Authors: Veronika Sedláková, Karel Lehmert Affiliation: Dept. of Criminology & Forensic Studies, University of Finance and Administration, Prague, Czech Republic Keywords: orphan sources, Prague, Radium-226, radiation safety, urban HAZMAT
Introduction
On 28 September 2011, a radiological incident was detected in a populated area of Prague. Elevated radiation levels were reported by a citizen using a personal dosimeter, which recorded unusual readings near the entrance to a children's playground on Sinkulova Street. This incident represents a case of radioactive material occurring outside state administrative and regulatory control. The source was later identified as a historical sealed source containing Radium-226, most likely a remnant from a defunct research or medical facility that had been improperly disposed of in the 1990s.
Methodology
The analysis is based on reports from the State Office for Nuclear Safety and documentation of the response by the Integrated Rescue System. The evaluation includes dosimetric measurements conducted by a mobile unit of the National Radiation Protection Institute. Analytical methods focused on isotopic identification, assessment of environmental risks, and analysis of institutional gaps in the registry of historical radiation sources in the urban environment of Central Europe.
Results
The source was identified as a lead cylinder measuring 2.8 cm in length, containing radium-226 with an estimated activity of approximately 660 MBq. The maximum measured dose equivalent rate in the immediate vicinity of the source reached values of up to 150 mSv/h, significantly exceeding the natural background radiation at the site. The source was located approximately 10 cm below ground level and was subsequently safely recovered by a specialized unit. The event was classified as Level 1 on the International Nuclear and Radiological Event Scale (INES) (anomaly). No environmental contamination was detected, and following removal of the source, radiation levels at the site returned to natural background levels (approximately 0.1 µSv/h).
Discussion
The Prague incident highlights the risks associated with orphan sources in urban environments. The primary issue in this case was the insufficient registry of older radionuclide sources, particularly those originating from the 1950s. The case also underscores the importance of preventive monitoring in areas with historical industrial or medical activity. Effective communication with the public also played a crucial role in preventing panic in the vicinity of the children's playground.
References
- State Office for Nuclear Safety (2012). Annual Report on the Results of Radiation Monitoring in the Czech Republic in 2011. Prague: SÚJB.
- National Radiation Protection Institute (2011). Internal Documentation and Dosimetric Analysis: Radiological Incident in Prague-Podolí. Prague: SÚRO.
- Gusev, I. A., Guskova, A. K., Mettler, F. A., editors (2001). Medical Management of Radiation Accidents. 2nd ed. Boca Raton: CRC Press.
- International Atomic Energy Agency (2004). Code of Conduct on the Safety and Security of Radioactive Sources. Vienna: IAEA.
- International Atomic Energy Agency (2004). Management of Orphan Radiation Sources. IAEA TECDOC Series No. 1388. Vienna: IAEA.
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