- Email: [email protected]
Current status of the continuous tritium recovery test campaign using PbLi droplets in vacuum
Fusion Engineering and Design 146 (2019) 898–901
Contents lists available at ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Current status of the continuous tritium recovery test campaign using PbLi droplets in vacuum
T
⁎
Fumito Okinoa, , Juro Yagia, Teruya Tanakab,c, Akio Sagarab,c, Satoshi Konishia a
Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Japan National Institute for Fusion Science, Toki Gifu, Japan c SOKENDAI, Toki Gifu, Japan b
A R T I C LE I N FO
A B S T R A C T
Keywords: Tritium recovery Continuous operation PbLi Droplets in vacuum Oroshhi-2 Vacuum sieve tray
This report introduces a current status of the continuous tritium recovery test campaign of PbLi droplets in vacuum, using vacuum sieve tray (VST). The campaign aims to verify the viability of VST method at a prototype design level. The following verification are to be performed. 1) Verify the steady state extraction efficiency of tritium using a 0.6 mm nozzle. The target is greater than 80%. 2) Verify the mutual interference effects on efficiency degradation by multiple droplets by comparing 1, 4, 7, and 19 nozzles. 3) Verify the reliability of VST in continuous operation. At least 24 h of non-stop operation without efficiency degradation is the primary goal, which can be extended up to 48 h. A dedicated extraction setup is to be installed March 2019 into the Oroshhi-2 PbLi experimental loop at the National Institute for Fusion Science (NIFS) Toki-Japan, followed by a stand-alone test with a short flowing period at Kyoto University which is already finished. Deuterium (D2), instead of tritium, is used for the experiment. Extraction efficiency is calculated by comparing the D2 concentration before-drop and after-drop. The amount of released D2 is also measured by a quadrupole mass spectrometer (QMS) and verified by the concentration difference. The PbLi temperature is between 375 ℃ and 450 ℃, and the flow velocity at the nozzle is between 1.5 m s−1 and 4.5 m s−1. The final report is scheduled to be completed by the end of 2019.
1. Introduction
2. Commitment items and targets
Tritium extraction efficiency (TEE) from liquid PbLi is a significant function of a liquid breeding blanket (LBB). Three tritium extraction technologies are considered for the conceptual design review (CDR) of the ITER test blanket module (TBM) program [1]: packed columns (PC) [2,3], permeators against vacuum (PAV) [4,5], and vacuum sieve tray (VST) [6]. Subsequently, PC is selected for CDR because of its high technical maturity. With regard to the VST, the following two issues are noted: a) possible performance degradation owing to the dense droplet arrays, needed in large-scale applications, and b) risk of plugging in nozzles less than 1 mm in diameter, needed for achieving a good TEE. It is concluded, thus far, VST technology has not been tested in relevant operational thermal-hydraulic conditions, such that the comprehensive….performance characterization test is needed [1]. This report describes current status of the experimental verification campaign of VST to identify a stable TEE under multiple droplets conditions, reliability of VST is also verified.
2.1. Extraction efficiency
⁎
The authors previously reported the estimated TEE [6] as a function of the droplet falling period and nozzle diameter, as shown in Fig. 1. A TEE greater than 80% is the assumed target requirement of this campaign, which is in accordance with the study by Demange [7]. As shown in Fig. 1, the falling periods and corresponding nozzle diameters which satisfy the target requirement are 0.05 s with 0.4 mm nozzle, 0.1 s with 0.6 mm nozzle, and 0.2 s with 0.8 mm nozzle. Owing to the design limitation, the combination of a falling period of 0.1 s with a 0.6 mm nozzle is selected as a set of representative parameters to perform the following experimental campaign. Among the three conditions, the one selected has a well-balanced sensitivity to TEE as a function of the falling period. A critical concern regarding estimated TEE, which is shown in Fig. 1, is that the mass transport data used for estimation are obtained under one nozzle droplet column experimental condition [8]. The mutual effects under multiple arrays of droplets are not included. The
Corresponding author. E-mail address: [email protected] (F. Okino).
https://doi.org/10.1016/j.fusengdes.2019.01.108 Received 25 September 2018; Received in revised form 28 December 2018; Accepted 22 January 2019 Available online 26 January 2019 0920-3796/ © 2019 Elsevier B.V. All rights reserved.
