A follow up of the decrease of non exchangeable organically bound tritium levels in the surroundings of a nuclear research center

• Published in: Journal of environmental radioactivity Vol. 102; no. 7; pp. 695 - 702
• Main Authors: Baglan, N., Alanic, G., Le Meignen, R., Pointurier, F.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.07.2011; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Atmospherics; Biological and medical sciences; Carbon; Earth sciences; Earth, ocean, space; Ecotoxicology, biological effects of pollution; Engineering and environment geology. Geothermics; Environmental monitoring; Exact sciences and technology; Exchange; Fundamental and applied biological sciences. Psychology; General aspects; Global environmental pollution; Magnoliopsida - chemistry; OBT; Plant Leaves - chemistry; Pollution; Pollution, environment geology; Radiation Monitoring - methods; Radioactive Pollutants - chemistry; Radioactivity; Sampling; Scintillation Counting; Trees; Trees - chemistry; Tritium; Tritium - chemistry; Vegetation; Wind; Essonne; France; Europe; Ile-de-France; OBT; Environmental monitoring; Tritium; Organic matter; Radioactive pollution; Risk assessment; Environment impact; Nuclear installation; Radioisotope
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2011.03.014

In the past decades limited amounts of tritium were handled on the CEA site of Bruyères le Châtel with authorised atmospheric releases. A small fraction of the tritium released entered into environmental samples under three forms: (i) as part of free water (TFWT – Tissue Free Water Tritium), or associated with organic matter in two ways; either (ii) bound to the oxygen and nitrogen atoms of the material as exchangeable organically bound tritium (E-OBT), or (iii) bound to carbon atoms as non exchangeable organically bound tritium (NE-OBT). The first two components provide only a picture of atmospheric tritium concentrations at the sampling time as they are in equilibrium with atmospheric moisture and soil humidity. Unlike these exchangeable forms, however, NE-OBT is tightly bound to the organic matter and provides an integrated record of atmospheric tritium during the growing phase of the vegetation. We mapped NE-OBT in tree leaf samples in an area of about 25 × 30 km 2 around the centre of the CEA site and compared the results with those obtained during a previous sampling exercise in 1989. At this time, the activity levels were almost ten times higher than those observed presently in a similar area almost 20 years later which is consistent with the decrease of atmospheric releases issued from the centre. As the activity levels are now close to environmental background specific attention was also paid to the analytical procedure to ensure reliable low level NE-OBT detection. ► OBT analysis to perform environmental tritium monitoring. ► NE-OBT analysis to follow tritium integration in tree leaves. ► Comparison for samples collected either on short term period (within a year) or larger time period demonstrates the interest of NE-OBT analysis.