COMPONENTS DISMANTLING AT NOVOVORONEZH UNITS 1, 2 SHUT DOWN FOR DECOMMISSIONING

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1 COMPONENTS DISMANTLING AT NOVOVORONEZH UNITS 1, 2 SHUT DOWN FOR DECOMMISSIONING Filatov Alexey Engineer, Decommissioning Department Novovoronezh NPP, Russia INTRODUCTION The first phase of Novovoronezh NPP consists of two Units: Unit 1 with electric capacity of 210 MW, and Unit MW-e. Thermal power is generated by vessel type water cooled and water moderated power reactor (VVER). Technologically it is a two-circuit power plant. The primary circuit consists of a VVER reactor and circulation loops. Each loop includes: primary coolant pump, steam generator, motor-operated isolation valves (4 valves per loop at Unit 1, and 2 valves per loop at Unit 2), pipelines ND 500 mm. The secondary circuit is not contaminated, it consists of steam generators, turbine generators and auxiliary turbine components. Service water supply is based on a straight-through water intake from Don River. Novovoronezh Unit 1 was commissioned on 30 September From 1965 to 1969 the reactor was in pilot operation at thermal power exceeding its nominal design level by 14 to 35%. Electric capacity reached 240 MW, and in 1969 due to use of turbine generator 4 of the second Unit under construction it was as high as 280 MW. In August 1984, after reactor vessel design life time expired, Unit 1 was shut down for reconstruction and modification, spent nuclear fuel was discharged to spent fuel pool. In 1986 after the Chernobyl accident, the nuclear power plant safety concept in USSR was revised, and the modification work at Unit 1 was terminated. According to Minatomenergo order No. 57 dated by Novovoronezh Unit 1 was transferred to decommissioning state, and the work was started to mothball the Unit systems and components, except the components and systems required to ensure nuclear and radiation safety in spent fuel storage, as well as safety significant systems and components related to operation of overall plant systems and those connected to Units 3-5. Novovoronezh Unit 2 was commissioned in December 1969, and on 1 April 1970 it reached design parameters. According to the regulation of USSR Council of Ministers dated by , due to significant deviation of its design characteristics from up-to-date safety

2 requirements, and economic inexpediency of its modification, Unit 2 was removed from operation ahead of design life expiration (30 years), by the order of the USSR Ministry of nuclear power and industry, dated by Spent fuel was transferred from the reactor core to spent fuel pool of Unit 1. The work to transfer the Unit systems and components to mothballing conditions was continued for both Units 1 and 2. It should be noted that no regulatory basis for decommissioning existed at that time. The work for preparation of Novovoronezh Units 1 and 2 for decommissioning, and development of regulatory and conceptual documents by research organizations were performed in parallel, and the practical work was often ahead of theoretical. DECOMMISSIONING OPTION SELECTION AND MAIN WORK DIRECTIONS In on request of USSR Ministry of nuclear power and industry experts of the leading Russian research institutions performed feasibility studies for various options of Novovoronezh units 1, 2 decommissioning that were used as a basis for selection of the main option long-term safe storage and monitoring of confined highly contaminated components with their further disposal. Selection of plant disposal option following its long-term safe storage and monitoring resulted from the following factors: absence of both national and regional radioactive waste repositories and disposal sites; presence of operating units at the plant site, whose operational safety has to be considered in decommissioning of the shut down units; unavailability of sufficient financial funds; use of radioactivity level reduction due to natural decay factor, and is implemented in three phases: - preparation of the plant for monitored storage; - monitored plant storage; - disposal of the plant unit as a nuclear facility. In accordance with the selected decommissioning option for Novovoronezh Units 1 and 2, and the results of the comprehensive engineering and radiation survey (CERS), a Decommissioning Program was developed in 1995 that became the main document specifying the list, sequence and schedule of decommissioning activities. At present Novovoronezh Units 1, 2 are in the phase preceding decommissioning, which includes plant preparation for decommissioning, when the operating organization shall provide: removal of spent nuclear fuel from the plant units and transfer to nuclear safe

