Fuel Manufacturing and its Environmental Effects

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2 ATS YGN meeting in Espoo 3 November Fuel Manufacturing and its Environmental Effects Ernst Thulin ernst.g.thulin@se.westinghouse.com Jakob Arborelius jakob.arborelius@se.westinghouse.com Slide 2

3 Outline of Presentation I. Overview of Fuel Factory in Västerås II. III. IV. Conversion and Pelletizing Overview of Fuel Rod Manufacturing Environmental Effects Slide 3

4 The Nuclear Fuel Factory in Västerås/Sweden General: In operation since 1966 One of the most modern fabrication plants in the world Licensed for 600 t UO 2 /y Products: BWR and PWR fuel, BWR control rods, UO 2 -powder Processes: UF 6 >UO 2 conversion to final assembly incl component manufacturing Certified to ISO 9001, and other standards Slide 4

5 The Nuclear Fuel Factory in Västerås/Sweden Some key process features: Conversion: Wet AUC-process. Gives free flowing powder. Simplifies blending, pellet manufacturing and U-scrap add-back Laser device for 100% in-line pellet diameter measurements Gravity feed rod loading with automated stacking and very soft pellet handling Electron beam (EB) welding of rod end plugs, 100% automatic ultra sonic and visual weld inspection Hot vacuum out gassing process for pellet moisture control Automatic horizontal BWR assembly line PVP coated rods in PWR assembly Slide 5

6 Sweden Fuel Fabrication Experience (31 May, 2005) BWR FA (10x FA) BWR Fuel Channels pcs. (20916 SVEA) Control Rods 5058 pcs. PWR 1934 FA (17x FA) Conversion 9234 ton UO 2 powder Slide 6

7 Over-all flow chart Slide 7

8 Conversion and Pelletizing Slide 8

9 Manufacturing of UO2-pellets Conversion of UF 6 to UO 2 (AUC process) Västerås UO2-pelletizing process - powder - blending -pressing - sintering -grinding - stacking and loading Slide 9

10 The Nuclear Fuel Factory in Västerås/Sweden Conversion Slide 10

11 AUC Powder and Pellets Properties AUC, Ammonium Uranyl Carbonate, (NH 4 ) 4 UO 2 (CO 3 ) 3, conversion process facilitates: simple blending technique in large bulks due to free flowing powder. WSE use enrichment blending as standard direct to press without pre pressing and granulation operations efficient and flexible recovery of chemicals and Uranium using standard processes low impurity levels in powder and pellet Slide 11

12 Conversion To pelletizing To pelletizing Slide 12

13 AUC powder characteristics Free flowing mean particle size 20 µm BET 5,0-6,0 m2/g 90% of area from internal porosity O/U ratio 2,08-2,12 Bulk density 2,2-2,4 g/cm3 Slide 13

14 The Nuclear Fuel Factory in Västerås/Sweden Pelletizing UO 2 -Pellet Shop Slide 14

15 Pelletizing H2+CO2 From conversion To fuel rod loading Gd2O3,U3O8 Al2O3, Dry Flow H2+CO2 Two step blending in V-shell blenders Slide 15

16 UO2 -pelletizing process: Blending Free flowing AUC powder allows: Easy enrichment blending as standard Blending in 500 l Bi-cone containers Direct to press after blending without prepressing and granulation. Enrichment blending qualified up to 5% of U-235. Slide 16

17 UO2 -pelletizing process: Pressing Pressing in Courtoy R 53 rotary press using die wall lubrication. Three production lines Random packing in sintering boats with a soft handling system Slide 17

18 UO2 -pelletizing process: Sintering Sintering in Degussa furnaces Trough push furnace with 5 heating zones Mass flow regulation of the sintering atmosphere Typical values in manufacturing: Temperatures up to 1800 C Atmosphere of H 2 and CO 2 Sintering time about 5 hours Slide 18

19 UO2 -pelletizing process: Grinding/visual inspection Grinding in centerless grinder Wet grinding, diamante coated grinding wheel In line diameter inspection using laser technique. Accuracy better than 2 µm Manual visual inspection Slide 19

20 UO2 -pelletizing process: Stacking and loading Automatic stacking of pellets up to 6 zones and 3 enrichments. Loading in an equipment using inclined position of tubes. Feeding of the pellets is very smooth since only gravity is used Slide 20

21 UO 2 -Pellets : Density and Grain size PWR Pellet density 10,50 g/cm 3 (95,8%) Typical grain sizes 7-9 µm BWR Optima 2 Pellet density 10,60 g/cm 3 (96,7%) Typical grain sizes 7-9 µm Slide 21

