module fabrication strategy for today's nuclear industry

MODULE FABRICATION STRATEGY FOR TODAY’s NUCLEAR INDUSTRY

Clayton T. Smith John H. Hammeran Fluor Enterprises Inc. Fluor Enterprises Inc. Greenville, SC, USA Greenville, SC, USA

Carl Lockwood Fluor Enterprises Inc. Greenville, SC, USA

ABSTRACT

First generation nuclear power plants were built onsite with large construction forces over a number of years using a design that was being revised during construction. Vendor supplied equipment skids were the closest thing to modular building techniques at that time. Modularization techniques are available today as a tool for performing parallel construction activities such as fabrication and assembly of components offsite to support the construction cost and schedule goals of a project. Accordingly, extensive planning and coordination is required by engineering, procurement, fabricators, and construction to support modularization.

The importance of developing a strategy for the utilization of modularization to the Nuclear Industry, Owners, and Engineering Procurement and Construction (EPC) entities, cannot be over emphasized, ensuring the development of a Corporate Modularization Fabrication Strategy, which incorporates and addresses the following, various elements:

Project Modularization Plan Definitions and terms for module, modularization,

and on-off-site fabrication Module types • Modularization boundaries Work processes for interface between Engineering ,

Procurement, Fabricator, and Quality to allow good communication between entities

Constructability reviews • Modularization schedule linked to integrated project schedule

Compliance with approved procedures and Quality Program requirements.

Commitment from management This paper and presentation will discuss and highlight

the following for a typical Advanced Boiling Water Reactor (ABWR) application:

Typical Corporate Modularization Fabrication Strategy;

Typical Modularization Concepts; Modularization: Friend or Foe.

Keywords: Home Office Modularization Planning, Project Modularization Fabrication, Modularization,

INTRODUCTION:

The traditional approach to nuclear power plant construction is to obtain project resources including materials, manpower, and equipment, at the project site so that the various components can be assembled piece by piece. This approach is referred to as "stick built" construction.

Stick built facilities of the past employed large construction forces at site with ranges of 5,000 to 8,000 personnel for approximately 6 to 8 years average duration for construction. Process equipment skids were the primary

1 Copyright © 2012 by ASME

Proceedings of the 2012 20th International Conference on Nuclear Engineering collocated with the

ASME 2012 Power Conference ICONE20-POWER2012

July 30 - August 3, 2012, Anaheim, California, USA

ICONE20-POWER2012-54818

type of modules for such conventional stick built plants where all components were delivered to the site and assembled at their permanent location in the facility. [1]

Modularization is an alternative to the traditional onsite construction method. Construction methods, including open top construction, prefabrication, preassembly, and modularization have seen increasing use in other industries in recent decades. These approaches to construction are receiving more attention by owners, engineers, and contractors, as a better way to support project goals, including reducing project schedules and improving project constructability.

Developers/owners of new nuclear facilities require that construction schedules are as short as practical in order to bring the unit(s) on line as soon as possible, and to accelerate their return on investment.

Nuclear Industry interest in modularization techniques is apparent with Nuclear Energy Institute (NEI), the Utility Steering Group (USG), Institute of Nuclear Power Operations (INPO), Reactor vendors, the International Atomic Energy Agency (IAEA), and owners of nuclear projects, all of whom have reviewed Modularization strategies.

The Corporate Modularization Fabrication Strategy as described in the following sections requires a different approach to some of the industry’s historical project functions and organizations. This Project modularization plan must be developed in accordance with a Corporate Modularization Fabrication Strategy which incorporates all aspects of modular construction. However, a strong Project Modularization Plan can be effective only if the Engineering , Procurement, Construction, and Quality planning activities occur earlier in the overall project plan.

Modularization Fabrication Strategy:

Modularization shortens the construction schedule by allowing work to be performed in parallel. A crucial activity for a new build nuclear power plant is to minimize the engineering schedule impact by providing fit, form, and functional requirements for equipment and components early in the conceptual/planning phases. Early identification of these requirements allows modularization planning to proceed before vendor supplied equipment is selected, and minimizes systems or system redesigns due to design development activities. In addition, the equipment and component deliveries must occur sooner than traditional stick built construction since the procurement schedule is driven by modularization assembly requirements to support the construction schedule.

