Technical summary: Feasibility study of conductivity monitoring for leak detection in double-walled plutonium containers

摘要

Currently, the storage container for the pit from a dismantled warhead is a sealed outer container, or drum, within which the pit is suspended. Since the pit itself is a sealed, stainless steel container for the plutonium, the inner plus the outer containers constitute the {open_quotes}double-walled{close_quotes} configuration for plutonium storage. If either inner or outer wall of the container fails, the fill-gas between the pit and drum walls will contain species that will modify the physical properties of that gas. The work summarized here reports the initial feasibility study for an innovative approach for monitoring for leakages both for radioactive materials from the pit and for the intrusion of outside into the drum by monitoring the electrical conductivity of the fill-gas. For the gas present in a drum containing a pit, alphas from decays of plutonium are stopped by the primary container wall of the pit itself unless pit leakage occurs. If plutonium leaks from the pit and enters the fill-gas (either noble gas or air) of the outer container, each of the alpha particles due to the decay of plutonium will create about 10{sup 5} electron-ion pairs along its track. If the fill gas is a noble gas, these electrons will diffuse in the gas as free electrons.