A senior plant official happened to spot a human-caused cooling shutdown at a Canadian nuclear reactor, narrowly averting a meltdown.

Ian McCleod wrote for ENENews 15 May 2013, ‘Significance Level 1′ incident at nuclear reactor — “The highest order” — Public not alerted by officials — Characterized as ‘near miss’

[…] a Chalk River nuclear operator mistakenly closed a vital pumping system that cools the immense heat generated within the NRU reactor’s core […]

[…] the Crown corporation said the Feb. 27 event — which the official report characterized as a “near-miss” — needs to be taken very seriously. […]

[Randy Lesco, vice-president of operations and chief nuclear officer for Atomic Energy of Canada Ltd] said that further categorizing the incident as at “Significance Level 1,” the highest order, means AECL is treating it with appropriate importance […]

CNSC President Michael Binder questioned why AECL and CNSC staff did not alert the public to the incident, which the Citizen first reported on May 8. […]

And why didn’t the reactor have automatic alerts? Ian MacCleod wrote for the Ottawa Citizen 7 May 2013, Human error blamed for “near-miss” at Chalk River reactor