Lessons learned during the recovery operations in the Ciudad Juarez accident

On or around 6 December 1983 a non-licensed teletheraphy source containing 16.65 TBq (450 Ci) of 60Co was broken and its 6000 pellets began to be dispersed. The consequences of this accident were the contamination of thousands of tonnes of metallic products that were sold in Mexico and the USA, the contamination of several foundries, streets, and hundreds of houses. Health effects in members of the public were also found. Big amounts of contaminated soil and scrap metal were removed from the two most contaminated places: Aceros de Chihuahua foundry, and the scrapyard 'El Fenix'. An intense search covered 17 States of the Mexican Republic, and more than 17,000 building and houses were surveyed. 814 constructions were totally or partially demolished by September 1985. Decontamination of streets of two cities: Ciudad Juarez and Chihuahua, was performed because dozens of pellets of cobalt fell from trucks carrying scrap. Other locations required decontamination, also. In the USA the authorities located constructions made with Mexican contaminated rebar, and in a search that covered the 50 States, they recovered 200 tonnes of table bases made in Falcon de Juarez. The decontamination of soil including pellets was carried out using containers with 18 cm of concrete shielding. Less contaminated soil was manipulated in drums without shielding and scrap and soil with very low levels of contamination were managed as raw material. The Comision Nacional de Seguridad Nuclear y Salvaguardias (CNSNS), recommended as an acceptable limit an exposure rate of 60 μR/h within 1 m of walls in constructions made with contaminated rebar. Because of the big amounts of wastes generated during the recovery operations, a disposal site was designed and constructed approximately 70 km from Ciudad Juarez, in a place known as 'La Piedrera'. 2 figs, 3 tabs