1 TECHNOLOGIES FOR DECOMMISSIONING OF NUCLEAR FACILITIES SAFE DECOMMISSIONING OF NUCLEAR POWER PLANTS Project BG04/B/F/PP , Leonardo da Vinci Programme Module “Dismantling”

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

3 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 2.1Dismantling 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.

4 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

5 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

6 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

7 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

8 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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 in progress should be evaluated;  waste containers, handling systems and routes should be defined before the start of dismantling work.

9 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci”  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.  ……………………. Preparatory activities before dismantling

10 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci”  ………………………..  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. Preparatory activities before dismantling (continuation)

11 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

12 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 2.2Dismantling 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.

13 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

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

15 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

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

17 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

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

19 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” Mechanical techniques  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. Circular cutting machine

20 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

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

22 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

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

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

25 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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 = o C).  use:  -fragmentation of metal pieces with thickness up to 15 cm.  -remote – in air and under water.  price:  -high.

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

27 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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 = o C.  -spear size: length from 0.5 to 3 m; diameter mm.  use:  -fragmentation of metal pieces without thickness limitation.  -manual and remote (limited) – in air and under water.  price:  -low.

28 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

29 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

30 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.

31 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 2.3Reactor 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.

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

33 Проект BG/04/B/F/PP , Програма “Leonardo da Vinci” 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.