18th International Conference on Structural Mechanics in Reactor Technology (SMiRT 18) Beijing, China, August 7-12, 2005 SMiRT18-H09-1
STRUCTURE ANALYSIS & DESIGN OF PCCV
FOR NEW GENERATION NPP
Mingdan Wang
Shanghai Nuclear Engineering Research
& Design Institute, No.29, Hongcao Rd.,
Shanghai, China, 200233
Phone: 8621-64850220-25021
Fax: 8621- 64852963
E-mail: [email protected]
Xiaowen Wang
Shanghai Nuclear Engineering Research
& Design Institute, No.29, Hongcao Rd.,
Shanghai, China, 200233
Phone: 8621-64850220-24252
Fax: 8621-64852963
E-mail: [email protected]
Xiaolin Huang
Shanghai Nuclear Engineering Research
& Design Institute, No.29, Hongcao Rd.,
Shanghai, China, 200233
Phone: 8621-64850220-24263
Fax: 8621-64852963
E-mail: [email protected]
Zufeng Xia
Shanghai Nuclear Engineering Research
& Design Institute, No.29, Hongcao Rd.,
Shanghai, China, 200233
Phone: 8621-64850220-24031
Fax: 8621-64852963
ABSTRACT
The paper documents the overall schedule work which has been done by Shanghai Nuclear Engineering Research and Design Institute (SNERDI) in the research and design scope of the new generational advanced prestressed concrete containment vessel (PCCV). It can be applied to the design of nuclear engineering and general prestressed concrete structures in civil engineering.
Keywords: prestressed concrete containment vessel (PCCV), nuclear power plant (NPP), finite element analysis (FEA), model experiment, research and design
1.0 THE CONTAINMENT SCHEME IN OVERALL PERSPECTIVE
The PCCV has evolved from the first generation and second generation to the third generation, since it is built in 1960's. Figure-1 shows the evolution of the PCCV. The evolution and development of the PCCV with the enlargement of the installed capacity of nuclear power plant (NPP), the difference of the controlled accident pressure, the improvement of the prestressing tendon material and the tensioning method of the tendons, and much experience accumulated in projects, and so on.
SNERDI has successfully designed two PCCVs of second generation, therefore acquired a lot of experiences in the project design. And we are also focusing on and following the over sea’s design of third generation PCCV in time. According to the demand of the domestic market, we take it for granted that it is necessary to design the third generation PCCV by ourselves. We also can reach the new level. Hence, we applied the study task of ‘the design performance and experiment research of PCCV for advanced NPP’ during the period of ‘ninth 5-years’, which is the key technology of the advanced NPP. We endeavored to reach to the first class in the world on the design of PCCV.
Table-1 the material quantity and cost comparison of the different PCCVs
PCCV Length of steel strand
Number of tendon
Concrete quantity
Reinforcing
rebars quantity Cost
First generation 1.4 2.5 1.1 1.1 1.2
Second generation 1 1 1 1 1
Third generation 0.9 0.66 0.85 0.8 0.85
We compared several typical abroad PCCVs of third generation. We did our best to collect their advantages and considered properly the overload in serious accidents. And then, we provided the conceptual design of third generation PCCV with the characteristic of China.
2.0 THE DESIGN PARAMETERS
2.1 Geometric parameters
Inner diameter of Containment: 40m, Thickness of cylinder wall: 1.1m Height of cylinder wall: 35m
Thickness of dome with the shape of hemisphere: 0.9m Total height of containment: 55.90m
The containment with a steel liner inside and two buttresses outside at the azimuth angle of 08 and 1808.
2.2 Material parameters
Concrete grade: C50
Reinforcing rebars: HRB400 (with yield stress of 400MPa)
Prestressing tendons: 37Φ15.7 tendons, the steel strand with yield stress of 1860MPa The ultimate capacity of each tendon:
T ψ×37×1.5×186 =0.95×10323 =9807kN
≈1000 metric tons
Type of corrugated pipes: with nominal diameter of 140mm, and 2.5mm thick
Terminal bearing plate: with the size of 480mm long, 480mm wide and 70mm thick.
2.3 Design interior pressure
Design interior pressure: 0.4MPa
Net free bulk volume of containment: greater than or equal to 60000m3)
2.4 Tendon spacing
Spacing of circumferential tendon: 0.40m
3.0 THE CHARACTERISTICS OF THIS DESIGN DISTINGUISHED FROM INTERNATIONAL POPULAR THIRD GENERATION CONTAINMENTS
The thickness of containment cylinder wall was reduced from popular 1.22m~1.30m to 1.10m, and the thickness of dome from 1.07~1.10m to 0.90m. So the consumed concrete was saved efficiently.
