Risk reduction benefits of cryogen-free refrigeration

Abstract

High Purity Germanium (HPGe) gamma-ray detectors are used at Los Alamos National Laboratory's Plutonium Facility (TA-55) for nondestructive assay. Liquid nitrogen (LN2), a cryogen, is commonly used to cool these detectors. Cryogen use is associated with several health risks and operational problems. This has prompted the development of cryogen-free refrigeration. Although the efficacy of the coolers has been proven for use with HPGe detectors, the health and safety aspect implications have not been studied. Both LN2 and mechanical coolers were examined and their application effectiveness on health and safety aspects in HPGe gamma-ray detector use at TA-55 was compared. Overall, cryogen-free refrigeration is an engineering equivalent to LN2 systems used in gamma spectroscopy and eliminates the health and physical hazards associated with LN2 systems without adding hazards.