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Rotating tritium target for intense 14-MeV neutron source
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Rotating tritium target for intense 14-MeV neutron source Sudhirsinh Vala a,b,∗ , M. Abhangi a , Ratnesh Kumar a , B. Sarkar a , M. Bandopadhyay a a b
Institute for Plasma Research (IPR), Fusion Neutronics Laboratory, Gandhinagar 382428, India Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai 400094, India
a r t i c l e
i n f o
Article history: Received 3 October 2016 Received in revised form 24 May 2017 Accepted 24 May 2017 Available online xxx Keywords: D-T neutron generator Rotating tritium target 14 MeV neutron source ECR ion source LEBT MEBT
a b s t r a c t In order to study the neutronics of fusion reactor blankets, a program is underway at the IPR using 14MeV Neutron Source (NS). An accelerator based neutron source is under development in which 30 mA deuterium beam will be accelerated up to 300 keV energy. It will then impinge on a rotating tritium target to producing nearly isotropic 14-MeV neutrons. The expected neutron yield is 3–5 × 1012 n/s. The rotating target has been developed for intense neutron source. Total estimated power density on the rotating target is 11.5 kW/cm2 for the diameter and power of D+ beam are 10 mm and 9 kW (300 kV, 30 mA). The simulation by CFD method have been carried out to investigate the heat transfer in rotating target system. In this paper, the design and analysis of the rotating tritium target system of intense neutron source is discussed and result of beam test performed using D+ beam at 90 keV, 20 mA, 15 mm beam diameter, resulting 1 kW/cm2 beam power stopped at the surface of dummy copper disk 3 mm in thickness and 180 mm in diameter is presented. © 2017 Elsevier B.V. All rights reserved.
1. Introduction A summary on the forthcoming research plan of international fusion program instantly reveals that this program cannot be realized without making of an intense 14 MeV NS for fusion reactor material testing and characterization. Therefore, interest in development of intense NS has been increased worldwide viz: International Fusion Materials Irradiation Facility, Facility for Fusion Neutron Irradiation Research (FAFNIR), New Sorgentina Fusion Source (NSFS). Table 1 shows the proposed accelerator driven intense NS in the international fusion community for fusion material irradiation and studies [1–7]. India is participating in the ITER, an international project for harnessing fusion power as well as participation in Test Blanket module (TBM) program [8,9]. To carry out the bench marking experiment for Indian TBM, to validate neutron transport codes and nuclear data (viz: The fusion Evaluated Nuclear Data, FENDL), neutron spectroscopy, differential cross section, double differential cross-section measurements on fusion reactor materials and to support the Indian fusion program the intense 14-MeV neutron source is being developed at Fusion Neutronics Laboratory, Institute for Plasma research [10–14]. The neutrons from the T(d,n)␣
∗ Corresponding author at: Institute for Plasma Research (IPR), Fusion Neutronics Laboratory, Gandhinagar 382428, India. E-mail addresses: [email protected], [email protected] (S. Vala).
