Sun Apr 1st, 2012 at 04:58:40 PM EST
On 10 May 2011, during the power-up after a maintenance shutdown, there was a fire in Reactor No. 2 of the Ringhals Nuclear Plant (which houses four of Sweden's ten active reactors). Today (1 April), the reactor has been down for a full year, costing operator Vattenfall over 300 million. Berlin's left-alternative daily taz reviews the reasons:
- The fire was caused by a vacuum cleaner that was left behind during a routine maintenance stop and short-circuited during the pressure test, burning all the plastic around it within the containment.
- The human error was a result of being in a hurry: the power-up of the reactor was brought forward compared to the original schedule.
- During the repairs, workers found litter in the piping of the emergency cooling system, enough to throttle it 15%.
- It was found that the litter rested there undiscovered since the early eighties.
- The reason for the lack of discovery was that the routine functionality test of the emergency cooling system was done with compressed air instead of water and there were no visual checks inside the piping.
- Checking further, the oversight authority found inadequate tests used for vents, too.
- Improper testing is apparently a widespread problem. In the 2006 incident at the Forsmark Nuclear Plant, the faultiness of the automatic startup of the emergency generators wasn't discovered because the generator's functionality was always tested manually.
(As far as I can see, none of this was covered on ET before, only implicitly in an askod comment
These problems underline my problem with the view that we could and should evaluate nuclear power with a risk/benefit analysis: there are just too many overlooked, unexpected failure modes with potential safety relevance to do a calculation that won't significantly underestimate the risk side.
Here is the one article in English I found on the vacuum cleaner, from last November:
'Vacuum cleaner' behind Swedish nuke plant fire - The Local
The fire broke out when performing a pressure test of the reactor's containment on May 10. Someone forgot to remove a wet vacuum cleaner from the premises, which then caught on fire.
"Those items aren't supposed to be left in the containment, when testing," said energy company Vattenfall's nuclear power head Peter Gango to SVT.
"It was a human error, and those shouldn't occur in our power plants."