[ RadSafe ] Re-starting San Onofre

Tue Mar 19 13:18:44 CDT 2013

A contributing factor may be in the design of the San Onofre facility's  
steam generators in Units Two and Three. The nuclear steam supply system in  
both of those PWR units was produced by Combustion Engineering Corporation 
and  feature (or at least used to) twice-through steam generators. The  
twice-through design yields higher heat-energy transfer efficiency (which  leads 
to higher profits from the same amount of fuel) than the once-through  
designs found in other PWRs like those at TMI and the now-closed  Rancho Seco. 

The twice-throughs are a great idea and work like gangbusters when  
everything is right. But operational experience as long as ago as 1981 at the  
Combustion Engineering- designed twin PWRs at the St. Lucie Nuclear Power Plant  
in Florida found that such steam generators have a higher  propensity for 
corrosion damage compared to once-through designs from  imprecise coolant 
water chemistry on the hot side, especially where the  twice-through steam 
generators' iconel-metal coolant tubes curve 180 degrees at  their top ends.

It could be that the recent San Onofre situation shows that such  
vulnerability of twice-through steam generators remains an unsolved  problem, despite 
years of industry experience with them and attempts at  remedies.

Steve 

In a message dated 3/19/2013 1:47:33 P.M. Eastern Daylight Time,  
cary.renquist at ezag.com writes:

How did the operator get in this fix? Now that's  a 
tale the should be very interesting. My 
understanding is that the steam generators were 
replaced  within the past few years. 

I believe that the problem was in the  thermo-hydraulic/mechanical
modeling of the generators...
Basically, at  full load, some of the tubes zig when they were expected
to zag -- this  un-damped out of plane motion is causing the wear.  I
would think that  if there is a defined subset of tubes that are subject
to this motion, then  perhaps they can just be plugged as a precaution --
of course, this will  likely shorten the lifespan of the generators.

Cary

---
Cary  Renquist
cary.renquist at ezag.com

-----Original Message-----
From:  radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu]  On Behalf Of Victor
Anderson
Sent: Tuesday, 19 March 2013 7:27 AM
To:  'The International Radiation Protection (Health Physics)
MailingList';  radsafe at agni.phys.iit.edu
Subject: Re: [ RadSafe ] Re-starting San  Onofre

Good Morning,

Visited the man's web site.  As with  most anti-nuke stuff, it sounds
good
until you get into the  details.  In the case of Mr. Large, he wants you
to
pay money for  many of his products.

But onward to restarting San Onofore.  The  main issue is those dam steam
generators.  Unfortunately, there is  little information to be had on
just
how badly the steam generators are  broke.  The problem lies in the
number of
and severity of tube  leaks.  The main problem that the tube leaks cause
is
the leakage  of primary to secondary coolant.  It is a real pain in the
ass
to  have to have health physics controls for the secondary side of a PWR.
It's  also embarrassing.  The other issue has to with how badly  the
tube's
are leaking.  At some point, you are generating enough  steam by directly
flashing the primary coolant to steam that you have to  make up the
primary
coolant.  Sort of like having a bizarre  BWR.  This is not good.

Depending on how much radioactivity is in  the primary coolant, you may
have
some low level releases off  site.  However, these releases should be
very
small.  So, the  main issues are violations of the plant technical
specifications and costs  to run the plant.

How did the operator get in this fix?  Now  that's a tale the should be
very
interesting.  My understanding is  that the steam generators were
replaced
within the past few years.   If so, then the cause could be bad chemistry
or
faulty tubes or  both.  If the equipment was not made correctly, the
lawyers
are  going to be very busy.  The chemistry issues can be a little  more
subtle.  Reactor plant chemistry is very difficult to  maintain.  With
the
big PWR plants Boron in the form of Boric Acid  is used to help control
neutrons.  Works fine in this role.   However, Boric Acid can play hell
with
piping and such.  Its all a  matter of materials and keeping the pH in
the
right range along of  Oxygen and some other stuff.  The materials are
controlled when the  plant is built.  The water chemistry is controlled
during plant  operations (both at power and off line).  If the plant
operators did  not do a good job of water chemistry, then they are now
paying
for their  sins.  About $300 million worth, if memory serves  me
correctly.

Which brings me to my pet peeve about the nuclear  industry.  Nuclear
power
is different.  The plants are  safe.  Nuclear power is not just another
way
of boiling  water.  Making electricity or any other form of energy via
nuclear  reactors requires an absolute mania for excellence.  You  cannot
run
a nuke plant on "just good enough" and expect to make a  profit or break
even.  This was a hard lesson that many NPP operators  did learn.  Having
been away from the industry for about 15 years, I  am not sure what the
current state of affairs is.  My hope is that is  that the American
nuclear
industry is still working hard to do an  excellent job of running its
plants.
Massive failures of steam tub  generators does give one pause.

Victor

-----Original  Message-----
From:  radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu]  On Behalf Of Steven Dapra
Sent: Monday, March 18, 2013 5:44 PM
To:  radsafe at agni.phys.iit.edu
Subject: [ RadSafe ] Re-starting San  Onofre

Mar. 28

Hirsch I've heard of.  Is  anyone familiar with John Large, a
nuclear

engineer, so the article  says, who is a consultant to Friends of  the
Earth?

http://news.yahoo.com/calif-nuke-plant-could-breakdown-full-power-211036
200.
html

Steven  Dapra

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