Table 1 Internationally proposed intense neutron sources for fusion applications. Particular
IFMIF
FAFNIR
NSFS
Beam Energy (MeV) Beam Current (mA) Target Source strength (n s−1 )
40 250 Li ∼1018
40 2.5/5/30 C ∼2/5/30 × 1015
0.20 2 × 104 T ∼1015
Table 2 Design Parameters of Intense Neutron Source. Particular
Value
Beam Energy (keV) Beam Current (mA) Target Source strength (n/s)
300 30 T 3 × 1012
reaction are produced by hitting the rotating tritium target with 30 mA deutron beam up to 300 keV or less energy. The expected neutron yield is 3–5 × 1012 n/s. The design parameter of intense neutron source is shown in Table 2. The tritium in titanium material is being used as target in the accelerator based 14-MeV neutron source. The target backing is a 2 mm thick piece of Oxygen Free High Conductivity (OFHC) copper. Titanium is evaporated in a band of 25 mm on the copper plate and in which tritium atom is absorbed with T/Ti ratio >1.5. Tritium gas will come out due to overheating (>200 ◦ C) of tritium target by 10 kW deuterium beam. It will degrade the lifetime of target
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Please cite this article in press as: S. Vala, et al., Rotating tritium target for intense 14-MeV neutron source, Fusion Eng. Des. (2017), http://dx.doi.org/10.1016/j.fusengdes.2017.05.117
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and also melting the target if temperature >1000 ◦ C. In order to avoid such problem the rotating target method with proper cooling arrangement is used [15–17]. Therefore a rotating water cooled target holder has been developed. 2. System description The Accelerator based 14-MeV neutron source mainly consists of SILHI Electron Cyclotron Resonance Ion Source (ECRIS), Low Energy Beam Transport (LEBT) system, Electrostatic Acceleration, Medium Energy Beam Transport (MEBT) system, 300 kV, 50 mA High Voltage Power Supply (HVPS), Beam diagnostic system (BDS), Switching Magnet (SM) and Rotating tritium target [18,19]. The ECRIS, LEBT, and sub-system of LEBT, are kept on a high voltage deck, which is at 300 kV floating with respect to the ground potential. The input electric power to the entire unit is provided through an isolation transformer. The MEBT, Switching magnet, subsystem of MEBT and rotating target are at ground potential. LEBT system is to transport the 30 mA, 40 keV deuterium beam from ECRIS to the Entrance of the acceleration column. MEBT system is to transport the 340 keV beam from acceleration column to the target assembly. Both LEBT and MEBT have Beam diagnostic system (BDS) which consists of Faraday cup, Beam profile monitor and slit type emittance scanner. The beam is first analyzed with the help of 90◦ Dipole magnet to exclude the unwanted particles from the beam. It avoids the extra heating of the target. The 40 keV beam is then focused into the acceleration column with the help of Magnetic Quadruple Triplet. The beam is accelerated to 300 keV with the help of acceleration column. The final 340 keV beam is then focused using another magnetic Quadrupole triplet at target. The target is kept at 1.8 m away from semicircular magnet. The Beam is guided using Switching magnet (+45◦ , 0◦ ,−45◦ ) to three beam lines. 0◦ beam line will be used for the neutron production, +45◦ beam line will be used for ion beam irradiation experiment and −45◦ beam line will be used for the future IPR programme. General view of 14-MeV Neutron source is shown in Fig. 1.
Fig. 1. Schematic diagram of 14-MeV neutron source.
3. Rotating target design TRIM calculation has been carried out to select the optimum tritium titanium thickness on the copper backing. To produce desired DT neutron yield, Deuterium beam should be stopped in TiT. Thin copper backing is chosen for fast removal of heat to outer surface [14–17]. Range of 340 keV deuterium ions comes out to be 4.54 m ± 0.3039 m where 0.3039 m is the straggling of Deuterium ions in TiT target as shown in Fig. 2. A finite element (FE) method code, ANSYS [20] software package was used to analyze the thermal response and resulting stresses in the target design. A 180 mm diameter and 3 mm thick OFHC copper disk was used as dummy target and same was modeled. 3D FE model has been properly discretized having 28,407 nodes and 154,605 elements. The inlet temperature 15 ◦ C, outlet pressure (0 Pa) and mass flow rate (10 lpm) are given as the boundary condition. The model has been analyzed in CFX. The outlet temperature 62 ◦ C is obtained from the analysis. A schematic view of the target holder is shown in Fig. 3. Accurate modeling was required around the beam spot because the heat deposit was much confined in circular area of 10 mm diameter. A uniform beam distribution was assumed at the beam spot [21–25]. The preliminary studies were based on water cooled stationary target. Fig. 4 shows the temperature profile of tritium target for steady state condition. In this condition, maximum temperature at the beam spot was ∼4038 ◦ C. This can melt the target. In next step, the target was considered as rotating and effect of number of rotations (rpm) on temperature distribution has been carried out. The result of the simulation is
Fig. 2. Trim calculated deuterium ion range in TiT target.
shown in Fig. 5. Typical simulation result for the target with rotation speed of 1000 rpm is shown in Fig. 6. Temperature at the beam spot reaches to maximum 62 ◦ C which is well below design criteria. The temperature distribution obtained from this analysis was used as the input for the thermal stress analysis and the von Misses equivalent stress field was estimated which are within the acceptable limit as shown in Fig. 7. ASME code is used in design and fabrication structural design code.
