Developments in in vivo monitoring for radionuclides at AWE

The Atomic Weapons Establishment (AWE) has routinely used high purity germanium crystals for in vivo monitoring, detection and measurement of radionuclides in the chest, wounds and whole body of personnel over the past 30 years. However, recent organisational changes have resulted in the relocation and modification of this capability. Hence, this paper reviews and compares the performance of the original twin six crystal detector arrays (contained within environmental radiation shielding), that were first used at AWE in 1980, with the latest unshielded systems that employ smaller numbers of larger crystals. It has been concluded that the required sensitivity of 20 mSv for actinides in the chest was achieved using the recently procured twin dual crystal detector arrays outside of the conventional heavy duty environmental radiation shield used with the original system. Sensitivities of around 1 µSv, for fission and activation products in the whole body and around 1 mSv, for actinides in wounds, were achieved using single large collimated, but otherwise unshielded, detectors.