The decommissioning of the Doel and Tihange power plants: a new industrial challenge in complete safety

The decommissioning will be a very large industrial and environmental project in Belgium. As a nuclear operator, it is our responsibility to see this through to a successful conclusion in a safe, humane, and environmentally friendly manner.

 

The decommissioning consists of the safe removal of all radioactive materials in the facility and to prepare the site for new uses. This project is a challenging, innovative undertaking which will be executed under strict safety procedures.

Our mission is to tackle this challenge professionally, as we have always done in the past, with the ambition of becoming a strong benchmark in decommissioning.

Decommissioning

After construction and operation, decommissioning is the final part of the life cycle of our nuclear power plants. This phase includes all administrative and technical measures taken from the time the decision is made to permanently shut down the units, until the site is cleared for new industrial activities.

The Post Operational Phase (POP) is covered by the operating license. Next, FANC has to issue a dismantling license to cover the dismantling. Demolition and soil remediation will begin once the plants are no longer under nuclear control.

Decommissioning timeline

Post operational phase (POP)

The purpose of the post operational phase is to prepare the plant for dismantling

The Post Operational Phase (POP) of the nuclear facility will begin as soon as the reactor is permanently shut down. The goal of this phase is to remove all nuclear fuel, hazardous materials, and liquids from the plants. The waste generated during the POP is processed at the nuclear sites. Spent fuel elements are gradually removed to the temporary storage buildings (DE-SF² in Tihange and SCG-SF² in Doel).

The POP activities are covered by the existing operating license and the permits (safety report and technical specifications) will evolve in line with the condition of the installations. The planning for the Post Operational Phase is divided into four activities that extend over several years. At the end of the POP, dismantling can start, after the FANC has issued the proper license.

POP in four phases:

Phase 1 Unloading the reactor and transferring the spent fuel elements to the fuel pools for cooling.
Phase 2 Removing radioactive particles from the primary circuit.
Phase 3 Transfer of the fuel elements to temporary storage buildings (DE-SF² at Tihange and SCG-SF² at Doel).
Phase 4 Removal of filters and resins. Final quenching of circuits, fuel pools, disposal of waste, liquid waste, and hazardous products.

Also during the post operational phase nuclear safety is our top priority

Several circuits, systems, and equipment guarantee a safe operation of the plant. These systems take care of i.e. cooling the fuel elements, containment of radioactive materials, and protection from ionising radiation. This is called the nuclear island.

During the various stages of the Post Operational Phase, the nuclear risks reduce, e.g. as soon as the nuclear fision stops, or while the fuel elements cool down in the fuel pools. As such we can gradually take circuits and systems out of service. Deciding which systems are no longer needed without impacting nuclear safety, and under the supervision from FANC is one of the main tasks during the preparation of the Post Operational Phase.

 

Dismantling

Dismantling consists of seven phases, including the dismantling of all nuclear and non-nuclear equipment

Dismantling phases


This phase mainly includes the removal of large pieces of equipment such as the reactor vessel, steam generators and the concrete shield around the vessel.

All decommissioning activities are subject to safety regulations issued by FANC. Dismantling will generate waste that must be disposed of immediately or treated on-site before being sent to Belgoprocess.

European experience

The approach taken at Doel and Tihange for decommissioning the plants is based on IAEA guidelines and feedback from other plants that have already been dismantled or are currently being dismantled, such as Obrigheim, Neckarwestheim, Mühleberg, Fessenheim, Ringhals and José Cabrera.

Their experience helps us determine the measures to be taken during the various phases of decommissioning. But also regarding the temporary storage and handling of spent fuel elements.

In addition we can also rely on experience from the dismantling of BR3 at SCK CEN (Study Centre for Nuclear Energy) in Mol.

Waste

Decommissioning a nuclear power plant leads to waste. 98% is conventional waste (concrete and metals), which will be recycled and recovered as much as possible. The remaining radioactive waste will be sorted, treated, and packaged before being transported for temporary storage. Depending on the type of waste, this will be on site or at Belgoprocess.

 

Funding

Since 1975, financial provisions have been accrued to cover the cost of dismantling. The provisions are managed by Synatom, under the supervision of the Nuclear Facilities Commission, which relies on the opinions issued by ONDRAF/NIRAS.

Future dismantling expenditures are regularly reassessed, taking into account current economic data, technological advances, and regulatory changes.

 

Conclusion

Not only the operation but also the decommissioning of nuclear power plants requires nuclear professionals willing to invest in ambitious, complex, and innovative projects. Inspired by our pride and professionalism, we will tackle this new industrial challenge in a safe, responsible, and professional manner.

 

 

Downloads

Decommissioning brochure (pdf, 613.65 KB)