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Goiânia: 12 years after the 137Cs radiological accident
R M Anjos1, N K Umisedo, A Facure
1Instituto de Física, Universidade Federal Fluminense, Niterói, RJ, Brazil. meigikos@if.uff.br
Radiation Protection Dosimetry
|October 18, 2002
Summary
Cesium-137 (137Cs) contamination from a 1987 radiological accident in Goiânia, Brazil, exceeded action levels in 1999-2000. Measurements revealed significant 137Cs soil concentration and dose rates, particularly in rubble-mixed soil layers.
Area of Science:
- Environmental Science
- Radiological Health
- Nuclear Safety
Background:
- The 1987 Goiânia radiological accident remains one of Brazil's most severe nuclear incidents.
- Persistent contamination from Cesium-137 (137Cs) from a dismantled radiotherapy unit required long-term monitoring.
Purpose of the Study:
- To assess residual 137Cs contamination levels in soil at a contaminated site in Goiânia.
- To compare measured radiological parameters with established Brazilian National Nuclear Energy Commission (CNEN) action levels.
Main Methods:
- In situ and laboratory gamma ray spectrometry were employed for measurements.
- Ambient dose equivalent rate at 1 meter above ground was determined.
- 137Cs concentration in soil samples was quantified.
Main Results:
- Measured ambient dose equivalent rates and 137Cs soil concentrations surpassed 1987 CNEN action levels.
- Specific activity of 137Cs reached up to 175 kBq x kg(-1) in soil layers mixed with rubble.
- The 137Cs distribution profile indicated elevated contamination between 10-40 cm depth.
Conclusions:
- Residual 137Cs contamination posed a significant radiological risk years after the Goiânia accident.
- The findings underscore the importance of thorough site remediation and long-term environmental monitoring post-radiological incidents.