CBRN event in Pakistan on Sat 9th January 2021

On January 09, 2021, C-1, C-2, C-3 and C-4 situated at Chashma Nuclear Power Generating Station faced severe grid fluctuations during operation at around 2341 hrs due to country wide power breakdown. C-1, C-2 and C-4 tripped on 'Reactor Coolant Pump (RCP) Bus Under Frequency' while C-3 tripped on ‘SRC Loop-A Coolant Flow Low’. Both offsite power sources (220 kV and 132 kV) were also lost and both Emergency Diesel Generators (EDGs) of each C-1, C-2 and C-4 started automatically and successfully connected to provide power to emergency buses. While one of the EDGs (EEG-001DG) of C-3 could not start on auto and it had to be manually started after some time. Hot shutdown was maintained at C-1, C-2, C-3 and C-4.
Standby (SB) was declared at 2356 hrs on January 09, 2021 at C-1, C-2 and C-4 while Plant Emergency (PE) had to be declared at C-3 due to unavailability of one of the EDGs (EEG-001DG). Being responder plants, C-1, C-2 and C-4 also declared Plant Emergency. At C-3, EEG-001DG became available at 0004 hrs on January 10, 2021 and Plant Emergency was downgraded to Standby while other plants also responded.
Later, Standby was terminated at C-1 (1510 hrs), C-2 (1310 hrs), C-3 (1335 hrs) and C-4 (1510 hrs) after restoration of offsite power sources on January 10, 2021.