Management criteria for damaged spent fuel in long-term storage

Full text: 1. Classification of Defects. a) Damaged Spent Nuclear Fuel (DSNF): technological history - Operational parameters (burnup, cooling time, defects registration time, defects detection system); b) Mechanical defects classifier - Fuel assembly: defects of structural elements, breakdown of geometrical integrity, visually detectable defects of fuel cladding; c) Cladding condition - Degree of cladding non-integrity (leakage), possibilities of identifying leaks, monitoring of the cladding condition in storage. 2. Defects identification in storage. a) Visual inspection to identify mechanical defects - The system for remote survey of fuel condition, ensuring quality of measurement and reliability of results; b) Cladding condition - Application of technologically justified methods of control, development of characterization criteria. 3. Design of facilities for DSNF retrieval, packing a) Designing for DSNF retrieval from storage - Selection of retrieval options ('hot' cell, underwater method, cutting and packing of fuel assemblies); b) Site selection for DSNF packing activities - Studying of options for local DSNF packing activities; c) DSNF drying - Ensuring water removal from outside of DSNF, removal of residual water from under the fuel cladding, as well as removal of chemically fixed water (in depositions); d) Organizational and technical actions for the management of DSNF spills - Ensuring collection, packing, storing of spills in compliance with safety requirements. 4. Selection of container types for long-term storage of DSNF. a) Ensuring two barriers of leak tightness when storing DSNF; b) Ensuring inert atmosphere in storage - Assessment of isotopic composition of the storage environment taking into account the release of gaseous materials from under the fuel cladding; c) Reducing the impact of corrosion during storage - Taking into account the effects of the storage environment on corrosion processes for fuel cladding, structural materials of the fuel assembly and the elements of the storage system; d) Excluding the possibility of exceeding critical pressure values during depressurization of fuel rods; e) Design criteria for mechanical loadings; f) Surface quality - Reduction of fixed contamination when packaging and storing DSNF; g) Chemical compatibility - Ensuring non-interaction of storage system components and DSNF elements (isotopes); h) Operational reliability - Assessing processes taking place in storage structures and structural materials for containers and DSNF during normal operation and design accidents, including corrosion, creep, fatigue, shrinkage, ageing, changes caused by radiation, and other possible processes; i) Costs; j) Supplier stability - Ensuring the required productivity during DSNF management. 5. Ensuring safety during transportation and storage of DSNF a) Organizing a list of events for DSNF storage conditions; b) Fulfilling criticality requirements; c) Ensuring that the requirements for radiation safety during normal operation, for emergency situations, design and beyond-design accidents are met; e) Ensuring compliance with maximal temperature limits for fuel cladding during storage; f) Ensuring fire- and explosion safety; g) Monitoring fuel conditions and the storage environment. (author)