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Contents. 1.1 Physical outline 1.2 Radiological outline 1.3 Description of materials flow. 1.1 Physical outline. Purposes of training Trainees should be able to:

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  1. Contents 1.1 Physical outline 1.2 Radiological outline 1.3 Description of materials flow Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  2. 1.1 Physical outline Purposes of training Trainees should be able to: • Identify the elements of a fuel-combustion cycle, in the course of which the basic radioactive wastes affecting decommissioning are produced. • List the parameters, which identify the type of radioactive wastes and their amount. • Describe the basic types of materials defined in the physical outline of radioactive wastes. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  3. 1.1.1 Connection between the type/construction of a reactor and the specific features in operation, and decommissioning-oriented activities Activities associated with decommissioning will depend substantially on: • Fuel composition • Type of retarder • Type of cooling agent Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  4. THERMAL REACTORS Light water retarder LWR Graphite retarder Heavy water retarder HWR Heat-transfer medium -water PWR Heat-transfer medium -water CANDU-BLW Heat-transfer medium – CO2 AGR Heat-transfer medium -water PWR Heat-transfer medium -water CANDU-PHW Heat-transfer medium - helium HTGR Types and designs of nuclear reactors Basic types of reactors according to type of retarder and type of heat-transfer medium Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  5. 1.1.2 Stock-taking of materials Main construction materials subject of treatment in the course of decommissioning: • Concrete • Low-alloyed types of steel • Building ceramics • Heat-isolating and electricity-isolating materials Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  6. Stock-taking of materials Main construction materials subject of treatment in the course of decommissioning: • Alloyed types of steel • Graphite • Water • Carbon dioxide Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  7. 1.2Radiological outline Purposes of training Trainees should be able to: • Identify the mechanism of how materials get contaminated. • Describe the methods of identifying the overall amount of radionuclides. • Describe the groups of radiation investigation according to the method of management of radioactive wastes in the process of decommissioning of nuclear facilities. • Identify the objectives of a final radiation investigation • Identify the objectives of a radiation outline/investigation in the process of decommissioning of nuclear facilities. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  8. 1.2.1. Objectives of a radiation outline The main objectives of a radiation outline of a nuclear facility consist in receiving reliable information on both amount and composition of the radionuclides and the distribution thereof within a nuclear facility Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  9. 1.2.2. Overall existing amount and composition of radionuclides in a nuclear facility in a process of decommissioning In the course of a nuclear reactor’s operation, three categories of radionuclides are generated: • products of fission • products of activation • trans-uranium elements Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  10. Overall existing amount and composition of radionuclides in a nuclear facility in a process of decommissioning. After the operation of a nuclear reactor has terminated, two categories of radionuclides dominate: • products of activation • radionuclides resulting from contamination of materials Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  11. 1.2.3 Activation of materials in a reactor Definition This is the process of generation of artificial radioactivity of nuclides, contained within the composition of materials of a reactor, being subject neutron radiation in the course of operation of a reactor. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  12. 1.2.3 Activation of materials in a reactor In the process activation of materials, the following products may be obtained: • steel: Fe-55, Ni-59, Co-60, Ni-63, Mo-93, Nb-94, Ag-108m, • concrete: CI-36, Ca-41, Fe-55, Ni-59, Co-60, Ni-63, Eu-152, Eu-154, Eu-155, • graphite: Ca-41, Fe-55, Ni-59, Co-60, Ni-63, Eu-152, Eu-154, Eu-155. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  13. 1.2.4 Contamination of materials Definition This is the accumulation of products of activation resulting from physical deposition, absorption and adsorption processes onto the surface and penetration into the surface layer thereof Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  14. Contamination of materials Internal and external surfaces of facilities within a nuclear power plant get contaminated as a result of: • Migration (advance) of activated corrosion and erosion products, • Migration of fission products, • Trans-uranium elements. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  15. 1.2.5. Parameters affecting the overall existing amount and composition of radionuclides in a nuclear facility in a process of decommissioning Overall existing amount and composition of radionuclides are affected by: • Constructive characteristics and parameters of the reactor • Operational parameters and events Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  16. Parameters affecting the overall existing amount and composition of radionuclides in a nuclear facility in a process of decommissioning Constructive parameters affecting the amount and composition of radionuclides • type of reactor, its design and rated output • chemical composition of constructive materials, impurities inclusive Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  17. Parameters affecting the overall existing amount and composition of radionuclides in a nuclear facility in a process of decommissioning Operational parameters and eventsaffecting the amount and composition of radionuclides • Chemical regime of reactor’s heat-transfer medium and technical servicing • Unscheduled events in the course of operation • Length of operation and period of safe storage Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  18. Methods for identifying the overall amount of radionuclides Quantitative data needed for outline of materials are produced by means of: • Methods for identifying induced activity • Methods for identifying the contamination level Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  19. Methods identifying the amount and composition of radionuclides in a nuclear facility in a process of decommissioning Identification of induced activity is performed by means of: • Accounting methods for identifying the radionuclide composition • Measuring of the nuclear facility (in-situ) • Analysis of samples of constructive materials from a nuclear facility Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  20. Methods identifying the amount and composition of radionuclides in a nuclear facility in a process of decommissioning Identification of the contamination level is performed by means of: • measuring the power of the dose taken in, • measuring the contamination level • Spectrometric measuring of values of relative activities of each existing radionuclide Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  21. 1.2.6. Radiation outline in the process of decommissioning of a nuclear facility . The radiation outline in the process of decommissioning is performed: • when materials are being sorted out • prior to processing thereof • at acceptability inspection thereof • when released Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  22. 1.2.7. Final radiation outline of buildings and grounds Objective A final radiation outline of both buildings and grounds aims at proving that all normative requirements have been met associated with release of a site for either limited or unlimited use in accordance with the approved plan for decommissioning Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  23. 1.3. Description of material flow Purposes of training Trainees should be able to: • Rate radioactive wastes, produced in the process of decommissioning of a nuclear facility . • Identify factors and methods oriented to minimising wastes. • Outline non-contaminated materials or wastes. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  24. 1.3.1. Rating of wastes Wastes produced in the process of decommissioning of nuclear facilities are classified as: • Wastes released for disposing into the environment • Radioactive wastes By definition, radioactive wastes are considered to be the following: Radioactive materials in gas, liquid or solid form any further use of which is not planned and which are controlled by the regulating authority as radioactive wastes pursuant to the adopted national legislation. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  25. Rating of radioactive wastes Solid radioactive wastes are classified into three categories: • category 1- transitional radioactive wastes • category 2- low and medium active radioactive wastes • category 3- high activity radioactive wastes Gas and liquid radioactive wastes are rated according to the features of eventually produced solid radioactive wastes, which are expected to be obtained after having been conditioned. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  26. 1.3.2. Minimising wastes Objective Minimising wastes in the process of decommissioning pursues the following: • Reduction of burden the environment suffers • Reduction of the risk of any radiation impacts over personnel, people and environment both at present and in the future • Reducing resources needed for decommissioning • Reduction of the burden transferred to generations to come within sensible limits. Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

  27. Minimising wastes Minimising wastesis achievable by means of: • Classifying materials • Separation of materials • Processing of wastes Проект BG/04/B/F/PP-166005, Програма “Leonardo da Vinci”

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