Dismantling Techniques applied at MZFR

Transcription

1 Wiederaufarbeitungsanlage Karlsruhe Rückbau- und Entsorgungs- GmbH The Decommissioning Project Multi-Purpose Research Reactor ( MZFR ) Dismantling Techniques applied at MZFR E. Prechtl Projekt MZFR WAK GmbH Research Reactor Decommissioning Demonstration Project (R²D²P) IAEA Workshop Decommissioning Technologies Forschungszentrum Karlsruhe 6 10 Juli

2 NPP and Prototype Reactors in Germany ( > 20 Nachhaltiger Rückbau: ( > 20 MWe ) Nuclear Facilities in the former responsibility of Karlsruhe Research Center and EWN, since July 1 st 2009: EWN NPP in Operation: 17 NPP and Prototype Reactors under Decommissioning: 15 NPP and Prototype Reactors in safe Enclosure: 3 Prototype NPP complete dismantled: 2 2

3 Decommissioning Projects on Site of the Karlsruhe Research Center ( incl. Dismantled Facilities KKN and HDR, State of Bavaria ) MZFR Multi-Purpose Research Reactor WAK (VEK) Karlsruhe Reprocessing Plant Compact Sodium- Cooled Nuclear Reactor KNK FR 2 Research Reactor Safe enclosure HDB Central Waste Treatment Department HDR Superheated Steam Reactor at Karlstein Green field KKN Niederaichbach Nuclear Power Station Green field 3

4 Multi- Purpose Research Reactor ( MZFR ): Basics Type: Power: Pressurized water reactor Heavy water moderated and cooled 200 MW th, 57 MW el (242 fuel elements) Erection: Operation: Purposes: Development and testing of nuclear materials Testing of heavy water systems Testing of fuel elements Staff training Decommissioning: Decom. Strategy: Dismantling and Removal in 8 steps (= 8 partial licences) Objective: Green field (IAEA Level 3) 4

5 MZFR Decommissioning: Fundamental Goals of Dismantling Perform the work safely (radiological and non-radiological) Dose minimization (but as low as reasonably achieviable ALARA ) Cost reduction as much as reasonably possible Waste minimization KIS - principle ( keep it simple ) 5

6 The Main Basic Objectiv: Safety Radiation Protection: workers, population, environment Technical Safety: selecting and developing dismantling techniques selecting and developing handling techniques 6

7 High Dose Rates Kontamination Typical Radiological and Non Radiological Hazards Chemical exposure: asbestos, etc. Welding and cutting: fire Operation of heavy equipment and power tools Ergonomics: heavy equipment, lifting, etc. Explosives: facility, demolition Environmental conditions: heat, cold, wet, slippery, limited visibility Confined spaces 7

8 MZFR Dismantling Technologies There is no single technique to address all dismantling boundary conditions on the MZFR decommissioning project, the techniques depends on The activity level of the systems, components and parts The selection of technologies depends also on the space conditions The physical/chemical properties of the systems and comp. to be dismantled (e.g. metal, concrete) Radioisotopes and contamination layer The type of isotopes present (Co60, H3, ) 8

9 MZFR Dismantling Technologies ( cont d ) Remote controlled dismantling (dry) for large and activated RPV components (metal): Band saw; > 500 T Autogenius burner (flame cutting under air); ~ 50 T 9

10 MZFR Dismantling Technologies ( cont d ) Remote controlled dismantling (dry) for activated metals and concrete (bioshield): RC jackhammer (excavator), with tools: ~ T 10

11 MZFR Dismantling Technologies ( cont d ) Under water remote controlled dismantling (thermal and electrical tec. for high activated metals): Plasma Cutting (UW); tool carrier, equipment: ~ T CAMC (Contact arc metal cutting (UW), adapted: ~ 100 T (without tool carrier) 11

