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arge series capacitor that was not working properly at a substation outside of Yuma, Arizona, and for reasons not fully understood this caused a chain of events eading to a massive cascading blackout that cut power o millions of customers in Arizona, California and Mexico. This same blackout also caused two reactors at he San Onofre nuclear power plant to shut down automatically and go off line, which they are designed o do as a safety precaution in the event of a local grid ailure. This exacerbated the situation by reducing the ocally available generating capacity at the same time as utility workers were trying desperately to restore power o San Diego and other areas.” =< arge series capacitor that was not working properly at a active reactor cores which are encased inside massive substation outside of Yuma, Arizona, and for reasons "containment vessels” with thick walls of concrete and not fully understood this caused a chain of events _ steel, the buildings surrounding spent fuel rod storage eading to a massive cascading blackout that cut power ponds will do practically nothing to contain radioactive o millions of customers in Arizona, California and contaminants in the event of prolonged cooling system Mexico. This same blackout also caused two reactors at failures. Since spent fuel ponds typically hold far he San Onofre nuclear power plant to shut down _ greater quantities of highly radioactive material than automatically and go off line, which they are designed the active nuclear reactors locked inside reinforced o do as a safety precaution in the event of a local grid containment vessels, they clearly present far greater ailure. This exacerbated the situation by reducing the potential for the catastrophic spread of highly ocally available generating capacity at the same time as__— radioactive contaminants over huge swaths of land, utility workers were trying desperately to restore power _ polluting the environment for multiple generations o San Diego and other areas.’ spanning hundreds of years. A study by the NRC determined that The Nuclear “Achilles Heel” the "boil-down time" for spent fuel rod So, what do extended grid blackouts : containment ponds runs from ave to do with potential nuclear Had It not been between four and 2) days after loss of catastrophes? Nuclear power plants for heroic efforts cooling system power before are aesigne to isconnect degenerating into a Fukushima-like automatically from the grid in the on the part of situation, depending upon the type of vent fe) : power failure, and once Japan’s nuclear puclear reactor and how recent y its isconnected they begin the process atest batch of fuel rods were of shutting down the reactor's core. workers to decommissioned." In the event of the loss of coolant flow replenish water in A few days after the tidal waves to an active nuclear reactor's core, the . destroyed the generators providing reactor will start to melt down and fail this spent fuel back-up electrical power to Fukushima catastrophically within a matter of a pool these spent Daiichi's cooling system, the > protective water bath boiled away rom the spent fuel pond for few hours at most. In an extreme GMD, nearly every reactor in the rods would have world could be affected. reactor no. 4, leaving the stored It was a short-term cooling melted down and spent fuel rods partially exposed system failure that caused the their Zirconium o the air. Had it not been for partial reactor core meltdown in . eroic efforts on the part o March 1979 at Three Mile Island, cladding would apan’s nuclear workers to Pennsylvania. Similarly, have ignited... replenish water in this spent fue pool, these spent rods would ave melted down and their zirconium cladding would have 11 March 2011 that caused the ignited, which most likely would Fukushima Daiichi nuclear ave released far more reactor disaster but the loss of electric power to the _ radioactive contamination than what came from the according to officials it was not direct damage from Japan's 9.0 magnitude Tohoku earthquake on cooling system pumps when the facility's massive back- hree reactor core meltdowns. up diesel generators were wiped out by the ensuing tidal Japanese officials estimate that, to date, the waves. In the hours and days after the tidal waves Fukushima Daiichi nuclear disaster has released jus shuttered the cooling system, the cores of reactors nos 1, _ over half of the total radioactive contamination released 2 and 3 were in full meltdown and released hydrogen rom Chernobyl, but other sources suggest that the gas, fuelling explosions which breached several radiation released could be significantly more. containment vessels. In the event of an extreme GMD-induced long-term Of even greater danger and concern than nuclear — grid collapse covering much of the globe, if just half o reactor cores themselves are the spent fuel rods stored he world's spent fuel ponds boil off their water and in on-site cooling ponds. So-called "temporary" nuclear — become radioactive zirconium-fed infernos, the ensuing fuel containment ponds are features common to nearly contamination will far exceed the cumulative effect o all nuclear reactor facilities and typically contain the 400 Chernobyls. spent fuel from 10 or more decommissioned reactor Most of us tend to believe that a nuclear reactor is cores. These fuel containment ponds are generally something that can be shut down in short order, like surrounded by common industrial-type buildings with | some massive piece of machinery that can be turned off concrete walls and corrugated steel roofs. Unlike the by simply flipping a switch or performing a series o are on the part of Japan’s nuclear workers to replenish water in this spent fuel pool, these spent rods would have cladding would have ignited... 24 * NEXUS Had it not been for heroic efforts melted down and their zirconium FEBRUARY - MARCH 2012 www.nexusmagazine.com