Located just 55 miles west of Phoenix, the Palo Verde Nuclear Generating Station has never incurred the slightest damage from earthquakes. After last November’s rumblings, can we still rest easy?
On a late Sunday night in early November, many people around Phoenix felt something rarely experienced in these parts: a series of light earthquakes.
The Arizona Geological Survey registered three quakes on November 2 near Black Canyon City, about 20 miles north of Phoenix. The first, with a Richter scale magnitude of 3.1, happened at 8:59 pm. The second – and the largest – with a magnitude of 4.1, occurred at 11:29, and a 4.0 magnitude aftershock hit at 11:49 pm.
All were under the 5.0 magnitude considered a medium-level quake, but the biggest one was still strong enough to be felt in many areas of the Valley, as evidenced by the many excited first-person accounts posted on Twitter, Facebook and the local TV news sites. “Our windows shook, felt like something hit the house outside,” posted a homeowner from Surprise on a leading earthquake reporting forum. “Puzzling short rumble,” reported another resident in Cave Creek, “as if an evaporative cooler was shutting off violently or something was galloping at the other end of the house.” Scottsdale, natch, felt the damage the least: “Patio umbrella hit windows. Birds flew out of cage.”
To our credit, most Arizonans exhibited a keen self-awareness of how our mild first-world earthquake problems would play to our shake-wise neighbors in California. A meme picturing a single white patio chair toppled back on a green manicured lawn went viral. Its caption: “November 2, 2015 Phoenix Earthquake. We Will Rebuild.”
Still, to people who study seismological activity in Arizona, November’s quakes were nothing to sneeze at. “We have not yet identified any active faults in the areas that those earthquakes occurred,” says David Brumbaugh, director of the Arizona Earthquake Information Center at Northern Arizona University. Nor has the AEIC been able to determine a cause of the quakes, which Brumbaugh says are rare for the region. “But the quakes are beginning to get large enough there that if you had one a tic larger, say in the magnitude 5 range, you could start seeing some damage,” he says. “So no, I don’t think people in Phoenix were overreacting at all. I think it’s appropriate to be concerned.”
That especially applies to folks who live downwind of the Palo Verde Nuclear Generating Station, just 55 miles west of downtown Phoenix. PVNGS is the largest generator of electricity in the U.S., serving the power needs of approximately 4 million people in Arizona, New Mexico, Southern California and west Texas. It’s also the only nuclear energy plant in the world not located next to a large body of water like a river, lake or ocean – typically necessary to cool the core and create hydroelectricity – relying instead on treated wastewater piped in from the 91st Avenue Wastewater Treatment Plant in Tolleson.
And that’s where Arizona’s admittedly far-fetched earthquake fears get an interesting plot twist.
When Palo Verde was built, science writers around the country heralded it as a technological marvel, one that, in the words of one journalist in Toledo, “defied the cardinal rule of nuclear power plant construction: Build near water, and plenty of it.”
Nuclear reactors are huge water consumers. They work by harnessing nuclear fission, an atom-splitting neutron dance that heats water pumped into a containment structure, which drives steam turbines to generate electricity. At its most basic level, a reactor core is simply a well-insulated, well-cooled pile of hot uranium rods. As long as the core receives a steady stream of coolant, everything works fine. But if anything interrupts or drains the water supply, the fuel rods can melt, breaching the containment and releasing harmful ionizing radiation into the environment.
Building such water-dependent, potentially earth-scorching technology in the middle of the desert required what the Toledo Blade’s Michael Woods called “unsettling ingenuity.” To keep Palo Verde generating power without a meltdown, he correctly observed, “cooling water will come from the toilets of the City of Phoenix.” In fact, some 60 to 80 million gallons of treated wastewater are piped in daily from the wastewater plant in Tolleson. And miraculously, the system has never failed, thanks largely to the Valley’s dependable supply of sewage coupled with Palo Verde’s location in one of the Southwest’s most earthquake-free zones.
