The Dismantling Project for the Large Electron Positron (LEP) Collider

The LEP accelerator was installed in a circular tunnel 27 km in length with nine access points distributed around the circumference in the countryside and villages which surround CERN's sites. The dismantling project involved the removal in less than 15 months of around 29000 tonnes of equipment from the accelerator itself and a further 10000 tonnes from the four experiments - all of which were located at an average depth of 100 m below ground level. There was no contamination risk in the project and less than 3% of the materials removed were classified as radioactive. However, the materials which were classified as radioactive have to be temporarily stored and they consume considerable resources. The major difficulties for the project were in the establishment of the theoretical radiological zoning, implementation of the traceability systems and making appropriate radiation measurements to confirm the zoning. The absence of detailed guidelines from the French authorities, having no threshold levels for release of radioactive materials and being the first dismantling project of a large accelerator made the task more difficult and more expensive. Further difficulties remain because materials classified as having very weak radioactivity (très faiblement actif -TFA) by the zoning study which have no induced activity have to be treated in the same way as radioactive waste. This paper describes the organisation of the project and its execution and examines some of the problems which arise from the INB system; the radiation protection aspects of the project are discussed in the paper entitled "Déclassement du grand collisionneur d'electrons/positrons (LEP) du CERN", also presented at this conference.