The Bells of Saint John - S7-E8
Revealing mistake: During the sequence where Clara sets foot on the TARDIS for the first time, and she and the Doctor then stop the plane from crashing, there are some shots which make it fairly obvious that the mug of tea she's carrying is empty. (00:25:35)
Chosen answer: 1) When Stephen Moffat took over he ignored a lot of what had been developed before (there is not in-universe answer). 2) It would have killed Rose, so the Doctor absorbed the energy. His body regenerated before the energy could do a significant amount of damage that would prevent regeneration.