Activity measurement of gamma-ray emitters in aerosol filters exposed in Lithuania, in March–April 2011

• Daily and weekly samples were analyzed by the gamma-ray spectrometry using different HPGe detectors and measuring geometries.
• Corrections of 8–12% for the true coincidence-summing in 134Cs decay were applied.
• The activity ratio 134Cs/137Cs was found to be in the range 0.99–1.09.
• This result is consistent with published data on Fukushima radioactive release.

Two aerosol sampling stations in Lithuania were simultaneously used for assessing consequences of the accident at the Fukushima Dai-ichi nuclear power plant. The maximum activity concentrations of 129mTe, 131I, 134Cs and 137Cs were 0.59±0.06, 3.5±0.3, 0.90±0.08, 0.90±0.07 mBq m−3 at station #1 in Vilnius, and 0.29±0.03, 1.0±0.1, 0.41±0.04, 0.41±0.04 mBq m−3 at station #2 in northeastern part of Lithuania, respectively.