## 2 Overview of Microreactors
### Microreactor Designs
\begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Reactor Name** & \
\begin{tabular}{c} **Power Output** \\ **(MWe)** \\ \end{tabular} &
\begin{tabular}{c} **Operating** \\ **Time (years)** \\ \end{tabular} & **Fuel** & **Coolant** & **Features** \\ \hline
**eVincTM** & 0.2-5 & \(\geq\)3 & HALEU TRISO & Liquid sodium & High-temperature heat pipe, compact design, reliability \\ \hline
**Aurora** & 1.5 & 20 & Metallic & Liquid sodium & Long autonomous operation, nuclear waste burning \\ \hline
**Holos Generators** & 1–100 & 3–20 & TRISO & Helium/CO\({}_{2}\) & Turbojet engine-like, simple design, high efficiency \\ \hline
**Xe-Mobile** & \(\geq\)1 & 3 & TRISO & Helium & Portable, autonomous operation \\ \hline
**NuScale** & 1–50 & \(\geq\)10 & HALEU & Pressurized water & Suitable for small power grids and remote facilities \\ \hline
**SEALER** & 3 & 30 & UO\({}_{2}\) or UN & Lead & Sealed core, long operation without refuelling \\ \hline
**U-Battery** & 4 & 30 & TRISO & Helium & Annular prismatic core, indirect Brayton cycle \\ \hline MMRTM & 5 & 20 & TRISO/FCMTM & Helium & Flexible heat transfer, high temperature stability \\ \hline
**Kaleidos** & 0–1 & 20 & UO\({}_{2}\) & Helium & Portable, autonomous operation \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Features of micro reactors [25]. \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Reactor Name** & \multicolumn{2}{c}{**Advantages**} & **Disadvantages** \\ \hline
**eVincTM** &
\begin{tabular}{c} High-temperature heat pipe, compact design, \\ reliability, \(\geq\)3 years without refueling \\ \end{tabular} & Limited operational data, high initial costs \\ \hline
**Aurora** &
\begin{tabular}{c} Long autonomous operation (20 years), nuclear \\ waste burning, compact design \\ \end{tabular} & Developmental stage, insufficient technical data, safety measures for sodium coolant \\ \hline
**Holos Generators** &
\begin{tabular}{c} Turbojet engine-like, simple design, high efficiency \\ (up to 60\%), scalable power options \\ \end{tabular} & Innovative design not widely commercially applied, potential safety and operational challenges \\ \hline
**Xe-Mobile** &
\begin{tabular}{c} Portable, autonomous operation, \(\geq\)3 years without \\ refueling, TRISO fuel \\ \end{tabular} & Requires sophisticated control systems for autonomous operation, increased costs \\ \hline
**NuScale** &
\begin{tabular}{c} Suitable for small power grids and remote facilities, \\ \(\geq\)10 years without refueling, high safety and efficiency \\ \end{tabular} & Not yet widely commercially applied, high initial investment costs \\ \hline
**SEALER** &
\begin{tabular}{c} Sealed core, long operation without refueling \\ (30 years), passive decay heat removal \\ \end{tabular} & Technical challenges with lead coolant management and operation \\ \hline
**U-Battery** &
\begin{tabular}{c} Annular prismatic core, indirect Brayton cycle, \\ 4 MWe power, 5 EFFY core life \\ \end{tabular} & Complexity due to helium turbine development requirements, developmental stage \\ \hline
**MMRTM** &
\begin{tabular}{c} Flexible heat transfer, high temperature stability, \\ 20 years without refueling, TRISO/FCMTM fuel \\ \end{tabular} & Developmental stage, high operational costs \\ \hline
**Kaleidos** &
\begin{tabular}{c} Portable and compact design, operates \\ autonomously, \(\geq\)5 years without refueling, \\ meltdown-proof TRISO fuel, air-cooled system, \\ eliminates the need for on-site water use \\ \end{tabular} & Developmental stage, high initial investment costs, potential regulatory challenges due to new technology \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Advantages and disadvantages of micro reactors [25].