Kola

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INES-event
INES 1

UNIT SCRAM CAUSED BY GRID DISTURBANCES DUE TO TORNADO

The unit was operating at 350 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. At 02:29 TG-6 was tripped by emergency protection. As a result of strong frequency oscillations in the system (from 44 to 52.5 Hz) TG 5 was disconnected from the grid at 04:11 and Unit 3 was scrammed by AZ1 protection. All safety system (SS) components started as designed except the auxiliary motor-driven feedwater pump (AFP-1) which was started directly from its subdistribution bus.

Category: Power Reactor Kola Russian Federation »

INES-event
INES 1

UNIT SCRAM CAUSED BY GRID DISTURBANCES DUE TO TORNADO

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.

Category: Power Reactor Kola Russian Federation »

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INES 2

UNIT SCRAM OWING TO LOSS OF DC PANEL POWER

The unit was at a thermal power 3% of rated (Nnom) power with TG-2 at coast down and TG-1 under maintenance. A short circuit occurred in the armature winding of the reversible motor generator (RMG-1) connected to the unit DC panel (UDCP-1). Automatic breaker which disconnects UDCP-1 from RMG-1 failed to open, and the DC grid continued to receive voltage which significantly differed from the nominal. The resulting current oscillations have led to the opening of the automatic breaker which supplies power to RPS emergency protections panels from UDCP-1.

Category: Power Reactor Kola Russian Federation »

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INES 3

UNIT SCRAM CAUSED BY GRID DISTURBANCES DUE TO TORNADO

The unit was operating at 370 MWe power. As a result of tornado the 330 kV, 154 kV and 110 kV transmission lines in the "Kolenergo" power system were damaged. At 02:27 and 02:32 TG-1 and TG-2 were tripped by system emergency protection as a result of strong frequency oscillations in the system. At 02:32 AZ1 protection (scram) actuated on core pressure difference increase above setpoint because of RCPs increased flowrate as a result of grid frequency rise up to 52.5 Hz. The normal DGs 1,2 and the standby diesel (SD) started for coast down as designed.

Category: Power Reactor Kola Russian Federation »

INES-event
INES 3

UNIT SCRAM CAUSED BY GRID DISTURBANCES DUE TO TORNADO

The unit was operating at 388 MWe power. As a result of tornado the 330 kV, 154 kV and 110 kV transmission lines in the "Kolenergo" power system were damaged. At 02:27 TG-4 was tripped by system emergency protection. The unit power was reduced to 47 MWe. Strong frequency oscillations in the system (from 44 to 52.5 Hz) at 03:42 led to power disbalance in the primary and secondary circuit causing TG-3 stop valve closure and AZ-1 protection (scram) actuation.

Category: Power Reactor Kola Russian Federation »

INES-event
INES 1

DEGRADED WATER CHEMISTRY IN THE PRIMARY CIRCUIT DUE TO CEMENT MORTAR INGRESS INTO THE BORATED WATER STORAGE TANK

The unit was in the maintenance outage in the stage of refueling. To prevent ground water filtration through the foundation into the Chemical and Volume Control Facility (CVCF) rooms cement mortar was being pumped through the drilled holes into the ground filling surrounding the building foundation.

Category: Power Reactor Kola Russian Federation »

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INES 0

LOW ACTIVITY WATER LEAK FROM THE CONTAMINATED CONDENSATE TANK

Unit 3 was maintained at the minimum controlled power level. Unit 4 was operating at 430 MWe power. The event is related to the equipment operating in the controlled zone of unit 3 and periodically participating in the process. As a result of the leak in the contaminated condensate tank (specific activity - 2*10(-5) Ci/l) 400 m3 of condensate were spilled and, over penetrations, got into some working rooms in the controlled zone, having changed the radiological situation up to the dose rate of 3 mkR/s and 2*10(3) beta-particles/(cm2*min) for the surfaces.

Category: Power Reactor Kola Russian Federation »

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INES 0

UNIT SCRAM DUE TO SHORT-TIME DEENERGIZATION OF AUXILIARY POWER BUSES

The unit was operating at 58% of nominal power. At 05:45 as a result of a thunderstorm disconnection of the 330 kV transmission line and opening of oil breaker of one of the two turbine generators occurred. In the course of automatic changeover (to feed the 6 kV auxiliary power buses from standby source) AZ-1 emergency protection (scram) actuated due to mismatch between the time for automatic changeover and time delay for AZ1 protection actuation. The remaining protections, controls and safety systems actuated as designed. Breach of limiting conditions of operation did not occur.

Category: Power Reactor Kola Russian Federation »

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INES 0

DAMAGE TO RCP MAIN THRUST BEARING WHILE PREPARING PRIMARY FOR HYDROTEST

While performing primary circuit warmup after preventive maintenance prior to leak tightness hydrotest at 10:48 damage to RCP-3 main thrust bearing occurred. The affected pump was tripped. The event had no consequences.
No breach of limiting conditions for operation occurred.
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Category: Power Reactor Kola Russian Federation »

INES-event
INES 2

FAILURE OF SAFETY SYSTEM TRAIN WHILE ROUTINE TESTING

The unit was operating at nominal power. During the routine test of the 3QW diesel generator (DG) the failure of this DG control system occurred. The DG was taken out of service for maintenance. 5 hours 41 minutes after the event the 3QW DG was tested under load and placed in expectation mode. While taking the affected DG out of service for repair personnel failed to test the two remaining safety system (SS) trains, which constitutes a breach of technological procedure requirements. Thus, a breach of safe operation conditions occurred.

Category: Power Reactor Kola Russian Federation »