Abstract
A decay heat removal system based on the natural circulation (NC-DHRS) is expected to be developed for the safety improvement of sodium-cooled fast reactors. Uncertainty evaluation of experimental data is a key issue to establish an experimental database regarding NC-DHRS. In this study, the uncertainty evaluation method has been developed for thermocouples in the test section of the sodium experimental facility PLANDTL-2, considering the effect of the heat loss in the test section and the uncertainty of reference thermocouples. Monte Carlo method has been used for the uncertainty evaluation of the temperature measurement data in the relative calibration and the steady state experiment. As a result, it was confirmed that the confidence intervals were asymmetric due to the heat loss in the relative calibration and the steady state heat removal experiment with DHX. Confidence intervals of thermocouples near the simulated core outlet were increased due to mixing the cold sodium from DHX and the hot sodium from the simulated core.
