Study on the uncertainty of passive area dosimetry systems for environmental radiation monitoring in the framework of the EMPIR "Preparedness" project

Highlights: • Dose rate level is crucial value for potential protective actions in emergency. • H*(10) simplified model function is required for passive dosimetry in emergency. • H*(10) uncertainty of is above 50% (k = 2) for a low dose rate by passive dosimeters. • Direct background measurements are useful close to passive area dosemeter position. • The external dose increment of 1 mSv/y can be measured by passive area dosemeters. One of the objectives of the EMPIR project 16ENV04 "Preparedness" is the harmonization of methodologies for the measurement of doses with passive dosimetry systems for environmental radiation monitoring in the aftermath of a nuclear or radiological event. In such cases, measurements are often performed at low radiation dose rates, close to the detection limit of the passive systems. The parameters which may affect the dosimetric results of a passive dosimetry system are analyzed and four laboratories quantitatively evaluate the uncertainties of their passive dosimetry systems. Typical uncertainties of five dosimetric systems in four European countries are compared and the main sources of uncertainty are analyzed using the results of a questionnaire compiled for this specific purpose. To compute the characteristic limits of a passive dosimetry system according to standard ISO 11929, the study of the uncertainty of the system is the first step. In this work the uncertainty budget as well as the characteristic limits (decision thresholds and detection limits) are evaluated and the limitations and strengths of a complete analysis of all parameters are presented.