Fusion Engineering and Design 146 (2019) 898–901
F. Okino et al.
Fig. 4. VST verification campaign schedule. VST is fabricated and Test-1, a commissioning under non-continuous flow condition is finished at Kyoto University. From 2019 Test-2 is scheduled to start at NIFS. Fig. 1. Estimated TEE as a function of falling period [6]. TEE results using four different nozzle diameters are plotted on a same chart. A TEE of 0.8 is the assumed target of this study.
A and type B, and some of the remaining T2 flows in a path directly to the exhaust port. According to the optimistic scenario, the dwell period of an incident molecule on a surface is very short, it eventually reaches an exhaust port and does not affect the TEE. A non-optimistic scenario estimates that the dwelling period of an incident molecule on a surface is not negligible and affects the TEE. The results under optimisticcondition indicate that the TEE is the same as under the one-column results, as shown in Fig. 1. In another case, results deviate from 20% to 60% compared with the one-column condition. These results must be verified in this campaign. 2.2. Reliable operation Regarding the reliable operation, it is mentioned in [1] “for the more innovative technology, it is needed to plan and execute… comprehensive test of performance characterization…”. However, there are few documents which describe the required continuous working hours. This campaign, therefore, assumed the 24 h as the reliable minimum continuous working hours. Within 24 h VST must run continuously without TEE degradation and unexpected stoppage. After 24 h of nonstop operation, a duration test will be extended up to 48 h.
Fig. 2. Typical behaviors of released tritium in an array of droplets [9].
3. Verification campaign procedures
authors, therefore, performed a study to analyze the TEE under arrays of multiple droplets as a function of nozzle pitch, number of arrays, and exhaust port ratio, schematically shown in Fig. 2 [9]. In a vacuum, two released tritium on a droplet surface recombine, form a T2 molecule, and are emitted. Next, they take three different paths, described as type
3.1. Experimental setup A schematic of the experimental setup is shown in Fig. 3a. The setup is consisted of a VST chamber, which includes a droplet formation nozzle, a deuterium gas (D2) dissolution unit, an electromagnetic pump Fig. 3. a. A schematic of VST experimental setup. D2 gas is dissolved by bubbling and is circulated by EMP. Liquid PbLi is turned into droplets by nozzles, and while falling in a vacuum chamber, the dissolved D2 is recombined and released into a vacuum. The released D2 is collected with a vacuum pump and measured by QMS. b. A schematic of the nozzle array. The pitch between each adjacent nozzle is equally assigned. Nozzle position is assigned at (n00) for one nozzle unit, (n00, n11, n13, n15) for four nozzles unit, (n00, n10, n11, n12, n13, n14, n15) for seven nozzles unit, and (n00, n10 - n15, n20 - n2b) for nineteen nozzles unit, respectively.
899
Fusion Engineering and Design 146 (2019) 898–901
F. Okino et al.
Fig. 5. a. A photograph of the VST experimental setup integrated into the standalone test-stand for basic function commissioning. Heat shield is removed for photograph taking. Hot liquid PbLi is supplied from the upper chamber through nozzles to the VST. b. A photograph of the array of droplets from four nozzles. Two photographs between time period of 0.002 second are overlaid to measure the falling velocity. Nozzle diameter is 0.6 mm, the measured falling velocity is 1.6 m s−1.