The keystone of a successful Corporate Modularization Fabrication Strategy is the implementation of a Home Office Modularization Planning Strategy that results in the

development of the Project Modularization Plan (ModPlan)), which describes modularization concepts, organizations, and work processes necessary to modularize a new nuclear facility, irrespective of project location. This strategy may be utilized when an EPC is involved in the early development of a Standard Plant Design (SPD), which provides the opportunity to develop modules starting at the conceptual phase, or when an EPC is involved only with the implementation/construction where the extent of modularization has been predetermined by an Owner. This strategy encompasses a Home Office Modularization Planning Strategy for an entire Nuclear Facility from project initiation through project closeout, or for select phases, as determined by specific project work scopes. [1]

Project ModPlan(s) identify and describe the following:

Modularization Influencing Factors

Modularization Concepts

Types of modules

Modularization Team (i.e., Organizations, roles, and responsibilities)

Modularization Process(i.e., Phases, methods, work processes)

Modularization Project Controls

Modularization Risk/Opportunity Areas

Modularization Lessons Learned The Home Office Modularization Planning Strategy is

flexible and designed for global execution around the world. Projects utilizing this strategy will see the greatest benefit when performing Open Top Construction, and adapt the strategy to incorporate Owner, Regional, Jurisdictional, and Local requirements. [1]

OPEN TOP CONSTRUCTION TECHNIQUE

The vertical or open top construction plan is an installation method that integrates modularization where structural steel, formwork, and rebar modules are placed from above by large capacity cranes. The open-top construction technique is coordinated with structural and equipment modularization fabrication as well as the staging, sequencing, and overall placement of construction components.

Once the initial concrete floor is placed, walls are built, and equipment modules are then installed. Commodities to be installed on that level, such as pre-fabricated pipe spools and electrical raceway, are then staged onto the floor from above. The next floor is constructed using concrete embedded modules, pre-cast components, or structural modules. The process of wall construction and equipment installation is then repeated for the next building elevation.


Meanwhile, the walls, floors, and ceilings of the elevation below are finish painted or coated according to design specifications. Previously staged pre-fabricated items are installed in their final location. Final connections are made to equipment, modules, pipe spools, and electrical wiring.

This open top construction technique allows structural work to continue on upper floors, while mechanical and electrical systems are simultaneously being completed on lower floors. Cost and schedule benefits can be maximized to the extent that equipment deliveries are on schedule, minimizing the use of large construction openings for late equipment deliveries. For sensitive electronic or electrical equipment, which is unlikely to be modularized due to high risk of damage, final placement in the building must be scheduled to support the construction tie in and testing activities. This construction technique reduces the overall project critical path schedule, and allows system turnover sooner to support Start-Up pre-operational testing.

Approximately three years of significant planning and coordination between Engineering, Procurement, Construction, Quality, and Fabricators is required for a successful modularization effort. The staging and sequence of construction on each building/floor/room must be supported by early engineering and procurement deliverables. [1]

Detailed procurement planning is crucial to support open top construction. Any delays at a building elevation can potentially become a critical path activity in the schedule. Obviously, early procurement schedules are dependent on the completion of engineering design deliverables on time. Thus, the construction schedule drives the engineering and procurement schedules so that the overall project schedule is met.

PROJECT MODULARIZATION PLAN

A new build Nuclear Power Plant is modularized to reduce the overall risk associated with the project, mainly cost and schedule risk. A strong modularization plan provides high quality through controlled modular construction, increased worker safety through risk mitigation, and cost savings via a shorter schedule. This is achieved by a strong modularization plan that allows the following:

Maximizing installation efficiency/minimizing costs

Minimizing the onsite construction duration

Enhancing safety performance

Increasing quality/minimizing rework

Decreasing the site workforce requirements

A strong Project ModPlan requires the following deliverables:

