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Re: NRC News release on Terrorists.



Title: RE: NRC News release on Terrorists.
I received the following private communication from a DOE employee during a previous discussion on this topic:
 
The TMI containments were designed against a Boeing 720 at Mach .85.  The Boeing
720 was the prototype to the 707.  This was the largest aircraft at the time of
the construction permit.  By the time of the operating license, interveners
raised objections since Boeing 747s were around, and a used DC-8 stretch was
kept at the airport by a travel club.  The operating license went through since
engineering studies were able to show that the body of the 747 wouldn't knock
down the containment, and only the jet engine shafts had a chance of
penetration.  And, of course, the reactor itself (except for the pressurizer) is
actually below the operating floor inside the containment building, so damage to
the containment does not lead to a reactor accident directly.


Jack Earley
Radiological Engineer
 
Enercon Services, Inc.
6525 N. Meridian, Suite 503
OKC, OK  73116
phone: 405-722-7693
fax:       405-722-7694
jearley@enercon.com
 
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----- Original Message -----
To: RadSafe
Sent: September 28, 2001 7:30 a.m.
Subject: RE: NRC News release on Terrorists.

Jaro,
Thanks for the reply.  I do not have access to this information, but have noted that comments have been made that the confinement building can take the impact of a 707, etc., but have never seen anyone backup these statements. 

-- John

-----Original Message-----
From: Franta, Jaroslav [mailto:frantaj@AECL.CA]
Sent: Thursday, September 27, 2001 2:05 PM
To: Radsafe (E-mail)
Subject: RE: NRC News release on Terrorists.

-----Original Message-----
From: Jacobus, John (OD/ORS) [mailto:jacobusj@ors.od.nih.gov]
Sent: Thursday September 27, 2001 1:14 PM
To: Franta, Jaroslav; Radsafe (E-mail)
Subject: RE: NRC News release on Terrorists.

Jaro,
I don't think you would say that the WTC buildings were fragile.  They stood for over an hour after inpact.  Will a four foot thick, reinforced concrete wall do as well?  If you don't know, say so.
-- John  
<><><><><><><><><><>
 
John,  the reference books I have say that sprayed asbestos or mineral fiber covering on steel columns has a fire resistance rating of roughly 2hrs per inch of thickness (more precise numbers depend on construction details, materials, quality, etc.).
Concrete offers roughly the same fire protection per unit of thickness, for the steel rebar inside.
But with wall thickness measured in FEET for NPP containment domes, we're looking at a fire rating measured in DAYS, not hours (there is, in addition, usually a steel plate liner on the inside surface of the dome).
PS. thanks for your expression of confidence, saying "I don't think you would say that the WTC buildings were fragile." ...indeed, if you check what I actually wrote (see below), you will note that I was talking about the sprayed-on fireproofing material, not the steel structure. I don't have any figures handy at the moment on the relative strength of sprayed-on fibrous material versus concrete in dome walls, but I presume its quite substantial (flame away if you must....).
 
Jaro
-----Original Message-----
From: Franta, Jaroslav [mailto:frantaj@AECL.CA]
Sent: Thursday, September 27, 2001 11:19 AM
To: Radsafe (E-mail)
Subject: RE: NRC News release on Terrorists.


OOOOPS -- I guess John meant burning jet fuel from the airliner ! (thanks Phil !)

...but if nothing gets through the wall, what difference does it make ? (ignoring destruction of the "balance of plant" for the moment).

As we saw in the WTC disaster, much of the fuel was gone in the initial fireball. I suspect this would be even more so in the case of a disintegration of an airliner on the outside of a containment dome.... in contrast to the WTC, where a significant fraction spilled throughout the interior of the structure and ignited any combustible materials there....

Also, in chemical/petrochemical industry, large concrete basins are used for emergency/accidental spills to safely burn-off the flammable liquid.

I think there is a big difference between the relatively skimpy & fragile fireproofing of steel structures in highrises, and rebar embedded in four-foot thick concrete walls !

Jaro