Scrap metal collectors dismantled a cobalt-60 radiation source, exposing themselves and others to ionizing radiation.
Symptoms of radiation sickness appeared and medical attention was sought weeks later.
The Office of Atomic Energy for Peace (OAEP) discovered the radiation source and contained it.
The accident resulted in potentially significant exposure of 1,872 people.
Background
Cobalt-60: Used in radiotherapy and sterilization, possesses highly penetrating gamma rays, and has a half-life of 5.27 years.
Regulatory Oversight: Licensing by the Thai Atomic Energy Commission for Peace was insufficient due to lack of resources.
Radiation Source Details: A Siemens Gammatron-3 teletherapy unit, imported in 1969, with a radiation source replaced in 1981. At the time of the accident, its activity was 15.7 TBq.
Accident Details
Initial Event: On January 24, 2000, scrap collectors acquired a lead cylinder containing a radiation source.
Dismantling: The cylinder was cut open on February 1, 2000; subsequent illness symptoms appeared among those involved.
Medical Attention: Symptoms worsened and patients were admitted to hospitals on February 15-17.
Discovery: Doctors suspected radiation exposure and informed the OAEP on February 18.
Response
OAEP Investigation: High radiation levels detected at the scrapyard; no contamination found.
Emergency Operations: Radiation source located and secured by February 19; identified as cobalt-60.
International Assistance: The IAEA assisted in managing the situation and treating victims.
Casualties
Hospitalizations: Ten people admitted with radiation sickness; three died from infection and sepsis.
Affected Population: 1,872 people potentially exposed; medical exams provided.
Public Reaction and Aftermath
Legal Actions: KSE fined; victims received compensation through lawsuits.
Media Criticism: Emergency response perceived as inadequate; IAEA defended the operation.
Public Misconceptions: Fear and misinformation about radiation led to protests.
Regulatory Changes: Highlighted the need for better regulatory practices and public education.
Lessons Learned
Main Contributing Factors: Poor disposal and storage, regulatory oversight failure, lack of warning symbols.
Recommendations: Improved regulations, accountability of sources, and development of new ISO 21482 symbol for radiation warnings.
Continued Incidents: Further unlicensed sources found in Thailand in 2008, emphasizing regulatory challenges.