Please cite this article in press as: S. Vala, et al., Rotating tritium target for intense 14-MeV neutron source, Fusion Eng. Des. (2017), http://dx.doi.org/10.1016/j.fusengdes.2017.05.117
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Fig. 3. Schematic of rotating tritium target holder.
Fig. 6. Temperature profile of target during rotation.
Fig. 4. Temperature profile for steady state condition.
Fig. 7. Thermal stress contour of rotating Tritium target holder.
The cooling system considered for the rotating target was required to be simple and robust. The maximum beam power deposited on tritiated target is up to 9 kW. The power density in the target is about 11.5 kW/cm2 for the beam size of 10 mm. In order to remove the heat form the tritium target, a water cooled rotating target has been design and developed [23–26]. 4. Mechanical configuration The rotation speed of the rotating target is 1000 rpm. Ferro magnetic fluid rotary feed through is used for rotary vacuum seal. The cooling water is fed through the rotating shaft to the cooling disk on which target is fixed. Both supply and return for the cooling water flow at the center of the target [14,23,24,27]. The cooling water is at rate of 10 lpm. A schematic diagram of the water-cooled target holder is shown in Fig. 3. 5. Experimental setup
Fig. 5. Temperature of the beam spot as a function of rotation speed.
For the testing of the rotating target holder, dummy target plate of 3 mm thick copper was used and it was fixed on water cooled cupper disk in the target holder. The rotating target was coupled at
Please cite this article in press as: S. Vala, et al., Rotating tritium target for intense 14-MeV neutron source, Fusion Eng. Des. (2017), http://dx.doi.org/10.1016/j.fusengdes.2017.05.117
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camera will be used to monitor the temperatures of respective locations in our future experimental campaign. 6. Current status of intense 14-MeV neutron source
Fig. 8. photographic view of Experimental setup.
the end of the beam line of SILHI ECR ion source bench followed by faraday cup and 75 kV acceleration column. For the testing purpose the rotating target was floated at 75 kV it is difficult to float the ECR ion source bench in existing setup [18,19]. The photograph of experimental setup is shown in the Fig. 8. Initially the rotating target was tested for high vacuum and achieved vacuum level was 3 × 10−7 mbar with 100 rpm rotation and 10 lpm water flow in target chamber. The deuterium beam of 20 mA and 80 keV was bombarded on dummy target. There was no melting of dummy copper target. Temperature of the inlet and outlet using RTD/thermocouple and the target temperature by IR
Beam dynamics studies for beam line of neutron source are carried out using Graphic Transport Framework and Trace Win simulation code. Fig. 9 shows optimized beam envelope for 30 mA, 0.2 mm mrad ion beam considering space charge effects. Beam line component with its beam diagnostics and High voltage platform are under fabrication and will be installed by end of 2018. PANTECHNIK made 2.45 GHz SILHI ECR ion source has been procured and installed for the production of stable deuterium ion beam. A 21 mA/32 keV d+ beam was obtained. Installation setup is shown in Fig. 8. Shielding and dose rate calculations of the proposed laboratory were performed using Monte Carlo code MCNP. With the ENDF-B/VI neutron cross section library. Shielding adequacy of the proposed Fusion Neutronics Laboratory (FNL) for a yield of 1012 nps was carried out. Calculations were carried out for both neutron and gamma transport with and without sky-shine effect at different locations. The calculated dose rates are less than the safety limit for general public (≤1 Sv/h) outside the FNL and for occupational workers (≤10 Sv/h) inside the occupational area [28]. Proposed laboratory building is under construction it will be ready by May-2018. To recover the released tritium from tritium target during operation, Tritium Handling and Recovery System (THRS) will be installed. It consists of Ni-bed, Zr-Fe getter bed and Uranium get-
Fig. 9. Beam envelope for 30 mA current throughout BTS using Trace Win.
