Radiological Characterization of TFA metallic tubes from CERN Accelerator Complex

The scope of this thesis consists in the radiological characterization of chilled water pipes used for air-conditioning and exposed to ionizing radiation in the PS accelerator, one of the CERN accelerators, for more than 40 years. Due to corrosion problems, the 1200 m of steel pipeline were removed from the PS tunnel during the long shutdowns between the years 2000 to 2004. The radiological characterization, that included the use of FLUKA Monte Carlo simulations and the JEREMY code, began in mid-2011 and revealed a radionuclide inventory with the presence of 55Fe as dominant radionuclide and 60Co as dominant gamma emitter. Due to operational reasons, only 5.5% of the pipeline were characterized for validation. In the course of this work it was found that the contribution of both aforementioned radionuclides corresponds to more than 90% of the total computed IRAS factor (Indice Radiologique d’Acceptation en Stokage). Two different methods were used for the characterization of the PS pipes, yielding two different values of IRAS factor, very close to each other and both of them fulfilling the radiological ANDRA acceptance criteria. Therefore, and as expected, the PS pipes will be most probably eliminated, as soon as operationally possible, as radioactive waste towards the French TFA (Très Faiblement Actif) final repository in the Aube district.