Addressing as low as reasonably achievable (ALARA) issues: Investigation of worker collective external and extremity dose data

Plutonium emits both neutrons and photons and when it is stored or handled inside a glovebox, both photons and neutrons are significant external radiation hazards. Doses to the extremities are usually dominated by gamma radiation in typical plutonium glovebox operations. Excess external dose can generates stochastic effects consisting of cancer and benign tumors in some organs. Direct doses from radiation sources external to the body are measured by thermoluminescent dosimeters (TLDs) placed on the glovebox worker between the neck and waist. Wrist dosimeters are used to assess externally penetrating radiation including neutrons and provide an estimate of neutron radiation exposure to the extremities. Both TLDs and wrist dosimeters are processed monthly for most glovebox workers. Worker collective extremity and external dose data have been analyzed to prevent and mitigate external radiation events through the use of Lean Manufacturing and Six Sigma business practices (LSS). Employing LSS, statistically significant variations (trends) are identified in worker collective extremity and external dose data. The research results presented in this paper are pivotal to the ultimate focus of this program, which is to minimize external radiation events.