Nuclear power plants still may pose a hazard after the end of their operational life. Thus, they have to be decomissioned in an orderly manner to protect man and the environment.
According to the International Atomic Energy Agency (IAEA), more than 500 reactors and about 275 nuclear fuel cycle facilities have been fully shut down until 2011.
The term “decommissioning” refers to all measures carried out after granting of a decommissioning licence for a nuclear facility until official supervision i. e. nuclear regulatory supervision, is no longer necessary.
This usually implies removal of all parts of the building and restoration of the site to its original condition in form of the so-called “green field”.
The nuclear facilities that are concerned by this decommissioning procedures are : Power reactors, Prototype reactors, Research reactors and Nuclear fuel cycle facilities
Huge challenges are facing a decommissioning project, they could be listed as follows :
Two different decommissioning strategies could be adopted by the owner of the power plant.
The immediate dismantling strategy has the advantage to avoid carrying the technical and the financial weight of dismantling on future generations. It also allows to benefit from the knowledge and skills of the teams present during the operational phase of the plant.
For instance, the adopted strategy in France is the immediate dismantling (note that there are some specific discussions with ASN about the particular case of UNGG reactors (Uranium Naturel Graphite Gaz)). In Germany, immediate dismantling strategy was as well adopted for most of the nuclear facilities. However, deferred dismantling program was selected for some facilities.
In the USA, the Nuclear Regulatory Commission gives the choice to the operators to select between the two strategies. So far, the deferred dismantling strategy has been much more chosen for the last decommissioning programs. In Sweden and most of Eastern Europe countries, the deferred dismantling strategy has been selected because of some constraints related to decommissioning facilities and/or funds availability.
The table below summarizes the main advantages and disadvantages of the two different dismantling strategies.
Overview of nuclear facilities dismantling legal steps
Overview of nuclear facilities dismantling technical steps