is described by diffusion theory as
(EMP), concentration measuring units, heating units, and vacuum pumping units. The vacuum chamber is formed with an inside diameter (ID) of 147 mm and height (H) of 800 mm. The temperature is controlled to range between 375 ℃ and 450 ℃, depending on the experimental conditions. Liquid PbLi is circulated with the nozzle flow velocity between 1.5 m s−1 and 4.5 m s−1. D2 gas is dissolved by bubbling; the aimed concentration is an atomic fraction between 10−6 and 10−7 [8]. The D2 concentration in PbLi is measured by the amount of permeation through two iron tubes, which are located before and after VST chamber, each with an ID of 10 mm, wall thickness(T) of 1 mm, and length (L) of 120 mm. The corresponding concentration is noted as Cin and Cout in mol m−3. The release amount of D2 from droplets is noted as M (rd, td, n, tf) in mol, where rd, td, n, and tf are the droplet radius in m, falling period in s, number of nozzles, and total falling period in s, respectively. M (rd, td, n, tf) is collected by a turbomolecular pump (TMP) and measured by a quadrupole mass spectrometry (QMS). A schematic of multiple nozzles arrays is shown in Fig. 3b. The nozzle array is designed such that distances between two adjacent nozzles, e.g., p0-10, p0-11, p11-10, are all equal to 6.0 mm, respectively [9]. The nozzle diameter is 0.6 mm and the length 2 mm. Four test units, each having a different number of nozzles per unit of 1, 4, 7, and 19, are equipped to identify the mutual effects on TEE under simultaneously falling droplets from plural nozzles. Nozzle material SUS316 is used for a maximum of 48 h of operation. For long term application, however, an anti-corrosive material must be utilized which is out of scope for this study.
R (rd, td ) = =1 −
(3)
where D is the quasi dispersion coefficient in m s amount is described as
M (rd, td, n, t f ) = Q (rd, n, t f ) Cin R (rd, td )
[8]. The release (4)
The different release amounts M (rd, td1, n, tf1) and M (rd, td2, n, tf2) are obtained by changing the droplet falling period from td1 to td2 under same dissolving condition. By dividing these two release amounts as
M (rd, td1, n, t f 1) Q (rd, n, t f 1 ) M (rd, td2, n, t f 2) Q (rd, n, t f 2 )
=
R (rd, td1, D) R (rd, td2, D)
(5)
Then Cin, ambiguous concentration, is neglected and one unique D is extracted. By using Eq. (3), the E(rd, td) can be validated with the result of using Eq. (1). The falling period td can vary between 0.25 s and 0.09 s. By reading Fig. 1, estimated corresponding E(rd, td) is 0.95 and 0.7, respectively with rd 0.3 mm. 3.3. Schedule The schedule for this campaign is depicted in Fig. 4. VST setup design and fabrication is finished by the first half of 2018 (2018/U). The first step commissioning under a non-continuous flow condition is performed at Kyoto University the latter half of 2018. After minor modification, VST will be integrated into the Oroshhi-2 PbLi test loop which has a 120 L PbLi inventory, flow capacity of 52.6 L min−1, and operating temperature of up to 450 ℃ at NIFS [11]. The continuous hydrogen isotopes recovery test will be performed in 2019. The campaign results are to be reported by the end of 2019.
TEE is hereafter defined as
Cin − Cout Cin
exp (−Dn2π 2td rd2) 2 −1
3.2. TEE validation
E (rd, td ) ≡
M (rd, td ) M (rd, ∞) ∞ 1 6 ∑1 2 π2 n
(1) 3.4. Current status
The reliability is verified by qualifying the mass balance as
M (rd, td, n, t f ) = Q (rd, n, t f )[Cin − Cout ]
As shown in Fig. 5a, the VST setup is fabricated and integrated into the standalone-test-stand and is under a commissioning of non-continuous PbLi flow condition at Kyoto University. As shown in Fig. 5b, temperature rise function of the VST, droplet formation under four nozzle array, PbLi liquid level measurement, and PbLi flow velocity measurements are pre-checked, and so far no serious problem is detected.
(2)
where Q is the total flow amount of PbLi in m3. The measurement of Cin and Cout, however, has wide range of ambiguity due to the uncertainty of the Sievert’s constant and diffusion coefficient [10]. The alternative validation method, therefore, is presented. The ratio of the amount of substance diffusing from a droplet during finite time t and infinite time 900
Fusion Engineering and Design 146 (2019) 898–901
F. Okino et al.
4. Summary [3]
This report introduces current status of the continuous tritium recovery test campaign using PbLi droplets in vacuum. Applicable experimental campaigns are established to verify the function of VST, TEE, effects of multiple nozzles, and 24 h continuous running in relevant operational thermal-hydraulic conditions. The experimental setup is fabricated, and a commissioning under non-continuous flow condition is finished by the end of 2018. In 2019, a continuous flow condition test is to be performed at the Oroshhi-2 PbLi flow test loop at NIFS. In this campaign, the viability of VST as a hydrogen isotope recovery method for DEMO as well as ITER-TBM is verified.
