Radioactive waste is the residual "useless" products generated from human activities entailing radioactive materials. Radioactive materials are commonly used in:
- medicine, for diagnostic examinations and nuclear medicine treatments (i.e. use of radiopharmaceutical products), as well as for radiotherapies (e.g., irradiation of tumors, intra-tissue implants);
- industry, for radiography purposes, sterilization purposes, quality control (e.g., measurement of thickness of materials), etc.;
- research and training, e.g. biological experiments, chemistry experiments;
- other specialized applications.
Radioactive waste in Greece originates from medicine, industry and research applications. The majority of them are medical waste, generated by the application of radioactive sources or materials in the medical sector. The medical waste is very short lived, low-level waste that following in-situ management can be released to the environment.
Apart from the medical waste, small quantities of other radioactive waste are generated in the country that require management. Indicatively:
- medium level radioactive waste are expected to be generated during the decommissioning of the NCSR “Demokritos” research reactor; an agreement for repatriation of the spent fuel to the country that provided the nuclear fuel is in place;
- radioactive waste are generated when equipment and consumer products containing radioactive materials, e.g. smoke detectors, lighting rods, fluorescent signs, complete their useful life;
- radioactive sources and materials detected in scrap metal imported by metal recycling industries are characterized as radioactive waste;
- radioactive sources out of regulatory control (cases of theft, loss or abandonment, etc.) become "orphan" and are characterized as radioactive waste.
Click to see the inventory of radioactive waste (September 2018).
According to the international standards, the final management solution for radioactive waste may be either release to the environment, provided that the established clearance levels are met, or disposal (emplacement without the intention of retrieval) within a radioactive waste disposal facility. The storage of radioactive waste is not considered as final management solution.
There does not exist a disposal facility in Greece. There exists a centralized facility for interim storage of radioactive waste. The interim storage facility operates under the Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES) of the National Center for Scientific Research “Demokritos” (NCSR “D”).
Pursuant to Directive 2011/70/Euratom, all Member-States are responsible for the management, from the production till the final disposal of the radioactive waste they generate. Greece is responsible for the safe management of radioactive waste generated within the Greek territory, according to the provisions of the art. 4 of the Presidential Decree no. 122 (Government Gazette no. 177/A/12.08.2013), as amended by the Presidential Decree no. 91 (Government Gazette no. 130/Α/01.09.2017), and the National Programme (published in the Government Gazette no.4317/B/02.10.2020).
The decay time
Just like all radioactive materials, radioactive waste decays based on the half-life of the isotope included therein. For example, an amount of cobalt (Co-60) will remain half after a period of 5.6 years, which is the half-life of cobalt (Co-60). Each isotope has its own half-life, which may be extremely short, e.g. just 12 seconds for barium (Ba-143) or even extremely long, e.g. 1577 years for radium (Ra-226), 5730 years for carbon (C-14) and 4.5 billion years for uranium (U-238). Thus, some isotopes, and consequently radioactive waste, never "die" and a long-term and careful treatment in special installations is required, whilst a simple in-situ management is enough for short-lived isotopes.
Due to the hazard to public health and environment, radioactive waste has to be managed either directly by their producer or in the long-term within specialized facilities. According to the international standards, the following two methods of radioactive waste management may be applied:
• by release to the environment, provided that the established clearance levels are met. Such clearance levels have been set, on the condition that no person should receive a radiation dose above 10 μSv (microsievert) per year due to the total releases of radioactive substances into the environment. It should be noted that the dose limit for a person from all practices with ionizing radiation is 1000 μSν per year.
• by disposal (emplacement without intention of retrieval) within a radioactive waste disposal facility. There are several types of installations for the disposal of radioactive waste, such as land field disposal, near surface disposal, borehole, etc. The selection of the type of the disposal facility depends on multiple factors, such as the kind, the form, the status and the quantity of radioactive waste, the packaging of radioactive waste, the existing and future environmental, geological, seismic and climate conditions, the conducted studies (e.g. environmental, geological, hydrological, seismic) and the related scientific, research and development programs carried out, the programs for area reformations, the existing and future infrastructure, financial and social factors, etc.
What is the difference with nuclear waste
Nuclear waste refers to the nuclear spent fuel (containing uranium and fission products), which no longer may be used for the operation of a reactor. Due to their characteristics, their hazard and the need for special treatment, spent fuel, although being radioactive waste, is referred to and handled separately. Deep geological disposal is the generally accepted method for nuclear waste management.