Normally, in RSTP when ALT port can't receive the bpdu from designated port ( ONLY bpdu packets can't through some transmission device between 2 switches ,but the physical link is normal ) ,it will be in Forward .But if the path from nonroot brigde to root bridge is also noraml . LOOP and BROADCAST Storm will occur.
I set bdpu-timeout-action block under the ALT port in rstp to avoid the situation above. That means when the ALT interface can't receive the bpdus from designated port it will be still in BLK (Role 
IS (Loop-Prev) ).
Details : set protocols rstp interface ge-0/0/2 bpdu-timeout-action block
But there IS the other problem that if the primary link is down and also the ALT interface is in BLK with Role IS (Loop-Prev). The ALT interface won't be forward . I have toally down .
Any command to aviod that even though the ALT interface in BLK (Loop-prev ) ,it will be forward when primary line(the path from nonroot brigde to root bridge) is down ?