Full System Decontamination at the Obrigheim Nuclear Power Plant Prior to Decommissioning Wilhelm Kukla, En. BW Kernkraft Gmb. H, Obrigheim NPP Christian Topf, AREVA NP Gmb. H, Erlangen • • • History of NPP Obrigheim Considerations Decontamination Targets Systems included in decontamination Technical description of the decontamination Results Energie braucht Impulse
Full System Decontamination at the Obrigheim Nuclear Power Plant time of construction: design 1. criticality: thermal reactor power: exchange steam generators: operating time: total gross production: capacity factor: 2 1965 – 1968 two loops Oktober 1968 1, 050 MWth 1983 01. 03. 1969 – 12. 05. 2005 90, 828 TWh 81. 4 %
Full System Decontamination at the Obrigheim Nuclear Power Plant Considerations After final shut down of the NPP - decontamination of primary coolant system - wait until activity is reduced by decay Decision Carrying out decontamination - activity is reduced faster as by natural decay - ensures that the experienced plant personal with intimate system and operating knowledge is still available - functionality and usability of all NPP systems is already given 3
Full System Decontamination at the Obrigheim Nuclear Power Plant Decontamination Targets: • Reduction of the activity inventory in all systems included in the decontamination • Reduction of the ambient dose rate in working areas • No significant shift of the gamma/alpha ratio • Minimum waste generation • Average decontamination factor of more than 10 4
Full System Decontamination at the Obrigheim Nuclear Power Plant Systems and components included in decontamination: • Reactor pressure vessel with internals, no fuel • Pressurizer • Primary circuit (two loops) including steam generators as well as part of: • Residuel heat removal system • Volume control system • Emergency injection system • Mechanical filters of the chemical purification system 5
Full System Decontamination at the Obrigheim Nuclear Power Plant Total volume: 160 m³ Surface total: 8, 100 m² Is composed of: Incaloy 800 (SG) austenitic weld cladding (primary circiut) austenitic Cr. Ni steel (auxilary systems) 6 6, 200 m² 1, 100 m² 800 m²
Full System Decontamination at the Obrigheim Nuclear Power Plant Additional supporting systems: • • • 7 chemical injection system component cooling system coolant storage building drains spent resin tanks
Full System Decontamination at the Obrigheim Nuclear Power Plant Technical description of the decontamination: AREVA NP Gmb. H obtained the contract, performance: first quarter 2007 AREVA NP used HP/Cord UV decontamination technology in combination with the AMDA equipment. HP: Permanganic acid (the chemical used for preoxidation). CORD: Chemial Oxidation Reduction Decontamination; represents the chemical decontamination process. UV: Represents the in-situ decomposition of the decontamination chemical with an ultraviolet light source. AMDA: Automated Mobile Decontamination Appliance, is the synonym for the external decontamination equipment of AREVA NP. 8
Full System Decontamination at the Obrigheim Nuclear Power Plant HP/CORD UV process is a multi-cycle process including following steps: Step 1: Pre-oxidation with HP Step 2: HP reduction with the decontamination chemical Step 3: Decontamination Step 4: UV decomposition of the decontamination chemical and solvent clean-up 9
Full System Decontamination at the Obrigheim Nuclear Power Plant Results: A total of four HP/CORD UV cycles were performed cation removal 224 kg activity removal 5. 6 E 12 Bq (151 Ci) with > 95 % Co 60 ion exchange resins 6. 7 m³ 10
Full System Decontamination at the Obrigheim Nuclear Power Plant before: SG 2100 µSv/h; channel head 72 m. Sv/h after: 11 1, 6 µSv/h; 1, 2 m. Sv/h
Full System Decontamination at the Obrigheim Nuclear Power Plant Results: Average decontamination factors (DF) DF auxilary systems 29 DF primary system 736 DF steam generators tubing DF overall average Gamma/alpha nuclide ratio: Total man dosis Estimated 12 1409 625 increased about factor 10 46. 1 m. Sv 97 m. Sv
Full System Decontamination at the Obrigheim Nuclear Power Plant RESULTS - Reduction of the ambient dose rate in the different areas: steam generators residuel heat removal heat exchangers chemical volume control system recuperative heat exchanger - Easy handling for dismantling and disposal of these components, especially for the steam generators 13
Full System Decontamination at the Obrigheim Nuclear Power Plant RESULTS - No controlled rooms more in this area, the single hot spots were shielded and will be decontaminated in a special prozess - Man-Sv savings for upcoming dismantling acitivities (1 - 1, 5 Sv) 14
Full System Decontamination at the Obrigheim Nuclear Power Plant Thank you for your attention! 15
Скачать презентацию Full System Decontamination at the Obrigheim Nuclear Power
d3f140f5ba4f9ed6d1eb9197035f185f.ppt