Complex sentence: The radio program introduced the concept of kryptonite into the Superman mythology, which was created to allow actor Bud Collyer the time occasional time off from recording as Superman would succumb to the baleful rays and be absent for some episodes.
Split into simpler sentences: The radio program introduced the concept of kryptonite into the Superman mythology. These fragments of radioactive debris from Superman's home planet were created to allow actor Bud Collyer the occasional time off from recording, as Superman would succumb to the baleful rays and be absent for some episodes.