On 11 March 2011 TEPCO’s Fukushima nuclear power plant was rattled by an offshore 9.0 on the Richter scale earthquake. The tremor subsequently generated a tsunami that effectively destroyed the complex, sending shock waves worldwide through the nuclear power industry, hoping that 24 years after Chernobyl, public amnesia and governmental commitments to curbing greenhouse gas emissions, nuclear power was moving back into the mainstream.
Instead of a nuclear renaissance, Fukushima refocused a most unwelcome spotlight on existing nuclear power plants (NPPS) and their safety procedures.
And in the U.S., of the nation’s 104 commercials, the NPP most assiduously avoiding the spotlight is Pacific Gas & Electric’s Diablo Canyon’s NPP, 12 miles southwest of San Luis Obispo, where twin Westinghouse designed four-Loop pressurized 1,100 megawatt water reactors (PWRs) annually produce about 18,000 gigawatt hours for more than three million people.
But Diablo Canyon NPP has been controversial from its inception, with many environmentalists objecting to the fact that the NPP was constructed directly over known seismic fault lines.
Nevertheless, two weeks after the Fukushima catastrophe, PG&E applied to the Nuclear Regulatory Commission (NRC) to renew their two current operating licenses for 20 more years, which would extend operations from 2024 and 2025 to 2044 and 2045.
The request has not gone without political commentary. California State Senator Sam Blakeslee (R, San Luis Obispo, 15th District), a geophysicist with a Ph.D. in earthquake studies and a member of the California State Senate Select Committee on Earthquake and Disaster Preparedness during the license renewal hearings by his committee repeatedly asked PG&E to withdraw its license renewal application and perform a new seismic study of the facilities site.
Blakeslee’s concerns were hardly unfounded. While the Diablo Canyon NPP was designed to withstand a 7.5-magnitude earthquake on the Richter scale, it exists in a seismically active neighborhood, 20 miles away from the Rinconada Fault and 45 miles from the better known San Andreas Fault.
And oh, in 1971, the offshore Hosgri Fault, two and a half miles away from Diablo site, was discovered by Shell Oil Co., whose officials informed PG&E while the Diablo Canyon NPP was under construction.
More recently, a forth nearby fault line was discovered. Blakeslee accordingly insisted that the known presence of the Hosgri earthquake fault, two and a half miles away, and the newly detected Shoreline Fault, runs within less than a mile of the plant, should be thoroughly charted and studied before PG&E applies for a license renewal.
Now it would seem that Mother Nature is sending yet another signal. Each Westinghouse Diablo Canyon reactor uses a thermal design flow (TDF) using 87,700 gallons of seawater per minute.
Well, that warm water returned to the Pacific from the reactors is apparently attracting “friends.” Salps, small barrel-shaped “tunicates” plankton similar to jellyfish, can grow to nearly four inches long, have flocked to the seawater intake at the Diablo Canyon NPP, forcing operators to reduce power at its Unit 2 reactor to about 25 percent.
The good news?
Diablo Canyon reactor number one was shut down earlier for scheduled refueling before the infestation, a procedure that usually takes about a month.
The bad news?
Salps can blanket many square miles of ocean in huge, gelatinous masses and no one at Diablo Canyon NPP knows how many are at the Avila Beach plant or how long they will remain. PG&E spokesman Tom Cuddy first said, “We then made the conservative decision to ramp down the affected unit to 20 percent and continued to monitor the situation. When the problem continued, we made another conservative decision that it would be safest to curtail the power of the unit.” Cuddy then optimistically told reporters, "We'll continue to monitor the intake structure and clean the salp off the (intake) screens. Once they decide to move on and it's safe to do so, we'll resume full power."
The salp infestation is hardly limited to Diablo Canyon, as in recent years the critters have been a problem at nuclear plants in the U.S., Japan, Israel and Scotland.
As sci-fi as the image of hordes of environmentally sensitive salps heroically sacrificing themselves for the greater good on the water intake screens of Diablo Canyon NPP is, joking aside, the water intake issue raises nasty echoes of Fukushima, where the tsunami knocked out power to the generators pumping coolant water to both the reactors and spent fuel rod storage ponds. At the end of the day, it is irrelevant as to what interferes with the water flow – no water, temperatures rise.
What both Fukushima and Diablo Canyon share in common is the fact that natural elements unanticipated when the NPP was built can remind engineers that it not possible to plan for and factor out every contingency.
As Diablo Canyon reactor number one came online in 1985, perhaps, 27 years later, given the facility’s proximity to not one but four faultiness, it’s time for PG&E stockholders to cash out their investment and shutter the plant, as the future cost of indemnifying California for a nuclear “incident” would most certainly affect their profits.
Mother Nature has spoken, in any case are PG&E management listening? On 28 April a magnitude 3.8 earthquake struck southern California at 8:07 a.m. Sign of things to come?
By. John C.K. Daly of Oilprice.com