## 6 Conclusions  
This work presents the efforts of KIT to develop and validate a software aimed at applying the best-estimate methodology discussed in [4, 5]. This rigorous methodology is based on the Bayes' theorem in conjunction with the information theory to assimilate the uncertainty-afflicted experimental and computational data. The purpose of the best-estimate methodology is to provide best-estimate/calibrated values of the _parameters_ used to describe the physical systems, the responses, and their _uncertainty_ used to describe the physical systems.  
The tool, called BeSYC, is an interactive MATLAB App equipped with a GUI. The software was developed in the frame of the KIT activities devoted to the validation of system codes (RELAP5-3D and MELCOR 1.8.6) against data gathered from the experimental campaigns performed in the HELOKA-HP facility [8]. The development of BeSYC was grounded on three fundamental aspects:  
* _Independency_ from the system code in use;
* _Modularity_ to ease the maintenance of the tool as well as to ease the introduction of new features or the support of new system codes;
* _Multi-platform availability_.  
The tool has been extensively validated against both examples provided in literature and hand-made test cases. Then, BeSYC was used for the analysis of several pressure drop characterization tests and a LOFA experimental campaign performed on a helium-cooled first wall mock-up in the KIT HELOKA-HP facility [8, 9]. These two works do not only represent the validation of the RELAP5-3D and MELCOR 1.8.6 codes in DEMO relevant conditions but also the last validation step of the BeSYC software. The findings of these latest activities pushed to introduce the support to the MELCOR 2.2 system code (not yet applied to any real-case scenario). The aim was to turn the BeSYC software in a simple yet powerful tool to perform BEPU studies. The use of a GUI without the prior knowledge of any programming language (Python, C++, etc.) also eases the introduction of young scientist/students to BEPU topics.  
Conceptualization, B.G., M.A., B.-E.G. and X.Z.J.; methodology, B.G., B.-E.G. and M.I.-B.; software, B.G. and M.A.; validation, B.G. and M.A.; formal analysis, B.G., M.A. and B.-E.G.; investigation, B.G. and M.A.; resources, R.S. and S.P.; data curation, B.G. and M.A.; writing--original draft preparation, B.G. and M.A.; writing--review and editing, B.G., M.A., B.-E.G., X.Z.J.,  
Figure 5: Results of the pressure drop characterization tests on two channels of the first wall mock-up (taken from [9]).  
M.I.-B., S.P. and R.S.; visualization, B.G. and M.A.; supervision, B.-E.G., M.I.-B., S.P. and R.S.; project administration, B.-E.G., X.Z.J. and R.S.; funding acquisition, X.Z.J. and R.S. All authors have read and agreed to the published version of the manuscript.  
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.  
Not applicable.  
The data used are not freely available.  
The authors declare no conflict of interest.