3 state, removal of radioactive fluids from plant components and process systems that used to support safe spent fuel handling; standard decontamination of plant components, systems and building structures; processing and removal of operational radwaste from the unit; comprehensive survey of the unit; development, review and approval of decommissioning project according to established rules; development of work performance project (WPP), engineering and process documents for the approved decommissioning project; bringing the unit to anticipated condition (by life time, component composition, use of storages, etc.); personnel training for decommissioning activities; preparation of documents needed for obtaining a license from Gosatomnadzor of Russia for decommissioning activities. The phase of the plant preparation for decommissioning is completed by obtaining the license from Gosatomnadzor of Russia for decommissioning of Novovoronezh Units 1 and 2. DISMANTLING IN THE PHASE OF PREPARATION FOR DECOMMISSIONING The purpose of dismantling in the process of decommissioning is to transfer the plant units to nuclear- and radiation-safe state. In the phase of preparation for decommissioning dismantling is performed to minimize decommissioning costs and to reach the following objectives: - process development and tools testing; - personnel training; - re-utilization of components and rooms for plant needs. Dismantling in the controlled access area is allowed provided a justification is available that dismantled components after their decontamination will fall into the non-radioactive waste category (for unrestricted use). PREPARATION OF WORK DOCUMENTS Documenting of the engineering solution for component dismantling process. Development of design and working documents for conversion. Documenting modifications in licensing conditions.

4 Development and documenting of a procedure for safe work performance in component dismantling. Performance of radiation survey of components subject to dismantling, and preparation of radiation survey report. Development and documenting of dismantling work procedure and actions to ensure industrial safety, industrial sanitation, fire safety and radiation safety in performance of dismantling activities. COMPONENT DISMANTLING AND DISPOSAL. ROOMS CONVERSION Overall dismantling schedule in the phases of preparation for decommissioning and decommissioning of Units 1, 2 is provided in Figure 1. Overall schedule of dismantling in the phases of Novovoronezh Unit 1(2) decommissioning Preparatory phase of NPP unit decommissioning Phase 1 Preparation of NPP unit for safe monitored storage Dismantling of "non-contaminated" turbine hall components Phase 2 NPP unit safe monitored storage Phase 3 Disposal of NPP unit as a nuclear facility Dismantling of low- and medium-active components of reactor department and special water purification plant Dismantling of high-active (confined) components of reactor department and special water purification plant Dismantling of buildings and structures Figure 1 According to regulations approved by Concern Rosenergoatom and endorsed by Gosatomnadzor of Russia dismantling was performed of turbine generators Nos. 1 to 3 at Unit 1, turbine generators Nos. 4 and 5 at Unit 2, dismantling is completed of

5 deaerator components at Unit 1. At present work has been started to dismantle turbine generator No. 6 at Unit 2. Dismantled components after their accounting and control are fragmented and sent for disposal or reuse. Dismantling of components and systems of turbine department at Units 1, 2 is caused by the opportunity to use the components, buildings and structures of the shut-down units for plant needs. Thus, in 2005 a project was implemented of Unit 1 turbine hall conversion to storage of insurance reserve of components for Concern Rosenergoatom. After removal of spent nuclear fuel from the units in 2004 the most important task is the processing and disposal of radwaste accumulated at Units 1, 2 over their operating period and generated in the process of decommissioning. Due to absence of regional repositories in Russia processed radwaste containers are located in temporary storages on Novovoronezh plant site, including converted rooms at Units 1 and 2. Dismantling in the controlled access area is allowed if it is justified that: dismantled components (after their decontamination if needed) will fall into the non-radioactive waste category for unrestricted use; use of the room is needed for conversion. As of today, according to developed designs a number of rooms at Units 1, 2 have been converted to storages for solidified waste containers. The total number of containers (200 l barrels) is 2780: in May 1993, after implementation of conversion project for control rod drive storage pool at Unit 2 a storage was commissioned for 540 containers with salt concentrate from deep evaporation plant (hard radwaste storage HRWS No. 18), and in January 2004, after implementation of conversion project for spent nuclear storage pool at Unit 1 a storage for 2240 containers (hard radwaste storage HRWS No. 20). Processing of all liquid radwastes accumulated at Units 1, 2 will be completed after commissioning of hard radwaste storage with the capacity of containers, which is under construction scheduled for completion in In the near future Novovoronezh NPP plans to install a plasma incineration plant for processing of hard radwaste, and electrochemical decontamination plant for metal radwaste. Tables 1.1 and 1.2 provide lists of completed and planned dismantling activities at Novovoronezh NPP.

