Dismantling and decontamination
The future of nuclear sites
After a nuclear power plant or nuclear installation has been shut down for good, it will have to be decontaminated and dismantled. Dismantling is a process of many years. Specialist personnel must disassemble and break down the installations, decontaminate the material and dispose of all (non-)radioactive waste. What do they want to achieve? Restoring the site in its original state and giving it a new destination.
Dismantling in the approved manner
Dismantling a nuclear power plant or another nuclear installation is not easy. You need specialists with the necessary expertise and knowledge of the prevailing rules and techniques. Over the years, SCK CEN has dismantled many installations. The research centre has thus built comprehensive expertise and developed new techniques such as the use of remotely controlled tools.
Every dismantling project has one golden rule: to limit the amount of radioactive waste to the bare minimum. Certain techniques of SCK CEN help specialists to succeed in this. SCK CEN has developed methods for cutting reactor parts and for the chemical treatment of metals. Parts that cannot be sufficiently decontaminated, are disposed to the Belgian Agency for Radioactive Waste and Enriched Fissile Materials (NIRAS) in view of their storage and disposal.
Three dismantling stages
Every nuclear installation, from a glove box to a nuclear power plant, will be dismantled. Every dismantling project goes through three stages: decommissioning, demolition and site redevelopment. Below, the specific dismantling process for a nuclear power plant is explained.
Before starting the dismantling operations, specialists will map the site. Which radioactivity values are measured? We refer to this as the characterisation of the building, installations and site. Subsequently, the reactor vessel and the different circuits are emptied and the fissile material is brought to the intermediate storage facilities.
The second phase covers a period of 10 to 20 years. It includes the demolition of both nuclear (e.g. reactor vessel and contaminated circuits) and non-nuclear buildings and equipment. The amount of radioactive waste that remains after the demolition is limited to the bare minimum by decontaminating all parts as thoroughly as possible.
The decontamination and demolition of all buildings is the final step of a dismantling project. The dismantling experts want to restore the entire site (again) in its original state and apply for the status of a greenfield. The site can then be given a new destination.
Safety is key
In every stage of the dismantling project, the safety of man and environment is key. All dismantling operations are subject to strictly regulated safety procedures. To ensure the safety of employees, SCK CEN has developed the software programme Visiplan. In a 3D environment, the software models the radiation dose that employees are expected to sustain. Subsequently, project managers can schedule the operations in detail and limit the exposure of their employees to an absolute minimum.
BR3 as learning experience
The Belgian Reactor 3 was the first pressurised water reactor in Europe. It was taken into service in 1962 and shutdown for good in 1987. The reactor served as a prototype for the reactors in Doel and Tihange. The European Commission selected BR3 as a pilot project to show the technical and economic feasibility of the dismantling of a reactor under real conditions. At this moment, the project is in its third stage: restoring the site in its original state. SCK CEN disseminates the expertise that it has developed with the decommissioning of BR3 both on a national and international level. These valuable insights are also an excellent guideline for the design of new nuclear plants.
Research leads to publications. The aim of these publications is to present results of research to scientists, to discuss their meaning and to draw up hypotheses and theories.