In the 30 years the PVNGS has been in operation, there’s never been an earthquake substantial enough to cause any damage to the station, or to the pipeline. While Arizona does get a fair amount of small earthquakes annually up around Flagstaff and down around Yuma, the entire area west of Phoenix lies far afield of any fault lines, and has seen little seismic activity since Palo Verde began operating in 1986. A small quake under 2.0 magnitude was recorded in the Harquahala Mountains, about 80 miles northwest of Phoenix, in 2005, and a 2.35 was detected a little further north in 2012.
But the November quakes were a significant step up – which might get more than a few Phoenicians nervously re-watching The China Syndrome on Netflix. Did a shift supervisor feel an unusual vibration while reaching for his cup of coffee on the night of November 2nd? Just how good is the integrity of those welds?
“The plant was designed very robustly,” assures Jack Cadogan, VP of nuclear engineering and fuels for APS, which operates Palo Verde. “Our plant is designed to withstand a magnitude 8 earthquake. People look at a 4.0 and think an 8 is just two times as big, but that’s not how the ranking system works – in reality, a magnitude 8 is thousands of times larger. So we don’t worry about earthquakes too much at the station. We know we can withstand even the quakes they see in California and in the Baja peninsula.”
Chris Wandell, the chief civil engineer at APS who has been overseeing the structural condition of the Palo Verde plant since 1990, agrees the PVNGS is one of the strongest fortresses in the nation. “I always tell people if there was a magnitude 8 earthquake in Arizona, I would want to be in our plant,” he says. “Because I personally know, from doing seismic analysis for all these years, that this structure will survive that kind of ground shaking.”
Even experts outside of APS concede the PVNGS is built right, and in the exact right place, to withstand the worst earthquakes the state has ever produced.
“When they engineered that plant, they engineered it with the worst-case scenario of a 7.5 occurring within 50 miles of the plant,” says Michael Conway, chief of the Geologic Extension Service of the Arizona Geological Survey (AGS) in Tucson, which operates eight ultra-sensitive broadband seismometers at strategic locations throughout the state to monitor ground motion. “And they modeled that after the 1887 earthquake on the Pitaycachi fault, south of Douglas, Arizona. That was a magnitude 7.5. And that was a monster of an earthquake.”
But some geologists maintain the patterns of the past are no longer useful in predicting what’s to come, particularly given the random whimsy of climate change.
“When you talk to anyone at Palo Verde, they are 110 percent confident that the structures will withstand anything possible in the region,” says Jeri Young, research geologist for the Phoenix branch of the AGS. “But so were the people at Fukushima,” she adds, harking back to the March 2011 disaster at the Fukushima nuclear power plant in Japan that was caused primarily by a tsunami following the 9.0 magnitude Tōhoku earthquake. “I mean, Japan is on the cutting edge of earthquake science and engineering, and they knew that the fault offshore there was capable of generating an 8.2 or 8.5 earthquake. But they discounted the idea that that fault could generate a 9-plus, and that was what got them into trouble.”
Unlike Fukushima, Palo Verde is located far away from any ocean, which makes it very tsunami-proof, but that raises another concern: Can a wastewater pipeline run by five municipalities – Phoenix, Mesa, Glendale, Scottsdale and Tempe – that can’t even civilly share a Super Bowl be trusted to earthquake-proof the vital network of plumbing that cools North America’s biggest nuclear plant?
Conway alleviates that fear, too. “There’s a misconception that a continuous flow of water from that pipeline is required to cool the reactor core,” he says. “But we always have enough water in the reservoirs to continue running the plant for up to 14 days. So even if we lost all that water supply due to an earthquake damaging the pipeline, all we would do is go into what we call safe shut-down mode and circulate water to the core from our spray pond.” Indeed, the pipes have had to be repaired three times, once in 1994 and twice in 1997, due to corrosion, but the water from the plant’s two reservoirs was sufficient to keep the cooling towers filled during the repairs, which took less than five days combined. Conway and Wandell are confident the pipeline could be repaired quickly enough following a quake to keep the plant running.