6 List of completed dismantling activities (Table 1.1) Year Dismantled component Dismantling purpose Basis for work performance 1993 Control rod drive storage pool at Unit 2 (HRWS No.18) Conversion for storage of 540 containers Regulation No. 91/93, approved by V.S. Zarubaev on , working documents Turbine generators Nos. 1 to 3 Conversion for storage of components Regulation approved by V.V.Antonov on , WPP Deaerator components at Unit 1 Conversion for storage of components Regulation No. 20//99-ТОSBE/36, approved by V.S. Zarubaev on , WPP 2004 Spent fuel pool at Unit 1 (HRWS No. 20) Transformers Т-2, Turbine generator No.4 Conversion for storage of 2240 containers Environment protection Conversion for expanded storage of insurance reserve Regulation 15-14/23, approved by V.V.Antonov on , Detailed design Regulation No ETs-12; 262\2003-ETs-12 Regulation No. NVNPP 2ТR-47К03, approved by N.М. Sorokin on , WPP Turbine generator No.5 Conversion for expanded storage of insurance reserve Regulation No. NVNPP 2ТR-47К03, approved by N.М. Sorokin on , WPP Planned dismantling activities (Table 1.2) Year Dismantled component Dismantling purpose Basis for work performance 2006 and on Components of contaminated workshop Conversion for installation of radwaste plasma incineration plant Regulation and design for radwaste plasma incineration plant 2006 and on Fresh fuel storage components Conversion for installation of metal radwaste electrochemical decontamination plant Regulation and design for electrochemical decontamination plant 2006 and on Components of turbine generators Nos.6 8 and deaerator components at Unit 2 Conversion for expansion of insurance reserve storage Regulation No. NVNPP 2ТR-47К03, approved by N.М. Sorokin on , WPP

7 Decontamination cost versus cost of utilized metal scrap Gained from utilization Spent for dismantling Spent for dismantling ,4 $ Gained from utilization ,6 $ Cost of new radwaste storage construction versus cost of rooms conversion Number of containers (pcs.) SFP-1 Cost of work (thousand rubles) Unit cost per container (thousand rubles) Number of containers (pcs.) HRWS Cost of work (thousand rubles) Unit cost per container (thousand rubles) , Savings from conversion of SFP-1 for storage of containers with radwaste from deep evaporation plant amount approximately to 20 mln. rubles (700000$) CONCLUSIONS ON RESULTS OF DISMANTLING IN PREPARATION FOR DECOMMISSIONING Dismantling can not be cost-effective just as it is; In case of rooms conversion for radwaste storage or other decommissioning purposes savings may compensate for expenses.

8 PROPOSALS BASED ON RESULTS OF DISMANTLING IN PREPARATION FOR DECOMMISSIONING Continue component dismantling and rooms conversion at Novovoronezh NPP according to decommissioning programs and projects; Continue the work to create and provide Novovoronezh NPP with a set of equipment needed for safe dismantling of components, buildings and structures, including: - equipment for outgoing radiation monitoring of unrestricted use waste; - equipment for dismantling and fragmentation using gas abrasive cutting method; - equipment for dismantling building structures; - mobile laser device (one for all NPPs).