How Safe Is Diablo Canyon in a Station Blackout?

PG&E's Nuclear Power Plant Is Tied to the Grid

Diablo Canyon Power Plant in San Luis Obispo | Credit: WikiCommons

In the wake of Pacific Gas & Electric’s bankruptcy due to the devastating wildfires, death, and destruction caused by its aging and vulnerable transmission lines, the big question is, how safe and secure is its “grid tied” Diablo Canyon nuclear power plant?

Diablo is dependent upon the electric grid to function. Without electricity, the operator would lose instrumentation leading to the inability to cool both reactor cores. Unfortunately, out-of-control forest fires and damaged power lines could cause a “station blackout” in which all off-site power is lost.

Every nuclear power plant has emergency diesel generators to counter off-site power loss. Now, especially because of President Trump’s threat to cut back on inspections at atomic power plants, including the Diablo Canyon Power Plant, my main concerns are whether Diablo’s emergency generators are in good working order and will there be enough on-site diesel fuel to power the facility if the regional electric grid goes down for a couple of weeks or longer? In the event of a station blackout, core damage is estimated to begin in approximately one hour if the auxiliary feed-water system and high pressure injection flow aren’t reestablished in time.

The loss of off-site power could also cause a failure of the spent-fuel-rod cooling systems. When the spent-fuel cooling pumps stop working, the water in the pools starts to boil off. Once the Diablo Canyon nuclear power plant’s overcrowded spent-fuel assemblies become uncovered, the fuel rods cladding will start to melt. As bits of the melting fuel fall into what’s left of the water, the water will flash to steam causing the pressure in the buildings to increase. Radioactive particles carried in the steam would then begin to exit the buildings through non-sealed portals and doors.

Exposing hot zirconium fuel-rod cladding to the air causes an exothermic reaction; the cladding will actually catch fire at about 1,000 degrees centigrade causing toxic radioactive isotopes to be released into the atmosphere. Even the Nuclear Regulatory Commission concedes that this type of fire cannot be extinguished.

Another reason why PG&E is caught between a rock and a hard place is because of its mandatory power cut-offs during hot, dry, and windy weather. Will Pacific Gas & Electric have to choose between power outages to curb the possibility of raging wildfires and the threat of a “station blackout” at its more-than-hazardous Diablo Canyon nuclear power plant? What if a major Fukushima-like-earthquake were to occur during a “station blackout” during which all off-site electricity is lost due to a mandatory power cut-off? This definitely is a lose-lose situation!  Why must we continue to live with this unnecessary danger?

Now more that ever, it’s time to Close Diablo Down!


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