Construction Schedule, by Area, Building, Floor, and Room

Onsite Crane, Logistics, and Transportation Plan

Onsite Preassembly Yard Plan

General Arrangement Drawings

Module Location Drawings

Piping and Instrumentation Drawings

Fabrication drawings of module components

Building Structural drawings

Detailed Procurement Planning

Module Inspection/Testing requirements

Fabrication Shop capacity

Project Transportation Constraints

Engineering and Vendor Schedule for modularization components

Each module is assembled by a specific number of qualified and certified modularization fabricators that are prequalified by the EPC’s Engineering, Procurement, Quality, and Construction departments. These modularization fabricators are on the EPC’s approved supplier/vendor list, and have demonstrated, as applicable, civil, structural, mechanical, electrical, instrumentation, or Heating, Ventilation, & Air Conditioning (HVAC) capabilities. This ensures compliance with all Regulatory, design, safety, and quality requirements.

Installation of critical path or near critical path structures and components in the Reactor Building (Reactor Pressure Vessel (RPV)) and the Turbine Building (Generator and Condenser) are crucial in order to meet the project schedule. Shortened erection times for these and other new build nuclear plant structures, equipment, and components reduces critical path activities resulting in overall cost savings. In addition, reducing the debt incurred during construction is of great value to Clients, and supports overall project goals. This is accomplished by moving construction activities that are on or near the critical path to earlier and/or parallel non-critical paths. Such construction activities are performed away from the main construction areas. Modules of various types are preassembled without interfering with ongoing construction activities. Completed modules are then lifted into their final placement location.

Modularization Concepts

EXTENT OF FABRICATION AND ASSEMBLY

The extent of fabrication and assembly is dictated by the size of the modules, location of the project site, trucking restrictions, and the availability of barge and rail service.


Modules may be totally fabricated and assembled off-site, totally fabricated and assembled onsite, or sub-modules fabricated off-site and assembled into a large primary module onsite.

Module Sizes help categorize the envelope for Engineering, Procurement, Fabricators, Quality, and Construction to base their respective plans on to standardize and support the modularization planning strategy. Specialized modules (multi-discipline and complex) are not easily categorized (like standard single discipline pipe racks), and may be uniquely handled as their own mini project. Examples of such specialized modules would be the reactor pressure vessel, hydraulic control unit room, or the reactor building rebar basemat.

Sections of plants designed as independent units have small, medium, and large modules that can be constructed remotely away from the project site or preassembled onsite. These sections consist of components from all disciplines including structural steel, piping, equipment, electrical installations, and instrumentation (protected or shipped loose). Specialized pre-engineering support for lift points, heavy hauling, center of gravity, and positioning equipment are evaluated as part of the modularization plan.

Large modules weigh over 300 tons. [1]

Medium modules are limited to 50-300 tons. [1]

Small modules are limited to 20-50 tons. [1]

Prefabrication

Prefabrication is part of the concept of preassembly on a smaller scale, both in size and complexity. Prefabrication is a common practice on most industrial projects with simple assembly work performed in a shop. Components are manufactured by vendors and preassembled at a shop or onsite. Fabrication shops routinely weld pipe spools or fabricate steel beams, columns, and connections. Other examples are the fabrication of handrails, stairways, and precast concrete components. Repetitive components such as pipe racks or spread footings are good module types for shop fabrication.

Skid Mounted Equipment

Skid mounted equipment is similar to small modularization pre-assemblies usually provided by manufacturers or vendors. They consist of discipline components mounted on structural bases or skids. These units are shop assembled by the equipment manufacturer or component supplier and may be assembled into a module. Examples of skid mounted equipment include pump/motor and motor/drive combinations, water and oil treatment equipment, and compressor units. Skid mounted equipment requires clear contractual agreements for lifting points,

transportation instructions, protection of instrument locations, and temporary weather protection. These issues must be addressed by engineering early in the procurement schedule.

Large and Small Preassemblies

Preassembly is the building of fabricated components, materials and equipment away from the final placement location onsite. Preassemblies or sub modules are portions of modules. They may be of any size or weight, but are classified as small or large depending on their complexity, and the method of transportation. Working definitions of preassembly range from the more conventional field construction work performed onsite to an onsite preassembly method of combining multiple components into a partially or fully completed module. Off-site preassemblies face the same transportation and handling constraints as modules. Smaller preassemblies are shop or site-assembled, and installed with conventional equipment.

