GRS informs the public about the topic of decommissioning with an updated brochure
In Germany, there are currently 21 nuclear power plants under decommissioning. In the first half of 2017 alone, five nuclear power plants have been granted the licence for decommissioning and dismantling, i.e. Isar 1, Neckarwestheim 1, Biblis A and Biblis B and Philippsburg 1. Between final shutdown and decommissioning, there is usually a period of several years, the so-called post-operational phase.
On behalf of the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMU), GRS has issued a brochure that informs about the topic of decommissioning. It gives an overview of the strategies and techniques of decommissioning and presents various examples from Germany and other countries and also deals with licensing and supervision, waste management and the costs of decommissioning.
What does the term “decommissioning” refer to?
As a technical term, decommissioning refers to all measures carried out after granting of a decommissioning licence for a nuclear power plant until official supervision, i.e. nuclear regulatory supervision, is no longer necessary. The aim of decommissioning is to restore the original condition of the site as it was before construction of the nuclear power plant: the so-called "green field". The complete process usually takes about 15 years.
Which are the steps of decommissioning of a nuclear power plant?
First, decommissioning must be applied for and licensed. For this purpose, the operator of the nuclear power plant must prove that the plant will be dismantled safely and in accordance with the nuclear rules and regulations . After granting of the licence, the actual dismantling can begin, which typically proceeds from the inside out. Dismantling work starts in areas of the nuclear power plant with no or only low contamination. This is followed by dismantling of the more contaminated parts, which partly takes place by remote control due to the high level of radiation. Contaminated objects and rooms must be decontaminated using special methods, such as sandblasting or surface scarification. Large components, such as steam generators, may be temporarily stored prior to their disassembly, so that the radiation continues to decrease. Finally, the buildings are demolished.
What happens to the waste?
When dismantling a power reactor, about 200,000 tons of residues are generated. Most of it is not radioactively contaminated. This waste can be recycled or conventionally disposed of after a control measurement and subsequent clearance by the authority. A small percentage of the residues are radioactively contaminated and must be emplaced in a repository for radioactive waste. As no repository is available yet in Germany for such radioactive waste, the waste is stored in local storage facilities.
What precautions are provided to protect workers against ionising radiation?
For the controlled area of a nuclear power plant, particularly strict radiation protection regulations apply. This is the area where people may receive an effective dose of more than 6 millisieverts or organ doses higher than 45 millisieverts for the eye lens or 150 millisieverts for the skin, hands, forearms, feet and ankles in a calendar year.
Depending on the area of work, the workers wear protective clothing to protect against ionising radiation. The workers in the control area wear a dosimeter . The dosimeter is used to measure the radiation dose received by the individual who wears it. They are evaluated by the competent authorities and checked for compliance with the legal limits.
Who bears the costs of decommissioning?
The costs of dismantling a nuclear power plant vary depending on the type of plant, the strategy and the duration of decommissioning. According to rough estimates, they amount to about 700 million euros per plant. The electric power utilities will bear these costs. The responsibility for storage and disposal lies in the hands of the state. For this purpose, the electric power utilities have paid around 24 billion euros into a public-law fund.
Work of GRS in the field of decommissioning
GRS keeps track of current developments as regards decommissioning in Germany, but also at the international level. Here, GRS activities are focussed on occupational radiation protection , waste management, clearance of radioactive material and the techniques and concepts of dismantling.
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