CONSTRUCTION EXPERIENCE FROM MODULAR NUCLEAR POWER PLANTS Presented by W.J. (Chris) Zhang University of Saskatchewan Saskatoon, Canada Email: chris.zhang@usask.ca
Outline 1. Modularization in NPP 2. Comparison of SMR and AP1000 3. Experience in Construction of AP1000 NPP 4. Conclusions
Modularization in NPP General modular system: 1. A system is designed into a set of modules which interact through a standard interface. 2. A module can be in itself a modular system, which follows 1, which reflects the concept of relativity in architectural definition. 3. A module plays an unique function alone in the system defined at that module level unless otherwise redundancy. 4. The primary expected benefit of modularization: rapid construction through parallel processing of modules and agile construction through standard interface. Modularization is not always right to go
Modularization in NPP Modularization is not always right to go 1. Fact: modularization of microelectronics product is very successful but modularization of large electricalmechanical systems is not prevailing. 2. Social constraint. 3. Economic constraint. 4. Technical constraint (NPP). Site-sensitive Equipment for transportation and installation Design change deadlock due to technical, economic, and time
Modularization in NPP Modularization in NPP: 1. Expectation: Modules are constructed in the local factory, transported to, and assembled on the site. 2. Modular design construction (MDC) in the NPP refers to that expected construction of modular reactors. 3. Kasiwazaki Kariwa-7 (BWR) in Japan, Qinshan-3 in China, Shin- Kori-1 in Korea. After 2000, MDC was widely accepted and used in NPPs (both the large power plants and SMRs). 4. Most of them are under construction (e.g., ABWR in Shimane-3, AP1000 in Sanmen-1/2 and Haiyang 1/2, etc.), some are ready to be built (CAP1400, SMRs, etc.).
Spray steel module in Qinshan phase 3 Steel liner of dome in Qinshan phase 2 HCU module in Shimane-3
KB26 module (mechanical) Nuscale power module CV module CA01 module
Comparison of SMR and AP1000: overall SMR (Nucale): electrical power less than 300 MWe; Large NPP (AP1000): electric power more than 1000 MWe. Table 1 shows more details of the comparison of them. No difference in general design (technology, safety feature, and architecture), which is the same with other light water SMRs. SMR: Non-stop refueling. SMR: more automation and less human intervention and specialized operation and maintenance.
Table 1 Differences between Nuscale and AP1000 Items Nuscale AP1000 Principle PWR PWR Safety features Passive Passive System architecture modularization Modularization Electrical power 45 MWe X 12 1090 MWe Fuel UO2 (<4.95%) UO2 (0.74~4.235%) Refueling interval 24 months 18~24 months Fuel assembly 37 157 Design life 60 year
AP1000 NPP overview Nuscale NPP overview
Comparison of SMR and AP1000: technology SMR takes the system operation principle of more automation and integration in both physical interface and signal communication among components originally in large NPP. Example: in AP1000, RCS consists of one reactor pressure vessel, two steam generators, four reactor coolant pump, one pressurizer and reactor coolant lines, etc. While in Nuscale, all these components are integrated into one module called Nuscale power module. Further, in Nuscale, 12 power modules can be added together so that the total power capacity size can vary. The major difference between AP1000 and Nuscale is RCS.
NSSS equipment Reactor building
NSSS equipment
Overall dimension of the containment module: AP1000 versus Nuscale
Comparison of SMR and AP1000: economics Items Nuscale AP1000 Construction period (NOAK) 36months 36 months Construction cost Less than 5000$/Kwe 6000~8000 $/KWe Operation cost 3.0~3.5 /k Wh Note: The above information may be disturbed by the fact that in construction of AP1000 in China, many mock tests and site engineering works for construction are made, which cause a significant amount of time and money. With the increasing maturity of AP1000, the cost and time for construction will be reduced.
