Structural analysis in support of the waterborne transport of radioactive materials Page: 9 of 10
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200
100
Ua
U
0
L.
Y -100
U
tW -200
UJ
a -3000o
~T
Top view with hatch cover
and upper deck removed.
-1-i- II
1110M(\VV" 1 - -
- -l
j l i-p
Ii i0.10 0.20 0.30 0.40 0.50
TIME (sec)
Average forces acting on the
simulated RAM packages.0.60
Figure 9. Maximum deformation and average force
on the simulated radioactive material
packages for Case 4M (v = 30 knots,
mass = 16,750 tonnes, t = 0.50 seconds).
eliminate the need to model the beam stiffeners makes these elements
more resistant to tearing. In all of these models the hatch covers were
assumed to be rigidly attached to the top deck. This assumption causes
the struck ship to be stiffer than it would be if the hatch covers were
allowed to slip off the top deck. The final source of limited tearing is the
mesh size. A coarser mesh distributes localized strains over a larger
area, thereby reducing the average strain in the element and delaying the
onset of tearing. It is likely the stiffening of the ship caused by these
factors does not decrease the crush forces seen by the simulated
radioactive material packages because these factors make the back hull
of the struck ship stiffer as well. So even though the penetration distance
and tearing of the forward portion of the ship are underestimated, the
forces acting on the package are probably conservative.CONCLUSIONS
The mechanics of collisions between two ships has been studied. For
this type: of collision to have the potential to damage on-board
radioactive material transportation packages three things must occur.
First, the collision must be severe enough so the bow of the striking ship
penetrates to the location of the package. Then, the striking ship must
have sufficient residual velocity to penetrate further into the ship, as the
initial collision between the bow and the package will be less severe
than the regulatory impact of the package onto an unyielding target.
Finally, the residual velocity of the striking ship must push the package
against something that is strong enough to crush it. In the finite element
analyses it was seen that the strength of the hull on the opposite side of
the ship modelled limited the magnitude of the crush force that could be
applied. It is possible, however, to postulate scenarios where other cargo
in the hold can distribute the force over a sufficiently large portion of the
hull that crushing of the package may occur. Detailed finite element
analyses of the package subjected to crush forces of this magnitude will
be performed to assess the amount of damage to the package and the
potential for radioactive material release.
REFERENCES
Akita, Y., et al. Studies of Collision-Protective Structures in Nuclear
Power Ships, Nuclear Engineering and Design, Vol 19, pp 365-401
(1972a).
Akita, Y., and K. Kitamura A Study on Collision by an Elastic Stem
to a Side Structure of Ships, Trans. Society Naval Architects of Japan,
131, 307 (1972b).
Gibbs and Cox, Inc. Criteria for Guidance in the Design of Nuclear
Powered Merchant Ships, prepared for the Office of Research and
Development, Maritime Administration, Three Volumes (1961).
Jones, N., Structural Aspects of Ship Collisions, Structural
Crashworthiness, N. Jones and T. Wierzbicki, eds., Butterworths,
London, pp 308-337 (1983).
Lenselink, H. and Thung, K. G. Numerical Simulations of the Dutch-
Japanese Full Scale Collision Tests, Proceedings of the Conference on
Prediction Methodology of Tanker Structural Failure (1992).
M. Rosenblatt & Son, Inc. Analysis of SS Arizona Standard/SS
Oregon Standard Collision (Minorsky's Method), DOT, US Coast
Guard, Contract No DOT-CG-10, 605A (1972).
McConnell, P., et al. SeaRAM: An Evaluation of the Safety of RAM
Transport by Sea, Proceedings of PATRAM '95, Las Vegas, Nevada
(1995).
Minorsky, V. U., An Analysis of Ship Collisions with Reference to
Protection of Nuclear Power Plants, Journal of Ship Research, Vol. 3,
No. 1 (1959).
Porter, V. L. Analysis of Water Effects during Ship Collisions as
Modeled by Lenselink and Thung, Sandia memo to D. J. Ammerman and
M. B. Parks (1995).
Taylor, L. M., and Flanagan, D. P., PRONTO-3D: A Three-
Dimensional Transient Solid Dynamics Program, SAND87-1912
(1989).r
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Ammerman, D.J. Structural analysis in support of the waterborne transport of radioactive materials, article, August 1, 1996; Albuquerque, New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc673141/m1/9/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.