PRELIMINARY DESIGN OF REACTOR PRESSURE VESSEL FOR RDE

Transcription

1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 6, June 2018, pp , Article ID: IJMET_09_06_100 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed PRELIMINARY DESIGN OF REACTOR PRESSURE VESSEL FOR RDE Sri Sudadiyo, Taswanda Taryo, Topan Setiadipura Center for Nuclear Reactor Safety and Technology, National Nuclear Energy Agency, Puspiptek Area Building 80, South Tangerang Indonesia Ari Nugroho Center for Assessment of Energy Nuclear System, National Nuclear Energy Agency, Jl. Kuningan Barat, Mampang Prapatan, Jakarta Indonesia Krismawan Center for Nuclear Facility Engineering, National Nuclear Energy Agency, Puspitek Area Building 71, South Tangerang Indonesia ABSTRACT In the present paper an attempt has been made to conduct the preliminary design of main elements of the reactor pressure vessel for RDE in Indonesia. Work is performed to find the geometry models and dimensions at materials of 2.25Cr 1Mo, Mod 9Cr 1Mo, SA508, and SA516-70, according to ASME Section III. An iterative calculation is performed by using Fortran code of RPV_RDE.exe. It is proven that RPV is safe for aforementioned materials. The highest Hoop stress is MPa for a thickness of 47 mm which occurs on the ellipsoidal head of the upper cover element. Key words: RDE Indonesia, Reactor Pressure Vessel, Flange, Head and Shell. Cite this Article: Sri Sudadiyo, Taswanda Taryo, Topan Setiadipura, Ari Nugroho and Krismawan, Preliminary Design of Reactor Pressure Vessel For RDE, International Journal of Mechanical Engineering and Technology, 9(6), 2018, pp INTRODUCTION Indonesia through BATAN and its stakeholders are designing a 10 MW thermal experimental power reactor or Reaktor Daya Eksperimental (RDE). RDE is one of the candidate of small and medium sized reactors types, basically employs spherical fuel elements for pebble bed reactor. Spherical fuel elements technology is a main innovation of high temperature gas-cooled reactor, editor@iaeme.com

2 Sri Sudadiyo, Taswanda Taryo, Topan Setiadipura, Ari Nugroho and Krismawan which effectively improves the safety of the reactors for higher stability at high temperature [1]. Pebble bed reactor core of the RDE type is cooled by flowing helium gas and moderated by a certain grade of graphite. In the RDE development plan, there will be a lot of knowledge related to the project management organization and all aspects, such as nuclear and safety, instrumentation and control, physical and chemical processes, civil, electrical, and mechanics particularly on reactor pressure vessel. Pressure vessel is an important component of RDE that prevents helium leakage from the reactor core. The following researchers described the results of further investigations on the status of reactor pressure vessel in few advanced countries in the globe. Ozkan, et al. scrutinized the influences of irradiation on damage to creep-fatigue for pressure vessel walls of helium-cooled pebble bed test blanket module [2]. Perillo, et al. had investigated experimentally on pressure vessel under low impact loads. They also evaluated the damage events by using finite element model [3]. Scari, et al. had simulated the steady state and transient behavior of a HTR-10 thermal model. They demonstrated a good agreement in thermal operation conditions between steady state and transient [4]. Shen, et al. determined the seal performance of metallic rings for a pressure vessel performance. Their results showed that finite element analysis agreed well with the experimental data [5]. Lang, et al. had analyzed of one control rod withdrawal out of the core. The graphite reflectors are enclosed by the carbon bricks, which provided the neutron shielding for metallic internals and reactor pressure vessel [6]. Jia, et al. had studied metallic rings in pressure vessel of pressurized water reactor for sealing the bolt connected flanges [7]. Zhao, et al. had studied numerical model for simulating heat transfer process from pressure vessel to the passive residual heat removal system at HTR- 10 [8]. Chen, et al. and Frisani, et al. also studied the passive residual heat removal systems of the modular high temperature gas-cooled reactor and the very high temperature reactor, respectively [9, 10]. Li, et al. provided analytic solution and model analysis on the stresses sensitivity in the fuel particles under irradiation alteration with material properties, temperature, and neutron fluence [11]. The objective of the present paper is to conduct the preliminary design and obtain the geometry models and dimensions for reactor pressure vessel of RDE. The materials selected for this study are 2.25Cr 1Mo, Mod 9Cr 1Mo, SA508, and SA516-70, which are widely used materials for the manufacture of reactor pressure vessel. The general method for the stress analysis of pressure vessel structures is formulated based on the circumferential wall condition. In the theoretical approach, there is assumption that pressure vessel having a wall structure with shear stresses of the inner and outer surfaces. Radius of the circle is accounted in the elastic region limitation. Inner surface does not undergo a dimensional change at pressure under maximum condition. Finally, all calculation results proved the preliminary design stage of RPV structure for RDE are very possible to use the candidate materials previously mentioned and manufacture technology to provide the increase of reliability, safety and vulnerability level and to enhance the environment protection. 2. REACTOR PRESSURE VESSEL RDE can be stipulated as a demonstration power reactor for experimental intention with thermal capacity 10 MWth in Indonesia [12, 13]. RDE core is comprised of thousands of graphite spheres as fuel element. Each pebble contains the tri-structural-isotropic (TRISO) nuclear fuel particles [11, 14]. The heat of the fuel particles is transmitted to a pressurized helium coolant and can reach a high temperature of up to 700 C. Reactor Pressure Vessel (RPV) at RDE refers to a high temperature gas-cooled reactor (in typical case similar with HTR-10 as reference power plant [4 7]) is a closed storage tank designed to hold helium at a pressure substantially different from the containment pressure. Table 1 shows reference operation conditions for RPV editor@iaeme.com