They’re also confident Palo Verde is safe from cyberterrorist threats like a computer attack on the electrical grid, the doomsday scenario Ted Koppel has been stoking in the media lately. “We’re completely isolated from the outside world, so nobody can do anything from a cyber standpoint that could affect us,” Conway says. “We have layered defensive barrier systems that prevent anybody from the outside being able to get into our control system. We also have a very robust physical security system and very highly trained security staff. It all comes back to the same thing, which is protecting the reactor core and the fuel from any kind of damage.”
Dr. Dean Kyne, a professor of environmental sociology at University of Texas Rio Grande Valley who has extensively studied the potential risks associated with Palo Verde, believes Arizonans may have become a bit too complacent about the dangers associated with having a highly volatile, 80-million-gallon-a-day water-guzzling nuclear power plant in the middle of the desert.
“I worry that they may be underestimating the probability of an accident occuring there,” says Kyne, a Thailand-born scholar who lived for a while near the Three Mile Island Nuclear Generating Station south of Harrisburg, Pennsylvania while he was studying at Pennsylvania State University in 2007. After his wife developed a thyroid condition during her second pregnancy, he wondered if living close to the site of the largest nuclear accident in the U.S., even though it had occurred nearly three decades earlier in 1979, could have been a contributing factor (her doctor claimed no conclusive studies had been done).
He began extensively researching what could happen in the event of a core meltdown at Palo Verde while studying for his doctorate in environmental social science at Arizona State University, and, in his 687-page dissertation on the subject, Kyne came up with some pretty scary scenarios. Based on what time of year an accident could occur and the prevailing weather conditions, Kyne says as many as approximately 3.5 million people in central Arizona could be exposed to the resulting radioactive plume. “In a worst-case scenario,” he says, “the potential risk of a core-meltdown accident at Palo Verde is a burden shared by more than half of all Arizonans.”
Kyne contends APS is under-reporting the incidents of concern, and suggests the news media has become accustomed to dismissing any fears arising over our quiet nuclear powerhouse. In 2013, the Associated Press cited an unreleased Government Accountability Office report claiming that Palo Verde had the second-highest total of safety violations at the nuclear-power facilities across the country, although most were classified as “low-level.”
“They had a crack about two years ago in one of the reactor vessels that holds the unit’s radioactive fuel,” Kyne says. “And another leak in a hydraulic fluid tank that caused a small explosion. But they didn’t even report that one to the NRC [U.S. Nuclear Regulatory Commission] for six months.” The NRC deemed the late 2013 incident a “failure to report an unusual event,” but issued no fines, and the story never made it to the headlines.
Kyne also worries that if there actually is catastrophic damage to a reactor, officials will be too hampered by bureaucratic red tape to get the people in the path of the radiation evacuated in time. “It’s impossible to get a Protection Action Decision, or PAD, done in the necessary 15-minute time frame,” says Kyne, who acquired the software the NRC mandates to test the documentation process. “The way it’s designed now, one form actually has to be completed twice!” Nevertheless, Kyne believes it would be impossible to shut down Palo Verde, as California did to its San Onofre plant and Japan did to all theirs following Fukushima. “There’s too much money involved,” he says, “and too much politics.”
Young has concerns about Palo Verde, too, most centering on the state’s lack of interest in supporting its best detection system, the AGS, which relies on federal grants for 80 percent of its funding. “There’s no real interest from state entities to fund our operation,” she laments, adding that APS relied on their data during the rigorous global check-up given nuclear plants following Fukushima. Recently one of its seismometers – coincidently, the one stationed closest to Palo Verde – was vandalized, and Young says the agency hasn’t had the funds (about $100,000) to replace it.
