Waste types

Radioactive substances (according to the definition of the Atomic Energy Act), for which no future use is foreseen, will be regarded as radioactive waste. Radioactive waste arises from the use of ionising radiation in nuclear power plants, research, industry and, in small quantities, medicine. It must be disposed of properly - i.e. in final storage - in accordance with the provisions of the Atomic Energy Act.

Waste containing very small quantities of radionuclides, which is not considered radioactive waste in a legal sense, must be disposed of in accordance with the provisions of conventional waste legislation. Many types of waste from the dismantling of nuclear facilities belong to this category.

Natural radioactive materials that accumulate as a waste product from other operations, for example in the oil and gas, raw phosphate and primary smelting industries (industrial residues), are not considered radioactive waste, either. They are referred to as residues requiring monitoring. Separate regulations apply to their disposal.

Classification options

There are numerous options to classify radioactive waste at international level. Classification of the waste depends on the planned way of disposal (in deep geological formations or near the surface) or the necessary handling of the waste.

Based on the dose rate, a distinction is often made between high-level radioactive waste (HAW), intermediate-level radioactive waste (MAW) and low-level radioactive waste (LAW). At the international level, experts agree that high-level radioactive waste must be stored in deep geological formations, to isolate the waste safely from humans and the environment. In some states, however, low-level and intermediate-level radioactive waste is stored near the surface and not in deep geological formations (as opposed to high-level radioactive waste).

The intention in Germany is to dispose of all types of radioactive waste in deep geological formations. The decisive factor is thus neither the dose rate nor the half-life period, but rather the heat generated during radioactive decay. The radioactive waste is divided into heat-generating waste and waste with negligible heat generation.

Radioactive waste with negligible heat generation

The term "radioactive waste with negligible heat generation" was quantified in the scope of the planning works for the Konrad repository. These works were based on the idea that the temperature conditions prevailing underground were only to be slightly affected by the emplaced waste packages. During the implementation of this planning requirement, it was determined that that the increase in the host rock’s temperature, which is caused by the decay heat of the radionuclides contained in the waste packages, must not exceed 3 degrees (Kelvin) on average. This value corresponds to the natural temperature difference at a 100m-depth difference in mines. Compared to the temperature change caused by ventilation, this is a small change. The host rock is already exposed to significantly greater temperature fluctuations. due to the cooler air supplied by ventilation. The temperature difference of 3 Kelvin corresponds to a mean thermal output of about 200 watt per cubic metre of waste.

Waste with negligible heat generation encompasses, among others, disused plant components and components such as pumps and pipelines, ion-exchange resins and air filters from waste water and exhaust air treatment, contaminated tools, protective clothing, decontamination and cleaning agents, laboratory waste, sealed radiation sources, sludges, suspensions or oils.

Waste with negligible heat generation corresponds to the established categories of low-level and most intermediate-level radioactive waste (LAW and MAW).

Heat-generating waste

Heat-generating radioactive waste is characterised by high activity concentrations and thus high decay heat outputs. This waste includes, in particular, waste from reprocessing and spent fuel elements, provided they are not reprocessed but are to be disposed of directly as radioactive waste.
Heat-generating waste corresponds to high-level waste (HAW) and part of the intermediate-level waste (ILW).

Spent fuel elements

Spent fuel elements are produced during the operation of commercial nuclear power plants (power reactors) and research reactors.

The waste status of spent fuel elements is determined by the Atomic Energy Act (AtG). Section 9a of the AtG distinguishes between the harmless recovery of radioactive residues on the one hand, and the proper disposal of radioactive waste on the other. Until 2005, radioactive residues were recycled by reprocessing spent fuel elements in Germany (e.g. at the Karlsruhe reprocessing plant) or in other European countries (Sellafield/UK, La Hague/F). Some of the resulting waste has already been returned to Germany, or will be repatriated in the future.

The disposal of spent fuel elements for the purpose of reprocessing has been prohibited under the Atomic Energy Act since 2005. This means that there is no fuel cycle anymore, and spent fuel elements must be properly disposed of directly. For this purpose, the fuel elements must be transferred to a repository, as the radiation will last for hundreds of thousands of years. The fuel elements are put into temporary storage at interim storage facilities until they are transferred to a final repository for high-level radioactive waste.