an alternative suggestion:
reactor damage in 2 stages, containment damage & containment breach.
containment damage - dynamic dps caused to reactor based on temperature above threshold (eg. starting at 1 dps at (max_heat - 50) and full dps at max_heat).
breach damage - if reactor is below hp threshold and still above heat threshold, start fires.
-- this could also fix a bug where some reactors don't appear to ever reach 1000C, instead being stuck on 999C in some configurations