Simplify the following text for a Grade 12 native English-speaking person.
Original: During this period there were controversies within the Sierra Club about how to lead the anti-nuclear movement , and this led to a split over the Diablo Canyon plant which ended in success for the utilities .
Simplified: In this period there were controversies within the Sierra Club about how to lead the anti-nuclear movement , and this led to a split over the Diablo Canyon plant which ended in success for the utilities .