NPP operational and decommissioning RAW and institutional RAW

The NPP operational radioactive waste category incorporates the waste generated in both the operation and decommissioning of NPPs. RAW gen­erated in institutional applications are also included in this group and in some countries are even managed (entirely or only for some steps) together with NPP waste. This category is the biggest from the point of view of the waste volume generated and covers a wide spectrum of wastes with respect to their radiological, chemical, physical, aggregate and other properties. Therefore the classification system is complicated, usually reflecting coun­try-specific approaches, national waste management strategy, regulations, and often technological and other aspects. The IAEA in its Radioactive Waste Management Status and Trends [ 1] has recognized more than 40 different country-specific RAW classification systems. It is obvious that under such conditions it is difficult to unify approaches, evaluate and compare national systems, and make a plan for optimization and recom­mendations for safe RAW management.

The IAEA has made a systematic effort to develop a unified and inter­nationally accepted classification (categorization) of RAW for a long time in order to facilitate communication between involved parties in various countries and organizations. At the beginning of the 1990s the first comprehensive IAEA document was published on Classification of Radioactive Waste [2], which based the RAW classification system on aspects related to waste disposal safety and proposed the boundaries of individual RAW categories using International Commission on Radiological Protec­tion (ICRP) recommendations for annual individual and collective doses for public. The two main radiological parameters used for the RAW classifica­tion system are the radioactive material concentration and the half-life of critical radionuclides. This proposed system has been accepted for develop­ment of a national RAW classification system in many countries.

Further evolution resulted in a new IAEA RAW classification system published in 2009 [3] [ which is more generic and almost exclusively based on long-term waste disposal safety considerations (in other words, for each RAW class there is a specific proposed/assigned waste disposal route). This recent waste classification system was modified in order to reflect a better relationship between RAW categories and the safety aspects of the consid­ered disposal options. While the 1994 IAEA document provided basic numerical boundary values for various RAW classes, the 2009 document offers only a general approach and leaves the development of more exact figures to the individual national regulations. For illustration and a better understanding of the boundary parameters and values for distinction of the

RAW categories, the data from the 1994 IAEA document [2] are given in Table 2.1. In spite of the fact that the 1994 IAEA document [2] is no longer applicable, while the updated IAEA 2009 document is available [3], these figures are still used as informative values in preparation of the national classification systems.

In accordance with the present IAEA approach to RAW categorization [3], six classes of waste are proposed for consideration in preparation of the national classification systems. It should be noted that precise values of applicable total activity content and eventually activities (activity concen­trations) of the most significant individual radionuclides for each waste category shall be specified on the basis of safety assessments for individual

Table 2.1 Typical characteristics of waste classes [2]

image056 Подпись: Activity levels at or below clearance levels given in IAEA draft documenta, which are based on an annual dose to members of the public of less than 0.01 mSv Activity levels above clearance levels given in IAEA draft documenta and thermal power below about 2 kW/m3 Restricted long-lived radionuclide concentrations (limitation of long-lived alpha emitting geological radionuclides to 4000 Bq/g in individual waste disposal facility packages and to an overall average of 400 Bq/g per waste package) Long-lived radionuclide concentrations exceeding limitations for short-lived waste disposal facility Thermal power above about 2 kW/ m3 and long-lived radionuclide concentrations exceeding disposal facility limitations for short-lived waste image058

Waste classes Typical characteristics Disposal options

a IAEA draft document: IAEA Clearance levels for Radionuclides in Solid Materials: Application of Exemption Principles, Safety Series No. 111-G-1.5, in preparation in 1994, IAEA, Vienna. Later reconsidered, rewritten and published as Reference [4].

disposal route and disposal site. This is the responsibility of the national authorities and the values used can differ significantly in individual countries.

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