Plutonium content in plants in the site adjusted to the radioactive waste storage facility in Obninsk

Plutonium is long-lived radioactive element of high radiotoxicity. The presence of anthropogenic plutonium in the environment is mainly caused by nuclear tests, nuclear power plants accidents, leaks from nuclear fuel cycle facilities and radioactive waste storages. The radioactive waste storage facility located in Obninsk is one of the first radioactive waste storage facilities built in Russia. Radionuclides leak in the storage from 1998 over 1999 was registered. A set of specific protective engineering measures was carried out in 1999. In subsequent studies, the presence of local radioactive spots, mainly contaminated with 90Sr, was found in the territory of the radioactive waste storage facility and adjacent area. The article presents the results of the 239+240Pu content accumulated by the vegetation growing in the area near the Obninsk radioactive waste storage facility. The analysis of 239+240Pu content in samples was carried out by alpha spectrometry following radiochemical separation. It was found that the plutonium content in the roots of herbaceous plants ranges from (7.9±2.0)∙10-2 Bq/kg to (1.7±0.1)∙100 Bq/kg, in the above-ground part from (3.4±1.0)∙10-2 Bq/kg to (1.2±0.4)∙10-1 Bq/kg. The distribution of 239+240Pu content in different parts of herbaceous plants are consistent with published data, it means that plutonium is accumulated by the plants root system mainly. The range of 239+240Pu content in parts of shrubs is estimated from (4.0±1.4)∙10-2 Bq/kg in branches to (9.0±2.7)∙10-1 Bq/kg in white currant berries, and from (4.0±1.4)∙10-2 Bq/kg in branches to (3.0±0.9)∙10-1 Bq/kg in hazel leaves. The content of 239+240Pu in organs and tissues of woody vegetation varied from (3.4±1.0)∙10-3 Bq/kg to (4.2±1.3)∙100 Bq/kg. The highest content of plutonium was found in tree bark.