vstp and rstp priority and will loops occur?

Hi All

I have the following scenario and was just wondering what the affect would be in a brief power outage. The core switch is connected to 3 access switches, on the core switch configuration. VSTP priority is set to 24000 - the remaing access switches have no priority so will default to 32768.

Now in a power on/off scenario i am assuming that all is ok because the lower priority is preffered and core will remain core and the rest will all just use core as the RB. Is this correct?

Also show spanning-tree bridge on all switches show:

STP bridge parameters
Context ID : 1
Enabled protocol : RSTP

STP bridge parameters for VLAN 2

As RSTP is running, does this mean that RSTP needs its own priority on the core? or will it use the VSTP priority configured?

I read that: . 'Switches configured to run VSTP automatically assign each VLAN to one spanning-tree instance that runs RSTP' 

To me this sounds like the VSTP bridge priority will be used, however if someone can clarify that would be great.

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Finally can anyone a way a loop can occur with this configuration?

Thankyou