A faulty resistor on an electronic card led to the failure of a module in the turbine control system. As a result, the control dampers on the low pressure turbines closed slowly. According to its design, the plant reacted by shutting down the turbines and automatically reducing the reactor power to 67% by inserting control rods and reducing the core circulation. Then, as described in a set of “Instructions for Abnormal Situations”, the operating staff reduced the reactor power to 22% of the rated output. During operation at reduced power, cavitation occurred for a short time in the feed water pumps, there was a leak in the main steam line drainage area, and fluctuations occurred in the reactor power.
The description of the event is only available in German.