A nondestructive analytical method based on autoradiography and gamma spectrometry was developed to perform activity distribution analysis for particulate samples. This was applied to aerosols collected in Fukushima Japan, 40 km north of the Daiichi Nuclear Power Plant for a 6 week period beginning shortly after the March 2011 tsunami. For an activity distribution of 990 "hot particles" from a small filter area, the hottest particle was nearly one Bq 137+134Cs but most of the activity in the filter was produced by particles having less than 50 mBq each. 134Cs/137Cs activity ratios corrected to March 20, 2011 ranged from 0.7 (σ = 28 %) to 1.3 (σ = 15 %). The average ratio for a large quantity of particles was 0.9 (σ = 3 %). Virtually all activity collected was beta and not alpha, suggesting little if any direct fuel debris was present at this site and time. These findings are expected to assist with separate efforts to better understand the emission events, radionuclide transport and potential environmental or biological uptake. The methods should be applicable to general environmental, radiotoxicological and similar studies for which activity distribution and particle chemistry are of importance.
Citation: Journal of Radioanalytical and Nuclear Chemistry
Pub Type: Journals
137Cs, 134Cs, activity distribution, Daiichi Nuclear Power Plant, detection limit, Fukushima, imaging plate autoradiography, particle microanalysis, size distribution