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ter bed. The objective of the THRS is to minimize airborne tritium release well below the permitted limit. In addition, the system is designed to minimize tritium exposure to staff by maintaining low levels of tritium. 7. Conclusion The simulation has been carried to design the tritium target holder for intense 14-MeV neutron source. The designed cooling system ensures acceptable levels of temperature and thermal stress in the copper backing plate. The simulation results show that above 500 rpm, the heat removal is efficient and temperature is within design value. Based on final design consideration in simulation, water cooled rotating tritium target has been fabricated. It was tested with 20 mA and 80 keV deuterium beam and neutrons due to beam target interaction were monitored. Acknowledgments The authors wish to acknowledge the assistance and contribution of Dhaval Rajyaguru, Asha Panghal, Mayank Rajput and Sanket Chauhan during the design and analysis work. References [1] J. Knaster, et al., The accomplishment of the engineering design activities of IFMIF/EVEDA: the European-Japanese project towards a Li (d,xn) fusion relevant neutron source, Nucl. Fusion 55 (2015), p086003 (30pp). [2] M. Pillon, et al., Feasibility study of an intense D-T Fusion source: the new Sorgentina, Fusion Eng. Des. 89 (2014) 2141–2144. [3] Patrizio Console Camprini, et al., Design optimization and performance of new Sorgentina fusion source (FNS) supporting material research, Fusion Eng. Des. 96–97 (2015) 236–239. [4] J. Knaster, et al., Material research for fusion, Nat. Phys. 12 (2016) 424–434. [5] E. Surrey, et al., FAFNIR: strategy and risk reduction in accelerator driven neutron source for fusion materials irradiation data, Fusion Eng. Des. 89 (2014) 2108–2113. [6] P.A. Di Maio, et al., Study of the thermo-mechanical performances of the IFMIF-EVEDA Lithium Test Loop target assembly, Fusion Eng. Des. 87 (2012) 822–827.
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[7] D. Bernardi, et al., Analysis of the thermomechanical behavior of the IFMIF bayonet target assembly under design loading scenarios, Fusion Eng. Des. 96–97 (2015) 217–221, references there in. [8] R. Srinivasan, et al., Strategy for the Indian DEMO design, Fusion Eng. Des. 83 (2008) 889–892. [9] E. Rajendra Kumar, et al., Overview of TBM R&D activities in India, Fusion Eng. Des. 87 (2012) 461–465. [10] M. Pillon, et al., A plan of fusion neutron benchmark experiments using the Frascati Neutron Generator (FNG), Fusion Eng. Des. 18 (1991) 293–296. [11] M. Martone, et al., The 14 MeV Frascati neutron generator, J. Nucl. Mater. 212–215 (1994) 1661–1664. [12] M. Pillon, et al., Characterization of the source neutron produced by The Frascati Neutron Generator, Fusion Eng. Des. 28 (1995) 683–688. [13] M. Angelone, et al., Neutronic experiment on a mockup of the ITER shielding system at the Frascati Neutron Generator, Fusion Eng. Des. 42 (1998) 255–260. [14] Z. Yao, et al., Design status of an intense 14 MeV neutron source for cancer therapy, Nucl. Instrum. Methods Phys. Res. A 490 (2002) 566–572. [15] R. Booth, et al., Rotating target neutron generators, Nucl. Instrum. Methods Phys. Res. 145 (1977) 25–39. [16] R. Booth, et al., Tritium target for intense neutron source, Nucle. Instrum. Method 99 (1972) 1–4. [17] K. Sumita, Tritium solid targets for Intense D-T Neutron Production and the related problems, Nucl. Instrum. Methods Phys. Res. A 282 (1989) 345–353. [18] R. Gobin, et al., High intensity ECR ion source developments at CEA Saclay, Rev. Sci. Instrum. 73 (2002) 922–924. [19] R. Gobin, et al., Development of a permanent magnet light ion source at CEA/Saclay, Rev. Sci. Instrum. 77 (2006) 03B502. ® [20] Finite Element code ANSYS v16.0, www.ansys.com. [21] G. Song, et al., Design and analysis of rotating trtium target system for high intensity D-T Fusion Neutron Generator, J. Fusion Energy 34 (2015) 183–190. [22] T. McManamy, et al., 3 MW slid rotating target design, J. Nucl. Mater. 