Installations Nucleaire de Base (INB)
LEP and the 4 experiments are being operated under an agreement with INB, the French authority in charge of all nuclear installations in France. This has major consequences for the dismantling of the LEP machine, but possibly also some consequences for the dismantling of the experiments.
The LEP dismantling document which describes the strategy and the procedure of the LEP dismantling (zoning, waste study, risk analysis) has been presented to INB in September 1999 but was rejected for various reasons. One of the main points of criticism was that the experiments were not treated in an adequate way.
It was felt that the fastest way to solve this problem, is to write a number of annex documents:
- The zoning analysis (i.e. a classification of the various parts of the experiments as conventional or radioactive zones), common for the 4 experiments, is mainly based on calculations performed by TIS (M. Silari et al.) in collaboration with the experiments (Many thanks to Vincent Hedberg who represented DELPHI in this team). In some cases the calculations have been verified by various activity measurements during the 1999/2000 shutdown. The main result is that, with the exception of the very forward luminosity monitors VSAT, any material may be classified as conventional. According to the calculations, a small level of induced radioactivity may be expected for the VSAT detectors, so that they have to be classified as "TFA" (très faiblement active).
- A waste study and risk analysis has been made for each of the 4 experiments individually. The DELPHI document (click here for the latest version), written by Christian Joram and Jean Renaud, describes the detector, the overall dismantling planning and discusses then in detail the various sub-detectors and their disposal paths. Special care has been given to detectors carrying radioactive sources.
The goal of these documents is to convince INB, that the expected and also measured radioactivity levels justify to dismantle the experiments without following the full set of strict regulations which are applied to the LEP machine. In particular a complete inventory and subsequent tracing of all dismantled pieces has to be avoided. The experiments should be considered as INBlight. The tracability requirement for all material coming from LEP and other INB constraints may have indirect implications for DELPHI since we are sharing the same site and in particular the same access to the site.
The modified LEP document together with the annex documents for the experiments have been presented to ISPN and subsequently to DSIN in January 2000. A final and firm approval of the proposed procedure can however only be expected by summer 2000. Semi-official information indicates however that the French authorities will accept the experiment's proposals.