Feasibility study on application of Laser Induced Breakdown Spectroscopy for detection & identification of failed fuel pin and sodium-water reaction in Fast Reactors
In a fast reactor, during the analysis of core cover gas, the presence of gaseous fission products, namely, Kr and Xe or presence of He (in case of He bonded fuel pins) would indicate the occurrence of fuel pin failure. Similarly detection of hydrogen (H2) in the surge tank cover gas can indicate the possibility of sodium water reaction. Analysis for the presence of such gases in cover gas is mandatory towards safety considerations of any fast reactor. This paper demonstrates the feasibility of application of Laser Induced Breakdown Spectroscopy (LIBS) for the detection of H2, He, Kr and Xe gases in ultra high pure (UHP) Ar, similar to the cover gas of a fast reactor. The characteristic emission lines at 656.21 nm (Hα), 587.4 nm, 877.67 nm and 881.84 nm are chosen for the quantitative analysis of the H2, He, Kr, and Xe, respectively. The calibration curve for all these gases shows linear fit with good correlation coefficient. The detection of H2 is found to have interference from the moisture content present in the LIBS sample chamber. In the paper, the results on identification of non-overlapping emission lines of the above gaseous species, calibration curve, limit of detection, reproducibility and potential application in fast reactors are discussed.