[4]
[5]
[6]
[7]
Acknowledgments [8]
This study is supported by the National Institute for Fusion Science (NIFS) Co-operation Research ProgramNIFS18KOBF039.
[9]
References
[10]
[1] I. Ricapito, A. Aiello, A. Buekki-Deme, J. Galabert, C. Moreno, Y. Poitevin, et al., Tritium technologies and transport modelling: main outcomes from the European TBM Project, Fusion Eng. Des. (2018), https://doi.org/10.1016/j.fusengdes.2018. 01.023. [2] I. Ricapito, A. Ciampichetti, R. Laesser, Y. Poitevin, M. Utili, Tritium extraction
[11]
901
from liquid Pb-16Li: a critical review of candidate technologies for ITER and DEMO applications, Fusion Sci. Technol. 60 (October) (2011) 1159–1162. M. Utili, A. Aiello, L. Laffi, A. Malavasi, I. Ricapito, Investigation on efficiency of gas liquid contactor used as tritium extraction unit for HCLL-TBM Pb-16Li loop, Fusion Eng. Des. 109–111 (2016) 1–6. B. Garcinuno, D. Rapisarda, I. Fernandez, C. Moreno, I. Palermo, A. Ibarra, Design of a permeator against vacuum for tritium extraction from eutectic lithium-lead in a DCLL DEMO, Fusion Eng. Des. 117 (2017) 226–231. B. Garcinuno, D. Rapisarda, I. Fernandez-Berceruelo, D. Jimenez-Rey, J. Sanz, C. Moreno, et al., Design and fabrication of a Permeator Against Bacuum prototype for small scale testing at Lead-Lithium facility, Fusion Eng. Des. 124 (2017) 871–875. F. Okino, P. Calderoni, R. Kasada, S. Konishi, Feasibility analysis of vacuum sieve tray for tritium extraction in the HCLL test blanket system, Fusion Eng. Des. 109111 (2016) 1748–1753. D. Demange, L.V. Boccaccini, F. Franza, A. Santucci, S. Tosti, R. Wagner, Tritium management and anti-permeation strategies for three different breeding blanket options foreseen for the European Power Plant Physics and Technology Demonstration reactor study, Fusion Eng. Des. 89 (2014) 1219–1222. F. Okino, K. Noborio, R. Kasada, S. Konishi, Enhanced mass transfer of deuterium extracted from falling liquid Pb-17Li droplets, Fusion Sci. Technol. 64 (3) (2013) 543–548. F. Okino, L. Frances, D. Demange, R. Kasada, S. Konishi, Tritium recovery efficiency from an array of PbLi droplets in vacuum, Fusion Sci. Technol. 71 (2017) 575–583. E. Mas de les Valls, L.A. Sedano, L. Batet, I. Ricapito, A. Aiello, O. Gastaldi, et al., Lead-lithium eutectic material database for nuclear fusion technology, J. Nucl. Mater. 376 (2008) 353–357. A. Sagara, T. Tanaka, J. Yagi, M. Takahashi, K. Miura, T. Yokomine, et al., First operation of the Flinak/LiPb twin loop Orosh2i-2 with a 3T SC Magnet for R&D of liquid blanket for fusion reactor, Fusion Sci. Technol. 68 (2) (2015) 303–307, https://doi.org/10.13182/FST15-126.
