Year : 2013 | Volume
: 36 | Issue : 2 | Page : 51-
Recycling of radiation sources in scrap - Radiation protection issues
Editor, Radiation Protection and Environment
|How to cite this article:|
Pushparaja. Recycling of radiation sources in scrap - Radiation protection issues.Radiat Prot Environ 2013;36:51-51
|How to cite this URL:|
Pushparaja. Recycling of radiation sources in scrap - Radiation protection issues. Radiat Prot Environ [serial online] 2013 [cited 2020 Mar 28 ];36:51-51
Available from: http://www.rpe.org.in/text.asp?2013/36/2/51/128864
A number of radioactive sources have various industrial and medical applications. In industry, medium- to high-intensity sources are used for measuring various process parameters (gauges) and in non-destructive testing (NDT - radiography). They have several therapeutic applications in medicine. In spite of the fact that these sources are regulated, the security of the sources (in the public domain) is not up to the required level of confidence.
There are many reported instances where Co-60, Ir-192, Cs-137, Am-241, and Ra-226 sources, often termed as decayed sources, are abandoned, stolen, lost, or misplaced, and ultimately, the sources find their way to the scrapyard and may lose their safe containment or housing. Such a source may lose its identity and get out of regulatory control. The source is likely to be melted along with the scrap, and get recycled into different metallic forms, as containers, contaminated metal (mainly steel) bars/pipes, consumer products, etc. Under such situations, the scrap metal recycling industry has high potential for exposure of the unsuspecting workers, users, and members of the public.
Radiation monitoring systems are being increasingly employed in scrapyards to detect any radiation sources reaching the sites. All the imported steel and other metals are screened using sensitive radiation detectors before they are taken up for further processing. However, it is extremely difficult to detect small sources in huge scrap dumping due to shielding provided by the other materials. Hence, there is always a possibility that small sources get recycled without being detected by the systems provided at various entry and processing points.
It is presumed by the International Commission on Radiological Protection (ICRP) that adequate security measures and controls are provided for the radiation sources to ensure radiological protection in all planned exposure situations. In support of this view, the International Atomic Energy Agency-Basic Safety Standards (IAEA-BSS) emphasized the requirement of proper control of radiation sources all the time to prevent accidental exposures of workers, malicious use of the sources for terrorism, theft, unauthorized possession, or causing environmental contamination.
Under the prevailing circumstances, the above threat scenarios are becoming real. Detecting a radiation source in the scrapyard before it causes harm to the workers and members of the public is an important issue of concern and calls for bringing in awareness amongst the workers of such possibilities and the harm that could be caused by exposure to radioactive sources.
There are radiation sources of various types in the public domain, which are non-penetrating or penetrating radiation-emitting sources such as alpha, beta, gamma, and neutron. Penetrating radiation is easily detectable, while non-penetrating radiation is difficult to detect due to self-shielding. We require different types of detectors to detect different types of radiation, and how low the detection limit should be - needs to be defined. What about the uncertainties associated with such detection methods? Do we need to detect such low radiation levels from well-dispersed radiation sources in the presence of much higher background radiation levels? How to manage the large quantities of the low-level contaminated materials? Should we not see the potential risks in proper perspective? Can we have a re-look at the exemption/clearance levels for bulk clearance of materials? There are many questions and hardly any practical answers!
Further reading: IAEA Specific Safety Guide on "Control of orphan sources and other radioactive material in the metal recycling and production industries", No. SSG-17, 2012, IAEA.