DESCRIPTION OF MODULE TYPES

A discussion of the module types is provided below. Samples of the various ABWR modules are shown in Figure 1, [1].

Discipline Module

Discipline Modules (DM) are driven by a single specific discipline such as civil, structural, mechanical, piping, HVAC, electrical, or instruments. Some examples include rebar, pipe spools, and cable tray.

Multi-Discipline Module

Multi-Discipline Modules (MDM) are comprised of a combination of two or more disciplines coordinated by the primary engineering discipline. An example of an MDM is a common structural support structure that may include pipe, tray, duct, or cable discipline components.

Room Module

A Room Module (RM) is a complex multi-discipline module which includes stay in place formwork for walls and ceilings. An example is the Hydraulic Control Unit (HCU) room module consisting of prefabricated HCUs mounted on metal stay in place forms. RMs may also include Q-decking, if feasible.

Structural Module

Structural Modules (SM) vary depending on size and scope. They include structural steel framing, liner plate, support members and potentially rebar mats. The Reactor Building Roof Truss Modules, the RPV Pedestal Modules and the Turbine Pedestal Column and Deck Modules are examples of SMs. Another module sub type is the Structural and Concrete preassemblies for floors, walls, and ceilings that has rebar, concrete, penetrations, conduit, etc.


that reduces the need for shoring placement and removal that can make for longer construction schedules.

Piping Assemblies

Piping assemblies are multiple large bore or small bore in line devices joined together prior to installation. Piping assemblies are different from piping modules because they do not include structural components such as a pipe rack. Piping assemblies are installed in the plant individually or assembled into other modules.

MODULARIZATION FLOWCHART

A Project Modularization Flowchart, Figure 2, [1] is developed to show modularization design tasks and deliverables and department/discipline work processes which require strong interfaces between Engineering , Procurement, Contractors, Fabricator, Construction, Quality, and Commissioning to allow good communication within the project team to support a Corporate Modularization Fabrication Strategy.

MODULARIZATION BOUNDARIES

The modularization boundary definition process begins when sufficient discipline design information is available in the engineering database and the 3D Model. Modularization boundary definition depends on the completion of conceptual design in the 3D model.

Boundary Definition Process Flowcharts and Interfaces

Flowcharts showing the typical Modularization Boundary Definition process, Figure 3, [1] relative to the design development of the 3D model conceptual, preliminary, and detailed phases along with Modularization boundary process interfaces showing the relationship between the Modularization definition/design process and Modularization procurement/fabrication process are useful tools for the various departments as they support the Corporate Modularization Fabrication Strategy.

Design Based Tools for Evaluation of Modularization Boundaries

A Corporate Modularization Fabrication Strategy utilizes information from the 3D model to develop conceptual outlines that serve as a means of defining a proposed modularization boundary. Engineering and construction conduct constructability reviews of the proposed modularization boundaries. These reviews take into account the staging and sequencing activities construction plans for execution of the open top construction technique. Once the modularization boundary reviews are identified, the Project Modularization Team issues a set of conceptual modularization boundaries for each area/building/room to the design team for their technical feasibility review. This is an ongoing process as the design develops from concept to detailed design. The results of the technical feasibility

reviews are used to eliminate impractical modules that do not meet project cost and schedule goals.

The conceptual and preliminary design of the 3D model represents approximately 30% engineering design development and includes building features such as equipment shapes, large bore pipe routing, cable tray routing, and HVAC duct routing. Conceptual modularization boundaries are established in the 3D design model. These conceptual modularization boundaries are identified during the engineering and construction constructability reviews. As the design develops additional modularization opportunities may be identified in the 3D model. The purpose of the 3D model shading, Figure 4, [1] of modularization boundaries is to focus the construction and engineering efforts on the requirements associated with modularization. This initial step in the modularization boundary definition occurs by building floor.

