The secondary enclosure cleanup system (SEC) is far superior to a standard purged enclosure for high activity processes.  When significant levels of tritium activity are expected to permeate from the process into the secondary enclosure it is preferred to capture the activity rather than purge and release up the stack.

            The SEC is a closed loop system that is attached to a helium atmosphere glove box for the purpose of capturing all tritium in the vapor and elemental form to reduce stack emissions.  The continuous closed loop operation provides a constant cleaning of the helium atmosphere to both provide maximum detritiation and minimize helium usage.  The SEC system is designed to handle water vapor, oxygen and hydrogen (Tritium) contaminates in the helium atmosphere.

            The SEC system is an ideal solution for any helium atmosphere glove box cleanup system.  With only one pump, passive cleanup beds, and a variety of instrumentation the SEC is a simple, robust, and well monitored system that provides very long run times with low maintenance.

Theory of Operation

            Helium is pulled from the glove box by a very robust Metal Bellows pump through a 1 Liter ionization chamber tritium monitor.  The helium is then sent through three beds to deal with contaminates in the gas stream.  The first bed is a 6kg 5A molecular sieve that removes all water vapor down to a dew point of -30 °C.  A dew point monitor after the bed is provided to notify the user when the bed needs to be replaced.  The next bed is a 1 kg Nickel Bed which is used to recombine any trace oxygen in the gas stream.  The final bed is a 6kg Zirc-iron bed used to capture any hydrogen isotopes in the gas stream.  The fully cleaned helium is then cooled and directed through a tritium monitor back into the glove box.  A helium makeup circuit is provided to maintain the helium glove box pressure.