Monday, August 20, 2012

The sweet spot for SanO Unit II...

To: "Elmo Collins" <>


Dear Mr. Collins,

I was told recently that "no one" in the legislature of California believes San Onofre Unit III can be restarted unless/until its steam generators are replaced. To this I replied, "No one else thinks so either."

I believe all this talk about Unit II restarting should be stopped cold as well because, in fact, neither unit is capable of being safely restarted, where "safely" is defined by standard nuclear industry benchmarks.

I believe the potential for the complete loss of a single Steam Generator in a two-steam-generator system with weakened tubing is utterly unacceptable. But that's the possible condition any restart of San Onofre's reactors leaves us in. In fact, at San Onofre it's almost the most likely point of failure, except for fire (with earthquakes, tsunamis, etc. also distinct possibilities).

I believe Southern California Edison cannot merely put flow restrictors on the inlets to the Steam Generators in order to guarantee that excessive, vibration-inducing flow cannot occur, because then they won't have enough maximum potential flow rate to cool the reactor sufficiently with only the other Steam Generator, should one Steam Generator fail. But without the flow restrictors, a flow rate would be possible above that which ensures that there is little or no flow-induced turbulence (a chaotic flow pattern), and NO chance of fluid elastic instability (a coordinated flow pattern).

I believe the reason SCE hasn't been able to come back to the NRC with a plan for restart as of this writing is that they can't find the magic "sweet spot" where the flow is restricted, but they could still cool the reactor sufficiently in an emergency with just one Steam Generator. I don't think such a combination of guaranteed low enough flow rates and guaranteed sufficient emergency cooling can be found.

They may also be having a difficulty ensuring there are not similar flow-induced vibration problems within the reactor core itself, since a whistleblower, Dan Johnson, has been adamant in the news media comments section that such vibrations have been a persistent problem at SanO since Unit I.

The difficulty of finding this "sweet (and profitable) spot" and other problems caused by SCE's failure to properly analyze their data during the design phase, their failure to properly inform both the NRC and the public about the extensive nature of the SG design changes, and the NRC's failure to independently analyze the new steam generator design has led to this billion-dollar boondoggle.

The solution is to withdraw SCE's license. It should be noted that they also do not have a solution to their ever-growing used reactor core waste problem, and nor does the NRC. Our coastline is too precious and too packed with people for dry cask storage, wet storage, or any storage of nuclear waste. So shut down San Onofre permanently. The production of waste has stopped -- thank goodness -- and it should never continue. Restarting also violates the spirit of California's state law that prohibits "new" reactors because what is a reactor core except a new reactor every couple of years?

I look forward to hearing the NRC response to these concerns.


Ace Hoffman
Carlsbad, CA

** Ace Hoffman,
** POB 1936, Carlsbad CA 92018
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