## 3 Thermo-Mechanical Analysis and Further Design Improvement of the WCLL COB Segment TC Region
### The Second Update of the TC Region Design
#### 3.2.2 \"TC Region-Mod+\" Thermo-Mechanical Analysis and Results  
Once the \"TC region-mod+\" configuration is set up, a pertinent 3D FEM model is developed, and its thermal performance under the nominal loading conditions are assessed. The thermal results, here not reported for the sake of brevity, are qualitatively analogous to those obtained for the \"TC region-mod\" configuration, indicating a substantial fulfilment of the requirement on the suggested temperature limit. In particular, the maximum temperature predicted within FW is equal to 531.6 \({}^{\circ}\)C, which is higher than the previous cases (because of the FW thickness increase in the TC slice) but below the limit. As for TC, a maximum temperature of 472 \({}^{\circ}\)C is predicted, whereas no significant variations can be observed in the SPs temperature spatial distribution. 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 performed on the same set of paths set up for the \"TC region-mod\" configuration. The 3D von Mises equivalent stress field calculated for the OP scenario is reported in Figure 12. Comparing these results with those shown obtained for the \"TC region-mod\" configuration, the improvement of the thermo-mechanical performance of the TC is clearly visible. In particular, almost all the TC geometric domain experiences von Mises stress values lower than 500 MPa. Figure 12: OP von Mises equivalent stress fields within the “TC region-mod+” geometric configuration. Then, in Tables 4-6, the results of the RCC-MRx Level D criteria verification are reported. As it can be observed, the considered criteria are completely fulfilled within the TC and FW-SWs domains, whereas there are still paths not satisfying them within the SPs, even with a reduced margin in comparison with the \"TC region-mod\" configuration. This means that the adopted geometric modifications allow significantly improving the TC structural performance, as well as having a certain impact on the SPs. The predicted outcomes have shown a significant improvement of the TC region structural performance in terms of RCC-MRx criteria fulfilment both in OP and NO scenarios. Since the Level D criteria are not globally satisfied, the results obtained in NO are not reported for the sake of brevity, and an additional set of design improvements is brought about in order to intervene on the most critical regions highlighted by the performed analyses. \begin{table}
\begin{tabular}{c c c c c} \hline \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 SP\_PR\_1.1 & 1.126 & 0.847 & 0.864 & 0.139 \\ SP\_PR\_1.2 & 1.219 & 0.888 & 1.078 & 0.226 \\ SP\_PR\_2.1 & 1.251 & 0.847 & 0.945 & 0.139 \\ SP\_PR\_2.2 & 1.356 & 0.921 & 1.149 & 0.204 \\ SP\_PR\_3.1 & 1.398 & 0.938 & 1.030 & 0.173 \\ SP\_PR\_3.2 & 1.560 & 1.042 & 1.085 & 0.219 \\ SP\_PR\_3.3 & 0.790 & 0.534 & 0.999 & 0.267 \\ SP\_TR\_1.1 & 0.526 & 0.385 & 0.846 & 0.156 \\ SP\_TR\_1.2 & 0.480 & 0.347 & 0.809 & 0.159 \\ SP\_TR\_1.3 & 0.611 & 0.418 & 0.705 & 0.203 \\ SP\_TR\_1.4 & 0.416 & 0.978 & 0.259 & 0.101 \\ SP\_TR\_1.5 & 0.444 & 0.855 & 0.209 & 0.115 \\ SP\_TR\_1.6 & 0.521 & 0.419 & 0.947 & 0.251 \\ SP\_TR\_2.1 & 0.588 & 0.399 & 1.077 & 0.192 \\ SP\_TR\_2.2 & 0.630 & 0.433 & 0.866 & 0.150 \\ SP\_TR\_2.3 & 0.626 & 0.419 & 0.720 & 0.208 \\ SP\_TR\_2.4 & 0.830 & 0.593 & 1.243 & 0.276 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: RCC-MRx Level D criteria verification within SPs domain.