Transcript Slide 1
Improved Techniques-Methods For Nuclear Power Plant Construction John Ioannidi, P.E. Bulatom, 2-4 June 2011 17-Jul-15 Introduction Existing NPPs constructed using methods/technologies from 1970’s-1980’s Since then, new technologies utilized and lessons learned applied A number of methods sufficiently mature and proven to result in: Proven Economic benefits Reduced construction time (again, € savings) New methods/technologies affect the following major activities: 2 17-Jul-15 Reinforced Concrete Placement Concrete and Cement High Strength Reinforcement Modularization Welding Cold Bending Steel Plate Reinforced Concrete Structures 3 17-Jul-15 Comparison of Construction Schedules for Reinforced Concrete 4 17-Jul-15 Advances in Concrete and Cement 5 Improved Cement Powder Quality Advanced Chemical Admixtures Improved Mixing and Placement Techniques Advanced Curing Techniques Pozzolanic Admixtures Development of Specialized Concrete Mix Designs 17-Jul-15 Self-Compacting Concrete (SCC) 6 New Reactor designs should take greater advantage of the benefits of advancing concrete technology… Self Consolidating Concrete (SCC), also known as Self Compacting Concrete: highly flowable, can be placed in formwork with no vibration, minimal finishing. SCC sets and cures in the same time as traditional vibrated concrete, but with much less labor. The product flows around inside and throughout very congested formwork with little human intervention, greatly reducing the risk of honeycombing and voids. 17-Jul-15 7 17-Jul-15 Use of SCC Mix Designs are Tested and Field Ready Use is spreading globally Benefits: Fewer Construction Workers 8 17-Jul-15 Reduces risk of injuries in field at any construction site Reduces cost of project delays Reduces probability of human error and negligence Steel Structure Erection Reduces overall cost of installation on large projects Other Concrete Composition Technologies High Performance Concrete (HPC) Made with several different admixtures (super-plasicizer, fly-ash, silica fume) to achieve mix design properties Must be properly mixed, transported, consolidate, cured Provides higher compressive strength, density, and lower permeability) than traditional concrete Steel Structure Erection Compressive strength: 101MPa (14.7ksi) – 131 MPa (19 ksi) versus 2.5 – 5 ksi. Reactive Powder Concrete (RPC) Capability for even higher compressive strengths than HPC (up to 200 MPa (29 ksi) Produced by including metallic fibers in a dense cement matrix 9 17-Jul-15 High Strength Reinforcement Steel is another basic building material that has undergone major improvements since the first generation of reinforcing steels applied to concrete. Better Quality Control Very Predictable Yield and Ultimate stress behavior Improved Corrosion Resistance Very wide range of sizes, shapes are available Very high strength steels are being produced 10 17-Jul-15 Benefits of High Strength Reinforcement Estimated that >200,000 m3 of Reinforced Concrete will typically be placed for a nuclear power plant By replacing the larger diameter bars with smaller diameter bars of high-strength steel Opportunity to reduce formwork congestion Lower quantities of shipped and stored materials. Reduced manual effort in field construction (lighter materials) 11 17-Jul-15 Prefabrication, Preassembly, Modularization Module: remote assembly operations, prefabrication and preassembly. Modules often the largest transportable unit or component of a facility. Modules can be constructed remotely or constructed at the work site and then placed in position. Equipment “skids” are an example of this technique used for a number of years by various industries 12 17-Jul-15 Examples of Skids 13 17-Jul-15 Modularization Must be planned in the early design and procurement stages. Increases engineering and procurement costs. Net cost savings primarily results from shortened direct construction stage. Is cost effective for critical or near critical schedule path work. Benefits exponentially increase with each “N” plant. Requires more integration of design discipline teams. 