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NRC Analyst Calls To Close Diablo Canyon, CA's Last Remaining Nuclear Plant
An anonymous reader writes Michael Peck, who for five years was Diablo Canyon's lead on-site inspector, says in a 42-page, confidential report that the Nuclear Regulatory Commission is not applying the safety rules it set out for the plant's operation. The document, which was obtained and verified by The Associated Press, does not say the plant itself is unsafe. Instead, according to Peck's analysis, no one knows whether the facility's key equipment can withstand strong shaking from those faults — the potential for which was realized decades after the facility was built. Continuing to run the reactors, Peck writes, "challenges the presumption of nuclear safety."
US starts buying more nuclear power from Canada, quickly pulling a Germany. In 5 years, subsidies much like those in Germany will then be gutted, and there will be a mass rush to build new coal and NG power plants until reactors can be refurbished or built anew.
Om, nomnomnom...
This is not a new story, basically a reprint. With that said, if there is any indication the the plant cannot withstand postulated earthquake levels it should be shut down. This was not ignored, and the article does mention that an evaluation was performed based on the new information.
"In 2012, the agency endorsed preliminary findings that found shaking from the Shoreline fault would not pose any additional risk for the reactors. Those greater ground motions were “at or below those for which the plant was evaluated previously,” referring to the Hosgri fault, it concluded."
Given our experience with plants holding up extremely well to seismic events and the large margins that are included in seismic design of these plants, the finding is not surprising. Work continues, as it should, to look for anything that could possibly have been missed or not enveloped by the new data.
The basis for the inspectors complaint is, in large part, not that the plant is not capable of withstanding the quake, nor that the analsyis is faulty or incorrect, but rather that the licensing basis document has not been revised to require a higher peak acceleration design level. It is debateable whether such a would make any difference, since they are already required to analyze for the higher levels. Meanwhile, the concern is being handled through the appropriate processes.
It's probably not a typo, but the stupid short title length limit striking again. The limit is guaranteed to be one character less than the title you really want.
In PWRs, the control rods are held above a reactor's core by electric motors against both their own weight and a powerful spring. Any cutting of the electric current releases the rods. Another design uses electromagnets to hold the rods suspended, with any cut to electric current resulting in an immediate and automatic control rod insertion. A SCRAM mechanism is designed to release the control rods from those motors and allows their weight and the spring to drive them into the reactor core, in four seconds or less, thus rapidly halting the nuclear reaction by absorbing liberated neutrons. In BWRs, the control rods are inserted up from underneath the reactor vessel. In this case a hydraulic control unit with a pressurized storage tank provides the force to rapidly insert the control rods upon any interruption of the electric current, again within four seconds.
Once the rods are inserted, the reactor is deeply subcritical and so due to the exponential nature of nuclear physics the reaction dies away in fractions of a second. Perhaps of interest to you might be to know that Chernobyl's RBMK reactor was neither a PWR nor a BWR. It was a graphite-moderated water-cooled reactor with very serious design flaws that made its operation inherently dangerous (it was basically a scaled-up plutonium-production reactor, for which safety was never a primary concern).
Per the usual, the simple fact that Natural Gas and Coal accidents/air pollution kills people every day is ignored compared to the remote risk of something happening to a nuclear powerplant.
If the 3 nuclear reactors in Fukushima Daichi were instead 3 coal thermal boilers, it would have killed hundreds of people in the decades it operated.
6.5 quake is peanuts for a nuclear reactor.
Nuclear require an extreme accident to become a hazard to human life, while coal/NG kills every day.
Even solar and wind kill more per TWh produced than nuclear, perhaps they can cleanup their act and have less work accidents before they can claim solar/wind is safer than nuclear.
SCRAM in 10 seconds is fine. But a SCRAMmed plant does not instantly become safe nor is it considered completely shut down. You still need heat removal for quite some time afterword ( which varies between designs) . That is where the seismic requirements come in. The heat removal systems must withstand the event and remain operational. Every single safety system and backup safety system is required to endure the event.
Turns out storage is not much needed at 80% renewable energy supply. http://www.engineering.com/Ele...
Yes, in 1999 (when I last toured the plant) the SCRAM time was 3.5 seconds with control rods fully placed in 0.5 seconds if the emergency circuit is tripped. This happens automatically in the event of a 6.0 or stronger quake. An emergency SCRAM requires 30 to 120 days to restart the reactor. Also like all reactors, it requires time to cool. Because DCNP is located on the ocean it does not require active cooling to safely cool the reactor core after a crash. flooding the core with sea water will probably be the end of that reactor, but it will not loose containment. The plant was originally designed to be operational after a 7.0 quake and to not loose containment in the event of a 9.5. After the discovery of the Hsgri fault the design was modified to withstand a 10.8 quake. Analysis after the 2004 6.2 quake in Paso Rubles suggests that the engineering was "very conservative" and that the plant may well be able to survive an 8.0 in operational condition.
On the other hand, the temporary on site storage of spent fuel was not part of the original plan, In the event of a major seismic event, it is the spent fuel casks that scare me.
Strive to make your client happy, not necessarly give them what they ask for
The real problem with Diablo Canyon, and the rest of the nuclear industry is managing the waste. There is no place to put nuclear waste in this country, so it's just stored on-site. That's crazy. You can't do that forever.
That being said, my expectation is that we'll continue to see tech advancements in solar and wind generation, and energy storage to the point where large central generation will be a thing of the past.