Geosystem pollution by radioactive strontium near a regional radioactive waste repository

Abstract

Radioecological studies were carried out in a territory polluted by ⁹⁰Sr delivered by groundwater after leakage from a tank in a near-surface radioactive waste repository. The layer-by-layer vertical distribution of ⁹⁰Sr in soil down to 3 m is analyzed. The area of radioactive pollution above the minimal significant activity level (1 Bq/kg by NRB-99/2009) in the examined soil layers decrease with depth as follows: 1808 m² at 0–5 cm, 302 m² at 5–10 cm, and 181 m² at 10–15 cm. The accumulation of ⁹⁰Sr takes place at a natural sorption geochemical barrier—a swampy area in a near-terrace depression. The radiation dozes were calculated for terrestrial mollusk of Bradybaena fruticum, accumulating strontium in its shell; the doses are in excess of the screening value of 2.4 μGr/day in 41% of the territory. This is higher than the acceptable risk level (5%) for this mollusk population. An excess of the intervention level for ⁹⁰Sr was recorded in both subsurface and surface waters in this geosystem during winter and summer dry seasons and autumn showers.