Detail of HAD 401/12-2020

Introduction of HAD 401/12-2020

1 Introduction 1.1 Purpose This guide provides guidance for the pre-disposal management of radioactive waste from nuclear facilities including: (1) nuclear power plants and installations such as nuclear electrical power plants, nuclear thermal power plants, nuclear steam supply and heating plants; (2) research reactors, experimental reactors, critical devices and other reactors other than nuclear power plants; (3) nuclear fuel cycling facilities such as nuclear fuel production, processing, storage and reprocessing facilities; (4) facilities for treatment, storage and disposal of radioactive waste. 1.2 Scope 1.2.1 This guide is applicable to the consideration of pre-disposal management of radioactive waste in stages of site selection, design and construction of nuclear facilities, and the pre-disposal management of radioactive waste generated in stages of operation and decommissioning. 1.2.2 This guide covers all steps of pre-disposal management of radioactive waste, including waste generation, pretreatment, treatment, conditioning, storage and transportation. 2 General requirements 2.1 Waste management shall be aimed at safety and centered on disposal. 2.2 Waste management shall include the management and optimization of the whole process from generation to disposal (including discharge) of waste, and the compatibility and coordination among different steps shall be taken into account. 2.3 The waste generated from nuclear facilities shall be under control, and the best feasible technology shall be adopted to keep its radioactivity and volume as low as reasonably possible. See HAD401/08 Minimization of radioactive waste from nuclear facilities for the specific management requirements for minimization of radioactive waste. 2.4 The waste package finally formed shall be intrinsically safe, so as to ensure its safety during storage or transportation, and prevent the nuclide contained in the waste body from spreading to the environment during storage, transportation and disposal. 2.5 The radioactive waste management program and the management procedures for pretreatment, treatment, conditioning, storage and transportation of radioactive waste shall be formulated and implemented. See Annex A for the waste management program and management procedures of nuclear facilities. 2.6 In each step of waste management, the radioactive waste shall be characterized and classified as required, and information on the generation, pretreatment, treatment, conditioning, storage and transportation of radioactive waste shall be recorded and saved. See Annex B for the typical characteristics and features that shall be considered for management of radioactive waste packages. 2.7 The final waste package (waste body and waste container) shall meet the acceptance criteria of waste disposal facilities. Each waste package shall have a unique and long-term effective (effective to the disposal step) identification, which can be associated with relevant records. 3 Specific requirements 3.1 Control of waste generation 3.1.1 Control shall be started from the generation of waste, and the following aspects shall be mainly considered: (1) the process, design scheme, materials, structures, systems and components of facilities shall be reasonably selected; (2) appropriate construction measures shall be selected; (3) the commissioning program and operation procedures shall be optimized; (4) effective and reliable technology and equipment shall be selected; (5) the integrity of containers and packaging of radioactive waste shall be ensured; (6) radiation partition shall be set reasonably in the plant to prevent the dispersal of radioactive contamination; (7) there shall be decontamination planning for each partition and equipment for preventing the dispersal of radioactive contamination. 3.1.2 Non-radioactive waste shall be sorted out from radioactive waste to reduce the amount of radioactive waste.   3.1.3 When the radioactive waste reaches the clearance level (or discharge limit) after storage (detention) decay or treatment, it shall be cleared (or discharged) in time to reduce the amount of radioactive waste. 3.2 Waste characterization and classification 3.2.1 Waste characterization 3.2.1.1 The following factors shall be considered to determine the appropriate pre-disposal management scheme of waste: (1) the source, type and physical state (solid, liquid or gas) of waste; (2) radioactivity characteristics (such as half-life, activity concentration of radionuclides, dose rate and heat release); (3) other physical characteristics (such as dimension, weight and compressibility); (4) chemical characteristics (such as composition, moisture content, solubility, corrosivity, flammability, gas release and chemical toxicity of radioactive waste); (5) biological characteristics (such as biological hazards related to waste); (6) expected treatment, storage and disposal methods. 3.2.1.2 The waste characterization contents shall include radioactive, physical, chemical and biological characteristics. 3.2.1.3 The waste characterization requirements, methods and results of different waste streams shall be determined according to the type, form and source of radioactive waste. 3.2.1.4 The waste characterization methods and procedures shall be controlled to ensure the reliability of characterization data. 3.2.2 Waste classification 3.2.2.1 The classification of radioactive waste shall meet the requirements of Classification of radioactive waste (Announcement of the Ministry of Environmental Protection, No.65 [2017]). For different purposes, radioactive waste may also be classified from other perspectives, such as according to form, composition and treatment methods.   