12 MZFR Dismantling Technologies ( cont d ) Mech. hand held tools (activated and cont. metals) : Orbital saw (< 1 T ) Hydraulic cutter (~ 2 T ) Nibbler (tanks, ~ 5 T ) Angle grinder (decontamination, < 500 ) Mechanical saws (< 1 T ) 12

13 MZFR Dismantling / Decontamination Technologies Contaminated concrete: Diamant wire saw (~50 T ) Scarifier (~10 T ) Hammers drills, Comb. Hammer (> 1 T ) Air needle scaler (> 1 T ) 13

14 MZFR Plant, 1987 ( Activity Inventory approx E16 Bq ) Controlled Area Rad. Prot. Area 14

15 MZFR Plant (cont d) 1992 Controlled Area Rad. Prot. Area 15

16 MZFR Plant (cont d) 1992 Controlled Area Rad. Prot. Area 16

17 MZFR Plant (cont d) 1996 Controlled Area Rad. Prot. Area 17

18 MZFR Plant (cont d) 1998 Controlled Area Rad. Prot. Area 18

19 MZFR Plant (cont d) : Pressure test at the manufacturer s Controlled Area Rad. Prot. Area 19

20 MZFR Plant (cont d) 2001 Controlled Area Rad. Prot. Area 20

21 MZFR Plant, 2009 ( Activity Inventory approx E13 Bq ) Controlled Area Rad. Prot. Area 21

22 RPV Dismantling: Conditions at the Beginning ( Jan ) Mass: Dimensions: Geometrical Conditions: RPV Total mass approx. 403 Mg Height: 7.7 m, Ø: 4.4 m Dismantling in present position (from top to bottom and from outside to inside) Dose Rate: DL Core-inside 11 Sv/h (01/1999) Radioactivity Inventory: Approx. E 16 Bq ( key nuclide: Co-60 ) Packaging and Disposal: 178 casks and containers (104 type II Konrad containers and 74 MOSAIK casks), interim storage at the Central Waste Treatment Department (HDB) 22

23 Installations on Reactor Building Level +10 m Ventilation area Staff entrance Repository casks Packing area Ventilation Lifting, moving, and sawing RPV components Cut-off pieces Secondary waste. 2 1 Dismantling area Dismantling table Intervention area RPV lid Band saw 1: In intervention area 2: In dismantling position 23

24 Manual Dismantling of all Components above the RPV ( Dez Feb ) Dismantling of absorber rods, guiding tubes, measurement systems, etc. Criteria: dose rate < 500 µsv/h Biological Shield 24

25 Manual Dismantling of all Components above the RPV ( Dez Feb ) On the reactor lid: Cutting of measurement tubes on the RPV lid On the reactor lid: Dismantling of the absorber rod drives 25

26 Remote One-piece Removal of the Rod shaped Components inside the RPV ( April Sept ) Cooling channels, guiding tubes, etc. 272 components 212 local transfers and transports to HDB (cutting in a hot cell) Biological Shield Difficulty: 5 unremovable cooling channels 26

27 Five Unremovable Cooling Channels: Solution of the Problem Leaving in core position Planning of back-up dismantling technology: Solution: Dismantling in the underwater campaign (2004) with the hydraulic shears Typical hazard: fragmentation Biological Shield 27

28 Removal and Remote Dismantling of the RPV Lid ( Band Saw, April July 2002 ) 1: Crane 2: Support system 3: Dismantling table 4: Band saw 5: Reactor 6: Manipulator system Longitudinal section of the dismantling area in reactor building 28

29 Preparation of Removal and Remote Dismantling of the RPV Lid ( Band Saw, April July 2002 ) Dismantling of the RPV lid bolts: Cutting off the 2 bolts, that could not be loosenened 29

30 Removal and Remote Dismantling of the RPV Lid ( Band Saw, April July 2002 ) Biological Shield 30

31 Optimization of Safe Handling and Training, Trials, and Demonstration with 1:1 Dummy Part I: Pulling up, transporting, and putting down ontothebasestructure 31

