The Kozloduy nuclear plant has cut power at its sixth reactor too, starting today, because the Danube's water level is too low, the energy ministry and the plant said. Until now, only reactor five had been cut. Each of the two working reactors is now producing about 90 megawatts less, a combined drop of nearly 180 megawatts.

A working group that oversees safe, reliable running of the nuclear units as river levels keep falling made the decision. The cut is a precaution, and each step is agreed with the energy ministry and the Electricity System Operator.

The plant has cut power before over the low Danube level. On August 21, reactor five dropped about 120 megawatts. From August 31 its output began climbing back up step by step, then on September 14 it was cut again, this time by about 60 megawatts. At that point, reactor six was still running on its normal output schedule.

The ministry says the August 21 cut was the first in the plant's 52-year history caused by conditions this severe from low water.

Forecasts point to the Danube falling further, and under the usual rules for cases like this, more cuts could follow.