After the Chalk River nuclear reactor in Canada narrowly averted a potentially catastrophic incident in February, the Canadian Nuclear Safety Commission (CNSC) has concluded that the “root cause has not been determined, but human error was a major contributor to this event.”
On Feb. 27 someone erroneously shut down a pumping system which nearly caused a “near-miss safety significant event” the just-released CNSC report says. Fortunately someone spotted the mistake before the NRU reactor started to overheat.
The report points out other irregularities as well, noting that “instead of closing the process water valves, the rods supervisor started to close main heavy water pump outlet isolation valves. The senior reactor shift engineer did not immediately identify this error, but it was noticed by the facility manager, who was present in the control room. The facility manager immediately proceeded to stop the closure of the main heavy water pump outlet isolation valves and reopen them.”
The CNSC also worries that Atomic Energy of Canada Ltd., who owns and operates the Chalk River reactor, in general “may be underestimating the possibility of operator errors.”