Palo Verde Nuclear Power Plant’s Unit 3 Shut Down

The unit was tripped on March 5th due to low departure from nucleate boiling ratio. The company reported that all systems operated correctly during the shut down with no release of radiation and no harm to plant or workers.

This means that Palo Verde is operating only one unit at full capacity, unit 2, and unit one is operating at 25% capacity since exiting its refuelling cycle. A vibration was detected in one of the pipes in the backup safety system. Unit 2 is operating at full capacity.

FILED UNDER: Economics and Business
Steve Verdon
About Steve Verdon
Steve has a B.A. in Economics from the University of California, Los Angeles and attended graduate school at The George Washington University, leaving school shortly before staring work on his dissertation when his first child was born. He works in the energy industry and prior to that worked at the Bureau of Labor Statistics in the Division of Price Index and Number Research. He joined the staff at OTB in November 2004.


  1. spaceman says:

    So what? Is this news?

  2. Richard Gardner says:

    OMG, Departure from Nucleate Boiling (DNB). And I bet the reactor was “Critical” at the time. Sounds scary. But what this really proves is that the Palo Verde Nuclear Generating Station, one of the last built in this county (early 80s) is very safe.

    DNB means that the expected (necessary) boiling in the reactor went from little bubbles to big bubbles, just like when you are making pasta. Nucleate boiling means little bubbles. Except in a nuclear reactor, they prefer the little bubbles as a safety factor. The little bubbles are also MUCH more effective in transferring heat than big bubbles.

    I do wonder why this event happened. And yes, this is important, as a major power plant was taken off-line – I would say without looking it up this is a 1 Gwatt Thermal, 300 Mw Electric plant (anyone who has ever worked in the industry would guess the same, 1 GW thermal is the fed limit on nuke plants). The Southwest has a significant power shortage, and taking over 300 MW offline is significant.

  3. Steve Verdon says:

    Spaceman, it is news for precisely the reason Richard points too, a 1,300 MW unit was taken off line. Fortunately we are at a point where such a loss of load is that big a deal.


    I wasn’t trying to imply a catastrophe here, but just point to a news story. I agree the plant is safe and the fears over nuclear plants is horrendously exaggerated.