Reactor demolition

Reactor demolition describes the orderly, standards-compliant deconstruction of nuclear facilities from the first planning step to the last base slab. It combines radiation protection, structural engineering, materials science, and logistics into a highly specialized process in which selective dismantling, controlled concrete demolition, and the safe separation of steel interlock. In this context, hydraulic and mechanical methods have become established that can be deployed precisely, with low emissions, and by remote control. Tools such as concrete demolition shear or stone and concrete splitter, operated via suitable hydraulic power packs, play a central role in special demolition inside containments, during the gutting of technical rooms, and later when removing massive shielding.

Definition: What is meant by reactor demolition

Reactor demolition refers to the entirety of all technical, organizational, and regulatory-supervised measures that lead to the final shutdown and dismantling of a reactor. These include planning and permitting, decontamination of accessible areas, gutting works and segmentation of activated or contaminated components, concrete demolition on biological shielding and building structures, as well as waste treatment with clearance measurement. The goal is the long-term safe removal of the facility and the preparation of a new use of the site. Depending on the strategy (immediate dismantling or delayed dismantling after safe enclosure), cadence, technique, and equipment change, but not the high standard for controlled methods with clear documentation.

Process and phases of reactor demolition

Reactor demolition follows a structured approach aimed at minimizing exposure, dust, noise, and vibrations inside the facility. Planning and execution teams consider construction type, material condition, activity distribution, and accessibility to define suitable cutting and separation methods. Essentially, the phases can be organized as follows:

1. Preparation: Inventory, radiation protection concept, access and ventilation routing, definition of low-emission methods.
2. Decontamination: Reduction of surface contamination to lower dose rates in work areas.
3. Gutting and cutting: Dismantling plant technology, lines, tanks, and support systems using cold-cutting methods (e.g., hydraulic shear, tank cutters, Multi Cutters).
4. Concrete demolition and special demolition: Removal of heavily reinforced, partly heavyweight concretes of the biological shield with concrete demolition shear as well as low-stress splitting of massive cross-sections using a concrete splitter.
5. Material logistics: Pure-grade separation, packaging, labeling, transport and disposal concepts including clearance measurement.
6. Deconstruction of the structural shell: Removal of foundations, shafts, and annexes, final surveying and documentation.

Structures, materials, and particularities in the reactor environment

Reactor structures differ significantly in configuration and material quality from typical industrial buildings. Biological shields often consist of highly compacted, sometimes heavier concrete types with dense reinforcement, steel-plate linings, or prestressing systems that require special demolition steps. Inside the facility, stainless steel, heat-treated steels, thick-walled pipelines, tanks, and built-ins dominate. This results in requirements for accessibility, tool sizing, low-stress methods, and consistent dust and chip capture. Experience from rock excavation and tunnel construction—such as controlled splitting of large cross-sections—can be transferred to massive concrete shields, while insights from natural stone extraction help with precise separation of brittle materials in sensitive environments.

Mechanical methods in concrete demolition: splitting and crushing

In reactor demolition, mechanical processing of concrete has become a central element because it works without thermal input and with low secondary emissions. Two methods are particularly relevant:

Stone and concrete splitter for massive shielding

Hydraulic splitting cylinders create locally high tensile stresses in previously drilled boreholes. The component fractures along defined lines without impact energy and with very low transmission of vibrations into adjacent structures. This method is valuable in concrete demolition and special demolition where dense reinforcement, adjacent sensitive components, or low vibration tolerances exist. In confined spaces, compact splitting cylinders can gradually expose cross-sections until concrete demolition shear efficiently reduce the free-standing webs.

Concrete demolition shear for reinforced concrete

Concrete demolition shear crush concrete members and cut reinforcement in a single operation. In the reactor environment, they excel where defined piece sizes, controllable edge breaks, and a deconstruction-friendly material flow are required. Used on a carrier machine with finely controllable hydraulics, they enable the selective removal of wall and ceiling areas. In combination with stone and concrete splitter, a demolition chain emerges that first opens massive shields with low stress and then converts them into transportable fractions.

Cutting metallic components: cold, controlled, low-spark

The separation of steel components, tanks, pipelines, and support systems in reactor demolition is preferably cold and low-spark. The following tool groups are used:

• Hydraulic shear: For thick-walled sections, beams, and pipelines; suitable for segmentation without thermal input.
• Tank cutters: For shell and lid openings as well as for cutting large-volume vessels into manageable segments.
• Multi Cutters and combination shears: For varying material thicknesses and geometric transitions when switching between cutting and crushing within one operation is required.

These tools support gutting and cutting in technical rooms and shafts, often operated remotely and combined with dust extraction and shielding concepts. The selection is guided by wall thicknesses, accessibility, permissible residual heat, and the required segment size for packaging and waste routes.