32 Training, Trials, and Demonstration with 1:1 Dummy Part II: Removal of the upper filler piece with base structure to core position (in case of interventions) 32

33 Removal and Remote Dismantling of the Upper Spacer ( Band Saw, Dec April 2003 ) Upper Spacer Optimizing the type of saw band Optimizing the chip sucking system Optimizing the grippers Biological Shield 33

34 Underwater Dismantling Equipment ( Wet dismantling ) Tests and Qualifikation in an external Mock- up 40 t Dismantling Crane Bridge Manipulator Rotating Ring Drying Unit Sledge 1 with Manipulator Mast with 2 Sledges Sledge 2 with Tool Carrier and Plasma Burner 34

35 Remote Dismantling of the Moderator Tank ( RC Plasma Cutting System, Sept June 2005 ) 1. Mock-up tests with dummies Moderator Tank 2. Real remote dismantling Biological Shield 35

36 Cutting of the Remaining Five Cooling Channels under Water ( RC Hydraulic Shears,, Nov ) Cooling Channels Biological Shield 36

37 Experience with Sediments and Slag Residues Deposits and slag residues on the moderator tank bottom: Development of new tools Deposits between the upper round cover plate and stagnation sheets Optimization of the cutting process 37

38 Segmentation of the Cylindrical Wall of the Moderator Tank: Experience with the Cladding 38

39 Cleaning of the Moderator Tank Bottom before Cutting 39

40 The Importance of the Water-Purifying System Change of filter cartridges of the water-purifying system

41 RC Dismantling of the Thermal Shield ( Plasma Cutting System, July Oct ) Thermal shield ( five segments ) Biological Shield 41

42 Special Requirements for Remote Dismantling of the Thermal Shield,, Segment No. Five (cont d) Boundary conditions: Increase in wall thickness: From 70 mm up to 130 mm Gap between TS and RPV body: Only 20 mm, filled with slag and sediments No gap between TS and lower spacer (support) RPV body Thermal shield 42

43 Back-up Dismantling Technique Contact Arc Metal Cutting Cutting ( CAMC ) ( Nov ) (cont d) Teaching, Cutting, Preparation, Result: 43

44 Lifting and Remote Dismantling of the Lower Spacer ( Band Saw, Jan. - July July 2006 ) RPV body Biological Shield Lower spacer (two pieces) 44

45 Removing of the RPV Insulation Removing of the upper RPV insulation (11/2000) Removing of the lower RPV insulation (03/2007) 45

46 Dismantling of the Cylindrical Part of the RPV ( Autogenous Burner and Band Saw, June Nov ) RPV Computer RPV flange simulation Real dismantling 46

47 Dismantling of the RPV Bottom ( Band Saw, Nov. Dec ) Dismantling area RPV bottom 47

48 Mock- up dismantling equipment in the turbine hall: excavator with dismantling tools 48

49 Mock- up dismantling equipment in the turbine hall: excavator with dismantling tools (cont d) 49

50 Decontamination Work in the Pool Storage Building 50

51 Decontamination Work in the Pool Storage Building Decontamination of the recirculation ventilation shafts 51

52 Decontamination of the Concrete Shieldings 52

53 Dismantling and Decontamination in the Auxiliary Building Dismantling of the tank bases Dismantling of the 200 m 3 liquid waste tank No. 4 (of 4) Milling of the contaminated screed 53

54 Dismantling and Decontamination in the Auxiliary Building: completed areas 54

55 Waste Management: Containers, boxes and drums (for low active or contaminated waste ) 20 Container and 10 Container 200 l drum Transport boxes 55

56 Waste Management: Repository Cask Type PSC V1 ( different shieldings for low and middle active waste ) Net weight: 14.5 Mg Max. Weight: 20.0 Mg Price: T 1600 Shielding lid Concrete nozzle 1700 Wall shielding [mm]: Steel: 10 Concrete: 180 Steel: 70 56

