## 3 Results and Discussion
### Sintering of Candidate Materials
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Sintering**} & \multicolumn{3}{c}{**RWS (500 to 1000 sim)**} & \multicolumn{3}{c}{**RRS**} & \multicolumn{3}{c}{**SOS**} & \multicolumn{3}{c}{**USOS**} & \multicolumn{3}{c}{**CB**} \\ \cline{2-13}  & & **Temperature** & **Sintering** & **Time** & **Sintering** & **Sintering** & **Dwell** & **Sintering** & **Time** & **Sintering** & **Dwell** & **Sintering** & **Time** & **Sintering** & **Dwell** & **Sintering** & **Time** & **Sintering** & **Time** \\  & [’C] & **Time** & **Time** & **Sintering** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** \\  & [’C] & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** & **Time** \\ \hline
1 & 800 & - & - & - & - & - & - & - & - & - & - & 20 & 5 & Yes** & - & - & - & - \\ \hline
2 & 1000 & 20 & 10 & No & 20 & 10 & No & 20 & 10 & No & 20 & 5 & Yes** & 20 & 5 & No \\ \hline
3 & 1100 & - & - & - & - & - & - & - & - & - & 20 & 5 & Fused** & 20 & 7 & Yes \\ \hline
4 & 1200 & 20 & 10 & No & 20 & 10 & No & 20 & 10 & No & - & - & - & - & - & - & - \\ \hline
5 & 1300 & 30 & 5 & No & - & - & - & - & - & - & - & - & - & - & - & - \\ \hline
6 & 1300 & 40 & 5 & No & - & - & - & - & - & - & - & - & - & - & - & - \\ \hline  & & & & & & & & & & & & - & - & - & - & - & - & - \\ \hline  & & & & & & & & & & & & & - & - & - & - & - & - \\ \hline
7 & 1300 & 20 & 4 & No & 20 & 5 & No & 20 & 3 & No & - & - & - & - & - & - \\ \hline
8 & 1300 & 30 & 4 & No & 30 & 1 & No & 30 & 3 & No & - & - & - & - & - & - \\ \hline
9 & 1300 & 40 & 4 & No & 40 & 1 & Yes & 40 & 3 & No & - & - & - & - & - & - \\ \hline
10 & 1300 & 50 & 4 & Yes** & - & - & 50 & 3 & Yes & - & - & - & - & - & - \\ \hline \hline \end{tabular}  
* A weak bond was determined between the particles of RWS,
* incompletely shared with significant crashes
* SOS model and formal jumps; No, it was excluded from further tests; due to its undesired sintering behavior, which makes it unsuitable for particle-based CSP.  
\end{table} 
Table 5: Sintering results of the candidate particulate materials at different temperatures and pressures. The screening results for CB were less reassuring. CB passed at 20 MPa and 1000 \({}^{\circ}\)C, which is likely the minimal but acceptable performance for the highest-temperature CSP applications. Since CB has a desirable dark color, it is highly preferred for directly irradiated PHR-based CSP. Since its resistance to sintering is questionable, further investigation and longer-term testing are recommended before deployment in even pre-commercial applications. The sintering results for USOS were very disappointing. As seen in Figure 4, it fused at rather a modest temperature and pressure, disqualifying it from any anticipated, even moderate-temperature, particle-based CSP applications. Figure 4a shows the sample after sintering at a temperature of 800-1000 \({}^{\circ}\)C. The pellet was formed, but it was broken due to the initiation of melting. Figure 4c shows the fused USOS lumps after sintering at 1100 \({}^{\circ}\)C. Figure 4b shows the leakage of molten USOS from the fine gap between the die and plunger. This result is especially disappointing since, as it is described as a magnesium-orthosilicate olivine material, it would be expected to have a very high melting point, maybe 1800 \({}^{\circ}\)C, and a correspondingly high sintering temperature. In fact, USOS is not a freshly mined material but a spent ore from a discontinued nickel production facility. It is, in fact, crushed from quenched molten ore. It is very likely that either the crystal structure was disrupted or impurities were introduced during processing.