3rd-INCC

Traces of Fukushima accident in Southern Poland.

21 Sept 2011, 12:50

15m

Paladini (Città del Mare, Terrasini - Palermo - Sicily - Italy)

oral presentation Radioecology and Geochemistry Session 9

Speaker

Mr Kamil Brudecki (The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences,)

Description

As a result of strong earthquake near Japan Islands followed by tsunami wave on 11 of March 2011 a serious damage caused by overheating occurred to reactors of the Fukushima Daiichi Nuclear Power Plant. Uncontrolled radioactive emission to the atmosphere started on 12 of March and was lasting for more than 2 weeks. Radioactive cloud migrated across Pacific, Northern America and came to Europe from northern-western direction The Institute of Nuclear Physics in Krakow operates high volume aerosol sampler MASS-500. The original flow rate of 500 m3/h is reduced to 250 m3/h when the charcoal gas double cartridge is added below the Petryanov filter. Collection of samples started on 21 of March and after detection of 131I on 24 of March the cartridges and filters were changed every day till 11 of April, later the measurements were continued in larger periods. Filters and charcoal were analyzes on low background gamma spectrometer with HPGe detectors. The fallout was collected in two weeks intervals using 2.2 m2 area collector and few persons (Polish citizens) who come back from Japan were analyzed using whole body spectrometer equipped with two HPGe detectors. The presence of 131I, 132I, 129mTe, 132Te, 134Cs,136Cs and 137Cs was established in air filters. Measurable concentrations of cesium appeared three days later that those from iodine. The maximum activity in Krakow for 131I, 134Cs and 137Cs was observed on 28 and 29 March and it was 6 mBq/m3 , 0.6 mBq/m3 and 0.4 mBq/m3 for 131I, 134Cs and 137Cs, respectively. Average activity ratio for 134Cs to 137Cs was 1.11. The ratio between activity in aerosol fraction 131I to gas fraction was changing with time, being almost equal to 1 in the maximum activity it was then increasing to less than 5 in mid-April. In thyroids of Polish citizens who came back from Japan up to 28012 Bq of 131I were found. The estimation of effective dose equivalent (including not well known details of inhalation scenario) yields in about 10 Sv. A search for Pu, Am and Cm isotopes was performed to two sets of filters and to fallout samples. Since the analyses are not finished at the time of writing the abstract all results will be presented during the conference.