398 (2010) 35–42. [23] A. Yoshida, et al., High Power rotating wheel targets at RIKEN, Nucl. Instrum. Methods Phys. Res. A 521 (2004) 65–71. [24] T. Kubo, In-flight RI beam separator BigRIPS at RIKEN and elsewhere in Japan, Nucl. Instrum. Methods Phys. Res. B 204 (2003) 97–113. [25] A. Yoshida, et al., Status and overview of production target for BigRIPS separator at RIKEN, Nucl. Instrum. Methods Phys. Res. A 590 (2008) 204–212. [26] S. Terron, et al., Nucl. Instrum. Methods Phys. Res. A 724 (2013) 34–40. [27] S. Tongling, et al., An intense 14-MeV neutron source, Nucl. Instrum. Methods Phys. Res. A 287 (1990) 452–454. [28] R. Makwana, et al., Shielding design of the proposed laboratory for intense 14 MeV neutron generator, Indian J. Pure Appl. Phys. 50 (2012) 799–801.
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Contents lists available at ScienceDirect
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Rotating tritium target for intense 14-MeV neutron source Sudhirsinh Vala a,b,∗ , M. Abhangi a , Ratnesh Kumar a , B. Sarkar a , M. Bandopadhyay a a b
Institute for Plasma Research (IPR), Fusion Neutronics Laboratory, Gandhinagar 382428, India Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai 400094, India
a r t i c l e
i n f o
Article history: Received 3 October 2016 Received in revised form 24 May 2017 Accepted 24 May 2017 Available online xxx Keywords: D-T neutron generator Rotating tritium target 14 MeV neutron source ECR ion source LEBT MEBT
a b s t r a c t In order to study the neutronics of fusion reactor blankets, a program is underway at the IPR using 14MeV Neutron Source (NS). An accelerator based neutron source is under development in which 30 mA deuterium beam will be accelerated up to 300 keV energy. It will then impinge on a rotating tritium target to producing nearly isotropic 14-MeV neutrons. The expected neutron yield is 3–5 × 1012 n/s. The rotating target has been developed for intense neutron source. Total estimated power density on the rotating target is 11.5 kW/cm2 for the diameter and power of D+ beam are 10 mm and 9 kW (300 kV, 30 mA). The simulation by CFD method have been carried out to investigate the heat transfer in rotating target system. In this paper, the design and analysis of the rotating tritium target system of intense neutron source is discussed and result of beam test performed using D+ beam at 90 keV, 20 mA, 15 mm beam diameter, resulting 1 kW/cm2 beam power stopped at the surface of dummy copper disk 3 mm in thickness and 180 mm in diameter is presented. © 2017 Elsevier B.V. All rights reserved.
1. Introduction A summary on the forthcoming research plan of international fusion program instantly reveals that this program cannot be realized without making of an intense 14 MeV NS for fusion reactor material testing and characterization. Therefore, interest in development of intense NS has been increased worldwide viz: International Fusion Materials Irradiation Facility, Facility for Fusion Neutron Irradiation Research (FAFNIR), New Sorgentina Fusion Source (NSFS). Table 1 shows the proposed accelerator driven intense NS in the international fusion community for fusion material irradiation and studies [1–7]. India is participating in the ITER, an international project for harnessing fusion power as well as participation in Test Blanket module (TBM) program [8,9]. To carry out the bench marking experiment for Indian TBM, to validate neutron transport codes and nuclear data (viz: The fusion Evaluated Nuclear Data, FENDL), neutron spectroscopy, differential cross section, double differential cross-section measurements on fusion reactor materials and to support the Indian fusion program the intense 14-MeV neutron source is being developed at Fusion Neutronics Laboratory, Institute for Plasma research [10–14]. The neutrons from the T(d,n)␣
∗ Corresponding author at: Institute for Plasma Research (IPR), Fusion Neutronics Laboratory, Gandhinagar 382428, India. E-mail addresses: [email protected], [email protected] (S. Vala).
