Hello readers,
Today, I would like to talk about the first part of my
research project. Every good researcher, and here I include my TRUSS
colleagues, consecrate time to refresh technical concepts and perform a literature
review. Fortunately, nowadays we have internet and thousands of articles are accessible
online. It makes the search for technical information much easier but, on the
other hand, reading and filtering that information still takes a lot of time. You
can imagine how tedious can this work be, but it is critical to get into the
state of the art, become aware of your level of knowledge, discover interesting
approaches and set your own path.
In my case, this stage lasted for about 6 straight months
due to the complexity of the topic. However, it doesn’t bother me since I truly
believe that successful results only come from the right initial conditions. Just
like in structural transient analysis! Even if my research topic is a very
specific problem in a special domain, I have been able to find out interesting
information about the different complex problems that affect the racks seismic
behavior. Actually, one could spend his entire life reading about structural
dynamics, fluid-structure coupling, computation algorithms, uncertainty
analysis, etc. However, besides that general bibliography, there also exist
some works particularly focused on the seismic behavior of racks. Since the
free-standing concept has been developed quite recently, most of these articles
have been written during the last 25 years. It is not surprising that this kind
of research was carried out in countries where the nuclear industry is well
established as USA, France and Japan. The ground-breaking authors where constrained
by the computing capacity of their time, so they used rudimentary numerical
1-rack numerical models occasionally supported by real scale physical models. As
a consequence, very few studies take into consideration the interaction effects
between the different racks nestled in the depths of the spent fuel pool. Nevertheless,
this a priori hidden interaction caused by the inertial coupling of the water
volume has proved to be decisive when clearance between units is small. In
other words, there is still much work to do!
Installation of a rack unit as a part of a rack system
In the same time, I have approached the ENSA’s analysis
methodology currently applied in the dynamic analysis of the nonlinear response
of HDSFS racks. This
cost-effective methodology considers the Fluid-Structure Interaction (FSI) through the hydrodynamic
mass concept and takes advantage of the thermal analogy to perform the ensemble of calculations in
unique software. It is in agreement of the international guidelines, validated
by the nuclear authorities and implemented in ANSYS Mechanical thanks to the
expertise of my supervisor Mr. Costas.
In order to summarize all of this work, I have written two
technical papers highlighting my personal conclusions. The first describes 6
sources of uncertainty in design identified to date, and the second details the
current analysis methodology and provides some numerical results. They are
already submitted for approval to a couple of international congress planned for
this summer. I promise to keep you posted on the progress.
See you down here soon!