3 Preliminary Design of Reactor Pressure Vessel For RDE at RDE [12, 13]. The pressure is variance between inside and outside of the RPV. The inside pressure (primary helium pressure) is normally greater than the outside pressure (containment pressure). Table 1 10 MW th operating conditions for RPV of the RDE [12, 13] NO Parameter Unit Value 1 Helium inlet temperature C Helium outlet temperature C Mass flow rate of helium kg/s Primary helium pressure bar 30 5 Design pressure bar METHODOLOGY The RPV for RDE has a combination of pressure and high temperature, and in the case of special materials exposed to radioactive. Table 2 shows the mechanical properties of candidate materials at temperature of 371 C for the manufacture of RPV [15]. These selected materials have good yield strength, good tensile strength, good fracture toughness, good temperature resistance, good corrosion resistance, and they can be manufactured in different several methods except casting. The available references have addressed the calculation of pressure vessel element design used in engineering practice [16, 17]. An iterative calculation of the preliminary design for RPV elements begins with developing Fortran code of RPV_RDE.exe file and executing it in obtaining the geometry models and dimensions. Figure 1 depicts the process flowchart of calculation steps to be solved in the RPV design. Input data are the ratio of the predicted outer radii to the inner radii on the wall circle; the ratio of the assumed elastic region limitation over the wall thickness; the intensity of inside pressure or primary helium pressure (as shown in Table 1); and material properties such as shear stress, yield strength, and tensile strength (as seen on Table 2) refer to code of American Society of Mechanical Engineers (ASME) Section III: Rulers of construction for boiler and pressure vessel of nuclear facility components [15]. Mechanical stresses analyses are also performed with the Fortran code of RPV_RDE.exe for each of the RPV elements. Based on Reference [16], the principal mechanical stresses can be classified into circumferential or Hoop stress, radial stress, longitudinal or axial stress, and von Mises stress. The von Mises is calculated by using the stress tensor. The mechanical stresses value obtained should be less than or equal to allowable stress of materials. Table 2 Mechanical properties of the selected materials at 371 C [15] Specification Product form Forging Forging Forging Plate Yield strength, [MPa] Tensile strength, [MPa] Allowable stress, [MPa] editor@iaeme.com