Table 1 Internationally proposed intense neutron sources for fusion applications. Particular
IFMIF
FAFNIR
NSFS
Beam Energy (MeV) Beam Current (mA) Target Source strength (n s−1 )
40 250 Li ∼1018
40 2.5/5/30 C ∼2/5/30 × 1015
0.20 2 × 104 T ∼1015
Table 2 Design Parameters of Intense Neutron Source. Particular
Value
Beam Energy (keV) Beam Current (mA) Target Source strength (n/s)
300 30 T 3 × 1012
reaction are produced by hitting the rotating tritium target with 30 mA deutron beam up to 300 keV or less energy. The expected neutron yield is 3–5 × 1012 n/s. The design parameter of intense neutron source is shown in Table 2. The tritium in titanium material is being used as target in the accelerator based 14-MeV neutron source. The target backing is a 2 mm thick piece of Oxygen Free High Conductivity (OFHC) copper. Titanium is evaporated in a band of 25 mm on the copper plate and in which tritium atom is absorbed with T/Ti ratio >1.5. Tritium gas will come out due to overheating (>200 ◦ C) of tritium target by 10 kW deuterium beam. It will degrade the lifetime of target
http://dx.doi.org/10.1016/j.fusengdes.2017.05.117 0920-3796/© 2017 Elsevier B.V. All rights reserved.
Please cite this article in press as: S. Vala, et al., Rotating tritium target for intense 14-MeV neutron source, Fusion Eng. Des. (2017), http://dx.doi.org/10.1016/j.fusengdes.2017.05.117
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and also melting the target if temperature >1000 ◦ C. In order to avoid such problem the rotating target method with proper cooling arrangement is used [15–17]. Therefore a rotating water cooled target holder has been developed. 2. System description The Accelerator based 14-MeV neutron source mainly consists of SILHI Electron Cyclotron Resonance Ion Source (ECRIS), Low Energy Beam Transport (LEBT) system, Electrostatic Acceleration, Medium Energy Beam Transport (MEBT) system, 300 kV, 50 mA High Voltage Power Supply (HVPS), Beam diagnostic system (BDS), Switching Magnet (SM) and Rotating tritium target [18,19]. The ECRIS, LEBT, and sub-system of LEBT, are kept on a high voltage deck, which is at 300 kV floating with respect to the ground potential. The input electric power to the entire unit is provided through an isolation transformer. The MEBT, Switching magnet, subsystem of MEBT and rotating target are at ground potential. LEBT system is to transport the 30 mA, 40 keV deuterium beam from ECRIS to the Entrance of the acceleration column. MEBT system is to transport the 340 keV beam from acceleration column to the target assembly. Both LEBT and MEBT have Beam diagnostic system (BDS) which consists of Faraday cup, Beam profile monitor and slit type emittance scanner. The beam is first analyzed with the help of 90◦ Dipole magnet to exclude the unwanted particles from the beam. It avoids the extra heating of the target. The 40 keV beam is then focused into the acceleration column with the help of Magnetic Quadruple Triplet. The beam is accelerated to 300 keV with the help of acceleration column. The final 340 keV beam is then focused using another magnetic Quadrupole triplet at target. The target is kept at 1.8 m away from semicircular magnet. The Beam is guided using Switching magnet (+45◦ , 0◦ ,−45◦ ) to three beam lines. 0◦ beam line will be used for the neutron production, +45◦ beam line will be used for ion beam irradiation experiment and −45◦ beam line will be used for the future IPR programme. General view of 14-MeV Neutron source is shown in Fig. 1.
Fig. 1. Schematic diagram of 14-MeV neutron source.
