Technical Meeting (TM) on Spent Fuel Storage Options IAEA Vienna, July

Transcription

1 Technical Meeting (TM) on Spent Fuel Storage Options IAEA Vienna, July External Spent Fuel Storage Facility at the Nuclear Power Plant in Gösgen Urs Appenzeller, Nuclear Fuel Division, KKG Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 1

2 Nuclear Power Plant Gösgen-Däniken AG (KKG) PWR Siemens / KWU Single reactor with 985 MWe net Commissioned in loop plant, similar to Neckarwestheim 1 and Trillo Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 2

3 KKG Fuel Strategy up to 2003 Closed Fuel Cycle Strategy After 3 years of interim storage in the pond of the reactor building the spent fuel was transported to the recycling facilities MOX-Fuel was fabricated under contract with AREVA at Belgonucléaire ERU-Fuel was fabricated unter contract with AREVA at MSZ (Russia) Waste from reprocessing is returned to Switzerland in form of CSD-V and CSD- C and stored in the central interim storage facility of ZWILAG Würenlingen -> no problems occurred and strategy proved to be successful and economically favourable Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 3

4 Need for additional storage Capacity Due to the Kernenergiegesetz of 2003, (nuclear energy law), the transport of spent fuel assemblies to the reprocessing plants (F/UK) had to be suspended for 10 years (from 2006 till at least 2016F) The capacity of the spent fuel pool within the power plant is limited ( positions for spent fuel assemblies) For an optimum interim storage at the dry cask storage facility in Würenlingen/CH (ZWILAG), the KKG spent fuel assemblies would have to be cooled down for a long period, specially for the MOX assemblies Construction of an on-site wet spent fuel pool (almost and independent fuel storage facility) in order to increase the capacity and further to enable longer cooling periods Decision on the wet fuel storage facility was based on safety, technical and cost aspects in comparison with a dry storage facility Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 4

5 Temporary solution to allow time for launching the Project for Wet Storage Facility Development of a optimized cask Type for the total of 144 FA Fuel from first reloads, long cooled, low Burn up Delivery of four TN 24 G casks (G stands for Gösgen) by Transnucléaire Each with a capacity of 37 FA with a total heat load of max. 34 kw Loaded and transported from 2001 to 2004 to the SWISS Interim Storage Facility (ZWILAG) ZWILAG has a dedicated cask Storage Building for vitrified high level Waste from Reprocessing and SF from running plants Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 5

6 Launching Project of the KKG Wet Storage Facility To scope with high burn up FA with up to 5%, enrichment kw To scope with high burn up MOX FA with up to kw To store the remaining SF arising form the KKG Plant within an expected lifetime of 60 years Immediate Transfer of SF after 2 years of cooling After shutdown of the plant a stand-alone operation of the storage facility is required Challenges: To be licensed according SWISS Regulations (difficulties due to fundamental adaptations in the law!) External effects 9/11 event new earthquake requirements Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 6

7 Location of the Project (I) KKG Area Structure of Buildings Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 7

8 Location of the Project (II) (from scale model) Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 8

9 Location of the Project (III) (from scale model) Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 9

10 Contract Terms Turn-Key supply of the wet spent fuel storage facility Signature of contract: July, 5th 2002 Taking Over: February, 28th 2008 Scope Description for AREVA NP (Germany): Basic and Detailed Design for mechanical and electrical equipment Licensing Documentation, responsibility for licensing process at KKG Construction Works (agreement with IMPLENIA a Swiss consortium partner, ~ 20% of contract value) Manufacturing and Delivery of the equipment (e.g. storage racks (REEL), heavy crane (Marti Dytan) etc.) Installation of the Equipment Commissioning Approx. 40% of AREVA NP scope was subcontracted to local Swiss companies From Total Price, Hardware: 75% / AREVA Engineering: 25% Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 10

11 Main Technical Features Main dimensions of fuel storage building (APC bunker): 35 m x 17 m Enclosed volume of fuel storage building: 20,000 m3 Requirements: Capacity for 1,008 spent fuel assemblies (Uranium and MOX FAs) Passive Cooling of the SFAs (max. 1 MW) by natural circulationin case of accidents Design against airplane crash (APC) and earthquake Only a few systems are connected with the plant (standalone operation after Plant shutdown), Personnel access via the plant Local control panel with connection of safety relevant information to the main control room Transport of the spent fuel assemblies from the reactor building to the fuel storage facility by a cask carriage on rails Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 11

12 Fuel Pool Cooling System Cooling Tower 2 Fuel Storage Building Cooling Tower 1 Heat Exchanger (FPCS) Fuel Pool Cooling System (FPCS) Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 12

13 Fuel Pool Cooling System Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 13

14 Fuel Pool Cooling System Functional characteristic of fuel pool cooling system: KTA 3303 Code sets out temperature limits and type of system failure to be taken into account Cooling during normal operation by natural circulation (temperature within fuel pool max 45 C with average outside temperature of 26 C) with support of fans in case of high outside temperatures (limited to a few days per year)and fully loaded fuel pool Cooling in case of severe accidents (SSE and APC) by natural circulation without need of electrical supply (temperature within fuel pool depending on specific accident up to max. 80 C) Possibility of connecting an independent Accident Management Cooling System Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 14

