RETROSPECTIVE METHOD VALIDATION AND UNCERTAINTY ESTIMATION FOR ACTINIDES DETERMINATION IN EXCRETA BY ALPHA SPECTROMETRY

Bioassay and alpha spectrometry in indirect monitoring of Spanish workers exposed to enriched uranium

Workers at risk of exposure to uranium compounds should be monitored and their internal exposure quantified in terms of committed effective dose E(50) in mSv. In vitro bioassay methods can quantify uranium in urine and faeces at low activity levels. Alpha spectrometry (AS) is the most common method used for monitoring alpha-emitting radionuclides in internal dosimetry services. It provides isotopic information and low minimum detectable activity (MDA) values (≤0.50 mBq per sample). This study reports the results of a five-year monitoring of workers exposed to uranium at a Spanish Juzbado facility, which produces nuclear fuel elements enriched with up to 5 % of 235U. Monitoring included about 100 workers per year, most of whom had worked at the facility for more than 10 years before the individual monitoring programme was established. We analysed nearly 550 samples of more than 200 workers over five years. The obtained results indicate that workers were adequately protected from uranium exposure through inhalation and had an acceptably low chronic intake at the facility.

THE CHALLENGE OF CIEMAT INTERNAL DOSIMETRY SERVICE FOR ACCREDITATION ACCORDING TO ISO/IEC 17025 STANDARD, FOR IN VIVO AND IN VITRO MONITORING AND DOSE ASSESSMENT OF INTERNAL EXPOSURES

The accreditation of an Internal Dosimetry Service (IDS) according to ISO/IEC 17025 Standard is a challenge. The aim of this process is to guarantee the technical competence for the monitoring of radionuclides incorporated in the body and for the evaluation of the associated committed effective dose E(50). This publication describes the main accreditation issues addressed by CIEMAT IDS regarding all the procedures involving good practice in internal dosimetry, focussing in the difficulties to ensure the traceability in the whole process, the appropriate calculation of detection limit of measurement techniques, the validation of methods (monitoring and dose assessments), the description of all the uncertainty sources and the interpretation of monitoring data to evaluate the intake and the committed effective dose.