Tim,
Another technically inept,  ignorant person that can benefit from your
willingness to educate on reactor basics would be Nils Diaz, nuclear
engineering professor and USNRC Commissioner. Here's what the benighted
Luddite had to say at the most recent Regulatory Information Conference,
" For example, we are dancing around how to resolve the Large Break LOCA. It
is in the books and so much of the design safety basis is dependent on it.
Yet, the Large Break LOCA is obsolete now, a true anachronism in today's
safety envelope. It needs to be abandoned in favor of what really affects
safety and is risk-significant. The Large Break LOCA was good in 1970 but it
is absurd now as a dominant safety LWR criterion. If risk and safety are
determinants, large (LBLOCA) is small and small (SBLOCA) is large."
 So Tim, if you know that large break loss-of-coolant-accidents( LOCA)
present more risk than small, you might just want to "educate" Commissiuoner
Diaz.

Also, Are you employed at a power plant? People sometimes call and want to
know which ones are the most dangerous.   Thanks for your willingness to
enlighten.

Ray
P.S.
 Aunt Millie says that her pressure cooker is worn paper thin in one small
area of the lid, should she reduce pressure from 12 to 8 psi or just let 'er
rip?     R.
----- Original Message -----
From: "Tim" <tstead@ntirs.org>
To: "Raymond Shadis" <shadis@ime.net>
Sent: Sunday, April 07, 2002 9:50 PM
Subject: Re: NRC Blasts Nuclear Plant Vigilance


