Criticality Control During the Dismantling of a Uranium Conversion Plant.

Ladurelle, L. ; Lisbonne, P.

Technical Information Center Oak Ridge Tennessee

关键词: Decommissioning;    Criticality;    Enriched uranium;    Fissile materials;    Safety analysis;   

RP-ID  :  DE2004825983

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Within the Commissariat a l'Energie Atomique, in the Cadarache Research Center in southern France, the production at the Enriched Uranium Treatment Workshops started in 1965 and ended in 1995. The dismantling is in progress and will last until 2006. The decommissioning is planned in 2007. Since the authorized enrichment in Uranium 235 was 10% in some parts of the plant, and unlimited in others, the equipment and procedures were designed for criticality control during the operating period. Despite the best previous removing of the uranium in the inner parts of the equipment, evaluation of the mass of remaining fissile material by in site gamma spectrometry measurement shows that the safety of the 'clean up' operations requires specific criticality control procedures, this mass being higher than the safe mass. The chosen method is therefore based on the mapping of fissile material in the contaminated parts of the equipment and on the respect of particular rules set for meeting the criticality control standards through mass control. The process equipment is partitioned in separated campaign, and for each campaign the equipment dismantling is conducted with a precise traceability of the pieces, from the equipment to the drum of waste, and the best final evaluation of the mass of fissile material in the drum.