Proficiency testing for official laboratories for 137Cs and 134Cs determination in soil.

Incidents involving the release of caesium radioactive isotopes into the environment have prompted the adoption of necessary measures to protect the public. A network of official laboratories has been established across Poland to routinely measure the level of radioactive contamination in food. The participation of nine selected laboratories in proficiency testing serves both to demonstrate competence and to confirm the reliability of results. The certified reference material IAEA-478 ″Radionuclides in Soil" was used for this testing. The value assigned from the certificate was determined on the basis of measurement results carried out by specialized laboratories. The International Atomic Energy Agency (IAEA) methodology was applied to evaluate the results, adopting criteria of trueness and precision that account for the measurement uncertainties estimated by the participants. The results obtained by the laboratories for 137Cs and 134Cs were within the reference values ± uncertainty for these caesium radioisotopes. Based on the obtained proficiency tests results, it can be concluded that the official laboratories perform reliable determinations of 137Cs and 134Cs activity concentrations.