How can I make sure original HDD is not accessible when operating from second installation windows on other HDD?

So I know how to create a bootable windows USB and install it to a second HDD, but after I install the second windows I dont want the original HDD with windows/files to be accessible or even show up when operating from the second windows installation. What do I need to do to make sure its not visible or accessible?

Example: original windows is drive: C and the new windows is drive: X, I dont want to see or be able to access drive: C

Also are there any other things I need to do to make sure that no potential virus could "migrate" from the original drive: C to drive: X (if possible) while operating from windows on drive X?