Re: NRC News release on Terrorists -Containment failure thread

[SAFarberMSPH@CS.COM]

Radsafe colleagues:


There are some major points of difference between a containment building being engulfed externally in say 40 tons [fully fueled Boeing 767 at takeoff ] of burning jet fuel and a raging fire as occurred inside the World Trade Center. Once a large jet easily crashed through the glass walls of the WTC  [leaving the structural steel intact with some insulation damaged] the interior instantly was converted into a raging inferno.


In the case of a nuclear plant. The containment structure at the average nuclear plants is unlike to be breached even by a 767 but if it were it would likely be  only very partially so.


In the WTC case, once the internal building fire heated the lightly insulated steel supporting steel beams to about 1000 deg. F the steel would weaken and begin to sag.  Even in a residence with a major steel beam supporting a floor, a steel beam will fair in a fire before a wooden beam would burn through.


Failure of only a few major steel support beams at the WTC would lead to a collapse under the load of the structure above and once the building started to collapse would take the entire building down since the floors below could not take the impact of the mass of material falling upon it,  with the weight building floor by floor. A major skyscraper is basically a house of cards that depends on all of the structural steel being entirely intact. The load must be evenly spread with 110 stories of structure.


In the case of a nuclear containment building engulfed externally in a raging fire, the structural steel rebar is "insulated" by 3 or 4 feet of concrete thermal mass not an inch [or so??] of spray-on insulation as at the WTC. Further the structural integrity of the containment does not depend on the steel but on the concrete structure itself.   The tightly woven rebar inside the concrete provides reinforcement but the structural strength of the entire containment does not hinge on the steel to support it. 


I'm confident that engineering analyses will show that the concrete containment  structure will never reach a temperature that could weaken the steel rebar as in the WTC case. The concrete will simply bake in a fire and due to the huge thermal mass, and tendency of some of the concrete to sublime, essentially nothing is likely to happen. Any input from structural engineers on the behavior of concrete to a short term fire?


I think it is unwise [as well as almost certainly untrue]  for anyone to promote the uninformed idea that a nuclear plant containment is likely to fail in a fire. My intuition is this is extremely unlikely especially where field tests done earlier have shown that a jet engine [the single largest component of a commercial jet] did not penetrate a reactor containment building in a full speed crash of a fighter jet.


Stewart Farber

Public Health Sciences

SAFarberMSPH@cs.com

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In a message dated 9/27/01 9:08:45 AM Pacific Daylight Time, jacobusj@ors.od.nih.gov writes:



> Jaro,
>
>
> Do you think the burning fuel would cause structural failure?
>
> -- John 
>
>
> John Jacobus, MS

====================

From: Franta, Jaroslav [mailto:frantaj@AECL.CA]

Sent: Thursday, September 27, 2001 8:50 AM


Subject: RE: NRC News release on Terrorists.

. . .

Although nobody has ever crashed a full-size airliner into a containment building, the impact of its jet engine(s) is more than adequately reproduced by the impact of a single- or twin-jet military fighter plane -- which has actually been done (the famous rocket-sled propelled Phantom jet slamming into a fixed reinforced concrete block...).