As additional design details are developed in the 3D model for detailed design phase, 3D model reviews and modularization definition meetings are continued to determine the specific components (i.e., pipe, equipment, cable tray, etc.) that are to be included in each module.

Once the final modularization boundaries are approved, the engineering and procurement databases are updated to reflect the equipment, structural steel, components, and commodities for individual modules.

CONSTRUCTABILITY REVIEWS

Constructability reviews begin during conceptual design and continue throughout the preliminary design and detailed design phases. Regular participation by Engineering and Construction is expanded to include Safety, Procurement, Logistics, Quality, and Fabrication Shops as appropriate, depending on the complexity of the modules. As a minimum, the following topics should be considered during these reviews:

Safety relative to modularization fabrication, transportation, and setting

Special rigging requirements or equipment

Evaluating the method of setting the modules (e.g., on temporary supports or pedestals, temporary connections, temporary location, final location)

Ensuring that the design documents provide sufficient detail to fabricate, transport, and set the module

Evaluating the need for temporary bracing and supports

Determining if the module can be utilized as a staging platform for other commodities during module rough setting activity


Formal detailed design reviews on the 3D Model by building by floor by room with input from Engineering, Procurement, Quality, and Construction supports a strong Project Modularization Plan and allows for an integrated overall all Plant design.

Modularization: Friend or Foe

ADVANTAGES OF MODULARIZATION

Modularization construction can be carried out at off-site and onsite facilities, in order to maximize schedule and cost benefits.

Off-site facilities have the advantage of a stable, trained, resident work force already familiar with modular construction techniques, so that work can be executed on the construction of multiple plants. Initial training of the nuclear workforce for higher quality deliverables is required. For additional projects, the work force’s experience curve provides higher quality and increased productivity. Labor costs are typically lower in an off-site shop due to generally lower wage rates and no necessity subsistence pay or per diem. Off-site modularization also has the advantage of reducing the number of required onsite workers.

An advantage of onsite facilities is that there are few limitations on the module sizes that can be assembled; small modules built off-site can be assembled into larger modules onsite. An onsite facility has no additional costs for shipping the completed modules. Another advantage is having a single delivery location for all bulk commodities, whether they will be installed individually or as part of a module.

In addition, Modularization provides a number of general benefits and advantages that can have major positive affects on a project.

Reduced Schedule

Project schedules can be reduced by performing staging and sequential construction activities in parallel with modularization activities off-site or onsite.

A smaller onsite construction work force reduces site craft work hours and has less impact on local skilled labor limitations. The local community economy and infrastructure is also not burdened by a large workforce for a single project. A smaller onsite construction work force causes less interference with onsite traffic and with existing plant operations. And lastly, lower labor costs and higher productivity can be achieved in the controlled environment of fabrication shops.

Also, a smaller onsite construction force requires less construction-related infrastructure. This reduction results in less site congestion and lower construction related direct and indirect costs. Space requirements for onsite laydown and marshaling areas will also be reduced.

Reduces congestion and craft in Construction Work Areas - Increases safety and productivity

Preassembly and modularization can transfer a significant portion of field man hours to an off-site fabrication shop or onsite preassembly yard separate from the primary construction area.

An onsite fabrication shop provides a stable environment with more accessible tools, materials, utilities, and inspection services. Such fabrication shops are easily equipped with automated welding machines and cranes.

An off-site shop can reduce manpower density in the field, and reduce craft interferences, resulting in better field productivity, better quality, and reduced field management.

Controlled Environment

A controlled environment at a fabrication shop provides greater labor productivity and higher quality work. Impacts by field weather conditions are minimal in the fabrication shop making schedule compliance easier. A controlled environment also lowers labor man hours.

Ground Level Work

Ground level work increases labor productivity and safety. Work performed at height can be moved to the ground via a modularization preassembly program. Structural steel components can be bolted together or welded at grade and lifted as modularization subassemblies. Thus, the work is performed more efficiently and safely which reduces overall cost.

Lower Overall Project Costs

Most large new build nuclear power projects are constrained by schedule. A strong Project Modularization plan can reduce overall project costs with shorter schedules and increased productivity in comparison to a stick built plant at the site.