22 ADOPT - Grain Size New pellet design for improved in-reactor behavior UO 2 pellet Grain size 9 μm Density 10.60g/cm 3 Cr 2 O 3 /Al 2 O 3 doped pellet Grain size 31 μm Density 10.67g/cm 3 Slide 22

23 Overview of Fuel Rod Manufacturing Slide 23

24 Fuel Rod Manufacturing Slide 24

25 Fuel Rod Line Overview Slide 25

26 Basics Cladding tubes are delivered ready to use, no extra cleaning required Chemically etched barcode in plenum region used when recording data for each rod From all manufacturing and inspection steps Reject rods to collection points Slide 26

27 ElectronBeamWeldingusedsinceDay 1 The weld is easy to inspect with UT Very low scrap rate, typically around 0.1% High vacuum, 10-5 mbar, protects against oxidation Slide 27

28 Mainly Automatic Weld Inspections UT used for circumferential weld, checks for presence of pores, penetration Vision system used for geometrical weld dimensions, end plug streightness and weld discoloration. Also verifies presence of weld in fill hole. Slide 28

29 Gravity loading of pellets Soft handling Pre-measurement of all zone lengths. Process computer in full control of loading, keeps track of all rod data Automatic plenum length measurement checked by computer against rod length, accumulated zone lengths and rod drawing Slide 29

30 Robot Handling of End Plugs & Plenum Spring No tooling change required when changing end plug designs All spring designs handled with one tool All top end plugs are checked for presence of non-obstructed fill hole Slide 30

31 Hot Vacuum Out-Gassing (HVOG) for all Rods Verified to eliminate any water content on pellets or in cladding tubes Batches of 90 rods processed in sequence Heated in nitogen to above 200 C Sits in vacuum for over 30 minutes Cooled down in nitrogen Slide 31

32 Seal weld using TIG All rods from HVOG handled in vacuum chamber until pressurized with He and seal welding completed Slide 32

33 Rod Scanning Automatic rescanning of rods with suspected defect Detection with 95% probability for defects: ± 10% deviant enrichment pellet ± 4% deviant enrichment zone Inter pellet gaps larger than 1mm Slide 33

34 Rod Streightness Measurement Each rod is slowly rotated on precision wheels forming a V Any wobble is measured at set distances Slide 34

35 Final Inspection Careful handling of rods on ramp Manual inspection of rod surface is last inspection step Slide 35

36 Environmental Effects Slide 36

37 Environmental Management System at WSE WSE achieved third party certification according to ISO in December 1997 Integrated with the Quality System (ISO 9001) Aim for constant improvement Slide 37

38 Significant Environmental Aspects Chemical handling Waste handling Suppliers Product and process development Energy consumption Pollution to the water Pollution to the air Transports Slide 38

39 Emissions to atmosphere Methanol (CH 3 OH), Ammonia (NH 3 ), Nitric Oxides (NO x ) Emissions to the atmosphere 140 0,95 1,33 0,75 1,69 2,61 4,43 3,12 4,08 3,92 1,82 0,14 1,77 1,59 0,08 1,86 1,20 0,14 1,64 1,21 0,24 2,60 1,37 0,32 2,94 1,72 4,00 11,55 25,00 34,30 35,00 42,12 50,08 59,61 67,85 65,04 82,26 100,57 109,36 118, REDOX-plant * Emissions-treatment facility * Combustion of : ammonia, methanol, nitric oxides * Significant reduced emissions Methanol Ammonia Nitric oxides Metric tons Permits and target 1999 REDOX Year Slide 39

40 Emissions to water Methanol (CH 3 OH), Ammonia (NH 3 ), Nitric Oxides (NO x ) Emissions to the local utility plant (MälarEnergi) ,910 54,056 59,359 62,231 Water purification * Joint effort with a local utility * Significant reduced emissions Metric tons ,149 Ammonia Nitrates ,397 4,450 5,445 5,577 2,100 0,021 0,017 0,022 0, Permits and target Improved denitrification system ,015 0,003 0,033 0,007 0,014 0,198 0,008 0,001 0,033 0,049 0,500 2,000 Year Slide 40

41 Emissions to atmosphere of Uranium Emissions to the atmosphere 0,05 0,04 0,06 0,07 0,04 0,01 0,02 0,02 0,03 0,01 0,05 0,41 3,00 2,00 3,0 2,5 2,0 1,5 Kg 1,0 0,5 0, Permitted pre 1998 Permitted since 1998 Year Slide 41 Uranium (actual)

42 sampling in the surroundings precipitation, grass, sediment, Slide 42

43 Tack! Slide 43