Uses of Liquid Nitrogen in a Plutonium Handling Glovebox

Changes of pressure in a plutonium handling glovebox were measured under various conditions of the use of liquid nitrogen in the glovebox. The conditions under which liquid nitrogen can safely be used were determined.It is concluded from the analysis of experimental results that the changes of pressure in the glovebox are proportional to the ratio (rate of evaporation of liquid nitrogen)/(rate of air flow through glovebox), and that the pressure can be maintained negative in reference to the atmosphere outside the glovebox as long as the volume of the glovebox is not too small and the amount of liquid nitrogen is within laboratory scale. The only exception is the case where a dewar vessel containing liquid nitrogen is upset in the glovebox, when positive pressure is easily created in the glovebox.