1. MODULE “PROJECT MANAGEMENT AND CONTROL” SAFETY ASSESSMENT DURING DECOMMISSIONING SAFE DECOMMISSIONING OF NUCLEAR POWER PLANTS Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”

2. 2 CONTENTS 1. Critical tasks of decommissioning 2. Areas of management

3. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”3 TRAINING OBJECTIVES Upon completion of training trainees should be able to:  Explain the conditions of the nuclear facility that impact on decommissioning safety assessment.  Identify the risks typical for separate decommissioning activities.  Describe the critical tasks of decommissioning.  Describe the parameters for assessment of decommissioning impact on the personnel.  Describe the parameters for assessment of decommissioning impact on the environment.  Describe the non-radiological risks during decommissioning.  List the areas of decommissioning management.

4. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”4 OPERATIONS RELATED TO CHANGE OF RISK AND SAFETY ASSESSMENT AFTER THEIR COMPLETION  Removal of spent fuel  Processing, conditioning and disposal (storage) of radioactive waste  Decontamination prior to dismantling, demolition and processing, conditioning and disposal (storage) of radioactive waste at decommissioning  Cleaning of site (demolition) and its environmental release or utilization in other nuclear facility

5. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”5 TYPICAL RISKS ASSOCIATED WITH DIFFERENT DECOMMISSIONING OPERATIONS  Decontamination prior to dismantling  Dismantling  Decontamination after dismantling  Decontamination of building materials

6. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”6 TYPICAL RISKS ASSOCIATED WITH DIFFERENT DECOMMISSIONING OPERATIONS – CONTN.  Dosimetric control  Demolition and reconstruction of site  Radioactive waste management  Treatment of non-contaminated waste

7. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”7 CRITICAL TASKS AT THE PHASE OF FINAL SHUTDOWN  Fuel cooling and removal  Standard decontamination of equipment with the help of operational systems  Circuit drainage  Treating and conditioning of operational radioactive waste  Tripping of equipment that is not further needed

8. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”8 INITIAL CHARACTERIZATION OF THE INSTALLATION  Ensures input data for safety assessment.  Allows for specification of inventory and layout of radioactive and dangerous materials.  Supports preparation of radiation maps and contamination maps.  Allows to determine penetration depth and contamination extent.  Used for choosing appropriate procedures for decontamination or dismantling.  Used to determine the inventory of hazardous chemicals, materials and substances.

9. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”9 FUEL REMOVAL  Time for implementation: At the end of operation; At the beginning of decommissioning activities.  Time for removal depends on: Type and size of reactor; Fuel condition; Constraints related to its transportation; Constraints related to its off-site management.  Utilization of on-site interim storage facilities for spent fuel.  Shipment of new fuel in case of stocks.

10. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”10 TRANSPORT OF SPENT FUEL

11. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”11 CONTAINMENT MAINTENANCE AND MODIFICATION  Important element of defence in depth.  Containment systems need to be retained as long as possible.  Changes: Radioactive materials are removed; Facility is modified.  Deferred dismantling: Ensures proper maintenance; Regular assessment of containment protection systems integrity and reliability.

12. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”12 DECONTAMINATION  Types: Partial or complete; Prior, during or after dismantling.  Decontamination objectives: Decrease exposure during decontamination activities; Minimization of volume of materials classified or disposed as solid radioactive waste; and Increase of possibilities for equipment, materials or buildings recycling or reuse.

13. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”13 DISMANTLING  Reactors shutdown at end of operations without accidents or incidents  Reactors shutdown after an accident  Decommissioning of facilities significantly contaminated with alpha-nuclides  Dismantling and demolition techniques and methods

14. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”14 MAINTENANCE  Important element ensuring safety in case of deferred dismantling.  Implementation of periodical monitoring of safety related components.

15. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”15 FINAL RADIOLOGICAL SURVEY  Objective: To demonstrate that residual activity complies with the criteria set by the National Regulatory Body. To demonstrate that all objectives of decommissioning are fulfilled.  Time for implementation: Upon completion of all decommissioning activities; In phases depending on implemented activities.  Survey results are included in final decommissioning report.

16. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”16 NON-RADIOLOGICAL RISKS DURING DECOMMISSIONING  Toxic materials – asbestos  Safety measures at its removal: Face masks; Special outfit; Ventilation; Temporary barriers.

17. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”17 PARAMETERS DEFINING IMPACT ON STAFF  Individual exposure dose External irradiation Internal irradiation  Collective dose

18. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”18 ENVIRONMENTAL IMPACT  Parameters: Gas releases; Liquid releases. CRITERIA FOR CLEARING MATERIALS FROM REGULATORY CONTROL  Disposal of RAW from decommissioning process Disposal facilities of surface type – 400 Bq/g for medium total concentration of alpha-emitting radionuclides  Release of materials in the environment “De minimis” principle Radiological standard limit for individual equivalent dose of 10 µSv/y

19. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”19 NON-RADIOLOGICAL HAZARDS AT DECOMMISSIONING  Work with electrical equipment  Work performed on heights  Work with toxic substances Asbestos Lead  Work with chemicals  Others – lifting heavy loads, noise, vibrations, etc....

20. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”20 ISSUES TO BE CONSIDERED DURING DECOMMISSIONING  Staffing and training;  Organization and administrative control;  Radiation protection;  On-site and off-site radiological monitoring;  Waste management;  Emergency planning;  Physical protection and safeguards;  Quality assurance and documentation.

21. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”21 REFERENCES  Decommissioning of Nuclear Power Plants and Research Reactors, Safety Guide, SS № WS-G-2.1 (1999)  Organization and Management for the Decommissioning of Large Nuclear Facility, TRS № 399 (2000)  The Decommissioning of WWER-Type Nuclear Power Plants, IAEA-TECDOC-1133 (2000)  The principles of radioactive waste management, SS № 111-F (1995)