It's actually a virtual file created by system kernel, which seems to be in /proc, but does not actually exist. It do not consume any H/D.
To check, once try to move or copy it:
~$ sudo mv /proc/kcore /proc/kcore.old
mv: cannot mv '/proc/kcore' to '/proc/kcore.old' : No such file or directory
~$ sudo cp -p /proc/kcore /proc/kcore.old
cp: cannot create a regular file '/proc/kcore.old' : No such file or directory
So you need not to worry about that.