In the frame of a thesis supervised at the LNM on advanced nuclear fuel and ATF claddings, some direct measurements of cylindrical samples have been performed. For this work the radial heat-flow setup was used. A better understanding of the connection of the thermal conductivity to the microstructure and its evolution due to irradiation has been established. The outcome of this available work could be put into context of ATF relevant conditions, and serve for the determination of reference data of theoretical models employed in simulations codes such as FALCON and TRACE.
Thermal conductivity measurements - apparatusRadial heat flow apparatus: axis-symmetric setup
- length: 3 to 25 cm
- Inner diam.: min 6 mm
- Outer diam.: max 40 mm
- Temperature: RT to 700 °C
| Heat exchange rates through radiosity analysis (Gebhart)
--> sensitive to uncertainties
|Can measure active samples||lengthy: 7-10 days per measurement|
|Decoupling of k∥ and k⊥||thermocouples attachement (with glue)|
IrradiationAt PSI, measurements of SiC samples are carried out on irradiated and non-irradiated samples.
Thanks to the Swiss Spallation Neutron Source SINQ samples can be neutron irradiated at PSI.
At the STARS project of LRT, methodologies for best-estimate steady-state and transient analysis of of LWR reactors have been continuously improved over years. All the developments aim at a reaching a capability to analyze typical DBA (Design Basis Accident) and BDBA (Beyond Design Basis Accident) prior to core-melt in line with standards from Industry and International Technical Safety Organizations (TSO). The simulation capability is illustrated in the figure below, which shows the STARS calculation scheme combining the CASMO-SIMULATE, FALCON and TRACE simulation codes. These codes are being developed at PSI in order to simulate the behaviour of SiC as cladding material. As indicated on the bottom right part of the figure, the simulation scheme is applicable to one of the scenarios that will be adopted in this proposal, namely the LOCA, RIA/REA and SBO.
For more details about the codes, please refer to the code dedicated STARS webpage.