i have a irules question

You can use

spilt

to split a variable into a list of it's constituent parts. Then use

lindex

to return the value of that list element

set a [split {9480} {}]
set a1 [lindex $1 0]
set a2 [lindex $1 1]
set a3 [lindex $1 2]
set a4 [lindex $1 3]

https://wiki.tcl-lang.org/page/split

If you don't know how many elements to expect in the list you can consider using

llength

and iterating through the list in a loop