Contents lists available at ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Current status of the continuous tritium recovery test campaign using PbLi droplets in vacuum
T
⁎
Fumito Okinoa, , Juro Yagia, Teruya Tanakab,c, Akio Sagarab,c, Satoshi Konishia a
Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Japan National Institute for Fusion Science, Toki Gifu, Japan c SOKENDAI, Toki Gifu, Japan b
A R T I C LE I N FO
A B S T R A C T
Keywords: Tritium recovery Continuous operation PbLi Droplets in vacuum Oroshhi-2 Vacuum sieve tray
This report introduces a current status of the continuous tritium recovery test campaign of PbLi droplets in vacuum, using vacuum sieve tray (VST). The campaign aims to verify the viability of VST method at a prototype design level. The following verification are to be performed. 1) Verify the steady state extraction efficiency of tritium using a 0.6 mm nozzle. The target is greater than 80%. 2) Verify the mutual interference effects on efficiency degradation by multiple droplets by comparing 1, 4, 7, and 19 nozzles. 3) Verify the reliability of VST in continuous operation. At least 24 h of non-stop operation without efficiency degradation is the primary goal, which can be extended up to 48 h. A dedicated extraction setup is to be installed March 2019 into the Oroshhi-2 PbLi experimental loop at the National Institute for Fusion Science (NIFS) Toki-Japan, followed by a stand-alone test with a short flowing period at Kyoto University which is already finished. Deuterium (D2), instead of tritium, is used for the experiment. Extraction efficiency is calculated by comparing the D2 concentration before-drop and after-drop. The amount of released D2 is also measured by a quadrupole mass spectrometer (QMS) and verified by the concentration difference. The PbLi temperature is between 375 ℃ and 450 ℃, and the flow velocity at the nozzle is between 1.5 m s−1 and 4.5 m s−1. The final report is scheduled to be completed by the end of 2019.
1. Introduction
2. Commitment items and targets
Tritium extraction efficiency (TEE) from liquid PbLi is a significant function of a liquid breeding blanket (LBB). Three tritium extraction technologies are considered for the conceptual design review (CDR) of the ITER test blanket module (TBM) program [1]: packed columns (PC) [2,3], permeators against vacuum (PAV) [4,5], and vacuum sieve tray (VST) [6]. Subsequently, PC is selected for CDR because of its high technical maturity. With regard to the VST, the following two issues are noted: a) possible performance degradation owing to the dense droplet arrays, needed in large-scale applications, and b) risk of plugging in nozzles less than 1 mm in diameter, needed for achieving a good TEE. It is concluded, thus far, VST technology has not been tested in relevant operational thermal-hydraulic conditions, such that the comprehensive….performance characterization test is needed [1]. This report describes current status of the experimental verification campaign of VST to identify a stable TEE under multiple droplets conditions, reliability of VST is also verified.
2.1. Extraction efficiency
⁎
The authors previously reported the estimated TEE [6] as a function of the droplet falling period and nozzle diameter, as shown in Fig. 1. A TEE greater than 80% is the assumed target requirement of this campaign, which is in accordance with the study by Demange [7]. As shown in Fig. 1, the falling periods and corresponding nozzle diameters which satisfy the target requirement are 0.05 s with 0.4 mm nozzle, 0.1 s with 0.6 mm nozzle, and 0.2 s with 0.8 mm nozzle. Owing to the design limitation, the combination of a falling period of 0.1 s with a 0.6 mm nozzle is selected as a set of representative parameters to perform the following experimental campaign. Among the three conditions, the one selected has a well-balanced sensitivity to TEE as a function of the falling period. A critical concern regarding estimated TEE, which is shown in Fig. 1, is that the mass transport data used for estimation are obtained under one nozzle droplet column experimental condition [8]. The mutual effects under multiple arrays of droplets are not included. The
Corresponding author. E-mail address: [email protected] (F. Okino).
https://doi.org/10.1016/j.fusengdes.2019.01.108 Received 25 September 2018; Received in revised form 28 December 2018; Accepted 22 January 2019 Available online 26 January 2019 0920-3796/ © 2019 Elsevier B.V. All rights reserved.
Fusion Engineering and Design 146 (2019) 898–901
F. Okino et al.
Fig. 4. VST verification campaign schedule. VST is fabricated and Test-1, a commissioning under non-continuous flow condition is finished at Kyoto University. From 2019 Test-2 is scheduled to start at NIFS. Fig. 1. Estimated TEE as a function of falling period [6]. TEE results using four different nozzle diameters are plotted on a same chart. A TEE of 0.8 is the assumed target of this study.
