Development of sodium small leak detection technique. Preliminary experimental study on sodium aerosol detection sensitivity using laser induced breakdown spectroscopy

A preliminary examination was carried out for evaluation of the detection sensitivity of Laser Sodium Leak Detector (LLD) based on a principle of Laser Induced Breakdown Spectroscopy (LIBS). Evaluation criteria and examination conditions were planned based on the results of preliminary experiments. The main results are as follows: (1) Signal intensity of LLD was obtained with parameter of sodium concentration in combustion aerosols. The signal intensity in the combustion aerosols was nearly equivalent to that in case of sodium mist using carrier gas of nitrogen. It was shown that LLD was effective to detect sodium in the combustion aerosols. (2) Diameter or chemical component of sodium aerosols are one of significant factors for the detection sensitivity of LLD. Preliminary experiments were carried out with parameters of humidity, oxygen concentration, and pressure of carrier gas. The obtained experimental data of a few cases showed that influence of these parameters was limited on the detection sensitivity of LLD. (3) Based on the preliminary experimental results, main conditions of a sensitivity evaluation test plan were decided for LLD. (author)