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Abstract

The large-scale decontamination of FBR sodium loops is a new task, with only a limited number of laboratory-scale results available to date. The principal objective of this work was to develop a suitable decontamination procedure for application to the primary loops of the RAPSODIE fast breeder reactor as part of decommissioning to stage 2. The reactor's primary cooling system and related circuits (excluding the main reactor vessel) were decontaminated with an average metal removal depth of 12 microns. The procedure involved alkaline washing to remove all the labile caesium, decontamination with a mixture of sulphonitric acids with addition of Ce(IV) to entrain the fixed contamination (including about 10% 60Co) and a final phosphatation step. The estimated initial contamination level of 5500 Bq/cm2 was reduced to less than 10 Bq/g, allowing hands-on dismantling operations to proceed without constraints. The dose rate in the areas to be dismantled was divided by ten. A decontamination factor of about 300 was obtained, which would allow austenitic steel parts to be melted in special furnaces for unrestricted release. The decontamination operations generated 2600 kg of dry extract, which was encapsulated by the local waste treatment station.

Additional information

Authors: COSTES J R, CEA, Unité Centrale de Déclassement des Installations Nucléaires, Bagnols-sur-Cèze (FR);GAUCHON J-P, CEA, Unité Centrale de Déclassement des Installations Nucléaires, Bagnols-sur-Cèze (FR);ANTOINE P, CEA, Unité Centrale de Déclassement des Installations Nucléaires, Bagnols-sur-Cèze (FR)
Bibliographic Reference: EUR 13489 FR (1991) 78 pp., FS, ECU 7.50
Availability: (2)
ISBN: ISBN 92-826-2576-1
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