14 17-Jul-15 Positive Aspects of Modularization Cost Savings – Time related, Quantity of field labor, Labor wage rate. Significant schedule compression if properly designed and planned Quality Improvement – Shop environment, “Out-of-hole” work. Enhanced Worker Safety – Less Man-hours of exposure 15 More efficient placement of labor on the site to prevent equipment traffic congestion problems. Higher utilization of specialized equipment and labor Increased flexibility, even permitting remote (off site) construction of very complex or specialized modules, which can be transported to the site 17-Jul-15 Examples of Modularization Applied at ABWR 16 17-Jul-15 Dome Lift and Placement: Tomari 3 Mitsubishi 17 17-Jul-15 Modularization Advantages 18 Onsite - assembly and modularization of equipment. Offsite – Equipment manufacturers provide a complete and assembled component skid to the jobsite Packaged - All equipment is provided to a central facility for assembly and installation in modules. These modules tend to be of a massive size and require very specialized transportation equipment and coordination. 17-Jul-15 Modularization Advantages Reduced Schedule Duration Sequential to Parallel Activities Construction Management Construction Facilities/Utilities Construction Equipment Shop Environment Productivity Site Weather Impacts Increased Productivity and Quality Shop Labor Environment & Skill Shop Advance Tool Use Out-of-hole Site Work Reduced Site Manpower Density Ground Level Work Increased Productivity Reduced Safety Risk 19 Reduced time Related Fixed Costs 17-Jul-15 Reduce Overall Project Cost Total Project Cost – 10%, more for “N” Plants. Onsite Labor 25% Construction Risk and Mitigation Cost Project Funding Interest Modularization Disadvantages Added Engineering Cost – 10 to15% Double Shipment – Manufacturer/Module/Site Wider, Longer, Heavier Loads Special Handling Added Risk for Transportation Damage More Detail Required More Intra-Discipline Planning Earlier Design Availability Risk More Procurement Cost – 17 to 20% Added In-shop Work More Coordination and Administration More Sacrificial Material Increase Cost & Schedule Risk if Late Delivery 20 17-Jul-15 More Transportation Cost More Construction Equipment Cost Special Cranes – Very Heavy Lift Larger Capacity Open-Top Installation 21 Capacity of cranes increased (up to 900 tons) Can Shorten construction schedule Reduce construction costs (direct and indirect) 17-Jul-15 High Deposition Rate Welding Welding processes used in nuclear plant construction include: Structural welds to connect structural members Pressure welds Weld cladding (deposition of weld metal on surface of other metal to improve characteristics) 22 Quality welding, crucial to construction of nuclear plant, is time consuming Deposition of metal at higher rates without compromising quality is desired and make a significant contribution to reducing construction times. 17-Jul-15 High Deposition Rates Welding Methods Gas Metal Arc Welding Gas Tungsten Arc Welding Submerged Arc Welding Robotic Welding (Can be used with most type of welding Process): 23 Gas metal arc welding (GMAW) Gas tungsten arc welding (GTAW) Flux core are welding (FCAW) Submerged arc welding (SAW) Robotic Welding most suited for shop work (Controlled environment and repeated) 17-Jul-15 3D Modeling Highlights 3D Modeling can be used at all stages: conceptual, detail engineering/design, construction, O&M Construction rework labor typically can cost as much as 12% of total construction labor using manual method of design Submerged Arc Welding 3D allows better: Visualization Early automated interference identification and resolution flux core are welding (FCAW) Work planning and sequencing 24 Result of above is reduction of rework labor to ~ 2% 17-Jul-15 Pipe Bends Vs. Welded Elbows Pipe bending is a simple alternative construction technique to: Speed up piping system construction Reduce the number of workers required 25 Pipe bending technology previously available, but at that time, welded-in fittings were more cost-effective Pipe bending may now be performed at a lower cost than welding. Development of portable bending machines allows on-site bending of pipe. 17-Jul-15 Bending Techniques Cold Bending Heat not applied to pipe to reshape pipe Types of cold bending 26 17-Jul-15 Bending Techniques Heat Induction Bending Hot Slab bending Whichever method or combination of methods used, appropriately used, process could results in time and money savings. 27 17-Jul-15 In Summary 28 New Approaches, Materials, and Methods available today that can help reduce the risk associated with mega project construction. Early planning, engineering and design involvement, and aggressive management will promote use of technological innovations. Higher costs in some areas of innovations are usually compensated for in Labor and/or Schedule savings Implementing improved construction techniques provides a much more secure environment for those financing a project, with on-time production of energy to the public/private consumer as a critical benefit to stakeholders. 17-Jul-15