3. Rotating target design TRIM calculation has been carried out to select the optimum tritium titanium thickness on the copper backing. To produce desired DT neutron yield, Deuterium beam should be stopped in TiT. Thin copper backing is chosen for fast removal of heat to outer surface [14–17]. Range of 340 keV deuterium ions comes out to be 4.54 m ± 0.3039 m where 0.3039 m is the straggling of Deuterium ions in TiT target as shown in Fig. 2. A finite element (FE) method code, ANSYS [20] software package was used to analyze the thermal response and resulting stresses in the target design. A 180 mm diameter and 3 mm thick OFHC copper disk was used as dummy target and same was modeled. 3D FE model has been properly discretized having 28,407 nodes and 154,605 elements. The inlet temperature 15 ◦ C, outlet pressure (0 Pa) and mass flow rate (10 lpm) are given as the boundary condition. The model has been analyzed in CFX. The outlet temperature 62 ◦ C is obtained from the analysis. A schematic view of the target holder is shown in Fig. 3. Accurate modeling was required around the beam spot because the heat deposit was much confined in circular area of 10 mm diameter. A uniform beam distribution was assumed at the beam spot [21–25]. The preliminary studies were based on water cooled stationary target. Fig. 4 shows the temperature profile of tritium target for steady state condition. In this condition, maximum temperature at the beam spot was ∼4038 ◦ C. This can melt the target. In next step, the target was considered as rotating and effect of number of rotations (rpm) on temperature distribution has been carried out. The result of the simulation is
Fig. 2. Trim calculated deuterium ion range in TiT target.
shown in Fig. 5. Typical simulation result for the target with rotation speed of 1000 rpm is shown in Fig. 6. Temperature at the beam spot reaches to maximum 62 ◦ C which is well below design criteria. The temperature distribution obtained from this analysis was used as the input for the thermal stress analysis and the von Misses equivalent stress field was estimated which are within the acceptable limit as shown in Fig. 7. ASME code is used in design and fabrication structural design code.
Please cite this article in press as: S. Vala, et al., Rotating tritium target for intense 14-MeV neutron source, Fusion Eng. Des. (2017), http://dx.doi.org/10.1016/j.fusengdes.2017.05.117
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Fig. 3. Schematic of rotating tritium target holder.
Fig. 6. Temperature profile of target during rotation.
Fig. 4. Temperature profile for steady state condition.
Fig. 7. Thermal stress contour of rotating Tritium target holder.
The cooling system considered for the rotating target was required to be simple and robust. The maximum beam power deposited on tritiated target is up to 9 kW. The power density in the target is about 11.5 kW/cm2 for the beam size of 10 mm. In order to remove the heat form the tritium target, a water cooled rotating target has been design and developed [23–26]. 4. Mechanical configuration The rotation speed of the rotating target is 1000 rpm. Ferro magnetic fluid rotary feed through is used for rotary vacuum seal. The cooling water is fed through the rotating shaft to the cooling disk on which target is fixed. Both supply and return for the cooling water flow at the center of the target [14,23,24,27]. The cooling water is at rate of 10 lpm. A schematic diagram of the water-cooled target holder is shown in Fig. 3. 5. Experimental setup
Fig. 5. Temperature of the beam spot as a function of rotation speed.
For the testing of the rotating target holder, dummy target plate of 3 mm thick copper was used and it was fixed on water cooled cupper disk in the target holder. The rotating target was coupled at
Please cite this article in press as: S. Vala, et al., Rotating tritium target for intense 14-MeV neutron source, Fusion Eng. Des. (2017), http://dx.doi.org/10.1016/j.fusengdes.2017.05.117
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camera will be used to monitor the temperatures of respective locations in our future experimental campaign. 6. Current status of intense 14-MeV neutron source
Fig. 8. photographic view of Experimental setup.
