Fritz
The short answer is no there should not be any loops if the root switch is reloaded because RSTP should elect a new root bridge and build a new loop free topology.
There will however obviously be an outage while the switches work out a new topology.
There will also be an outage when the reloaded switch comes back online because if it was root before because of it's lower bridge ID then it will become root again when it is fully up and running.
But you should not see any loops.
Note the word "should" because you can never be fully sure.
If you are proposing to do this on a live network you should always schedule an outage for this sort of thing because you never know what could happen.
Jon
