Radioactive waste disposal in Greece

Radioactive waste is any material which contains or is contaminated by radionuclides and for which no use is foreseen. According to this definition, a large number of sources, solid, liquid and gaseous, within the Greek territory can be - and, actually, is - declared as waste. The types of such solid sources are presented. It is estimated that these solid sources represent above 90% of all disused sources in Greece. The medical sources of Co-60 and Cs-137 were used in Teletherapy units, while the Ra-226 ones are in the form of needles or tubes used in Brachytherapy. All the industrial sources had been used for measuring moisture, density, thickness, elementary composition, etc. The small sources used by research labs are mainly in the form of discs. The above sources had been imported a long time ago (even 3 decades ago), had been used, and then stored as useless inside the user's premises. Since 1990 all the users of radioactive sources are obliged to return them back to the suppliers when they are no longer in use. In fact, no source is imported unless there is a written declaration of acceptance by its producer. A project concerning the export of all disused sealed sources is in progress. For every source a certificate will be issued, proper container will be purchased and all the necessary documents will be prepared so that it can be transported for final disposal or reuse in a foreign repository facility. Apart from this 'old generated' waste, unsealed radionuclides have always been used in nuclear medicine producing waste. The above radionuclides are used either in vivo (injected or ingested by patients) or in vitro (labeling of blood and other cells). Both uses leave some radioactive waste inside the needles, the tubes, or other material. Since 1991, Greece has a well-established regulatory system for controlling waste from nuclear medicine labs, so that disposing such solid or liquid waste does no harm to the environment. A revision of these regulations has already been published with new, stricter restrictions on waste management. This is described as follows: Liquid: The disposal of liquid radioactive waste to the public drainage is permitted only if the maximum concentration in any part of it is less than 1 GBq/m3. Under no circumstances the daily disposed quantity should exceed 18 MBq for in vitro labs, 37 MBq for in vivo diagnostic labs, and 110 MBq for in vivo diagnostic and therapeutic labs. H-3 and C-14 used as organic solvents in liquid scintillators can be disposed if they contain less than 3 GBq and 0.3 GBq per day, respectively. Solid: Solid radioactive waste is permitted to be thrown away as normal waste if it does not contain reusable objects and its concentration is below the clearance levels for each radionuclide. For example, the clearance levels for Tc-99m, Mo-99, I-131, I-125, and Tl-201 are 10, 1, 1, 10 and 10 Bq/g, respectively. The clearance levels are below the exception levels used to declare a substance as radioactive or not. Short-lived (half-life < 60 days) solid waste that cannot be disposed according to the regulations is stored in vaults inside the labs until their radioactivity falls below the limits. All the other solid waste is returned to its supplier abroad. In summary, the Greek Atomic Energy Commission, which is the national competent authority for radiation protection, controls the use of all radioactive sources and their proper disposal, according to our effective regulatory system, which assures control of inventory, placing responsibility on people, transfer, storage, and disposal to prevent any accident