Internal dosimetry terms Derived Air Concentration ( DAC ) is the activity concentration of a radionuclide in air which , if breathed for an entire working year , would result in exposure equal to the Annual Limit on Intake ( ALI ). To calculate dose uptake over a shorter timescale , DAC-hours ( DACh ) are used . DAC is based on 2000 working hours per year , so 2000 DACh = 1 ALI .
ICRP dose limits are based on the Committed Organ Dose Equivalent ( CODE ) which is the organ dose equivalent received over a period of 50 years from the intake . The Committed Effective Dose Equivalent ( CEDE ) is the CODE for each organ or tissue multiplied by the respective organ or tissue weighting factor and summed over all organs or tissues .
Radiation Protection Today Summer 2021 beta , there was a false sense of security that the improved contamination control measures were adequate to protect workers . The actual airborne activity due to transuranics was only confirmed weeks later at an off-site laboratory , and this was when the significance of the conditions became clear . Airborne alpha activity levels were shown to have been 139 DACs alpha in the workplace and 4 DACs alpha in surrounding work areas , indicating that potentially significant exposures to workers had occurred .
Refurbishment work was stopped for several months while dosimetry and recovery efforts were undertaken . This was an exceptionally emotional event for the workers involved and resulted in a significant loss of confidence in radiation protection staff by both workers and stakeholders . A new Radiation Protection Manager and several consultants were brought in to make improvements to the radiation protection programme . These included the introduction of new
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