the end of the beam line of SILHI ECR ion source bench followed by faraday cup and 75 kV acceleration column. For the testing purpose the rotating target was floated at 75 kV it is difficult to float the ECR ion source bench in existing setup [18,19]. The photograph of experimental setup is shown in the Fig. 8. Initially the rotating target was tested for high vacuum and achieved vacuum level was 3 × 10−7 mbar with 100 rpm rotation and 10 lpm water flow in target chamber. The deuterium beam of 20 mA and 80 keV was bombarded on dummy target. There was no melting of dummy copper target. Temperature of the inlet and outlet using RTD/thermocouple and the target temperature by IR
Beam dynamics studies for beam line of neutron source are carried out using Graphic Transport Framework and Trace Win simulation code. Fig. 9 shows optimized beam envelope for 30 mA, 0.2 mm mrad ion beam considering space charge effects. Beam line component with its beam diagnostics and High voltage platform are under fabrication and will be installed by end of 2018. PANTECHNIK made 2.45 GHz SILHI ECR ion source has been procured and installed for the production of stable deuterium ion beam. A 21 mA/32 keV d+ beam was obtained. Installation setup is shown in Fig. 8. Shielding and dose rate calculations of the proposed laboratory were performed using Monte Carlo code MCNP. With the ENDF-B/VI neutron cross section library. Shielding adequacy of the proposed Fusion Neutronics Laboratory (FNL) for a yield of 1012 nps was carried out. Calculations were carried out for both neutron and gamma transport with and without sky-shine effect at different locations. The calculated dose rates are less than the safety limit for general public (≤1 Sv/h) outside the FNL and for occupational workers (≤10 Sv/h) inside the occupational area [28]. Proposed laboratory building is under construction it will be ready by May-2018. To recover the released tritium from tritium target during operation, Tritium Handling and Recovery System (THRS) will be installed. It consists of Ni-bed, Zr-Fe getter bed and Uranium get-
Fig. 9. Beam envelope for 30 mA current throughout BTS using Trace Win.
Please cite this article in press as: S. Vala, et al., Rotating tritium target for intense 14-MeV neutron source, Fusion Eng. Des. (2017), http://dx.doi.org/10.1016/j.fusengdes.2017.05.117
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ter bed. The objective of the THRS is to minimize airborne tritium release well below the permitted limit. In addition, the system is designed to minimize tritium exposure to staff by maintaining low levels of tritium. 7. Conclusion The simulation has been carried to design the tritium target holder for intense 14-MeV neutron source. The designed cooling system ensures acceptable levels of temperature and thermal stress in the copper backing plate. The simulation results show that above 500 rpm, the heat removal is efficient and temperature is within design value. Based on final design consideration in simulation, water cooled rotating tritium target has been fabricated. It was tested with 20 mA and 80 keV deuterium beam and neutrons due to beam target interaction were monitored. Acknowledgments The authors wish to acknowledge the assistance and contribution of Dhaval Rajyaguru, Asha Panghal, Mayank Rajput and Sanket Chauhan during the design and analysis work. References [1] J. Knaster, et al., The accomplishment of the engineering design activities of IFMIF/EVEDA: the European-Japanese project towards a Li (d,xn) fusion relevant neutron source, Nucl. Fusion 55 (2015), p086003 (30pp). [2] M. Pillon, et al., Feasibility study of an intense D-T Fusion source: the new Sorgentina, Fusion Eng. Des. 89 (2014) 2141–2144. [3] Patrizio Console Camprini, et al., Design optimization and performance of new Sorgentina fusion source (FNS) supporting material research, Fusion Eng. Des. 96–97 (2015) 236–239. [4] J. Knaster, et al., Material research for fusion, Nat. Phys. 12 (2016) 424–434. [5] E. Surrey, et al., FAFNIR: strategy and risk reduction in accelerator driven neutron source for fusion materials irradiation data, Fusion Eng. Des. 89 (2014) 2108–2113. [6] P.A. Di Maio, et al., Study of the thermo-mechanical performances of the IFMIF-EVEDA Lithium Test Loop target assembly, Fusion Eng. Des. 87 (2012) 822–827.
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Please cite this article in press as: S. Vala, et al., Rotating tritium target for intense 14-MeV neutron source, Fusion Eng. Des. (2017), http://dx.doi.org/10.1016/j.fusengdes.2017.05.117