A and type B, and some of the remaining T2 flows in a path directly to the exhaust port. According to the optimistic scenario, the dwell period of an incident molecule on a surface is very short, it eventually reaches an exhaust port and does not affect the TEE. A non-optimistic scenario estimates that the dwelling period of an incident molecule on a surface is not negligible and affects the TEE. The results under optimisticcondition indicate that the TEE is the same as under the one-column results, as shown in Fig. 1. In another case, results deviate from 20% to 60% compared with the one-column condition. These results must be verified in this campaign. 2.2. Reliable operation Regarding the reliable operation, it is mentioned in [1] “for the more innovative technology, it is needed to plan and execute… comprehensive test of performance characterization…”. However, there are few documents which describe the required continuous working hours. This campaign, therefore, assumed the 24 h as the reliable minimum continuous working hours. Within 24 h VST must run continuously without TEE degradation and unexpected stoppage. After 24 h of nonstop operation, a duration test will be extended up to 48 h.
Fig. 2. Typical behaviors of released tritium in an array of droplets [9].
3. Verification campaign procedures
authors, therefore, performed a study to analyze the TEE under arrays of multiple droplets as a function of nozzle pitch, number of arrays, and exhaust port ratio, schematically shown in Fig. 2 [9]. In a vacuum, two released tritium on a droplet surface recombine, form a T2 molecule, and are emitted. Next, they take three different paths, described as type
3.1. Experimental setup A schematic of the experimental setup is shown in Fig. 3a. The setup is consisted of a VST chamber, which includes a droplet formation nozzle, a deuterium gas (D2) dissolution unit, an electromagnetic pump Fig. 3. a. A schematic of VST experimental setup. D2 gas is dissolved by bubbling and is circulated by EMP. Liquid PbLi is turned into droplets by nozzles, and while falling in a vacuum chamber, the dissolved D2 is recombined and released into a vacuum. The released D2 is collected with a vacuum pump and measured by QMS. b. A schematic of the nozzle array. The pitch between each adjacent nozzle is equally assigned. Nozzle position is assigned at (n00) for one nozzle unit, (n00, n11, n13, n15) for four nozzles unit, (n00, n10, n11, n12, n13, n14, n15) for seven nozzles unit, and (n00, n10 - n15, n20 - n2b) for nineteen nozzles unit, respectively.
899
Fusion Engineering and Design 146 (2019) 898–901
F. Okino et al.
Fig. 5. a. A photograph of the VST experimental setup integrated into the standalone test-stand for basic function commissioning. Heat shield is removed for photograph taking. Hot liquid PbLi is supplied from the upper chamber through nozzles to the VST. b. A photograph of the array of droplets from four nozzles. Two photographs between time period of 0.002 second are overlaid to measure the falling velocity. Nozzle diameter is 0.6 mm, the measured falling velocity is 1.6 m s−1.
is described by diffusion theory as
(EMP), concentration measuring units, heating units, and vacuum pumping units. The vacuum chamber is formed with an inside diameter (ID) of 147 mm and height (H) of 800 mm. The temperature is controlled to range between 375 ℃ and 450 ℃, depending on the experimental conditions. Liquid PbLi is circulated with the nozzle flow velocity between 1.5 m s−1 and 4.5 m s−1. D2 gas is dissolved by bubbling; the aimed concentration is an atomic fraction between 10−6 and 10−7 [8]. The D2 concentration in PbLi is measured by the amount of permeation through two iron tubes, which are located before and after VST chamber, each with an ID of 10 mm, wall thickness(T) of 1 mm, and length (L) of 120 mm. The corresponding concentration is noted as Cin and Cout in mol m−3. The release amount of D2 from droplets is noted as M (rd, td, n, tf) in mol, where rd, td, n, and tf are the droplet radius in m, falling period in s, number of nozzles, and total falling period in s, respectively. M (rd, td, n, tf) is collected by a turbomolecular pump (TMP) and measured by a quadrupole mass spectrometry (QMS). A schematic of multiple nozzles arrays is shown in Fig. 3b. The nozzle array is designed such that distances between two adjacent nozzles, e.g., p0-10, p0-11, p11-10, are all equal to 6.0 mm, respectively [9]. The nozzle diameter is 0.6 mm and the length 2 mm. Four test units, each having a different number of nozzles per unit of 1, 4, 7, and 19, are equipped to identify the mutual effects on TEE under simultaneously falling droplets from plural nozzles. Nozzle material SUS316 is used for a maximum of 48 h of operation. For long term application, however, an anti-corrosive material must be utilized which is out of scope for this study.
