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ALARA considerations in upgrading a radiation calibration facility
The Los Alamos Radiation Calibration and Evaluation Facility has been upgraded with Cs-137 sources which replaced the Co-60 and Ra-226 radiation sources in the gamma wells used for calibration of beta-gamma exposure rate meters. The facility upgrade involved the transfer of 33.7 TBq of Cs-137, 2.4 TBq of Co-60, and 74 MBq of Ra-226. Due to the intense radiation fields anticipated from the transfers, several phases of planning were conducted addressing each specific job task (source leak testing, source removal, source transportation, and source installation). Controls used to reduce personnel exposures ALARA for the various jobs included: the determination of direct and scattered radiation dose rates using the Los Alamos Monte Carlo Code and by knowledge of process to estimate collective dose; the completion of mock-up exercises or ``dry-run`` of the transfers to reduce time in the actual handling of the sources; the use of a 3.7 m electromagnet and 0.91 m mechanical handling tool to increase distance during the transfers; consideration of localized shielding to reduce exposure; the set up of remote video cameras and monitors over the well ports and lead storage casks to ensure proper source removal and installation; the issue of alarming electronic pocket dosimeters (EPDs) to personnel directly involved in the transfers to measure the integrated and peak dose rates to limit stay times in the radiation areas; the incorporation of a contingency plan to cover unexpected events during a transfer; and the establishment of an exclusion zone to minimize dose to the public. Completion of the facility upgrade resulted in a collective dose of 1.14 mSv
Two non-gypsy rudimentary mutations and their suppression by mutations of suppressor of Hairy-wing in Drosophila
Meshing strategies for the alleviation of mesh-induced effects in cohesive element models
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