Turning Undead in the White Box rules

One of my players made a cleric of Moradin in my Whitebox FR game.  So I was reading the Turn Undead ability.  Woah... no range described, "all creatures of the type are turned" etc... so a single 4th level cleric could turn an entire army of skeletons to dust without a roll...  I'm not sure I like that.

I'm not sure why the saving throw system wasn't used for turning undead (I wonder if there is a historical context for this table that I'm not aware of, dating back to Chainmail...).

If you used the saving throw system, the cleric would use the turn undead ability and then the undead critter would get a saving throw to resist the ability,  Higher Undead/Demons would automatically be harder to turn.  You could give a penalty to the save equal to the clerics level/2 and if the save is missed by 10 the creature immediately turns to dust.  I'd give it a range of 100 ft, so:

Turn Undead (Lawful Cleric Ability)

When using Turn Undead, a lawful cleric channels the might of their god, sending penetrating waves of power toward the undead foe, within 100 ft.  All undead in the range must make a saving throw or flee the cleric, the undead get a penalty to this saving throw equal to the (cleric's level)/2, round down.  If trapped, or otherwise unable to flee, the DM may rule that the undead may attack.  If the saving throw is missed by 10 or more, the undead is destroyed in whatever way the DM describes (turn to dust, explode into buckets of ectoplasm, etc...)

To further limit this powerful ability a DM may rule that it may only be used 1 time per level of the cleric per day.

I think this balances the power of the ability in a way that will work for my game.