57 Waste Management: Repository Cask Type MOSAIK ( middle activ waste ) Net weight: 8.30 Mg Load: 0.52 Mg Price: T 1060 Lead shielding: 60 / 80 mm Outer wall: cast iron with spheridiodal graphit 160 mm 1500 Lid with shielding 57

58 Waste Minimization Step 7 Remote Dismantling of the RPV incl. Internals Primary waste (disposal): Secondary waste (treatment): concept plan detail planning real (1995) (ab 1999) (2008) Tertiary waste (new installations), decont. or reuse: approx. 403 Mg approx. 95 Mg, (approx. 80 Mg contaminated water) approx. 250 Mg 58

59 Collective Dose, Steps 6 to 8 [msv] ( as of ) SG: Dismantling primary system 7.SG: Remote dismantling RPV 8.SG: Dismantling bioshield and plant decontamination Plan Real 0 6.SG 7.SG 8.SG 59

60 Collective Dose of Step 7: RC Dismantling RPV + Internals ( as of ) Plan: 1177 msv, Ist: 318 msv (27%) 60

61 Modifications / Revision Procedures under the Atomic Law (Supervisory Authority Approval) ( 01/ /2008 ) Änderungsanzeigen MZFR Gesamt / nur 7. SG von nderungsanzeigen MZFR Gesamt / nur 7 SG von hr Anzahl 40 (7. SG) Gesamt Total: Step 7 (RPV-Dis.): Anzahl Jahr 7. SG Gesamt 61

62 Comparison of MZFR Data with Those of a Reference PWR-Type Power Reactor Activity after 2.6E17 Bq defueling 3.6E16 Bq Mass of 970 Mg reactor 400 Mg pressure vessel 11,500 Mg Mass of contaminated system and installations 3,500 Mg Masses of 157,000 Mg buildings 44,000 Mg DWR: 1300 MW el MZFR: 57 MW el 62

63 Special Experience from Mock-up Testing and the Underwater Cutting Elaboration, optimization, and implementation of the dismantling concept and objectives in close cooperation with industry, university and research institutes Simulation of all cutting steps as a basis of a safe cutting procedure as well as for high availability and performance during mock-up tests and real cutting 3-D-simulation to demonstrate collision-free operation and accessibility of all cutting areas as well as implementation of locking and interlocking systems Allow sufficient time for testing and training on a mock-up Implementation of a powerful control unit for the process, parameter variations and documentation High cutting flexibility by separate use of tool carrier and manipulator system Elaboration and optimization of maintenance plan and repair strategies Short technical examination periods of documentation and equipment for all relevant cutting steps in close cooperation with the independent experts starting with mock-up testing Development of back-up techniques 63

64 MZFR Decommissioning Project: Short Summary 8 partial atomic licences: High quality of application documents New technical developments and designs necessary High activity inventory: Remote dismantling techniques (mechanical and underwater thermal dismantling techniques) Complete dismantling of the highly activated reactor Mock-ups and simulations Treatment of H3-contaminated concrete structures Expected total collective dose: < 1 man Sv Project costs: Approx. EUR 320 million 64

65 Dismantling Techniques Summary Criteria for selection of dismantling tools and techniques Staff safety Radioprotection optimization Waste minimization Cost reduction Further criteria : Installation duration Reliability Maintenance Waste minimization Replacement equipment disposability No primary criteria is the cutting speed 65

66 Conclusions Dismantling technologies are based on methods and processes applied in conventional areas Special developments and optimizations are required to fulfil special boundary conditions and to reduce the costs Remote dismantling of highly activated and contaminated RPV components is the technically most challenging step Early planning and demonstration of the interaction of the handling system and dismantling technologies in test rigs reduce the dismantling times and, hence, the costs Advanced planning tools (3D simulation, modern control and robot techniques) increase the overall system availability Experience gained from the dismantling of prototype facilities may well be used for the dismantling of industrial NPPs 66

67 The and MZFR in the Site near today Future Thank You for Your Attention! 67