Radiation Agents
Primary reference(s)
IAEA, 2018. IAEA Safety Glossary: Terminology used in Nuclear Safety and Radiation Protection, 2018 edition. International Atomic Energy Agency (IAEA). Accessed 15 November 2019.
Additional scientific description
Radioactive materials (natural and human-made) are widely used in industry, medicine and research but can also be used as radiation agents as part of Chemical, Biological, Radiological, Nuclear and Explosive (CBRNE) incidents.
- Alpha-radiation: consists of heavy, positively charged particles emitted by atoms of elements such as uranium and radium. Alpha radiation cannot penetrate skin and can be stopped by a thin paper sheet. However, alpha-emitting radioactive material entering the body by breathing, eating, or drinking, can affect organs and tissues and cause biological damage (IAEA, no date a).
- Beta-radiation: consists of electrons, is more penetrating than alpha-radiation and can pass through the skin surface. In general, a sheet of aluminium a few millimetres thick will stop beta-radiation (IAEA, no date a).
- Gamma-rays: electromagnetic radiation similar to X-rays, light, and radio waves. Depending on their energy, gamma-rays can pass right through the human body, but not through a concrete wall or lead (IAEA, no date a).
Metrics and numeric limits
The magnitude of a source of alpha- or beta-radiation is given by its activity, measured in Curie (Ci) or Becquerel (Bq). 1 Bq corresponds to 1 radioactive decay/second. The impact of radiation on health is measured by the unit ‘Sievert’ symbolised as Sv. Translation of Sv in the units of Disability Adjusted Life Year (DALY) is possible but rarely done. For a radiological dispersal device, an initial ‘hot zone’ boundary should be established at ~1600 feet (500 m) in all directions from the point of dispersion until measurements are made. If it is known that the source used in the incident had an activity of <10,000 Ci (370 TBq), then the initial hot zone boundary can be established at a radius of ~800 feet (250 m). Decisions should not be based on the perceived wind direction, especially in an urban setting in which the wind field can be very complex. Projections with environmental models will not provide accurate predictions of consequences on a distance scale of ~1600 feet (500 m). The location of the hot zone boundary shall be adjusted as radiation measurements become available. This boundary definition is appropriate for both alpha-, beta- and gamma-emitting radionuclides (Musolino and Harper, 2006).
Key relevant UN convention / multilateral treaty
The Code of Conduct on the Safety and Security of Radioactive Sources (the Code) was established to achieve and maintain a high level of safety and security of radioactive sources across the globe. The idea for the development of the Code was first discussed at an international conference in Dijon, France, in 1998 that addressed measures necessary for the safe and secure use of radioactive sources. The conference noted that many countries have weak radiation protection programmes and suggested that the establishment of an ‘international undertaking’ could ensure continuity in regulatory control. The Code was drafted over several meetings. Following the terrorist attacks on 11 September 2001 in the USA, the provisions in the text addressing the security of radioactive sources were enhanced. In September 2003, the Code was approved, and the International Atomic Energy Agency (IAEA) General Conference invited States to make a political commitment to work towards the principles therein and currently 119 States have done so (IAEA, no date b).
The IAEA Preventive Measures for Nuclear and Other Radioactive Material out of Regulatory Control elaborates upon the recommendations given in IAEA Nuclear Security Series No. 15, Nuclear Security Recommendations on Nuclear and Other Radioactive Material out of Regulatory Control, in relation to preventative measures (IAEA, 2019). It serves as a guidance document for Member States interested in strengthening their nuclear security regime as it relates to nuclear and other radioactive material out of regulatory control and in improving their capabilities.
Examples of drivers, outcomes and risk management
Studies following survivors of atomic bomb events and radiation industry workers have confirmed that the radiation exposure increases the risk of cancer, and the risk increases as the dose increases Kodama et al. (2012).
A significant effect from a nuclear explosion is ionising radiation. Intense radiation is produced by the nuclear fission process that creates the explosion and from the decay of radioactive fission products (radionuclides resulting from nuclear fission) (Kodama et al., 2012).
Fission products primarily emit gamma- and beta-radiation. Radiation from a nuclear explosion is categorised as prompt radiation, which occurs within the first minute, and latent radiation, which occurs after the first minute and is mostly emitted by radioactive fallout (NATO, 1996).
Radiological hazards can also occur through accidental spills of radioactive chemicals in laboratories, reprocessing plants or hospitals (such as a spill of uranyl nitrate) or accidents during radiation therapy. Accidents in nuclear power plants can lead to contamination of territories over thousands of square kilometres over tens to hundreds of years by alpha-, beta- and gammaradiation, requiring zoning and evacuation measures (NCRP, 2010).
References
IAEA, no date a. Radiation in everyday life. International Atomic Energy Agency (IAEA). Accessed 1 December 2019.
IAEA, no date b. Code of Conduct on the Safety and Security of Radioactive Sources and Guidance on the Import and Export of Radioactive Sources. International Atomic Energy Agency (IAEA). Accessed 30 April 2021.
IAEA, 2019. Preventive Measures for Nuclear and Other Radioactive Material out of Regulatory Control. International Atomic Energy Agency (IAEA). Accessed 30 April 2021.
Kodama, K., K. Ozasa and T. Okubo, 2012. Radiation and cancer risk in atomic-bomb survivors. Journal of Radiological Protection, 32:N51. Accessed 30 April 2021.
Musolino, S.V. and F.T. Harper, 2006. Emergency response guidance for the first 48 hours after the outdoor detonation of an explosive radiological dispersal device. Health Physics, 90:377-385.
NATO, 1996. Effects of nuclear explosions. In: NATO Handbook on the Medical Aspects of NBC Defensive Operations: A Med P-6(B). Chapter 3. Departments of the Army, the Navy, and the Air Force. North Atlantic Treaty Organization (NATO). Accessed 5 December 2019.
NCRP, 2010. Responding to a Radiological or Nuclear Terrorism Incident: A guide for decision makers. NCRP Report no. 165. National Council on Radiation Protection and Measurements (NCRP). Accessed 1 December 2019.