FUKUSHIMA ACCIDENT THROUGH SLOVENIAN RADIOACTIVITY MONITORING Jasmina Kožar Logar 1, Marijan Ne čemer 1, Katarina Vogel Mikuš2, Branko Vodenik 1, Denis Glavi č–Cindro 1

1 Jožef Stefan Institute, , 2 Department of Biology, Biotechnical Faculty, Ljubljana, Slovenia

ABSTRACT Precipitation samples After Fukushima accident additional attention was stressed to the aerosol and Precipitation samples are collected in black plastic 50 L canisters trough the 2 precipitation samples from regular monitoring programmes. In rain water stainless steel funnel with the area of 0.25 m and mounted 1 m above the samples, aerosol and iodine filters which were collected in the second half of ground. Within the regular monitoring programmes in Slovenia monthly March and in April 2011 I-131, Cs-134 and Cs-137 were detected. In May 2011 composite samples from precipitation collectors in , and Dobova in the activities of I-131 and Cs-134 were close or below detection limit and vicinity of Krško NPP and in Ljubljana (reference location) are taken. Cs -137 reached values from period before Fukushima accident. Beside this additional mussel sample was taken and analysed in April 2011. Activities of I-131, Cs-134 and Cs-137 were below detection limit.

REGULAR MONITORING PROGRAMME

Aerosol and iodine samples Within regular monitoring programme of the environment of Krško NPP aerosol samples are sampled at 8 locations around Krško NPP (, Krško – Stara vas, Leskovec, Brege, , Gornji Lenart, Spodnja and Dobova) and in Ljubljana as reference location.

•Aerosol sampling comprises continuous pumping of air through aerosol quartz filters with pore size 0.45 µm and area 30 cm × 30 cm, the average air flow rate is approximately 11,000 m 3/month or 270 L/min. •At reference locations in Dobova and Ljubljana two pumps for aerosol sampling with high flow rate are placed. They permit sampling of high volume of air of 150,000 m 3/month or 1800 L/min through a specially designed quartz filter with area 0.87 m 2 and pore size 0.45 µm. Due to high volume of pumped air these pumps are very sensitive and therefore also traces of radionuclides Fig. 2: Activities of I-131, presented in the air can be detected. Cs -134 and Cs-137 in rain water samples •Sampling of iodine presented in air is performed separately with special pumps and filters at the same locations as that of the aerosol sampling locations (except for the locations Dobova and Ljubljana). Iodine presented in air in molecular or atomic form are sampled through a plastic disc filter with diameter of 9 cm and height of 5 cm, at bottom side is quartz filter, upper part is filled with active charcoal impregnated with TEDA. These pumps work at low air flow SPECIAL MUSSELS SAMPLING AND ANALYSIS rate of 1,300 m 3/month or 30 L/min. As it is expected that mussels accumulate heavy metals including caesium, we decided to sample and analyse them to trace deposition of radionuclides originating from Fukushima accident. Therefore 3.68 kg of mussels ( Mytilus galloprovincialis ) was sampled on April 7, 2011 in Izola at the local shell breeder. The shells, interior liquid and soft tissues were separated. 0.48 kg of whole soft tissues (WST) was rapidly frozen in a liquid nitrogen and freeze dried via the Alpha Christ freeze drier at -25 °C and 0.02 mbar for 2 days. Concentrations of gamma-ray emitters in dry weight of WST and remaining liquid from mussels were determined with high resolution gamma-ray spectrometry. Beside this gross alpha / beta emitters were determined by liquid scintillation counting in the water residue which left after freeze drying of WST and tritium concentration in sea water sampled separately at same location.

Table 1

P11-HM6320SI-41 P11-HM6320SI-42 Sample code (whole soft tissues) (water from mussels) Specific activity ISOTOPE (Bq/kg) Be-7 4,2 ± 0,3 2,1 ± 0,2 K-40 39,2 ± 4,0 41,3 ± 4,2 I-131 <0,04 # <0,03 # Cs-134 <0,02 # <0,03 # Cs-137 <0,03 # 0,08 ± 0,03 Pb-210 3,5 ± 0,3 2,4 ± 0,2 Ra-226 0,20 ± 0,08 0,4 ± 0,1 Ra-228 <0,1 # 0,08 ± 0,06 Th-228 0,17 ± 0,03 0,13 ± 0,03 U-238 0,9 ± 0,5 3,3 ± 1,8 Fig. 1: Activities of I-131, Cs-134 and Cs-137 in air filters # Results labeled with # are detection limits.

CONCLUSIONS In second half of March and in April 2011 the influence of radioactive plum from Fukushima was detected in aerosol and precipitation samples in Slovenia, values are similar as measured at other laboratories within Europe and in accordance with predictions of Fukushima radioactive plum spread. In May 2011 the activities diminished and are reaching values from the time before Fukushima accident what indicates that there were no additional releases from Fukushima NPP that reached region of Central Europe.