Contribution to the study of the meso-scale atmospheric dispersion of a pollutant: use of krypton 85 released by the COGEMA La Hague nuclear reprocessing plant as atmospheric tracer

Titre du congrès :10th conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes Ville du congrès :Crète Date du congrès :17/10/2005

Operational atmospheric dispersion models (Gaussian Model) are normally valid for releases on the ground, in the near-field where the topography is simple and up to a distance of a few tens of kilometres based on topography complexity. In fact few model validation campaigns have been conducted in the near-field for at-height releases and in complex topography or beyond a few tens of kilometres. IRSN/LRC has therefore conducted a study on the atmospheric dispersion of meoscale pollutants, using krypton-85 (85Kr) released by the COGEMA nuclear spent fuel reprocessing plant at la Hague (north-western France) as the plume tracer (Maro et al., 2001,2002). 85Kr is emitted chronically by two 100 metre-high chimneys 200 metres apart. During a six months compaign, it was measured in real time in the air using proportional counters or plastic scintillators at two stations, one at the Laboratoire de Radioécologie de Cherbourg-Octeville (LRC) 18 km south-east of the release point) and the other at la Hougue signal station (45.4km south-east of the release point). This paper aims to present the 85Kr measurement results obtained from both stations and how they have been interpreted by the atmospheric dispersion operational models developed by Pasquill(1974) and Doury (1976).