When this occurs there is a rapid rise in temperature and pressure within the reactor causing emergency vent valves to open in order to reduce the pressure within {TAIL ~ the reactor} and vent {HEAD ~ the reactor contents} 
When this occurs there is a rapid rise in temperature and pressure within the reactor causing emergency vent valves to open in order to reduce the pressure within { TAIL ~ the reactor } and vent { HEAD ~ the reactor contents }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD