Quarterly Journal of Engineering Geology, 28, $95-S104. 0481-2085/95 $07.00 © 1995 The Geological Society The Geology and Hydrogeology of the Sellafield Area The geology and hydrogeology of the Sellafield area: development of the way forward

This paper summarizes the way in which Nirex has used knowledge of the Sellafield site gained through experience to establish a forward strategic programme of work. The use of iteration between data collection and model refinement inorder to ensure the programme r mains focused on key uncertainties is discussed. These iterations are described as cycles of site characterization. A broad framework for site characterization activities is discussed, which identifies the work under three broad head-ings; potential repository zone (PRZ) studies, regional studies and hydrochemical studies. Work performed under previous cycles of site characterization is summarized and activities planned for the next cycle of site characterization are presented. These are placed in context with the uncertainty which they are designed to address. The paper concludes by restating the need for the programme of site characterization undertaken by Nirex to be flexible, and to evolve as necessary to ensure new understanding is accommodated, and used to redefine strategy on a regular basis