> Ray,
>
> You obviously have a profound lack of understanding on
> stresses imposed on materials and how to calculate it.
>
> As far as the LOCA that would have resulted, it would
> have been only a few square inches in size.  The DB
> LOCA is a double guilletine break of the 29" RC
> piping.  The surface area of that break is hence much
> larger than the surface area of the break that could
> have resulted from the D-B thinning.
>
> That doesn't take too much brain power to figure that
> one out.
>
> As far as problems, et. al...there have been many
> SBLOCAs in the past but not one resulted in the
> release of any radiation outside of the normal
> regulatory limits for discharge under normal operating
> conditions.
>
> If we had plants blowing their lids left and right and
> exceeding regulatory limits then you'd have a point.
> That is just not happening, though, and I doubt it
> ever will at any US reactor.  I can't speak for other
> countries because I don't know how they are run.
>
> As far as an impending anyerism, that happens to be a
> much different scenario than a thinned portion of a
> pressure vessel.  For one, the area that is
> thinned/bulging in an anyerism is often times many
> times greater in size than the actual vessel.  With
> the D-B scenario, the relative size of the thinned
> portion to the overall vessel was very small so one
> cannot comapre the two scenarios.  The physics and
> mechanics are totally different.
>
> I'm not making excuses for D-B's inadequate and
> totally unacceptable surveillance procedures, I'm just
> identifying the engineering behind the scenario and
> pointing out to you that your comments were way off
> base because you have absolutely no idea what you are
> talking about.  The stresses imposed in the wall of a
> pressure vessel when it is of uniform thickness is
> much different than if just a small area were
> affected.
>
> Chances are, the thinned portion would not have burst
> because the stainless steel does not corrode.  The
> bulging is to be expected and the amount of the bulge
> corresponds well to what is predicted from the
> pertinent equations.  Those same equations that
> accurately predicted the degree of the ulge also
> predicted that the stresses would not have exceeded
> the allowable stresses in the material.  Was it an
> acceptable condition?  Absolutely not.  Would it have
> burst any time soon?  No.
>
> The NRC said that the incident posed no risk to the
> health and safety of the public and that is true.
> Why?  Well, first of all, the mechanics is such that
> it would not have burst unless more carbon steel were
> corroded away.  Even if it would have burst, all other
> safety systems that could have been called upon to
> mitigate a SBLOCA were operable.  Hence, the public
> was in no danger.
>
> So, if nobody was ever in any danger, then why fix the
> problem?  The answer is that the margin of safety was
> reduced and that is not acceptable.  Hence, the NRC
> was only telling the truth when it said that the
> health and safety of the public were never in any
> danger.
>
> You might want to stick to a topic you know more about
> - like perhaps drawing stick men.
>
> Tim
>
> --- Raymond Shadis <shadis@prexar.com> wrote:
> > Tim,
> >  One loves being "educated." How is a SBLOCA of the
> > size that could have
> > resulted at Davis-Besse, as you say " *much* smaller
> > than the design basis
> > LOCA " and  'even if it would have burst the
> > protective systems would have
> > allowed the reactor to shut down and remain safely
> > '? Haven't small break
> > loss-of-coolant accidents proven to be more
> > problematic than large?  Please
> > see NRC Commissioner Diaz' speech at the recent
> > Regulatory Information
> > Conference (NRC website).  Doesn't it bother that
> > this naked patch of SS
> > cladding was bulged out an eighth of an inch? Or
> > that the bozos at
> > Davis-Besse had  missed this cavity over an eight
> > year period? Or that, but
> > for chance, it could have gone another eight years
> > or until rupture which
> > ever came first?  Your take on pressurized systems
> > will come as a relief to
> > people with cerebral aneurysms That is: localized
> > thinning and ballooning
> > means nothing because the boiler code says so (
> > doesn't) and  Tim is
> > prepared to "educate" you all about it.
> >
> > ----- Original Message -----
> > From: "kemps89" <tstead@ntirs.org>
> > To: "Raymond Shadis" <shadis@ime.net>
> > Sent: Saturday, April 06, 2002 11:20 PM
> > Subject: Re: NRC Blasts Nuclear Plant Vigilance
> >
> >
> > > Before commenting on the issue at hand and
> > "proving" that the NRC is
> > > lying, you might do well to understand a thing or
> > two about stresses
> > > and strains and their effects on cylindrical
> > pressure vessles vs.
> > > fixed-end plate phenonema.
> > >
> > > In essence, your conclusion is way off base and
> > demonstrates a high
> > > degree of confusion in the area of mechanics of
> > materials.  Allow me
> > > to educate you on why you are wrong...and the NRC
> > is right.
> > >
> > > The forces on a pressure vessel are directly
> > proportional to the
> > > pressure times the cross-sectional area and the
> > hoop/longitudenal
> > > stresses of a pressure vessel the size of
> > Davis-Besse's could not be
> > > built out of 3/8 SS and hold anywhere near that
> > pressure.  A smaller
> > > pressure vessel could withstand the stresses and
> > strains imposed on
> > > that material.
> > >
> > > In a pressure vessel, those stresses are equal to
> > the internal
> > > pressure times the radius divided by the thickness
> > (or two times the
> > > thickness, depending on the stress you want).  Of
> > course, for thick-
> > > walled pressure vessels, this equation is modified
> > slightly wherein
> > > the the above equation is for a thin-walled
> > pressure vessel.  Of
> > > course, the thin-walled theory yields higher
> > stresses and strains and
> > > is therefore conservative.
> > >
> > > In this case, since the entire pressure vessel was
> > not constructed of
> > > 3/8" S.S. the weak point was essentailly a
> > fixed-end plate with a
> > > uniform pressure load.  The stresses and strains
> > imposed on the
> > > thinned material are greatly different than the
> > stresses and strains
> > > of an entire pressure vessel of 3/8" thickness.
> > >
> > > In this case, the matieral was thick enough to
> > withstand the stresses
> > > and strains exerted on it and it would not have
> > burst unless the hole
> > > got apreciably larger.  Since the maximum stresses
> > and strains on
> > > that section of the RPV were within the allowable
> > loads for that
> > > material, the NRC concluded that the public was
> > never in any danger.
> > > Further, even if it would have burst, the
> > resulting LOCA would have
> > > been *much* smaller than the design basis LOCA and
> > so the protective
> > > systems would have allowed the reactor to shut
> > down and remain safely
> > > shut down.
> > >
> > > Of course, for those people that have no knowledge
> > of mechanics of
> > > materials and how stresses and strains are exerted
> > on materials given
> > > various loading configurations, they might
> > conclude what you did.  To
> > > a trained eye, however, there is a big difference.
> > >
> > > If you require further explanation and/or
> > references to the pertinent
> > > ASME codes and standards, I would be more than
> > willing to supply them
> > > to you.  A brief review of any mechanics of
> > materials textbook,
> > > however, would provide more than adequate
> > explanation of the
> > > difference in a section of thinned wall vs. the
> > entire wall of the
> > > thinned thickness.
> > >
> > > Tim
> > >
> > > --- In doewatch@y..., "Raymond Shadis"
> > <shadis@i...> wrote:
> > > > "The NRC said the damage did not pose a safety
> > threat" (see article
> > > below).
> > > >  If a reactor pressure vessel reduced to the
> > thickness of Aunt
> > > Millie's
> > > > pressure cooker isn't a threat to safety, why
> > not build them all
> > > out of
> > > > sheet stainless steel and save a whopping amount
> > of weight and
> > > nuisance and
> > > > resources now wasted on six inches of carbon
> > steel?
> > > > And NRC wonders why the public doesn't have
> > confidence in the
> > > agency.
> > > > Ironical, ain't it?
> >            Ray
> > >
> >
>
>
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