I don't know Vivienne. If it hasn't been moved and the conditions have been constant your buds shouldn't be blasting. Actually, just how consistant is your atrium temperture? I know you don't want to do this, but can you see the roots?? Maybe there is something going on with your Phal that you cannot see and it couldn't support the spike.
With all the discussion about moving Phals in bloom I need to mention this again. I'm not bragging! but I rarely have blasted buds and I don't know why.
The way I move my orchids around I should have buds blasting everywhere! In January I moved a blooming equestris from my upstairs orchid room (warmer, moister, brighter) to my kitchen window (cooler, dryer, darker) and all 14 buds lasted months. It even took a road trip with me to my orchid society meeting on a cool night. I really don't know, but I'm sorry you have lost all your beautiful little buds. I would cut the spike and look at the roots, just to be sure.