Hydraulic power pack as the heart of the system technology

Hydraulic power packs supply concrete demolition shear, stone splitting cylinders, hydraulic shear, and tank cutters with the necessary energy. In reactor demolition, compact, reliably controllable units are required that deliver stable flow rates with moderate noise emission. Maintenance aspects such as oil filtration, leak avoidance, and decontamination-friendly surfaces carry particular weight. In isolated areas, the power pack and tool are routed via suitable hose lines; operation can be performed outside the immediate work area to minimize exposure.

Gutting works and selective deconstruction in sensitive zones

Before the actual concrete removal comes gutting: dismantling of platforms, lines, fittings, inspection opening, cable routes, and secondary structures. Hydraulic shear and Multi Cutters allow plant-friendly work with a defined cut edge, which simplifies subsequent steps in special demolition. Where plant parts must remain on the component, surrounding concrete can be released with stone and concrete splitters with low stress to avoid overloading sensitive components.

Waste routes, segment sizes, and documentation

The choice of segment sizes for concrete and steel follows the requirements of packaging, load-bearing capacity, and clearance measurement, as well as subsequent treatment. Mechanical splitting and crushing produce well-sortable fractions: concrete, reinforcement, inserts. Short transport routes, load-bearing gripping edges, and reproducible piece sizes simplify handling. Complete documentation of origin, processing method, mass, and, where applicable, activity classes is an integral part of every work step.

Occupational safety, radiation protection, and emissions control

Strict safety standards apply in reactor demolition. The selection and use of tools must be geared to minimizing dust, aerosols, noise, and vibration. Mechanical, cold-working methods support this objective. Personal protective equipment, enclosures, extraction and filtration measures, as well as qualified personnel, are mandatory. Radiation protection and occupational safety requirements must always be planned specific to the site and coordinated with the authorities. Statements in this text are of a general nature and do not replace a project-specific assessment.

Application areas and transferability of the methods

The tools and procedures proven in reactor demolition can technically be transferred to other application areas:

• Concrete demolition and special demolition: Selective removal, opening of breakthroughs, dismantling of heavily reinforced components.
• Gutting and cutting: Cold cutting of steel structures, segmentation for transport and packaging.
• Rock excavation and tunnel construction: Splitting techniques for controlled opening of massive cross-sections without impact energy.
• Natural stone extraction: Precise splitting of brittle materials with defined crack guidance.
• Special operations: Work in tight shafts, overhead, or underwater with remotely operated units.

Selection criteria for tools in reactor demolition

The selection of suitable systems is based on transparent criteria:

• Component geometry and material: Wall thicknesses, reinforcement density, inserts, linings.
• Accessibility: Space conditions, required tool dimensions, routing of hose lines and power packs.
• Emission targets: Dust and noise emission limits, permissible vibrations, spark-free operation.
• Segmentation concept: Desired piece sizes and shapes, downstream logistics.
• Operating mode: Manual, mounted, or remotely operated; continuous operation vs. intermittent work.

In many cases, concrete demolition shear and stone and concrete splitter complement each other: first the controlled opening or relieving of a component, then efficient downsizing into transportable fractions.

Special operations: confined spaces, elevated requirements, remote-controlled work

Reactor structures contain areas with restricted access, complex geometry, or special requirements for shielding and ventilation. Compact, precisely controllable hydraulic devices and mechanical shears that can be used on a carrier machine or with remote-control solutions offer advantages here. Stone and concrete splitter make it possible to open components initially without large reaction forces before concrete demolition shear and hydraulic shear complete the segmentation.

Practice-oriented guidance for process design

A robust process design links technology and organization:

1. Pre-tests on sample components or mock-ups to optimize splitting distances, shear geometry, and cutting sequences.
2. Combining methods in a defined sequence to control force paths and reduce residual stresses.
3. Early integration of waste disposal logistics so that segment sizes and material separation align from the outset.
4. Ongoing measurement-based accompaniment (dust, vibration, noise) to adapt parameters to the environment.

Qualification, organization, and documentation

Reactor demolition requires experienced teams qualified in radiation protection, demolition technology, and hydraulics. A clear roles and communication plan, regular briefings, and documented inspections of tools and hydraulic power packs contribute to process safety. Inspection and maintenance intervals must be planned to harmonize with the cadence and accessibility in the controlled area.

Developments and trends in reactor demolition

Advances in sensors, remotely operated carrier machines, and data-based process control improve precision and reproducibility. For concrete demolition, intelligent concrete demolition shear geometries and adaptive hydraulic control are gaining importance. Stone and concrete splitter are being further developed in terms of power density and usability to target massive cross-sections even more precisely. In steel cutting, versatile combination shears and Multi Cutters are becoming established, enabling multiple work steps with one hydraulic power pack.

Darda GmbH supports these developments with a clear focus on mechanical, hydraulic methods that play a pivotal role in reactor demolition, gutting works, and special demolition. Crucial remains the proper, project-specific selection and expert use of the tools.