Large LOCA event tree (reactor PRA)
A large-break loss-of-coolant accident branched through four reactor safety functions. The engine computes every sequence frequency from the initiating rate and per-function failure probabilities, then highlights the dominant accident sequence.
For the PRA / reliability engineer
What this shows
The textbook nuclear probabilistic-risk-assessment (PRA) tree. One initiating event — a large pipe break draining the coolant at a frequency of 1e-4 per year — is asked, left to right, whether each safety function holds: reactor trip, emergency core cooling (ECCS), containment heat removal, then containment integrity. Each * prunes a path that has already terminated, so the tree stays compact instead of ballooning to a full 2⁴ ladder.
The engine does the arithmetic an event tree exists to give. It multiplies the initiating frequency by the success leg (1 − p) or failure leg (p) at each branch to get every sequence frequency, sums the two "Late release" leaves into one rolled-up outcome, and paints the largest-frequency path — the dominant accident sequence — in red. That computed answer, not the forking picture, is the deliverable a drawing tool can't produce.