Fire at a generator of a power plant

A catastrophic failure of the low pressure turbine followed by fire and flooding severely damaged the generator.

The main turbine automatically tripped due to an erroneous mechanical over speed signal caused by high vibrations. The reactor, which was operating at 93 percent power, received an automatic scram signal triggered by the turbine trip. The high vibration was caused by catastrophic failure of the turbine blades. Ejected blade parts ripped through the turbine casing and severed condenser tubes and other piping.
Water from the fire suppression system and the damaged water lines accumulated in the basement of the turbine building and the adjacent radioactive waste processing building.
There was also a hydrogen fire in the generator's exciter due to breakage of generator sealing.
The reactor scrammed and the safety systems worked as expected.

INITIATING CAUSE was high vibration and sudden failure of the turbine blades.

ROOT CAUSE(S)
Safety systems functioned properly. Some sources reported the lack of emergency procedure in case of water flooding. According the "List of nuclear power accidents by country" provided by Wikipedia, the main turbine experienced this major failure due to improper maintenance (ttps://en.wikipedia.org/wiki/List_of_nuclear_power_accidents_by_country (accessed November 2020).

steam turbine, generator, cooling system

According to a source, "The accident happened without any warning. "

Repair cost are estimated at US$67 million. Radioactive releases were confined to noble gases in the steam within the turbine. (some sources report also release of contaminated water). Fire and flooding damaged other parts of the system, including exciter and condenser.
Plant was down for all of 1994 to repairing the turbine and clean the water contamination.

For a general on the risk of fire in power plant turbine buildings, see HIAD ID = 042.
Assuming that improper maintenance could have been one root cause, it confirm a general on the fact that regular maintenance and inspection could have helped to prevent the catastrophic turbine failure.