more on jet engine penetration - Scott Portzline

[Norman Cohen <ncohen12@HOME.COM>]

To those of you, including Jaro, who were discussing jet engine penetration of

containment:



"Scott D. Portzline" wrote:



> Norm,

> Sorry it took so long to address this issue due to other priorities. The

> point of airline crashes into nuclear plants is already proven by Argonne

> National Laboratory in 1982 which virtually equated penetration by larger

> jets with direct release of radiation.

>

> The reason for showing that the block moved (as designed for the test) is

> that containment buildings are quite inelastic. At severe loads, the

> concrete and steel fail and penetration occurs. Reactor building domes are

> most vulnerable. The 4% difference Jaro mentions is virtually meaningless as

> he states for smaller loads. But, that difference for a jumbo jet is

> enourmous for destructive force.

>

> Anti-nuclear folks may find it ironic that jet engines (hardened with

> thorium) are the most solid part of the airliner and are likely to penetrate

> a containment building fairly intact (in mass) and potentially striking

> reactor systems.

>

> Additionally, there is a troubling unanalyzed condition at nuclear plants

> concerning elasticity and truck bombs. The explosive shock wave propagated

> through the ground will cause lateral accelerations which far exceed the

> peak magnitude of an earthquake. This can occur from a bomb hundreds of feet

> away and even 1/4 mile. This could cause pipe breakage - LOCA, fire from oil

> line break, short circuiting from water jets etc. etc.. I brought this up at

> a roundtable discussion this week. The NRC offered no response.

>

> Furthermore, the shock wave through the air from a truck bomb can be

> reflected from walls of adjacent buildings (nuclear plants have many large

> walls where tons of force can be reflected) and can combine with other waves

> for devastating results. These reflected waves has never been analyzed for

> each plant that I'm aware of. Therefore, a small bomb can have greater power

> than indicated by simple calculations which have not accounted for the

> reflective waves.

>

> The military wants 400 foot setback distances from its assets. Nuclear

> plants may actually require more if the ground shock lateral accelerations

> were ever to be factored.

>

> Scott Portzline

> (please forward this to the appropriate discussion)

>

> Marvin Resnikoff  wrote on Monday November 05, 2001 7:18 PM :

>

> <SNIP>

> Our calculations for concrete penetration do not assume the structure moves.

> As must be clear to you, one cannot infer from the Sandia test that a 767

> engine moving 500 mph will penetrate 6 cm of concrete.  If the building or

> storage cask were stationary, the penetration depth of the 767 jet engine is

> closer to 4 feet, and several U.S. reactors have a thinner concrete

> containment.  Our method of calculating the penetration depth is identical

> to the method used by NRC staff and DOE contractors.

> Marvin Resnikoff

> END QUOTE>

>

> Marvin, this is pure nonsense !

>

> Whether the impact block in the 1988 Sandia F-4 Phantom crash test moved or

> not makes very little difference. I will tell you exactly how little

> difference.

>

> The Sandia test was performed much the same way one would do the classic

> Ballistic Pendulum experiment for measuring the impact speed of a bullet : a

> block of wood is suspended by strings, so that there is no external force,

> such as friction, acting along the line of impact -- the same was achieved

> (nearly) by putting the reinforced concrete block atop an air-bearing

> platform. Quoting from the report,

> The target consisted of a block of reinforced concrete 7 m square and 3.66 m

> thick mounted atop an air-bearing platform with a combined weight of 469

> tonnes (almost 25 times the weight of the F-4)

> .....

> Ten air bearings were installed in "pockets" in the lower surface of the

> air-bearing platform. After inflating the air bearings, a force of only 816

> Kg (less than 0.2% of the weight of the target) was required to initiate

> movement of the target.

> When the bullet in the Ballistic Pendulum experiment hits the block of wood,

> it stops within it and thus transfers all its kinetic energy to the combined

> block-with-bullet mass. The movement of the block-with-bullet mass can then

> be used to calculate the initial speed of the bullet, or -- and this is the

> important part -- if you know the speed of the bullet, it can be used to

> measure the amount of energy expended in different ways in the collision.

> It turns out that in the case of such an inelastic collision, its easy to

> demonstrate that the fraction of energy going into destruction of the

> colliding objects is simply the total energy (i.e. initial kinetic energy),

> minus the ratio of the mass of the bullet (or the F-4 Phantom) versus that

> of the target-with-bullet. For example, a 5-gram bullet hitting a 2000 gram

> block of wood will result in ( 1 - 5/2005 = ) 99.75 % of the total impact

> energy converted to destructive energy (mechanical crushing, heat, shrapnel

> spray, etc.).

> Similarly for the Sandia impact test, where the ratio of airplane mass to

> concrete block mass was 1-to-25, the amount of impact energy converted into

> destructive energy is ( 1 - 1/26 = ) 96.2 % of the total.

> This may be compared to the case where the concrete block had been fixed

> perfectly to the ground, which is exactly analogous to having a block with

> infinite mass. In this case the amount of impact energy converted into

> destructive energy is ( 1 - 1/10000000.... = ) 100 % of the total.

> Note that there is a difference of only ( 100% - 96.2% = ) 4 % between the

> case where the block is fixed to the ground (infinite mass equivalent), and

> where it is floating frictionlessly. That of course is because of the large

> mass difference in both cases.

>

> Note also that Mr. Resnikoff and other critics are telling us is that a 4%

> difference in impact energy conversion to destructive energy, makes the

> difference between the 2½" penetration of the concrete wall in the actual

> experiment, and the 4 feet ( 48") penetration calculated by them.

> A 4% difference in energy results in 19-times deeper penetration according

> to them.

> AMAZING !!!

>

> Just as amazing is that this is grade eleven high school physics.... the

> bullet example I cited above comes from my 1966 edition of the Physics text

> book by Halliday & Resnick, page 220.

>

> Radsafe colleagues, please make sure everyone gets the message !  ...no more

> screwing around with antinuke-motivated misinterpretations of the historic

> Sandia crash test !

>

> Thanks.

> Jaro

>



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