Simplify the following text for a Grade 11 native English-speaking person.
Original: Then , after defecting from the Soviet Union in 1976 , he won consecutive Candidates cycles to qualify for World Championship matches with Karpov in 1978 and 1981 , losing both .
Simplified: Then , after defecting from the Soviet Union in 1976 , Korchnoi won two Candidates cycles to qualify for World Championship matches with Karpov in 1978 and 1981 .