4 Sri Sudadiyo, Taswanda Taryo, Topan Setiadipura, Ari Nugroho and Krismawan Figure 1 Calculation procedure of RPV_RDE.exe for preliminary design of reactor vessel 4. RESULTS AND DISCUSSIONS Figure 2 shows a preliminary design of the RPV for RDE. The main elements of this RPV consist of upper cover as upper part and vessel shell as lower part. Upper cover elements are upper closure head with ellipsoidal shape and upper flange. Vessel shell elements are lower flange or shell flange, upper cylindrical shell, lower cylindrical shell, and lower closure head with hemispherical shape. The upper part of the RPV is cover which connected to lower part with bolts. The lower part of the RPV is a cylindrical shell with a hemispherical bottom head. A metallic O-ring and an omega (Ω)-ring can be used for sealing the upper and lower parts. During the preliminary design phase of the RPV for RDE application, a theoretical approach is developed to provide the minimum geometry models and vessel size dimensions under dynamic loading conditions. An iterative calculation has been undertaken to determine the required thickness of the initial tentative vessel wall including the use of ASME Section III, but only a limited assessment of the mechanical loading performed. The geometry models of the main elements for RPV are displayed from Figure 3 through Figure 8. The dimensions of each of RPV elements are shown from Table 3 to Table 8 for selected materials of 2.25Cr 1Mo, Mod 9Cr 1Mo, SA508, and SA The calculation results show that this preliminary design of the RPV for RDE is safe as long as the value of Hoop stress is less than that occurring in a editor@iaeme.com

5 Preliminary Design of Reactor Pressure Vessel For RDE tensile test specimen at yield and allowable stress of materials. The highest Hoop stress is MPa at an ellipsoidal head of upper cover element with a minimum wall thickness of 47 mm. Figure 2 Reactor pressure vessel for the RDE: (a) upper part; (b) lower part Figure 3 Geometry model of an ellipsoidal top head editor@iaeme.com

6 Sri Sudadiyo, Taswanda Taryo, Topan Setiadipura, Ari Nugroho and Krismawan Table 3 Dimensions and mechanical stresses at an ellipsoidal top head Height, [mm] Outer diameter, [mm] Inner radius of curvature, [mm] Inside knuckle radius, [mm] Wall thickness, [mm] Cont. rod hole diameter, [mm] Channel diameter, [mm] Hoop stress, [MPa] Axial stress, [MPa] Radial stress, [MPa] von Mises, [MPa] Figure 4 Geometry model of an upper flange Table 4 Dimensions and mechanical stresses at an upper flange 2.25Cr1Mo Mod 9Cr 1Mo SA508 SA Height, [mm] Outer diameter, [mm] Wall thickness, [mm] Bolt hole diameter, [mm] Number of bolts Hoop stress, [MPa] Axial stress, [MPa] Radial stress, [MPa] von Mises, [MPa] editor@iaeme.com

7 Preliminary Design of Reactor Pressure Vessel For RDE Figure 5 Geometry model of a lower flange Table 5 Dimensions and mechanical stresses at a lower flange Height, [mm] Outer diameter, [mm] Wall thickness, [mm] Bolt hole diameter, [mm] Number of bolts Hoop stress, [MPa] Axial stress, [MPa] Radial stress, [MPa] von Mises, [MPa] Figure 6 Geometry model of an upper cylindrical shell editor@iaeme.com

8 Sri Sudadiyo, Taswanda Taryo, Topan Setiadipura, Ari Nugroho and Krismawan Table 6 Dimensions and mechanical stresses at an upper cylindrical shell Height, [mm] Outer diameter, [mm] Wall thickness, [mm] Hoop stress, [MPa] Axial stress, [MPa] Radial stress, [MPa] von Mises, [MPa] Figure 7 Geometry model of a lower cylindrical shell Table 7 Dimensions and mechanical stresses at a lower cylindrical shell Height, [mm] Outer diameter, [mm] Wall thickness, [mm] Nozzle diameter, [mm] Hoop stress, [MPa] Axial stress, [MPa] Radial stress, [MPa] von Mises, [MPa] editor@iaeme.com

9 Preliminary Design of Reactor Pressure Vessel For RDE Figure 8 Geometry model of a hemispherical bottom head Table 8 Dimensions and mechanical stresses at a hemispherical bottom head Height, [mm] Outer diameter, [mm] Wall thickness, [mm] Man hole diameter, [mm] Hoop stress, [MPa] Axial stress, [MPa] Radial stress, [MPa] von Mises, [MPa] CONCLUSION In the present work, the preliminary design of the RPV for RDE has been conducted. Computer code of Fortran is developed to perform an iterative calculation of the design. The geometry models and dimensions of RPV elements have also been obtained by employing materials of 2.25Cr 1Mo, Mod 9Cr 1Mo, SA508, and SA The selection of these materials has been carried out according to ASME Section III. Regarding the geometry models, RPV elements referred to HTR-10 as reference power plant. In the calculation analysis has been gained the dimensions for the minimum wall thicknesses namely 90 mm for 2.25Cr 1Mo, 47 mm for Mod 9Cr 1Mo and SA508, and 60 mm for SA The highest value of Hoop stress is MPa at the candidate material of Mod 9Cr 1Mo. The above results show that this preliminary design of the RPV for RDE is safe. ACKNOWLEDGEMENT The authors are grateful for the financial support of Ministry of Research, Technology and Higher Education of Indonesia (under Program of Insinas Flagship for RDE BATAN 2018). The authors acknowledge Head of Center for Nuclear Reactor Technology and Safety BATAN for strong support in this work editor@iaeme.com