Fluor Global Modularization experience indicates that modular plant construction can save up to 10 percent of the plant costs and cut the on-site labor by 25 percent for a petrochemical facility. Recent petrochemical project estimates show an 8 percent savings in the total cost due to increased labor productivity at the off-site fabrication shop. Of course, the petrochemical industry has been perfecting modularization for many years as have the Oil & Gas and Shipbuilding industries. [1]

A strong modularization strategy for new build nuclear power plants, once developed and executed, has the potential for immediate cost savings. Then as additional projects are implemented, experience is gained, and designs are standardized, the benefits of using the modularization strategy increase.


Off-site Assembly Locations

Off-site Fabrication Shops performing modularization activities reduces onsite construction labor. Peak onsite construction manpower decreases significantly and occurs sooner in the project schedule when a modularization strategy is executed. In addition, the local economic and labor markets at the project locations are not impacted as much by needs of a new build nuclear plant. In fact, remote project locations make the use of modularization a necessity since there are limited skilled workers and infrastructure to support project needs. Another effect is a fixed labor pool of onsite skilled labor which allows for more hiring selectivity at the project.

Off-site Fabrication shops and Off-site Assembly locations allow relocation of structural and mechanical work activities from the field to off-site locations. This allows a large portion of equipment and bulk/commodity materials to be shipped directly to the off-site shops. Reductions in onsite material tracking, equipment maintenance, storage, and theft/loss control activities are achievable. The off-site shops perform these activities in a more controlled and cost effective manner in the shop environment.

Off-site Modularization Strategy starts early

Off-site Fabrication and Assembly activities can begin prior to receipt of a Combined Operating License (COL). A Limited Work Authorization is not required in order to start fabrication of modules off-site. Starting these activities early and in parallel with the onsite construction activities shortens the overall project schedule. Thus, packaged modularization work which is fabricated off-site can begin at the time of contract award.

DISADVANTAGES OF MODULARIZATION

There are some disadvantages that must be evaluated along with the aforementioned advantages. Onsite construction costs may decrease, while other costs, such as Engineering, Quality Assurance, and transportation, may increase significantly.

Increased Early Engineering Costs

Higher initial engineering costs associated with the modularization design process are required for an extensive and effective modularization plan. More front end engineering resources are required to develop extensive preliminary information in order to support early modularization decision making. Such information includes additional drawings, 3D modeling work, lifting/rigging calculations along with center of gravity calculations for modules. Drawings showing modularization interfaces and interconnections are required along with modularization location plans. Major equipment procurements (identified as long lead items) are required earlier in the project schedule in order to support development of vendor engineering data for equipment or components within a modularization design.

Modularization can alter the sequence of equipment design. A strong modularization strategy requires knowing the location of the equipment and piping prior to starting the structural design of the modules. This is significantly different from a stick build design process.

Modularization design can change the design requirements and must be analyzed and defined early in order to optimize modularization. Equipment and pipe rack modules require additional analysis for dynamic transport loads. Temporary bracing is necessary to protect the equipment and structure of the module during transport to the site. The cost of additional permanent steel in the design must be evaluated against the cost of removing the temporary steel at site.

Office engineering costs can increase from 5-15 percent on modular projects. It is estimated that engineering costs were 15 percent higher for modularization on a petrochemical plant project vs. engineering for a stick build design. Hence, decisions for implementation of each module must be reviewed for the project as a whole, and evaluated for total project benefit. [1]

Increased QA Program and Oversight Costs

Establishing adequate QA Program controls at each work location

Conducting work to approved/controlled work instructions

Maintaining/providing records of completed work

Establishing appropriate oversight at all locations (to include audit and inspection as required)

Increased Transportation costs

Modularization transportation is an additional activity and an additional cost that is not required on a stick build project. It is also a crucial modularization design consideration that must be addressed at the beginning of the project. The design also has to consider the transportation loads.

Extensive route surveys are required to ensure that the modules can be transported to the site, and the availability of specialized transportation and handling equipment may actually drive the project schedule.