3.2.2.2 The radioactive waste may be classified into gas waste, liquid waste and solid waste according to physical forms. Different nuclear facilities generate different radioactive waste. See Annexes C, D and E for examples of radioactive waste of various nuclear facilities. 3.2.2.3 The radioactive waste gas may be classified into oxygen-containing waste gas, hydrogen-containing waste gas and the like according to its composition; it may also be classified into process waste gas, plant waste gas and the like according to its source. 3.2.2.4 The radioactive liquid waste may be classified according to the half-life (such as short life and long life), activity concentration, chemical composition, component state and treatment method of contained radionuclides. 3.2.2.5 The radioactive solid waste may usually be classified into wet waste and dry waste. Wet waste usually includes: resin, mud, concentrated solution, activated carbon, zeolite and so on; dry waste includes radioactive contaminated solid materials (such as radioactive contaminated protective articles, wiping materials, paper, plastics and rubber products) generated during the operation and maintenance of nuclear facilities, and radioactive contaminated equipment, spare parts and components, tools and thermal insulation materials abandoned in the control area. 3.2.2.6 The radioactive solid waste may be classified into combustible or non-combustible, compactable or non-compactable, metal or non-metal and fixed surface contaminated or non-fixed surface contaminated wastes according to the waste treatment methods. 3.3 Waste pretreatment 3.3.1 Pretreatment includes collection, sorting, chemical conditioning, decontamination, etc. 3.3.2 The radioactive waste shall be collected by category according to its radioactive, physical and chemical properties, including: (1) liquid waste, waste gas and wet waste are usually collected in storage tanks; (2) according to the difference of radioactivity level, different plastic bags, barrels or boxes are usually used to collect dry waste so as to meet the subsequent waste handling, treatment and radiation protection requirements; (3) organic liquid waste shall be collected separately to avoid mixing with other liquid waste.   3.3.3 Guiding procedures for waste sorting shall be established. During sorting: (1) waste shall be sorted as close as possible to the place where it is generated; (2) non-radioactive waste and the waste that is slightly contaminated by radionuclides and can be cleaned, recycled or discharged directly or after storage and decay shall be sorted out as possible to reduce the amount of radioactive waste; (3) according to the requirements of waste operation and management, different types of waste shall be grouped as much as possible, such as separating the waste containing short-lived radionuclides from those containing long-lived radionuclides, or separating compactable waste from non-compactable waste, etc. 3.3.4 Waste radioactive sources shall be stored separately from other wastes. 3.3.5 Waste containing α nuclide, flammable, explosive, corrosive or other harmful substances, free liquid or compressed gas shall be collected separately to avoid mixing with other wastes. 3.3.6 Chemical conditioning (such as pH adjustment) shall be adopted to pretreat the waste so as to adapt to further treatment. 3.3.7 When mechanical, chemical and electrochemical methods are used to remove surface contamination, the amount of secondary waste shall be limited to ensure the effective treatment of secondary waste. 3.3.8 When waste is collected at the waste generating point, the compatibility of radioactivity and chemical characteristics of waste shall be considered, and the collection of waste shall meet the waste acceptance criteria of waste management facilities (such as treatment, storage or disposal). When wastes with different chemical characteristics are collected, the possible chemical reactions, especially exothermic reactions, shall be evaluated to avoid uncontrolled or accidental reactions and prevent accidental release of volatile radionuclides or radioactive aerosols. Organic liquid wastes with different chemical characteristics need to be treated by taking different treatment measures and shall be separated from water. Adequate ventilation and fire prevention measures shall be considered during the collection and storage of organic liquid waste. 3.4 Waste treatment 3.4.1 The treatment purposes and methods of radioactive waste include: (1) reducing the volume of waste (by incineration, compaction, cutting, disintegration, etc.); (2) removing radionuclides (by evaporation concentration, ion exchange, filtration, reverse osmosis, ultrafiltration, decentration, etc.); (3) changing the state or composition of waste (by precipitation, flocculation, chemical oxidation or thermal oxidation, solidification, etc.). 3.4.2 Waste gas treatment 3.4.2.1 When operating the radioactive waste gas treatment system, the amount of waste gas to be treated, activity concentration, nuclide contained in the waste gas, chemical composition, humidity, toxicity, possible corrosive or explosive substances shall be considered. 