15 Airplane Crash (APC), SSE/OBE Earthquake Significant changes after project start!! Airplane Crash: Code HSK-R-102 plusadditional requirements resulting from the 9/11 event (big commercial plane with full tanks) increased reinforcement of the walls Earthquake requirements as for the the existing plantf plus additional requirements of PEGASOS OBE original: 0.07 g horizontally, 0.035g vertically OBE revised: 0.12 g horizontally, 0.060g vertically SSE original: 0.15 g horizontally, 0.075g vertically SSE revised: 0.25 g horizontally, 0.125g vertically Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 15

16 Airplane Crash (APC), SSE/OBE Earthquake: consequences of the revised/additional requirements Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 16

17 Airplane Crash (APC), SSE/OBE Earthquake Cooling Tower Fuel Storage Building Process Building 12m 8m GERB Damping elements for reduction of induced vibrations below fuel pool Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 17

18 Modularinstallation of components in two stages (I) 1st Stage: Storage Capacity for 504 spent fuel assemblies (Uranium and MOX FAs) Cooling of the SFAs (max. 0.5 MW by natural circulation in case of accidents) Operational experience and advanced technologies have to be taken into account for 2nd Stage Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 18

19 Modular installation of components in two stages (II) 2 nd Stage (including «lessons learnt»): Increase Storage Capacity to 1056 spent fuel assemblies (Uranium and MOX FAs) -> by optimised positioning of the racks (gain of additional 48 storage positions) Increase cooling capacity of the SFAs to total max MW by natural circulation in case of accidents -> by optimising heat exchangers (increase capacity by >50%) Improve Filtering system for the air intake (additional HEPA Filters) and additional installation of UV-lamps in the pond to avoid biological contamination Improve air condition system Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 19

20 International / National Standards The external Wet storage facility at Gösgen is in compliance with the requirements of IAEA (2012) WENRA (2011) Swiss Federal Nuclear Safety Institute (ENSI)(2012) ENSREG Stress tests as a follow up after Fukushima (2013) Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 20

21 Wet and Dry Storage: International Standards (I) IAEA Safety Standards, Specific Safety Guide No. SSG-15 Storage of Spent Nuclear Fuel (2012). Although designs of spent fuel storage facilities may differ, in general they should consist of relatively simple, preferably passive, inherent safe systems intended to provide adequate safety over design lifetime of the facility, which may span several decades.. The spent fuel storage facility should be such that retrieval of spent fuel or spent fuel package for inspection or reworking is possible. For storage beyond the original design lifetime of the facility, testing examination and/or an evaluation may be necessary to assess the integrity of the spent fuel or the storage cask. Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 21

22 Wet and Dry Storage: International Standards (II) IAEA-TECDOC-1012, Durability of spent nuclear fuels and facility components in wet storage, Zr alloys are highly durable cladding materials in wet storage, based on a series of hot cell examinations after wet storage periods from 5 to 27 years. Results of the examinations are supported by laboratory data, by specific observations during fuel shipments and other fuel handling operations, and by visual surveillance by storage pool operators for periods approaching forty years. Results of data and experience continue to support a conclusion that wet storage of fuel with Zr alloy cladding will be acceptable for periods in the range 50 to 100 years, including exposures to relatively aggresive water chemistry. Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 22

23 Wet and Dry Storage: International Standards (III) WENRA (Western European Nuclear Regulators Association) The Report on Waste and Spent Fuel Storage Safety Reference Levels (2011, working Group on Waste and Decommissioning (WGWD) F.. refers to the IAEA recommendations addressed on durability/ageing, long-term storage aspects, retrievability, etc. and incorporates more facility specific requirements Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 23

24 Wet and Dry Storage in Switzerland: National Standard: ENSI-Guideline «The applicable operational requirements for the storage of spent fuel assemblies and reactor wastes in spent fuel pools are given in chaps. 7.6 to 7.10.» Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 24

25 Follow up after the Fukushima accident by the European Nuclear Safety Regulators Group Stress Tests Performed on European Nuclear Power Plants as a Follow-Up of the Fukushima Accident Peer Review Country Report of Switzerland «The seismic robustness of the Spent Fuel Pools (SFP) in Swiss NPPs can be rated as high and the newer NPPS KKG and KKL have spent fuel pool cooling systems which display a high safety margin in relation to an earthquake of hazard level H2 ( ) with margins». «Cooling of SF in the SFP is ensured for 72 hours without external technical support in case of extreme naturally induced impacts leading to a total failure of the SFP cooling systems» «In order to counteract the incipient evaporation phenomena, which could affect the implementation of accident management, back-fitting measures consisting in the installation of filling level indicators ( ) are planned for all plants. Implementation of temperature measurements reported in the control rooms has been also requested.» Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 25

26 ENSI resolution after Fukushima: Required back fitting at KKG Spent Fuel Pools 3 Pools in Gösgen: SFP in reactor building, loading pool in reactor building, and external SFP physically separated connections for external emergency water supply (e.g. fire brigade) exists for external SFP Indicators in control and emergency control room of SFP temperature new for external SFP Indicators in control and emergency control room of SFP water level new for external SFP Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 26

27 Conclusion KKG has opted for a temporary storage of spent fuel assemblies in an external spent fuel pool, with the capabilities to be qualified as an intermediate storage fulfilling all international and national standards. The external SFP is constructed and is operating according to the latest international and national standards Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 27

28 Thank you for your attention Technical Meeting (TM) on Spent Fuel Storage Options, IAEA on July EDMS # Folie 28