Increased Project planning and Procurement administration

Performing off-site fabrication shop work or onsite preassembly work rather than stick building at the project site offers the opportunity to spread out the work over a number of new and smaller work sites and perform it in parallel with the onsite construction schedule. Unfortunately, this requires additional supervision and inspection of the work performed at these locations. Each fabrication yard becomes another construction site that must be managed in accordance with all project requirements.


Therefore, some duplication of overhead and administrative processes may occur.

The use of off-site modularization increases the level of project planning required to schedule the design, fabrication, and delivery of modules. Procurement activities also increase due to the need for equipment and bulk commodity materials being ordered and shipped sooner to support modularization delivery dates. In addition, the equipment and bulk materials are shipped to the primary site, as well as to the separate Modularization site(s), and are required earlier to support a strong modularization plan.

Preliminary site plans, logistics, and transportation must address modularization layout and location from the very beginning of the project. Management of module receipt, storage, handling, pre-assembly and placement must be part of the overall construction planning from the beginning of the project.

Increased Materials

Additional material quantities are required for support framework structures, module frames, and primarily structural steel. This may lead to added material quantities and cost. Also, increased labor costs occur when fabricating and installing the additional quantities.

Increased Equipment Damage Potential

Movement of equipment, materials, and modules during handling and shipment increases the risk of damage. Off-site or onsite preassembly activities with equipment and steel in modules also increases risk associated handling, lift incidents, and shipping that could cause module damage. Repair or replacement of damaged modules can cause schedule delays, especially if the damage occurs near the time of final placement.

Additional Rigging/Lifting requirements

A strong Project modularization plan requires larger onsite cranes for lifting larger modules into buildings and structures during construction. The maximum module size is determined by rigging/lifting requirements. The physical dimensions of a module are contingent on the module center of gravity and the weight capacity of the large crane to safely lift the module and place it.

Specially engineered lifting rigs are required for placement of larger modules. Also, standardized lifting rigs can be re-used for different module types to avoid waste.

Large onsite crane utilization for module lifts and heavy equipment lifts must be planned in conjunction with construction to minimize overall number of cranes required for the project.

Project Modularization Plan Interfaces

Additional drawings to support the modularization plan showing the location of all components is required since

modularization boundaries cross multiple systems. The off-site fabrication shop or off-site preassembly shop must maintain control of dimensional tolerances to avoid problems with final placement at the site. This requires timely design deliverables and off-site fabrication with high quality to avoid costly rework at the site during final placement.

The installation accuracy of anchor bolts and embedded pipe in concrete is a good example of fit ups that require a higher level of accuracy. Column bases and pipe spools that must fit up to these components may allow only millimeters or a few degrees in rotation to prevent site rework.

Additional onsite infrastructure

Additional onsite infrastructure and equipment may be required, such as module assembly pads, additional heavy haul roads, platens, utilities at the assembly pads, module transporters, cranes, and module storage/staging areas.

CONCLUSION:

In order for a Corporate Modularization Fabrication Strategy to be successful there are certain Key points that must be clearly understood:

The cost and schedule impacts of using a modularization and preassembly strategy

Using offsite modularization and preassembly methods for identified critical path schedule activities

Significant coordination and planning (up to 3 years prior to construction mobilization) may be required to support a modularization fabrication and preassembly strategy

Management commitment is crucial since it establishes the tone for all Engineering, Procurement, Contracts, Construction, Quality, and Commissioning departments to plan and execute their home office and site activities with offsite fabrication and preassembly in mind.

Management must understand the design approach and upfront costs required to support a modularization fabrication strategy which demands more budget and resources in the home office environment to reduce the onsite labor and schedule needs in accordance with project schedule goals.

MODULARIZATION AS A FRIEND

Modularization is a friend when the Modularization Fabrication Strategy is developed and executed in parallel with other construction activities to reduce on-site costs and shorten construction schedule durations based on the critical path activities identified in an integrated project schedule.


Benefits:

Supports Open Top Construction Method Reduces site man hours and construction schedule

duration Improves productivity and quality in an off-site

fabrication facility Leverages off modularization experience in other

industries such as Ship building, Oil & Gas, Chemicals, and Industrial

Less craft exposure to field conditions reduces safety risks

MODULARIZATION AS A FOE:

Modularization is a foe when the Modularization Fabrication Strategy is executed to just prove it is possible and not factored into the cost and schedule goals of the project. Practical application of modularization techniques is a tool for ensuring the cost and schedule benefits are achieved.

