(3)H activity comparison between FTMC, VNIIM and LNE-LNHB.

An activity comparison of tritiated water was organized in 2013 between 3 laboratories: FTMC (Lithuania), LNE-LNHB (France) and VNIIM (Russia). The solution was prepared by LNHB and ampoules were sent to the others laboratories. This solution was standardized in terms of activity per unit mass by participant laboratories using the Triple to Double Coincidence Ratio (TDCR) method in liquid scintillation counting (LSC).

A long-term performance evaluation of the gamma-ray activity measurement laboratory in CPST, Lithuania.

The quality control procedures used for two HPGe detectors (a well-type and a GAMMA-X coaxial) are described. Since 2001, check sources containing (137)Cs have been measured weekly for 7200s each, and the gamma-ray spectrometry system background was determined once per month for an acquisition time of 100,000 s. The laboratory participated in the international comparisons at environmental radioactivity level organized by the IAEA, Risø National Laboratory and NPL.

Measurements of some radionuclides using a new TDCR system and an ultra low-level conventional LSC counter in CPST, Lithuania.

Beta-emitters (36)Cl and (63)Ni, and the electron capture radionuclide (55)Fe were used to calibrate a secondary standardization instrument Quantulus-1220(TM). An external standard technique was applied to assess the quenching level of samples. Nitromethane as an artificial quencher was used for sample preparation at different quenching levels.