The Goiânia accident was a radioactive contamination accident that occurred on September 13, 1987, at Goiânia, in the Brazilian state of Goiás, after an old radiotherapy source was stolen from an abandoned hospital site in the city. It was subsequently handled by many people, resulting in four deaths. About 112,000 people were examined for radioactive contamination and 249 were found to have significant levels of radioactive material in or on their body. In the clean-up operation, topsoil had to be removed from several sites, and several houses were demolished. The demolition sites and the contaminated waste cannot be used or moved for the next 300 years.

The accident was caused by a small capsule containing only 93 grams of highly radioactive caesium chloride (a caesium salt made with a radioisotope, caesium-137) encased in a shielding canister made of lead and steel.

The above scenario clearly shows why a Radiation Security Plan must be implemented. A source security plan provides a comprehensive description of the security systems surrounding the use, transport and storage of a radioactive source and demonstrates how the responsible person will meet the requirements of the code. This includes how risk-based security measures will be implemented to achieve the outcomes appropriate to the categorisation of the source as defined by the Code.