R (rd, td ) = =1 −
(3)
where D is the quasi dispersion coefficient in m s amount is described as
M (rd, td, n, t f ) = Q (rd, n, t f ) Cin R (rd, td )
[8]. The release (4)
The different release amounts M (rd, td1, n, tf1) and M (rd, td2, n, tf2) are obtained by changing the droplet falling period from td1 to td2 under same dissolving condition. By dividing these two release amounts as
M (rd, td1, n, t f 1) Q (rd, n, t f 1 ) M (rd, td2, n, t f 2) Q (rd, n, t f 2 )
=
R (rd, td1, D) R (rd, td2, D)
(5)
Then Cin, ambiguous concentration, is neglected and one unique D is extracted. By using Eq. (3), the E(rd, td) can be validated with the result of using Eq. (1). The falling period td can vary between 0.25 s and 0.09 s. By reading Fig. 1, estimated corresponding E(rd, td) is 0.95 and 0.7, respectively with rd 0.3 mm. 3.3. Schedule The schedule for this campaign is depicted in Fig. 4. VST setup design and fabrication is finished by the first half of 2018 (2018/U). The first step commissioning under a non-continuous flow condition is performed at Kyoto University the latter half of 2018. After minor modification, VST will be integrated into the Oroshhi-2 PbLi test loop which has a 120 L PbLi inventory, flow capacity of 52.6 L min−1, and operating temperature of up to 450 ℃ at NIFS [11]. The continuous hydrogen isotopes recovery test will be performed in 2019. The campaign results are to be reported by the end of 2019.
TEE is hereafter defined as
Cin − Cout Cin
exp (−Dn2π 2td rd2) 2 −1
3.2. TEE validation
E (rd, td ) ≡
M (rd, td ) M (rd, ∞) ∞ 1 6 ∑1 2 π2 n
(1) 3.4. Current status
The reliability is verified by qualifying the mass balance as
M (rd, td, n, t f ) = Q (rd, n, t f )[Cin − Cout ]
As shown in Fig. 5a, the VST setup is fabricated and integrated into the standalone-test-stand and is under a commissioning of non-continuous PbLi flow condition at Kyoto University. As shown in Fig. 5b, temperature rise function of the VST, droplet formation under four nozzle array, PbLi liquid level measurement, and PbLi flow velocity measurements are pre-checked, and so far no serious problem is detected.
(2)
where Q is the total flow amount of PbLi in m3. The measurement of Cin and Cout, however, has wide range of ambiguity due to the uncertainty of the Sievert’s constant and diffusion coefficient [10]. The alternative validation method, therefore, is presented. The ratio of the amount of substance diffusing from a droplet during finite time t and infinite time 900
Fusion Engineering and Design 146 (2019) 898–901
F. Okino et al.
4. Summary [3]
This report introduces current status of the continuous tritium recovery test campaign using PbLi droplets in vacuum. Applicable experimental campaigns are established to verify the function of VST, TEE, effects of multiple nozzles, and 24 h continuous running in relevant operational thermal-hydraulic conditions. The experimental setup is fabricated, and a commissioning under non-continuous flow condition is finished by the end of 2018. In 2019, a continuous flow condition test is to be performed at the Oroshhi-2 PbLi flow test loop at NIFS. In this campaign, the viability of VST as a hydrogen isotope recovery method for DEMO as well as ITER-TBM is verified.
[4]
[5]
[6]
[7]
Acknowledgments [8]
This study is supported by the National Institute for Fusion Science (NIFS) Co-operation Research ProgramNIFS18KOBF039.
[9]
References
[10]
[1] I. Ricapito, A. Aiello, A. Buekki-Deme, J. Galabert, C. Moreno, Y. Poitevin, et al., Tritium technologies and transport modelling: main outcomes from the European TBM Project, Fusion Eng. Des. (2018), https://doi.org/10.1016/j.fusengdes.2018. 01.023. [2] I. Ricapito, A. Ciampichetti, R. Laesser, Y. Poitevin, M. Utili, Tritium extraction
[11]
901
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