 1 was commissioned in 1996, and unit 2 in 2007. A modernisation is also planned, and it is expected to double the plant’s capacity. Nuclearelectrica produces electricity, heat, and nuclear fuel and operates under the supervision of the Energy Ministry. The Romanian state holds an 82.49% stake in the company, with the remainder held by other shareholders following its 2013 stock exchange listing.
There have been total shutdowns before but only for a few hours, due to storms (2014) or frequency fluctuations in the European network. The shutdown of both units deprives the National Energy System of some 1,400 MWe. The impact could be mitigated during sunny days by photovoltaic energy production, but problems will arise during evenings, at peak consumption. To make up the shortfall, Romania will have to resort to electricity imports and increased production in gas and coal-fired power plants, which currently operate below nominal capacity.
The long-term unavailability of nuclear capacities will become a constant from 2027, when the upgrading of unit 1 is scheduled to begin. The project, estimated at €1.85bn ($2.17bn), with a total support package valued at €3.2bn, will last over two years and aims to extend the life of the reactor by another 30 years. However, the shortfall will be compensated by the entry into operation next year of the Mintia thermal power plant (1,700 MWe).
Currently, the financing mechanism for this strategic project is being examined by the European Commission. The President of Romania’s Competition Council, Bogdan Chirițoiu, said the investigation is a standard procedure for nuclear projects of great complexity and a favourable decision is expected in 2027. “We will continue to collaborate closely and transparently with the representatives of the European Commission to ensure the compliance of the measure with the European rules”, said Chirițoiu. The Commission is considering whether the support package (which includes a grant of €600m, State guarantees and a 30-year Contract for Difference (CfD) is proportionate and does not distort competition excessively.