We designed prestress level of PCCV 20% high than the popular third generation ones, in order that the radioactive steam was hold back in containment in case of over pressure in serious accident. So the very expansive exhaust plan with filtration was not necessary. Although the serious accident had not been included in related containment design specification now, it had already been the unavoidable fact.
The enhancement for the weakness of equipment hatch was shifted from the popular inside of the containment to outside. And this greatly enhanced the local stiffness of the stress concentrated areas around large opening. It could efficiently reduce the risk of local failure in this area because of overpressurization in serious accident. And this was also coordinate with the design of two second generation containments which were designed by us.
As for the aspects of detail constructing, we took the improvement of abroad third generation PCCVs, combined with the design and construction experience of the past second generation containments. For example, reduce the spacing of circumferential tendons in the root of containment.
4.0 THE SCHEME OF DESIGN PERFORMANCE ANALYSIS AND EXPERIMENT RESEARCH OF PCCV
4.1 Goal of research
Although China started the research and design of containment late, SNERDI had design two second generation PCCVs independently, from the beginning of 1980's up to now. The containments passed structural integrity test (SIT) and integrated leakage rate test (ILRT) at first time. And It filled up the gap with advanced countries in containment structural design. SNERDI accumulated a lot of experience and information in the aspects of research, design and engineering practice.
At the end of 90's, we faced with new challenge again. The government emphasized and intended to develop and build 1000MW NPP in the base of 300MW NPP. It required us to reach to a high level in containment design again.
4.2 Research contents and key techniques
The research work was divided into three large parts according to the plan of the feasibility study report on this subject, as following:
Part one was the concept design of third generation PCCV. It mainly contented the basic design parameters of containment, the actual layout of prestressing tendons and some principal detail constructions.
Part two were about the analysis of main design performance of PCCV. It could be divided into five subtopics again. There were two special subtopics focusing on the main loads of containment, i.e. the interior pressure in lost of water accident (LOCA) and load because of tendon tensioning. The other special subtopics were primarily concerned with behaviors of containment under serious accident. However, how to handle serious accident was an unavoidable fact, inspire that serious accident had not yet been included in design base scope until now.
The bearing behavior of PCCV over the designed pressure was studied all over the world. It was necessary to extend the structural performance from traditional elasticity phase to nonlinear plastic condition aiming at the ultimate bearing capacity. The simplified nonlinear finite method analysis (FEA) using membrane elements could give approximate result scope of model experiment and particular nonlinear FEA. The particular nonlinear FEA on prototype containment was conducted to deduce the ultimate bearing capacity. And then we could verify the model experiment result with the prototype calculation independently.
Part three was about model experiment. The model was made up of the same material with the prototype. It was reduced to 1:10 scale of prototype containment in conceptual design. The model bore the interior pressure until it was destroyed. And the experiment could provide necessary validation for the calculation and analysis of design performance.
The research work was divided to three parts.
Analysis of prestressed compressive stress and
tensioning sequence of tendons Completed by SNERDI Simplified nonlinear FEA of model Completed by SNERDI
Nonlinear FEA of model Completed by Tsinghua University
Ultimate bearing capacity analysis of
containment Completed by SNERDI
Part three Model experiment
Completed by Architectural Research Institute of Metallurgy Ministry
The above three parts aimed at three key techniques of containment research respectively:
The first key technique was how to realize a brand new layout of prestressing tendons distinguished from second generation containment, and how to collect the advantages widely from international existed third generation containments. Then we designed the new generation containment with Chinese characteristic, more economic and reasonable than the popular third generation PCCVs.
The second key technique was how to establish the calculation and analysis model matching with third generation PCCV structure characteristics, and how to realize nonlinear FEA of containment which can be verified with model experiment mutually.
The third key technique was how to fabricate 1:10 containment model reasonably. The advanced measure and test method were adopted to guarantee the realization of model failure because of interior pressure.
4.3 Synthesized conclusion
The above seven special topics, which were about the design and experiment research work on PCCV in advanced NPP, were done after two years effort.
SNERDI finished five special topics as the duty institute. Architectural Research Institute of Metallurgy Ministry and Tsinghua University finished two special topics (model tests) and one special topic (detail analysis of model) respectively, which were assigned by SNERDI.
In the coordination and overall arrangement of SNERDI, the three institutes concluded the same result and verified each other using different method from different point of view about the design performance of containment in advance NPP, including the ultimate baring capacity in design base and serious accident, the performance of 1:10 model experiment and theoretical calculation.
First generation Second generation Third generation Palisades Rancho Seco Trojan
