The U.S. Nuclear Regulatory Commission wants to know by next March how well the Palo Verde Nuclear Generating Station can withstand the shock of earthquakes.
In 2012, the Nuclear Regulatory Commission ordered Palo Verde and all other U.S. nuclear plants to re-evaluate their seismic risk following the Fukushima disaster. (The risk to some plants was already being reviewed before the 2011 disaster.)
The large plant west of Phoenix sits on one of the most geologically stable land masses in the country, but a new look at the hazard potential "makes sense" in light of Fukushima, says NRC spokesman Scott Burnell.
"Palo Verde is taking into account the most up-to-date info available," Burnell tells New Times. "There is a defined process they're going to follow to determine where the earthquake sources are, how those sources would transmit energy to the Palo Verde site, and how the specific geology the reactors sit on could transmit energy directly to the buildings."
The new risk assessment for Palo Verde and two other nuclear plants in the West is due March 15. It will be similar to the updates handed to the NRC two months ago by 59 plants located in the central and eastern United States. On Friday, the NRC said that 21 of those plants will need to turn in an "expedited" review by December to make sure they could safely shut down operations after a large earthquake, and then submit a more-detailed risk analysis, with deadlines in 2017 and 2019.
Palo Verde is part of a group of 23 other plants that will turn in their updated hazard assessment over the coming months, although it's one of three plants that has received extra time due to the "complicated" geology of the Western United States, Burnell says.
Nuclear officials will compare the "new hazard with what was considered when the plants were built," he says. "If the new hazard is larger . . . Palo Verde would have to do some detailed risk analysis."
The Phoenix metro area rarely experiences a quake. No records exist indicating that any Arizonan has ever been killed by one, although several hundred "microquakes" occur each year in the state. An earthquake in Mexico caused a few rock slides in Arizona back in 1887.
But the situation reminds of a line we heard earlier this year about asteroid impacts: Low risk, high consequence.
The 2011 tsunami-caused Fukushima reactor disaster caused the permanent evacuation of tens of thousands of people from the surrounding area. Its radiation pollution continues to taint the Pacific Ocean.
Tsunamis are not a problem for Palo Verde, and earthquakes may or may not hurt the plant. But the radiation released by an extreme malfunction of the plant, which is one of the world's largest and provides about one-third of Arizona's electricity, would affect half the state, according to a dissertation by an Arizona State University graduate student touted in an ASU news article last week.
If Palo Verde had a meltdown, a radioactive plume could float into Phoenix within five hours, depending on wind conditions, according to research conducted by Dean Kyne, who graduates this May with a doctorate in environmental social science from the School of Human Evolution and Social Change.
Burnell hadn't heard about Kyne's research, but he pointed to a February 2012 NRC news release about a study of two U.S. nuclear plants -- one in Pennsylvania, the other in Virginia -- that suggested nuclear accidents at the plants would likely cause minimal damage to people and the environment.
Back to the Palo Verde earthquake risk: Officials with Arizona Public Service, which oversees operations at the nuclear plant, tell us this is a well-studied issue. APS and Palo Verde maintain a "seismic team" of experts to evaluate the area's geology and possible impact on the plant.
The review due to the NRC in March of next year is about two-thirds complete, says Jim McDonald, APS spokesman.
"Current analyses continue to confirm that the plant is designed to withstand the greatest level of ground motion or shaking that experts reasonably believe could be generated by faults in the region," he says, reading from a prepared statement.
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Still unknown: How the plant might withstand a tsunami of human errors.
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