The Utilization of On-Line Monitors at EBR-II for Sodium Purity

Abstract

The Experimental Breeder Reactor-II (EBR-II) primary sodium system is equipped with continuous monitors for oxygen and hydrogen impurities in the sodium. The sensors of these monitors have been incorporated into a modularized system that was developed for nuclear reactor applications for sodium temperature and sodium flow-rate conditioning. The oxygen meter calibration is provided by periodic analysis of the oxygen in sodium by the vanadium-equilibration method. The hydrogen meter is a direct reading device and does not require on-line calibration. Typically, the impurity content of the sodium has been shown to be quite stable at 0.6- to 1.0-ppm oxygen and 0.06- to 0.08-ppm hydrogen. On-line carbon monitors are not presently in use at EBR-II. A single determination of the chemical activity carbon in sodium gave a result of 0.002 relative to graphite and is about the same value as measured in other “clean” stainless steel-sodium systems.

Plans are being made to equip the EBR-II secondary system with ten hydrogen meters that will be used for detecting the onset of steam-to-sodium leaks such that corrective action can be taken before the leak enlarges and propagates to adjacent tubes.