Sr/Y and Calibration of Contamination Superficial Monitors at SSDL-ININ-Mexico

In the Metrology Department at ININ, there is a Secondary Standard Dosimetry Laboratory SSDL, since 1987 it has an Alpha-Beta calibration room. In this room there are: the Beta Secondary Standard BSS Nr. 86 with traceability to the primary laboratory Physikalisch-Technische Bundesanstalt PTB and a reference class extrapolation chamber EC, which had been accredited as Mexican National Standard for realizing the unit of absorbed dose rate to air ) 0 ( Dair & for Sr/Y. The developed activities with these standards are: a) Calibration of ophthalmic applicators with the EC for the determination of ; b) Measurement of at the equivalent tissue deep 0,07 mm , for ) 0 ( Dair & ) 07 , 0 ( Dt & Sr/Y sources of the BSS; c) Monte Carlo MC simulations for ) 0 ( Dair & with the Penelope algorithm; d) Construction of control charts of for the BSS of ) 0 ( Dair & Sr/Y, (Shewhart technique); e) Calibration of personnel dosimeters and ionization chambers in terms of: personal dose equivalent Hp(0.07) and directional dose equivalent H’(0.07,α) with the BSS; f) Testing of personnel dosimetry performance for beta particles in terms of shallow dose equivalent HS(0.07) for Laguna Verde Mexican Nuclear Power Plant. Also, the expanded uncertainties U are presented for , in agreement with the BIPM recommendations, and the percent deviations respect to PTB values. In the other hand, the SSDL-ININ (Nuclear Centre of Mexico) is located at 3 000 meters over the sea level, at Salazar town where P≅71,0 kPa, P/T≅ 0,24 kPa K ) 0 ( D air & ; therefore it was necessary to apply the correction factors: kad and kab; the first one, in order to correct the measurements for atmospheric reference conditions T0 y P0, the second one to take account the attenuation and scattering radiation in the external air to EC. However, for SSDL atmospheric conditions this later factor is out to the range of conditions considerate at PTB. That is why we used correction methods with a broad range, mainly: the NIST procedure and others employed for European laboratories. Additionally, the SSDL-ININ had taken in account another correction factor kdis, this to correct the attenuation and scattering radiation in the air inside the EC volume. Finally, the SSDL has been doing calibration services for contamination superficial monitors by the determination of instrument efficiency εi, and for these services, we utilized reference sources calibrated in terms of surface emission rate q2π.