“In places like California, where they’re really prepared for earthquakes, when they do come, the damage is minimal,” she says. “It’s really the places you don’t expect those events to occur that get damaged the most when they actually do.”
Young is also concerned about Palo Verde’s water supply, although not about it being interrupted by earthquakes. “Water could become scarce, and then even that effluent water from the treatment plants could become in higher demand,” she says. Already the Arizona Municipal Water Users Association claims Palo Verde administrators are in talks with water and power managers from around the world to find alternatives to using reclaimed or recycled water, which could cost the plant about $200 an acre-foot by 2025.
“As water becomes more precious, that problem could come to a head at Palo Verde,” Young says. “It’s one of those things where we just don’t know.”
Slip Sliding Away
Arizonans have enjoyed trash-talking Californians over their state’s vulnerability to earthquakes since at least 1969, when a Calypso-style novelty record titled “Day After Day (It’s Slippin’ Away)” became a heavy-rotation hit on Phoenix Top 40 radio. Co-written and produced by soon-to-be Valley favorite Jerry Riopelle, the tune, recorded by a four-man band from L.A. called Shango, played off the growing fear that an earthquake along the San Andreas Fault would cause a big part of the state to shake off, creating oceanfront property in Arizona – and further north (“Where can we go, when there’s no San Francis-co?” went the lyrics. “Better get ready to tie up the boat in Idaho”).
Riopelle, who was then living in L.A., now splits his time between Scottsdale and Kona, Hawaii. But he and wife Naomi were at their Scottsdale house when the November quakes hit.
“This earthquake was more like Hawaii’s than California’s,” says the veteran rocker. “Over there they call ‘em ‘volcano farts.’ It sounded like somebody had run into their garage door down the street. In L.A., they go on for a while.”
Always the humorist, Riopelle honored the jolt by picking “Day After Day” as the show opener for his January 2nd concert at Talking Stick Resort. “I think people here can relate to it differently now,” he says. “Who knew we could have earthquakes in Arizona?”
He wasn't the last artist to musically mock our Western neighbors. In 1996, the progressive-metal band Tool – led by Arizona resident Maynard James Keenan – envisioned an apocalyptic California earthquake in the song “Aenema.” It contains the refrain, “Any [expletive] time, any [expletive] day/Learn to swim – see you down at Arizona bay.”
Melt with You?
Notable nuclear power plant accidents since the dawn of the nuclear age.
Date/Location - January 3, 1961, Idaho Falls, Idaho
Description - A control rod mishap in a prototype reactor at the National Reactor Testing Station causes an explosion and kills three operators; they are the first known nuclear power fatalities.
Deaths - 3
Cost (US millions $) - 22
Date/Location - February 22, 1977, Jaslovské Bohunice, Czechoslovakia
Description - The second of two accidents within a 13-month span – in this instance, a radioactive cloud release caused by reactor corrosion – necessitates a full shut-down of the plant.
Deaths - 0
Cost (US millions $) - 1,700
Date/Location - March 28, 1979, Three Mile Island, Pennsylvania
Description - In the “no nukes” era’s signature incident, loss of coolant causes a partial core meltdown and small release of radioactive gases; the accident resulted in no known cases of cancer and the plant is currently operational.
Deaths - 0
Cost (US millions $) - 2,400
Date/Location - April 26, 1986, Chernobyl, Ukrainian SSR
Description - History’s deadliest, most costly meltdown – stemming from a steam explosion – results in the resettlement of approximately 350,000 people; by conservative estimates, it will also eventually cause 4,000 cancer deaths.
Deaths - 56
Cost (US millions $) - 6,700
Date/Location - March 12, 2001 Fukushima, Japan
Description - Tsunami flooding damages all five reactors, leading to three meltdowns and release of radioactive materials; history’s second so-called “Level 7” event alongside Chernobyl.
Deaths - 2*
Cost (US millions $) - 105,000
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