Challenges:

Coordination and communication of multiple entities on a Global scale

Strong organizational leadership to support early planning

Obtaining earlier design and procurement deliverables

Applying modularization techniques to the nuclear industry

Developing interfaces and work processes electronically between Engineering, Procurement, Construction, and Quality.

Always ask if modularization is efficient and whether a

strong Corporate Modularization Fabrication Strategy will result in a cost or schedule benefit to the project. If the answer is YES, then modularization will be your friend.

REFERENCES:

[1] Fluor Corporation, Fluor Nuclear Power (FNP) Modularization Planning Strategy, Dated 12-2-2011, pp. 1-60


Figure 1, Typical ABWR Module List [1]

No. Module Components of module Dimension Weight Onsite/offsite Fabrication Remark

1 Central Mat module Upper layers of base mat rebar with radial pattern RPV pedestal anchor bolts Quencher anchor bolts RCCV liner plate anchors

42 meters diameter

3.5meters height

900MT

(Metric Ton)

Ground assembly on the table surface at onsite

2 RCCV (Reinforced Concrete Containment Vessel) Lower Shell Module

RCCV lower liner shell (Suppression chamber portion)

RCCV inner rebar (vertical and circumferential)

35 meters diameter

21 meters height

1050MT Ground assembly on the table surface at onsite

3 Diaphragm Floor Module RCCV liner Ring (diaphragm floor portion) Upper RPV pedestal block Diaphragm floor slab rebar Embedments (DEPSS plates, conduits, pipes) Radial structural steel supports

29 meters diameter

4 meters height


4 RCCV Upper Shell Module RCCV upper liner shell (Drywell portion)

RCCV inner rebar (vertical and circumferential)

35 meters diameter

8 meters height


5 DEPSS (Drywell Equipment and Piping Support Structure) Module

RPV shield wall Piping Cable trays HVAC ducts DEPSS structure steel

29 meters diameter

8 meters height

940MT Ground assembly on the table surface at onsite (Semi-blocks are pre-assembled at offsite.)

6 Top Slab Module RCCV top liner plate Top slab shell flange Top slab rebar Embedments (conduits, pipes) Internal structural steel supports

33 meters diameter

2 meters height


7 Pool Liner Module

(consists of 4 Modules)

Pool liner SFP (Spent Fuel Pool) liner module (Part 1):

14 meters length

9.5 meters width

11.8 meters height


SFP module (Part 2):

L14 meters x W8 meters x h8 meters, 25MT

DSP (Dryer and Separator Pool) module: L14 meters x W15 meters x H8 meters, 35MT

RWP (Reactor Well Pool) module: Dial 4 meters x H8 meters , 25MT

8 R/B Truss Modules

(consists of 2 modules)

Truss beam structure

Lighting (luminaries and conduits)

HVAC ducts

40 meters length

20 meters width

3 meters height

150MT/each Ground assembly onsite

9 RPV (Reactor Pressure Vessel) Module

RPV

RPV internals

20 meters length 11 meters width 10 meters height

895MT RPV internals are pre-assembled into the RPV factory

10 RPV Pedestal Module

(consists of 3 modules, including CRD SCRAM Piping Module (actually 3-5 sub- modules)

RPV pedestal RIP (Reactor Internal Pump) heat exchangers CRD scram piping Support structures Platform structures

16.3 meters diameter

12.7 meters height

500MT Ground assembly on the table surface at onsite (CRD scram pipes are pre-assembled into a piping block at offsite and assembled into the module onsite.)

The RVP Pedestal may be transported in a round shape, if necessary


Figure 2, Typical ABWR Project Modularization Flowchart [1]


Figure 3, Typical ABWR Modularization Boundary Definition Flowchart [1]


Figure 4, Typical ABWR Modularization Shading Isometric [1]


module fabrication strategy for today's nuclear industry

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