Bulgaria’s state nuclear power plant Kozloduy reconnected on Sunday its 1,000 megawatt Unit 5 nuclear reactor after successfully completing increased capacity tests on July 13-14, the plant said, reports Reuters.

The tests followed a planned maintenance and refueling, Kozloduy, situated on the Danube river, said in a statement, adding the Soviet-made reactor was reconnected to the national power grid at 1328 local time (1028 GMT), according to Novinite.

The other reactor, Unit 6, is working at full capacity, the plant said.

Last week NPP Kozloduy’s sixth block was shut down from the country’s energy system after the electrical protection was triggered. All systems of the block have worked according to the design algorithms, the company states. This was the second such incident occurring in Kozloduy in less than a week. Bulgarian nuclear power plant Kozloduy has shut down one of its two 1,000 megawatt units the previous week after a protection system was activated at the unit’s generator.