Comparison of Lagrangian atmospheric dispersion models (DIFPAR, SPRAY) with 85Kr measurements taken around La Hague spent fuel reprocessing plant.
Michel Bouzom1, Denis Maro2, François Bompay1, Christine Lac1 and Didier Hebert2
actes du congrès "8th conference on harmonization within atmospheric dispersion modeling for regulatory purposes" - The national institute of meteorology and hydrology, Bulgarian academy of sciences, sofia, bulgarie 14-17 octobre 2002
Ekaterina Batchvarova and Dimiter Syrakov (Eds) - pages 205 à 209.
In June 1997 the Institute for Radiological Protection and Nuclear Safety (IRSN) in collaboration with Météo-France began a joint in situ investigation around COGEMA's La Hague spent fuel reprocessing plant (France) with the aim of reducing the uncertainties surrounding near field (< 4 km) operational atmospheric dispersion models (Pasquill, 1974; Doury, 1976) for elevated emissions. The program was to look into krypton-85 (85Kr), the chemically inert gas, released in the gaseous waste (release stack 100 m high) as a plume tracer (Maro, 2001).
Krypton-85 is a radioactive b- and g-emitting isotope with a radioactive half-life of 10.71 years, which is both naturally occurring and produced in nuclear reactors. Furthermore it has been released into the atmosphere following atomic bomb explosions, but most emissions are currently discharged by spent fuel reprocessing plants such as COGEMA's La Hague plant.
The goal of this investigation is to compare the Atmospheric Transfer Coefficients (ATC) obtained from 85Kr measurements in La Hague with the findings of two Lagrangian atmospheric dispersion models: DIFPAR (developed by Electricité De France) and SPRAY (an ARIA Technologies product). The meteorological data is supplied by the meso-NH model, a non-hydrostatic meteorological model developed jointly by Météo-France and the Aerology Laboratory of the French National Scientific Research Center (CNRS). In this paper the computations of the two models are presented and compared with the ATCs measured in the environment over the course of two measurements campaigns held on 23 April 1998 and 15 June 2000.
1Météo-France, DP/SERV/ENV, 42 avenue Coriolis 31057 Toulouse Cedex (France)
2Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Département de Protection de l'Environnement, Service d’Etudes et Recherches radioécologiques dans les milieux NATurels, LERFA F-50130 Cherbourg - Octeville (France).