Radioactive waste can be divided and define from numerous points of view. The most important of them are divisions according to their state, level of activity, half life of change of prevailing radionuclides, origin of RAW, treating technologies and the like.

Division of RAW according to state:

> solid RAW,
> liquid RAW,
> gaseous RAW.

Solid RAW originates in nuclear power plants either by contact of solid materials, used in respective facility, with active media, as for example coolant in the primary circle (contamination), or by direct influence of radioactive radiation, when solid materials become emitters (activation). They originate first of all at maintenance works. They comprise replaced parts of technological facilities, assembly tools, construction material, etc. Some of them can be cleaned of radionuclides, i.e. to be decontaminated and used again; other must be processed and stored in storage. Activated parts of a facility and contaminated parts of building constructions, which will have to be liquidated at decommissioning a nuclear power plant, represent a special category.

Liquid RAW from nuclear power plants represents a wide range of waste water originating not only within operation of NPP, but also during maintenance and various repairs. These liquid RAW forms, from the point of view of its volume, the largest part of operational radioactive waste. It contains first of all isotopes of fission and corroding products. We can divide it into that, which can be, after refining, repeatedly used or released from NPP area, and waste, which is necessary to be modified by special technologies into form appropriate for long-term storing in corresponding storages. Liquid RAW unusable and unreleasable from NPP area represents concentrates from evaporating station, saturated ion exchangers and sludge. It is characteristic for this waste that it originates as secondary RAW within treating of repeatedly usable water, and it is, first of all, from low to middle-active concentrated remnants.

Gaseous RAW represents gaseous radioactive elements, scattered particles or aerosols. Its amount and composition is denoted first of all by activity from exhaustion systems of technological facilities and operational rooms. It is stored in the power plant and, after certain period of time, when its activity decreased on required level, it is released in form of gaseous escapes.

Gaseous RAW represents, compared to other types of RAW, evidently the smallest problem, which is connected with its relatively short time lives of contained radionuclides and low biological effectiveness.

Division of RAW according to level of activity:

> low-active RAW,
> middle-active RAW,
> high-active RAW.

Except for spent fuel, first of all also some activated parts of reactor, as for example shielding cartridges, can be included among high-active waste from nuclear power plants. Next, part of concentrated remnants from the evaporation station, some ionexes, special cooling media (chrompik at A1 NPP) belong to this category and a special group will be formed by high-active RAW, which will originate in the course of NPP decommissioning. Also product from retreating of spent fuel has properties of a high-active waste.

Among middle-active RAW belongs middle-active aerosol filters and part of solid waste, a small part of concentrated remnants and others.

Low-active RAW, making up the largest amount, are soft waste, low-active aerosol filters, part of hard waste and the largest part of liquid RAW.

Division of RAW according to the half-life of prevailing radionuclides:

> RAW with short-term radionuclides,
> RAW with long-term radionuclides.

According to the half-life of prevailing radionuclides, we can, except the spent nuclear fuel, small part of solid metallic and liquid RAW and some other high-active RAW, which are treated in the course of NPP decommissioning, consider virtually all other radioactive waste to be short-term with longest period of danger for order of several hundreds to thousands years.

Division of RAW according to origin:

> institutional RAW,
> RAW from nuclear power plant,
> RAW from other sources (e.g. military ones).

Institutional radioactive waste originates beyond power engineering in all areas, where radionuclides are used, thus, in medicine, industry, water management, agriculture, geology, protection of sights of culture and also at specialized schools and laboratories. It becomes radioactive waste only after it is put out of operation (e.g. emitters).

In nuclear power plants so called power engineering nuclear waste originates. It is materials, which were contaminated with radionuclides by intensive contact with radioactive medium and they become waste in this way. The second group is represented by originally non-radioactive materials, which were, in the course of operation of a certain facility, subject to effect of radioactive radiation and they were activated to such a level that they can be denoted as RAW.