Complex sentence: The VVER 1200 can experience a Loss Of Coolant Accident and Loss Of Power Accident due to turbogenerators that'coast down' after shutdown and backup power supply, set of diesel generators that restore cooling to the reactor, within about 30 seconds.
Split into simpler sentences: The VVER 1200 would experience a Loss Of Coolant Accident and Loss Of Power Accident if the turbogenerators'coast down' after a shutdown. A backup set of diesel generators is kept on standby to restore cooling to the reactor within about 30 seconds.