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CONTENTS

CONTENTS. 2.1 Dismantling and demolition during the decommissioning period – aims, time schedules, activities 2.2 Dismantling techniques – scope of application 2.3 Reactor dismantling techniques 2.4 Novel (modern) techniques.

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CONTENTS

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  1. CONTENTS • 2.1 Dismantling and demolition during the decommissioning period – aims, time schedules, activities • 2.2 Dismantling techniques – scope of application • 2.3 Reactor dismantling techniques • 2.4 Novel (modern) techniques Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  2. 2.1 Dismantling and demolition during the decommissioning period • Training goals • The trainees must be capable of: • - Determine the goals of dismantling and demolition during the decommissioning. • - Enumerate the preparatory activities before dismantling. • - Characterize dismantling performance. • - Characterize the post-dismantling activities. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  3. Dismantling of Nuclear Facilities • Consists in dismounting and removal of all nuclear equipment structures, systems and components during the process of the nuclear facility decommissioning. • (Radioactive Waste Management Glossary, IAEA, Vienna 2003) • The dismantling of a nuclear facility comprises cutting and demolition of the following structures: • reactor vessel. • reactor core components. • heat screens and other structures contaminated with radioactive products. • tanks and pipelines with surface contamination. • protective biological screens. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  4. Selection of dismantling methods techniques • equipment size, shape and accessibility. • radiation hazards to the workers and the general public. • workplace conditions. • radioactive waste produced. • non-radioactive waste produced. • necessity of post-dismantling activities performance. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  5. Selection of dismantling methods and techniques • the types and characteristics of materials,equipment and systems to be dismantled; • the availability of proven equipment; • the radiation hazards to the worker and the general public; • the environmental conditions of the workplace; • the radioactive waste produced; • the non-radioactive waste produced; • the requirement for development work. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  6. Ensuring efficiency and safety of the activities • simplicity of operation, decontamination and maintenance. • control over aerosol radionuclides. • control over discharges to the environment. • water treatment (in case of underwater techniques). • effect of the activities on the adjacent systems. • determining the type of waste containers, handling systems and transportation routes. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  7. Осигуряване на ефективността и безопасността на дейностите • equipment should be simple to operate, decontaminate and maintain; • effective methods for controlling airborne radionuclides should be implemented; • there should be effective control of discharges to the environment; • when underwater dismantling and cutting is used, provision should be made water processing to ensure good visibility and assist in effluent treatment; • the effect of each task on adjacent systems and structures and on other work inprogress should be evaluated; • waste containers, handling systems and routes should be defined before the startof dismantling work. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  8. Preparatory activities before dismantling • Determination of the radiation protection conditions during the activities performance. • Placing of protective floor covering. • Installation of ventilation equipment. • Installation of electric power supply and the necessary working environment. • Scaffolding mounting. • ……………………. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  9. Preparatory activities before dismantling (continuation) • ……………………….. • switching off the unnecessary equipment. • marking the location of the cuts. • mounting of protective covering (“protective tent”) around highly radioactive equipment. • transportation of dismantled equipment. • preparation of waste transportation containers. • training of the working team. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  10. Post-dismantling finishing activities • removal of the ventilation system. • removal of the feeding lines to the auxiliary working environment. • removal of the scaffolding. • moving the equipment and tools. • removal of the protective coverings and “tents”. • transportation of containers filled with dismantled materials. • cleaning the premises. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  11. 2.2 Dismantling technologies – scope of application • Training goals • The trainees must be capable of: • Enumerate and describe the various manual and remote dismantling techniques (mechanical cutting, hydraulic cutting, thermal cutting, explosive cutting, novel techniques, etc.) • Explain the specific requirements to dismantling in zones with increased radioactivity. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  12. Classification of dismantling techniques • with respect to the physical-chemical principle: • - mechanical, hydraulic, thermal, explosive, novel (modern) technologies. • with respect to the medium of process implementation: • - air, underwater. • with respect to the application method: • - manual, remote. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  13. Manual dismantling • pipelines. • heat exchangers. • fittings, pumps. • ventilation equipment. • steel structures. • electrical equipment, cables. • heat insulation of pipelines. • steel lining of pools. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  14. Remotely-controlled dismantling Steps in the remotely controlled operations: • handling the equipment or device. • visual control of the activities. • cutting of material. • cleaning. • radioactivity monitoring (follow up control) • packing of material. • thorough radioactivity measurements. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  15. Remotely-controlled dismantling • steam generators. • reactor vessel. • intra-vessel devices. • volume compensator. • other components of primary coolant system. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  16. Mechanical techniques Mechanical hand cutting tools, hack-saws and guillotine shears • use: • - widely used, especially for cutting of pipelines. • - high cutting speed. • - easier radioactive contamination control • (as compared with the thermal techniques). • - fragmentation of metal pieces and pipelines with diameter up to 60 cm. • - manual, remote. • price: • - low. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  17. Mechanical techniques Mechanical hand cutting tools for small-diameter contaminated pipes. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  18. Mechanical techniques Circular cutting machine • use: • - cutting as the self-propelled circular saw moves on the object’s outer surface. • - for cutting pipes with particularly large diameter. • - fragmentation of metal pieces and pipelines with diameter up to 6 m and wall thickness up to 7.5 cm. • - remote. • price: • - low. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  19. Abrasive cutting technique • principle: • - cutting by means of rotating abrasive disk made of oxide (Al) or carbide (Si) powder and resin as bonding material and glass fiber as strengthening material. • use: • - for cutting pipes with particularly large diameter. • - fragmentation of metal pieces and pipelines with diameter up to 6 m and wall thickness up to 7.5 cm. • - remote. • price: • - low. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  20. Hydraulic techniques • Cutting by means of water jet with abrasive materials. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  21. Thermal techniques • Classification with respect to the heat source • - flame cutting. • - electric-arc cutting. • - electric-arc plasma cutting. • - oxygen (heat) spear. • - laser cutting. • - combined cutting. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  22. Thermal techniques Flame cutting Flame Cutting with an External Ignition Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  23. Electric-arc cutting technique • principle: • - utilization of the cutting action of a low-voltage electric arc created between the hack-saw cutting disk (d=760-1630 mm) and the material. • use: • - fragmentation of metal pieces with thickness up to 90 mm. • - remote – in air and under water. • price: • - high. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  24. Electric-arc plasma cutting technique • principle: • - utilization of the cutting action of a d.c. electric arc created in an ionized gas medium (stainless steel - argon) between an electrode and any conducting material (the temperature in the plasma jet is T0 = 10 000 - 27 000 oC). • use: • - fragmentation of metal pieces with thickness up to 15 cm. • - remote – in air and under water. • price: • - high. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  25. Electric-arc plasma cutting technique Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  26. Thermal (oxygen) spear • principle: • - utilization of the chemical reaction of burning a thermal mixture (steel, aluminum, magnesium) in oxygen at the spear output. • parameters: • - T0 = 2 250 - 5 500 oC. • - spear size: length from 0.5 to 3 m; diameter 6 - 10 mm. • use: • - fragmentation of metal pieces without thickness limitation. • - manual and remote (limited) – in air and under water. • price: • - low. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  27. Explosive techniques • Segmentation of materials by means of explosives (PETN, TNT, dynamite) • principle: • - the shock waves and the fragments of the shell (Pb, Al, Cu) in a directed explosion cause cracks (cuts). • use: • - fragmentation of metal pieces with complex geometry and thickness up to 15 cm. • price: • - high. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  28. Laser cutting • principle: • -local heating of the metal above the melting point by using a laser beam. • advantages: • -melts practically all materials. • -absence of noise and vibrations. • -easy operation. • use: • -fragmentation of metal pieces with thickness up to 10 mm; suitable for remote dismantling • -in air and under water. • price: • -high. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  29. Novel (modern) techniques • Techniques under development yet to find widespread application in projects for decommissioning of nuclear facilities. • liquefied gas cutting. • utilization of alloys with “memory effect”. • use of microwave equipment. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  30. 2.3 Reactor dismantling techniques • Training goals • The trainees must be capable of: • -characterize the specific features of the mechanical, thermal, and hydraulic techniques applied in reactor dismantling. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  31. Reactor dismantling techniques • Remotely controlled processes • mechanical: • -mechanical hack-saws, disk cutters. • hydraulic: • -water jet. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  32. Reactor dismantling techniques • Remotely controlled processes • thermal: • -thermal spear, contact electrode cutting. • -(non)melting electrode electric-arc cutting. • -plasma arc or circular saw cutting. • -laser cutting. • explosive cutting. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

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