3.4.2.2 The radioactive particle and aerosol in waste gas may be removed by high efficiency filter (HEPA), and iodine may be removed by activated carbon filter, etc. Inert gas may be subjected to storage and decay or decayed in activated carbon retention bed. Scrubbers may be used to remove chemicals, particles and aerosols in waste gas, and redundant design shall be considered for safety-related parts. The exhaust gas system shall be equipped with condition monitoring devices for temperature monitoring, differential pressure measurement, etc. 3.4.3 Liquid waste treatment 3.4.3.1 Appropriate treatment process shall be selected according to the characteristics of radioactive waste (such as physical and chemical characteristics, radionuclide type and activity concentration, organic content, salt content, suspended solid content and pH value) and discharge limits. At the same time, the process restrictive conditions with risks such as corrosion, scaling, foaming, fire and explosion shall be considered. If the liquid waste contains fissile materials, it shall be evaluated within the practical range by designing and adopting management measures, and potential critical risks shall be eliminated. The increase of activity concentration of concentrated liquid waste may lead to changes in the classification level of waste, so appropriate process shall be taken for conditioning. 3.4.3.2 The short-lived radionuclides may be reduced by temporary decay before the liquid waste is discharged, and the radionuclides in the liquid waste may also be removed by treatment system or other means. Waste water that meets the reuse requirements after treatment shall be reused in the plant as much as possible to reduce the discharge amount. 3.4.3.3 The liquid effluent generated after the treatment of liquid waste shall meet the discharge requirements.   3.4.3.4 For the management of organic liquid waste, not only the influence of radioactivity but also the influence of chemical organic components shall be considered. 3.4.4 Treatment of solid waste 3.4.4.1 Appropriate treatment process shall be selected according to the waste characteristics, and mature or validated advanced technology shall be adopted. 3.4.4.2 The volume reduction of combustible waste can be achieved by incineration. The following contents shall be take account in the selection of incineration process: (1) reasonable furnace type and operating conditions shall be selected according to waste characteristics (such as chemical composition, enthalpy, moisture content, non-combustible content) to ensure complete combustion and prevent coking, blockage and generation of toxic or explosive substances in the furnace; (2) the incineration system shall be designed by taking into account expected operating events and accident conditions that may endanger the safety of operators or cause uncontrolled discharge of radionuclides to the environment; (3) the offgas treatment and radioactivity monitoring system shall be set up to ensure that the discharge concentration and amount of radioactive and non-radioactive hazardous substances are lower than the prescribed limits; (4) incineration will increase the activity concentration of ash content, which may lead to changes in the classification level of waste, so the ash content generated shall be safely conditioned. 3.4.4.3 Compactable waste can be reduced by compaction. The compaction method used shall define and control the characteristics of the material to be compacted and the expected volume reduction factor. The following shall be taken into account in the selection, design and implementation of compaction operations: (1) the possibility of release of volatile radionuclides and radioactive aerosols; (2) the outflow of contaminated liquid; (3) the chemical reactivity of materials during and after compaction; (4) fire and explosion hazard caused by inflammable and explosive materials or pressurized components; (5) the criticality risk that may be introduced by the increase in the content of fissile material per unit volume after compaction of waste containing fissile material. 3.4.4.4 Large waste shall be pretreated by cutting, disintegrating and other technologies. During technology selection and equipment operation, measures shall be taken to prevent dispersal of contamination and fire prevention. 3.4.4.5 For non-combustible and non-compactable solid wastes, direct conditioning shall be considered when decay and decontamination effects are not good. The radionuclide in scrap metal shall be removed by metal smelting to realize material reuse or clearance. 3.4.5 Low- and medium-level radioactive waste suitable for near surface disposal shall be subjected to cement solidification, and high-level radioactive liquid waste shall be subjected to glass solidification. The characteristics of waste solidification shall usually meet the following requirements: (1) good compatibility with matrix materials and package containers; (2) the texture is uniform and dense, with low porosity and good integrity; (3) the leaching rate of radionuclides is low. (4) the chemical, biological, thermal and radiation stability is sufficient; (5) there is certain mechanical strength and resistance performance.

Contents of HAD 401/12-2020

1 Introduction 1.1 Purpose 1.2 Scope 2 General requirements 3 Specific requirements 3.1 Control of waste generation 3.2 Waste characterization and classification 3.3 Waste pretreatment 3.4 Waste treatment 3.5 Waste conditioning 3.6 Waste storage 3.7 Transport of waste 3.8 Safety considerations during the service life of pre-disposal management facilities for waste 3.9 Consideration of decommissioned waste management 4 Quality assurance 4.1 Quality assurance requirements 4.2 Quality control Annex A Waste management program and management procedures of nuclear facilities Annex B Typical characteristics and features that shall be considered for management of radioactive waste packages Annex C Radioactive waste examples of nuclear power plants and research reactors Annex D Examples of radioactive waste from facilities in the earlier stage of nuclear fuel cycle Annex E Examples of radioactive waste from facilities in the later stage of nuclear fuel cycle