I quite often shoot D100 at ISO 50. It works fine, you just develop normally.

D100 has a straight-line region that extends from about 3 stops below nominal exposure for ISO 100, to about 7 stops above. So if you shoot it at ISO 50 you gain a stop on the low side and lose a stop on the high side, giving you a straight-line region from about 4 stops below nominal (at ISO 50) to 6 stops above. This gives you more protection against blocked shadows, provided you don't have any extreme highlights to worry about.

My only concern would be if you have bright highlights or over-expose, you might find the negative density exceeds the Dmax of your scanner. I have no practical experience of this as I print in the darkroom.