## 3 Thermo-Mechanical Analysis and Further Design Improvement of the WCLL COB Segment TC Region
### The Third Update of the TC Region Design
#### 3.3.2 \"TC Region-Mod++\" Thermo-Mechanical Analysis and Results  
Once the \"TC region-mod++\" configuration is set up, its thermal performance under the nominal loading conditions is assessed. The thermal results, here not reported for the sake of brevity, still indicate a substantial fulfilment of the requirement on the suggested temperature limit. No significant variation in the maximum temperatures is obtained. Therefore, thermo-mechanical analysis under NO and OP steady-state loading scenarios is performed, and the verification of the RCC-MRx Level A and Level D criteria is carried out on the same set of paths considered so far. The obtained 3D spatial distributions of the von Mises equivalent stress field under the OP scenario are reported in Figure 14. Comparing these results with those shown obtained for the \"TC region-mod+\" configuration, a sensible improvement of the SPs thermo-mechanical performance can be observed. Figure 13: The \"TC region-mod++\" geometric configuration. Moreover, in Tables 7-9, the results of the RCC-MRx Level D criteria verification are reported. It can be seen that TC and FW-SWs fully match the criteria, whereas for SPs, some criteria are not satisfied along some paths, even with a narrow margin and better global performance than the previous configurations. Then, looking at Tables 10-12, it can be observed that the RCC-MRx Level A criteria, namely those related to the NO scenario results, are totally fulfilled within TC, FW-SWs and SPsv. Nevertheless, criticalities are still present in SPsh, where some paths do not verify the criterion against the IPI and that against the IPFL. These results seem to suggest the necessity of further updating the TC region design, increasing also the thickness of the horizontal SP. Such a design modification is not addressed in the present work, and it could be matter of a follow-up research activity. In any case, the proposed \"TC region-mod++\" geometric configuration is robust enough to achieve the correct classification. Figure 14: OP von Mises equivalent stress fields within the “TC region-mod++” geometric configuration. to be integrated in the first version of the WCLL COB conceptual design. Indeed, the design solutions found for the TC and the FW-SWs allow fulfilling, for these components, all the design requirements both in the case of nominal and accidental configurations. Moreover, a promising solution is found also for the SPs, even if their design will affect the overall segment geometric configuration; for this reason, it should be further investigated in the next phases. Lastly, the soundness against accidental electro-magnetic loads must be proved in the following design iterations, but at the moment, the found geometric layout can be considered worthy to be integrated in the segment's geometric layout. \begin{table}
\begin{tabular}{c c c c c} \hline
**Path** & **P\({}_{\text{m}}\)/S\({}_{\text{m}}\)** & **(P\({}_{\text{m}}\) + P\({}_{\text{b}}\))/(K\({}_{\text{eff}}\)\(\times\) S\({}_{\text{m}}\))** & **(P\({}_{\text{m}}\) + Q\({}_{\text{m}}\))/S\({}_{\text{em}}\)** & **(P\({}_{\text{m}}\) + P\({}_{\text{b}}\) + Q + F)/S\({}_{\text{et}}\)** \\ \hline TC\_1.a & 0.205 & 0.454 & 0.255 & 0.156 \\ TC\_1.b & 0.522 & 0.424 & 0.626 & 0.267 \\ TC\_1.c & 0.176 & 0.244 & 0.109 & 0.153 \\ TC\_2.a & 0.198 & 0.471 & 0.242 & 0.122 \\ TC\_2.b & 0.489 & 0.421 & 0.590 & 0.234 \\ TC\_2.c & 0.203 & 0.253 & 0.102 & 0.139 \\ \hline \end{tabular}
\end{table} 
Table 7: RCC-MRx Level D criteria verification within TC domain.