any method to save bitlocker startup key on other volumes on the same hard disk

hi friends

i have a windows 2008 R2 enterprise

when i enable bitlocker on any drive except windows volume, system allows me to save startup key on other volumes. but when i want to enable bitlocker on windows volume, doesn't show me other volumes to save startup key. it only let me save it on removable USB.

is it by design ? is there any settings so that it allow me to save the key on other volumes on the same hard disk?

thanks in advance