There's not much to do, this is workable ksh code, but to be sure the ksh interpreter runs it, add (as the first line in the script), the ksh "shebang", i.e.
#!/bin/ksh
T=/kk/ras/tools
U="$T"/upgrader
mv "$T"/ra_updates "$U"/ra_updates.br.d712
cd "$U"
grep "^BR" config.alpha > config.br
./ConbaseUpgrader config.br ra_updates.br.d712 s
It's almost always good practice to surround variable references with dbl-quotes. I have added them here.
make sure to chmod 755 myScript.ksh
as appropriate.
If this code has passed thru MS-Windows (via original creation, editor, ftp (others)), then run
dos2unix myScript.ksh
IHTH