Comparison of SMR and AP1000: economics Items Nuscale AP1000 Construction period (NOAK) 36months 36 months Construction cost Less than 5000$/Kwe 6000~8000 $/KWe Operation cost 3.0~3.5 /k Wh The highly integrated design of RCS, namely NSSS, has contributed to: Construction cost reduction, Construction lead time reduction, and Less wastes from construction
MDC experience out of AP1000 NPP Modular design construction (MDC) in NPP WBS GT modular design prefabrication assembly transportation lifting installation
MDC experience out of AP1000 NPP Plant construction Site preparation More interfaces between the two in MDC
MDC experience out of AP1000 NPP Top opening construction technique: Nearly all the modules and equipment in AP1000 need to be put into the containment building the top of the building. This is completed by the lift crane. The large size modules and equipment are first transferred into the CV. Heavy Lift Crane Availability of the life crane can be a problem in MDC. Modules to be installed CV Modul e
MDC experience out of AP1000 NPP Site layout planning (site-sensitive) technique: The best plan is to facilitate the transportation of the wharf, site assembly yard, and the plant, e.g., to make the road straight and short. The best plan is also to make the road reusable, less re-work. Wharf Assembly Yard B+C Assembly Yard A Wharf NPP NPP An integrated planning and scheduling is very useful, which can achieve the best plan, which thus save cost and time.
MDC experience out of AP1000 NPP Flexible yard system technique: In AP1000, nearly all the structure modules are assembled on a temporary place which is called yard for the duration of several months to one year. Flexible and modularized yard is needed to accommodate different modules. Yard design should take into account the assembly and non-modular manufacturing needs, as yard severs as a temporary or buffer shop floor IHP (integrated head package) module assembly yard
MDC experience out of AP1000 NPP Counter-deformation techniques for modules: In AP1000, deformations of modules are serious problems. Construction has to consider various tools and jigs to counter deformation during the assembly, transportation, and lift processes.
MDC experience out of AP1000 NPP Special lift rig for CA01 module Special lift rig for CA03 module Anti-deformation tool to adjust CA03 module
MDC experience out of AP1000 NPP Assembly interface control technique: Use of actual dimension instead of design dimension. Adjustable interfaces of modules are favorable. Deformation of CA04 module leads to the unfit at interface between CA04 module and CA04 top flange
MDC experience out of AP1000 NPP Finished product protection technique : Modules before being put to the site need to be protected from harsh environments that can be created by the nature such as weather condition and engineering works nearby. Protection of the modules is thus needed in construction of AP1000. CV temporary cover
Conclusions 1. Promise of modular NPP (including SMR) is rapid construction and without consideration of pre-manufacturing of modules. 2. Modular NPP (including SMR) can reduce the construction cost and thus total cost without consideration of the capacity of power generation. 3. Construction of modular NPP has more challenges in technology, as the NPP is site-sensitive and the large size of the modules does matter, while the notion of modular is against the change due to any external reason. 4. Construction of modular NPP has more challenges in management due to parallel processing of activities.
Conclusions 5. Challenges in both technology and management to construction may compromise the benefits of construction lead time and cost reduction. 6. Modularization of NPP seems to have missed the consideration of construction. 7. Adjustable modular architecture may be promising to modular NPP.
End and thanks Questions and comments
Conclusions 2.1 Pros and cons of MDC (1) Pros: Construction lead time has been shortened depends on the degree of modularization Quality of the construction has been improved Construction safety was improved Construction schedule control is relative feasible Work productivity was improved Site work volume was decreased
2 Pros and cons of MDC 2.1 Pros and cons of MDC (2) cons: The design shall be completed without changes prior to assembly and installation. Design changes often lead to rework, which would be hard to execute. Costs of transportation, temporary assembly yards and heavy lift crane can be a large mount of investment. Relationships among the design, vender of materials and site contractor become much closer. Especially for the venders who should closely follow the site schedule than ever before. Deformation of modules caused unmatch of interfaces Increased depth cross construction (between civil construction and mechanical/electrical installation) leads to challenge to project management Finished product protection during construction
3 Comparison between SMR and AP1000 3.3 Differences in construction RCS is vital important in NPP and also hard to install on site which requires large amount of precise measurement and fit-up work, machining and welding work. It could save a lot of time and manpower during construction. So it is a breakthrough in Nuscale to integrated the RCS into one power module. Because so many important components in the Nuscale power module, the fabrication might be a difficult. Except for the RCS, the other facilities are nearly the same between the two NPPs. The construction methods will be described in following chapter.
3 Comparison between SMR and AP1000 3.4 Difference in environment friendliness Global environmental deterioration has been a focus for long time, as is known to all, nuclear is the one non-carbon resource which is classified as clean energy. In the following table, we can see the tons of carbon dioxide equivalent per GWeH is very low of 17. Then during the construction of NPP, with the MDC, the numbers of components and site construction activities were decreased, which might decrease the construction waste.