10 Sri Sudadiyo, Taswanda Taryo, Topan Setiadipura, Ari Nugroho and Krismawan REFERENCES [1] Yang, M., Liu, Q., Zhao, H., Li, Z., Liu, B., Li, X. and Meng, F. Automatic X-ray inspection for escaped coated particles in spherical fuel elements of high temperature gas-cooled reactor. Energy, 68, 2014, pp [2] Ozkan, F. and Aktaa, J. Creep fatigue assessment for EUROFER components. Fusion Engineering and Design, 100, 2015, pp [3] Perillo, G., Grytten, F., Sorbo, S. and Delhaye, V. Numerical/experimental impact events on filament wound composite pressure vessel. Composites: Part B, 69, 2015, pp [4] Scari, M. E., Costa, A. L., Pereira, C., Velasquez, C. E. and Veloso, M. A. F. HTR steady state and transient thermal analyses. International Journal of Hydrogen Energy, 41, 2016, pp [5] Shen, M., Peng, X., Xie, L., Meng, X. and Li, X. Deformation characteristics and sealing performance of metallic O-rings for reactor pressure vessel. Nuclear Engineering and Technology, 48, 2016, pp [6] Lang, M. and Dong, Y. The ATWS analysis of one control rod withdraw out of the HTR- 10GT core in addition with bypass valve failure. Nuclear Engineering and Design, 271, 2014, pp [7] Jia, X., Chen, H., Li, X., Wang, Y. and Wang, L. A study on the sealing performance of metallic C-rings in reactor pressure vessel. Nuclear Engineering and Design, 278, 2014, pp [8] Zhao, H., Dong, Y., Zheng, Y., Ma, T. and Chen, X. Numerical simulation on heat transfer process in the reactor cavity of modular high temperature gas-cooled reactor. Applied Thermal Engineering, 125, 2017, pp [9] Chen, Li., Ma, T., Zheng, Y., Zhao, H., Li, F., Chen, X. and Ma, Y. Experimental verification on design model of the passive residual heat removal system of MHTGR. Progress in Nuclear Energy, 98, 2017, pp [10] Frisani, A. and Hassan, Y. Computation fluid dynamics analysis of the reactor cavity cooling system for very high temperature gas-cooled reactors. Annals of Nuclear Energy, 72, 2014, [11] Li, R., Liu, B., and Tang, C. Sensitivity of stresses in TRISO-coated fuel particles to the coating layer properties. Nuclear Engineering and Design, 307, 2016, pp [12] Sudadiyo, S. Preliminary design of RDE feedwater pump impeller. Tri Dasa Mega, 20(1), 2018, pp [13] Pancoko, M., Nugroho, A., Priambodo, D. and Setiadipura, T. Design study of a straight tube bundle steam generator for Reaktor Daya Experimental. International Journal of Mechanical Engineering and Technology (IJMET), 9(5), 2018, pp [14] Rohbeck, N. and Xiao, P. Evaluation of the mechanical performance of silicon carbide in TRISO fuel at high temperatures. Nuclear Engineering and Design, 306, 2016, pp [15] ASME. Boiler and Pressure Vessel Code. In: Section III Division 5, New York, 2015, pp [16] Sinclair, G. B. and Helms, J. E. A review of simple formulae for elastic hoop stresses in cylindrical and spherical pressure vessel: What can be used when. International Journal of Pressure Vessels and Piping, 128, 2015, pp [17] Li, H., Huang, X., Yang, P. and Yang, H. A new pressure vessel design by analysis method avoiding stress categorization. International Journal of Pressure Vessels and Piping, 152, 2017, pp editor@iaeme.com