In 2011 a measurement intercomparison was launched by EURADOS WG7, with the objective of providing the participants with the tools to calibrate their detection systems for detection of 241 Am in the skull bone, and evaluate the variability due to the used of the different calibration phantoms. Three skull phantoms were used in this intercomparison: the USTUR Case 0102 skull phantom, the BfS skull phantom and the CSR skull phantom. Very good agreement was found between the results of the twelve participating laboratories, with relative deviations of less than 15% for the BfS phantom and less than 17% for the USTUR phantom when measurement efficiency in defined positions was compared. However, the phantoms' measured absolute 241 Am activities showed discrepancies of up to a factor of 3.4. This is mainly due to the physical differences between the standard calibration phantoms used by the participants and those used in this intercomparison exercise.

The values of the iodine 131I uptake determined from the measurements with a NaI scintillation counter might be significantly influenced by the thyroid position in the human neck. It is shown that the ratio of the counting rate in the energy peak of 364 keV to the counting rate in the Compton scattering band can be used for the determination of the effective depth of the thyroid. The uncertainties of the standard method are discussed basing on results of calibration measurements. The investigations of 95 patients with different thyroid diseases showed that the measured iodine spectrum was considerably different from the standard for about 20% of them, indicating possible high uncertainties of the standard measurements, which assume a fixed thyroid depth of 20 mm.

Abstract. The studies aimed at determining low activities of alpha radioactive elements are widely recognized as essential for the human health, because of their high radiotoxicity in case of internal contamination. Some groups of workers of nuclear facility at Otwock are potentially exposed to contamination with plutonium isotopes. For this reason, the method for determination of plutonium isotopes has been introduced and validated in Radiation Protection Measurements Laboratory (LPD) of the National Centre for Nuclear Research (NCBJ). In this method the plutonium is isolated from a sample by coprecipitation with phosphates and separated on a AG 1-X2 Resin. After electrodeposition, the sample is measured by alpha spectrometry. Validation was performed in order to assess parameters such as: selectivity, accuracy (trueness and precision) and linearity of the method. The results of plutonium determination in urine samples of persons potentially exposed to internal contamination are presented in this work.

Ocena narażenia wewnętrznego za pomocą licznika promieniowania ciała człowieka Proces oceny narażenia wewnętrznego na skażenia substancjami promieniotwórczymi jest skomplikowany i towarzyszy mu wiele czynników, które są źródłem niepewności szacowania obciążającej dawki efektywnej. W niniejszym artykule przedstawiono sposób właściwego postępowania podczas szacowania obciążającej dawki efektywnej za pomocą Licznika Promieniowania Ciała Człowieka.

The elevated concentration of 210 Po attached to aerosol particles inside a non-ferrous metal refinery was studied. The aerosols were collected on Petrianov or glass-fiber filters and subsequently subjected to radiochemical procedure consisting of acid leaching and concentration by micro co-precipitation with manganese oxide. For the activity determination alpha spectrometry and liquid scintillation counting (LSC) were applied. The obtained results showed that usually observed polonium concentration inside the plant was lower than 78 mBq m −3 , however short spikes up to 7430 ± 710 mBq m −3 (related to the specific thermal process) were also observed.