| Abstract: | Precipitation rates of sodium impurities on orifices of a plugging indicator and dissolution rates of precipitated impurities into sodium were studied to improve determination accuracy of the plugging and unplugging temperatures measured by the indicator. Precipitation rates, obtained from decreasing sodium flow rates and orifice temperature, are proportional to the 0.8 power of the Reynolds number and to the square of the super-saturated concentration below 10 ppm. Dissolution rates, determined from increasing sodium flow rates and orifice temperature, are proportional to the 0.8 power of the Reynolds number and to the subter-saturated concentration below 10 ppm. An analytical model, using the precipitation and dissolution rates, describes well the differences between cold trap temperature and the plugging and unplugging temperatures observed during periodical operations of the plugging indicator. |
