Stichting Laka

Event Report Forms (ERFs) are filed to the IAEA. Sometimes there are multiple event reports, updating the rating, the event description. Here you only see the latest event report

ERF send date: Tue, 06-07-1993
ERF description: The unit was operating at 365 MWe power level. As a result of tornado the 330 kV, 154 kV and 110 kV transmission lines of the "Kolenergo" power system were damaged. As a result of strong frequency oscillations at 02:28 TGs 7, 8 were disconnected from the grid by emergency protection, and unit power was automatically reduced to 4% Nnom. RCPs 5 and 6 were tripped by hi-hi SG level protections. At 03:59 as a result of loss of power to normal buses the "trip of 4 RCPs or more" signal was formed causing AZ1 protection (scram) actuation. All safety system (SS) features started as designed except auxiliary motor-driven feedwater pump (AFP-2) which was started in-situ.
At 04:47 due to loss of power in the 330 kV grid the normal buses got deenergized. Essential buses had already been connected to the operating DGs and therefore all SS features remained in service. Stable regime of primary coolant natural circulation was established.
At 05:00 the power was supplied through the L-148 transmission line to the 1TR standby transformer and the power to essential loads was transferred to the 1TR transformer.
At 06:15 due to external impacts the L-148 line tripped. As a result of loss of power to the 1TR transformer the normal buses got deenergized and the "total loss of unit power" signal was formed. Meanwhile the essential buses had already been connected to DGs and all SS features were in service. At 07:40 the normal buses were connected to the 2TR transformer. At 8:40 the 330 kV open switchyard was energized under the normal configuration.
ERF rating date: 22-02-1993
ERF contact person: I. Jouk
ERF address: (VNIIAES) FERGANSKAYA 25, MOSKOW 109507, Russian Federation
ERF affiliation: Ministry of the Russian Federation for, Atomic Energy, All Russian Research Inst. for Nuclear P

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