Control system of liquid effluents generated in treatment with I-131

In recent years, nuclear medicine has developed greatly in our country and around the world. Techniques for both medical diagnosis and therapy have increased the use of radiopharmaceuticals, notably the I-131. In Mexico there are around 150 nuclear medicine establishments authorized by the Comision Nacional de Seguridad Nuclear y Salvaguardias. Most of these establishments do not have an appropriate facility for the treatment of radioactive liquid effluents, to ensure compliance with the concentration limits established in the regulations. The Instituto Nacional de Investigaciones Nucleares (ININ) developed and implemented successfully, a control system of radioactive effluents (named SACEL) from a nuclear medicine facility. This system ensures an effective compliance with regulations and also better management and control of these radioactive effluents. Calculations and design of SACEL were made with respect to I-131, because is one of the most commonly used in radiotherapy and medical diagnostics, besides its half-life is greater in relation to other radionuclides. SACEL is comprised of four storage tanks and decay and a fifth tank for measuring the concentration of I-131 and later discharge to the drain; these tanks are connected to an automated system that controls the effluents passage. The calculation to determine the volume of the tanks was carried out according to the demand that has the hospital, to the maximum activity being poured in effluents and time required to decay. In this paper the design and installation of SACEL system, in addition to functioning as a facility that enables the Hospital meet the required standards is presented. Dose calculations performed with MCNPX and the methodology used in the calibration of the detection system is also presented. (Author)