# Status, Features, and Future Development of the LIFUS5/Mod4 Experimental Facility Design
## 3 Materials and Methods
### Main Components  
The main components of the facility have the duty of correctly reproducing the dynamical behavior of the system during the simulated transient. They are:  
* The recirculation tank SE-LSS-001. This tank will be built with the same dimensions as the recirculation tank foreseen in the TBS. Since the mock-ups utilized during the in-box LOCA experimental campaign will be smaller than the actual TBM box, the tank will be oversized. However, it was decided to keep the same internal volume to reproduce the damping of pressure waves that could be generated during the PbLi-water interaction phase and that are foreseen to travel upstream through the piping. * The TEU equivalent volume mock-up SE-LTS-001. This component simulates the presence of the TEU in the circuit. Its internal volume was kept equal to the one present in the original systems. This was due to the presence of gas inside the volume that is expected to damp pressure waves while they travel through the component. * The pipe forest. Pipes that run from the isolation valves to the test section will maintain the same length and layout to reproduce the pressure wave propagation following an in-box LOCA event. * The Relief Tank SE-LRS-001 is used to suppress excessive pressure inside the piping system. This component will be connected through a rupture disk designed to burst at the same pressure as the TBS-mounted one. * The isolation valves VP-LLL-01/02. These valves will be equivalent both in size and performance to the SIC-1 valves foreseen to protect the TBS circuit during incidental scenarios. Not only will the valves be equivalent but also the sensor and control system that detect anomalies in the nominal performance of the loop will be installed and designed to reproduce the final foreseen configuration. This will allow the testing of the detection and protection system used to mitigate the incidental outcomes and also to test different response strategies applied to the system by the control logic. The whole facility will be thermally insulated to maintain the temperature inside the components and the piping and ensure that the molten alloy does not freeze during each  
Figure 3: L5M4–TBS piping comparison. **Left**: comparison between main lines length. **Right**: comparison of the number of 90\({}^{\circ}\) bends between the two piping systems. test execution. The temperature will be controlled through heating cables that allow the control system to reach the desired state in each of the sections and components. Moreover, the whole plant is connected to a pressurization system that allows the complete filling and draining of the loop with Argon gas. The main goals of this system are:  
1. Migrating PbLi from one point of the facility to another via pressure difference. This method will be used for filling, draining, and controlling the facility during the first phase of the experimentation, when no recirculation pump will be installed. 2. Avoiding PbLi contact with air. This protects the alloy from oxidation due to the contact with both oxygen and the moisture present in the air. During facility operation, the PbLi alloy will be stored in two main tanks, the SE-LCS-001 and the SE-LDS-001. The first one is the loading tank, its duty is to hold the fresh, unused PbLi alloy under an inert atmosphere, ready to be loaded into the recirculation tank before each test is performed. The latter one is the drain tank, which is used to store the alloy contaminated with oxides and other chemical reaction products after each test. This method of having two separate tanks allows performing in-box LOCA experiments in the same conditions that would happen inside the reactors, avoiding plugging and other issues due to the presence of metal oxides that melt at a higher temperature. Moving the alloy to and from these tanks is performed via a pressure differential. The pressure inside the recirculation and loading/draining tanks is controlled via the argon distribution system, and isolation valves (VP-LCS-01 and VP-LDS-01) allow the PbLi to flow between them.