SESAME Newsletter #3 (March 2018)
PORTRAIT OF A YOUNG PROFESSIONAL: HELEEN UITSLAG-DOOLAARD
Could you briefly describe your role and responsibilities in the SESAME project?
I’m one of the computational fluid dynamics specialists from NRG working on the SESAME project. Computational fluid dynamics (CFD) is a method of modelling flow and heat transfer in 3D.
One of my tasks in SESAME is to create the CFD model of the sodium-cooled Phenix reactor and couple that CFD model to the system thermal-hydraulics (STH) model from my colleague. The strength of the CFD model is to include 3D effects like thermal stratification and jet directions. The strength of the STH model is to model the primary pumps and the intermediate heat exchangers with small computational effort. After the end of the blind phase of the Phenix dissymmetry test benchmark in October 2017, my current task is to improve the CFD model according to the released experimental results and the experience of the project partners.
Another task is to do pre-test CFD analyses of the Inter Wrapper Flow (IWF) experiment that is currently under commissioning at KIT. With the pre-test analyses I provided input for the design of the measurement equipment in the experiment. This collaboration of designing the experiment was presented at NURETH and I was rewarded with a young professional award for the paper.
Finally I’m involved in the CFD benchmark of the 19-rod bundle NACIE from ENEA where a part of the grid-spacer will be blocked. The pre-test calculations are done and the results from several partners have been compared. I’m curious for the test results and the post-test analyses. The validation from the post-test will provide model validation. Our validated model will be the base for a reduced mesh resolution model allowing to model a complete fuel assembly.
What would you say are your biggest challenges?
The biggest challenge of the blind phase of the Phenix dissymmetric test was to create a stable coupled model. The STH stand-alone model was made by a colleague and I had made a steady state CFD model. However, determining what variables should be exchanged by the codes and which boundary conditions should be applied to reach a common steady state took quite some trial and error. Looking at the results of the blind benchmark we managed reasonably well.
The biggest challenge in the current open phase is to grade the list with improvement options to determine which option is most relevant for the transient. Another challenge is to be not too ‘fast’ so to do the improvements step by step, though the computational time is huge, to be able to determine the sensitivity to each individual improvement.
The challenge in the IWF post-test comparison and the NACIE post-test comparison will be to draw conclusions from the comparison of the measurement data and the post-test CFD results. Hopefully the results will match reasonably well and we’ll be able to validate our CFD model and be able to explain the differences between simulation and experiment. An additional challenge for NACIE will be to quantify the error that you introduce by the reduced mesh resolution method.
What will you remember most?
The enthusiastic group of researchers within SESAME, supporting the young professionals like me, asking lots of questions out of curiosity and in order to help you and the project to achieve the best results. Also the openness of all research partners, always open for discussing their modelling method, the issues they have solved and are currently struggling with.
Finally I won’t forget the Heavy (liquid) Metal Concert during last progress meeting in Brasimone, for its music and its very special location.