[ RadSafe ] More on San Onofre - Engineer's input needed

Mon Apr 9 11:58:59 CDT 2012

All,
Yes, U tubes can be repaired (plugged) and the SG can operate as normal up to a certain point. If the number of tubes is great enough, then other limitations result from the change in flow/temperature of the coolant returning to the reactor from the effected SG. (Flux tilt was one such effect). However, I feel the cause for the U-tube failure is the overarching issue here.

Another broad based cause of the tube/tube weld failures could be the chemistry corrosion control system used by San O. I am not sure but I believe the chemistry control system used might be based upon the use of one or more volatile chemicals. If that's the case, the composition of the tubes/tube sheet interfaces might be a factor. These components are usually welded together and welding increases interstitial point defects in the metal alloys. Given the presence of the right agent, corrosion (pitting type, stress type, etc.) might be accelerated. The construction materials would only have to be subtly different than the original (old SG) materials for this effect to take place. 

A similar problem was observed to affect certain SG's in Naval reactor plants decades ago in both volatile chemistry systems and non-volatile, phosphate based, chemistry systems. In volatile chemical corrosion control, one solution to arrest this phenomenon was to use nitrate's in the corrosion control system. I believe the susceptible material in the SG U tubes was an alloy of Inconel. I am not a materials scientist, but I hope that this kind of effect is being investigated by San O and the NRC.

John E. Dixon, CHP

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of ROY HERREN
Sent: Sunday, April 08, 2012 8:17 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] More on San Onofre - Engineer's input needed

Sandy,

    I was surprised to read your e-mail about the Steam Generators being "relatively new".  I had initially assumed that they had merely replaced the old tubing in the old generator with new tubes; I didn't know that they had completely replaced the Steam Generators.  Given that these are "relatively new" 
generators it is all the more disconcerting that some of the tubes are already leaking.  Hopefully the root cause of the leak(s) will be determined and a timely solution can be applied to get the units up and operating. 

   We are in a quandary of sorts regarding electrical energy production!  Some folks don't want coal fired electrical generating plants, some folks don't want oil or gas fired electrical generating plants, some folks don't want Solar thermal plants, some folks don't want windmills, and some folks don't want Nuclear Power plants (hell, here in northern California some folks want to tear down some old dams and do away with water reservoirs and the hydroelectric energy produced by those systems).   Clearly there doesn't appear to be any practical solutions that will please all of the parties.   What are we to do to produce electricity for a (post) industrial society?  Solar voltaic, Fusion?  At least Solar voltaic is a proven technology, but we can't possible produce enough panels in a short enough time frame to replace the loss of San Onofre, much less all of the other Nuclear Power plants.  What are we to do?
Roy Herren 

________________________________
From: "Perle, Sandy" <sperle at mirion.com>
To: "SAFarber at optonline.net" <SAFarber at optonline.net>; TheInternational Radiation Protection (Health Physics) Mailing List <radsafe at health.phys.iit.edu>
Cc: The International Radiation Protection (Health Physics) Mailing List <radsafe at health.phys.iit.edu>
Sent: Sun, April 8, 2012 2:27:17 PM
Subject: Re: [ RadSafe ] More on San Onofre - Engineer's input needed

Stu,

Correct. Only a couple of tubes have had issues. The question is will others fail and at what rate. This could be an isolated random issue since the SG is relatively new. I drive by the plant frequently. The NRC may over-react due to public concerns, and the media is giving into the anti-hype, as expected. Count p. this being the scenario whenever any issue arises.

Regards,

Sandy Perle
Sent from my iPhone

On Apr 8, 2012, at 3:22 PM, "Stewart Farber" <SAFarber at optonline.net> wrote:

> The two SG at San Onofre have about 10,000 individual tubes in total.
> Depending on whether all tubes have a manufacturing defect and are 
> likely to keep failing regularly, I know in the past it was a routine 
> procedure for a plant to weld defective  SG tubes shut so that nothing 
> from the primary side can get carried over to the secondary loop. Back 
> some time, Prairie Island for example had to plug about 600 SG tubes 
> and continued operations. It's a question of how many tubes get welded 
> shut and how much efficiency lost is acceptable as a fraction of the approx. 5000 tubes in each SG.
> 
> I would think it all comes down to how many plugs are defective or are 
> likely to fail soon and can be repaired before the plant goes back on-line.
> The grid operators, and regulatory agencies involved,  are likely to 
> give alternatives like welding defective tubes closed serious 
> consideration when they think about the consequences of a shortage of 
> generating capacity by taking San Onofre offline.
> 
> Of course the NRC, may just torpedo the whole idea of SG repair and 
> keep the plant offline in their pursuit of what they state is the need for zero risk.
> I guess operating old coal and gas plants with the significant 
> environmental and health effects to be realized with certainty is OK 
> with zealous forces against nuclear electric generation.
> 
> Stewart Farber
> SAFarber at optonline.net
> ==============
> 
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu
> [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Joel C.
> Sent: Sunday, April 08, 2012 1:35 PM
> To: radsafe at health.phys.iit.edu
> Subject: [ RadSafe ] More on San Onofre - Engineer's input needed
> 
> It sounds like SCE spent $670 million on defective steam gennies.  I'd 
> like to hear from a knowledgable engineer about that.
> 
> 
> Joel Cehn
> joelc at alum.wpi.edu
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