Post-Mortem

Case Studies in System Failure

1979

Three Mile Island

1986

Chernobyl

2011

Fukushima Daiichi

The Failure Spectrum

Nuclear accidents are rarely caused by a single event. They are a "chain reaction" of failures.

H

Poor training, misinterpreted data, or protocol violations.

M

Valve malfunctions, sensor errors, or cooling pump loss.

ERROR_LOG: CRITICAL

Swiss Cheese Model

When all the "holes" in safety layers align.

Unlike modern reactors, Chernobyl used Graphite as a moderator but water as a coolant.

Positive Void Coefficient:

If water boiled away, the reaction actually sped up. This is the opposite of modern safety standards.

A steam explosion (not nuclear!) blew the 1,000-ton lid off, followed by a graphite fire that released radiation for days.

"The absence of a containment dome allowed radiation to spread globally."

A 9.0 Earthquake + Tsunami knocked out the electrical grid and drowned the backup diesel generators.

Even after the reactor shuts down, the fuel is still hot. Without pumps to move water, the fuel melted.

Lesson: Safety requires active power for weeks, not just seconds.

Modern (Gen III+) reactors use gravity and convection instead of pumps and electricity.

"Designing systems that fail safely even if humans do nothing."