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Workload foreseen for the IFMIF Post Irradiation Examination Facility
Fusion Engineering and Design 86 (2011) 2522–2525
Contents lists available at ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Workload foreseen for the IFMIF Post Irradiation Examination Facility J. Molla a,∗ , M. Yamamoto b , A. Polato c , M. Soldaini d , H. Takeuchi b , E. Wakai e a
EURATOM-CIEMAT Association, IFMIF/EVEDA Project Team, Rokkasho, Japan JAEA, IFMIF/EVEDA Project Team, Rokkasho, Japan INFN-LNL, IFMIF/EVEDA Project Team, Rokkasho, Japan d CEA, IFMIF/EVEDA Project Team, Rokkasho, Japan e JAEA, Fusion Research and Development Directorate, Ibaraki, Japan b c
a r t i c l e
i n f o
Article history: Available online 13 April 2011 Keywords: IFMIF Materials Mechanical properties Irradiation Post Irradiation Examination
a b s t r a c t The workload for the Post Irradiation Examination Facility during the operation of IFMIF is evaluated in this paper based on the users’ specifications. The foreseen irradiation and Post Irradiation Examination programmes presented in this paper are based on the IFMIF specifications proposed by IFMIF users’ community, available irradiation volumes in the test modules and materials properties required to compile the materials database needed for design of DEMO reactors. Candidate materials to be tested, number of specimens, temperature range or radiation damage levels are the main parameters used as input for this assessment. The main assumptions made to draw a realistic scenario for the irradiation campaigns and post irradiation experiments are also described in this paper. An assessment of the required test machines is done. Long lasting experiments like fatigue test or crack growth test will determine the time required to complete the characterization of each set of specimens. In these cases several test machines working in parallel will be required. © 2011 Elsevier B.V. All rights reserved.
1. Introduction 1.1. Objective IFMIF and ITER define nowadays the reference international fusion programme required for the design of DEMO. The main role of IFMIF is to provide a database on material properties irradiated under radiation fields similar to Fusion reactors. Although important in situ experiments will be performed in IFMIF directly in the test modules under irradiation, most of the information will be provided by post irradiation experiments (PIE). Nearly 1000 small specimens can be irradiated simultaneously to be tested afterwards in the PIE Facility. Currently the irradiation programme in IFMIF and the examination programme in the PIE Facility are still under definition. A first proposal can be found in ref. [1] and more recently new approaches were proposed according to the test module performances [2]. The engineering design of the PIE Facility – to be performed during the IFMIF – EVEDA in the framework of the BA Agreement – requires as a first step to transform the expected workload into technical specifications. IFMIF specifications and irradiation performances in the test modules are the basis to foresee in this paper
∗ Corresponding author. Tel.: +34 91 346 6580; fax: +34 91 346 6068. E-mail address: [email protected] (J. Molla). 0920-3796/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.fusengdes.2011.03.037
the irradiation schedule, the workload in the PIE Facility and the requirements in terms of testing machines to accomplish with the expectations for IFMIF.
1.2. The role of IFMIF The latest specifications for IFMIF are summarized in the “IFMIF Users Specifications and Proposals” [3,4] which is intended to be the input requirements for the IFMIF-EVEDA project. These specifications are an updating of the needs for an intense neutron source for testing materials as described in a number of papers along the last two decades [5–9]. Information to be provided by IFMIF is structured according to its urgency in three packages [3,4]: (1) data up to 30–50 dpa for the engineering design of DEMO; (2) data up to 100 dpa for DEMO lifetime evaluation and (3) data up to 150 dpa for application to commercial power plants. Regarding the materials to be investigated in IFMIF two groups of materials are considered: (a) primary candidate materials and (b) candidate structural materials for advanced blanket concepts. Within the first group, only Reduced Activation Ferritic/Martensitic (RAF/M) steels including Martensitic Oxigen Dispersion Strengthened (M-ODS) Steels are considered. Ferritic-ODS steels, V-alloys, W-alloys and SiC/SiCf composites are candidate materials for advanced blanket concepts. The priority should be given to primary candidates. The irradiation temperatures should be up to the maximum expected operation temperature in DEMO, i.e. 550 ◦ C for
J. Molla et al. / Fusion Engineering and Design 86 (2011) 2522–2525 Table 1 Experiments to be performed in the PIE Facility for each specimens’ bundle representing one irradiation condition (temperature and damage level); number of specimens required for each test (and recommendation in [2]); time required per specimen (t) and total time for the minimum number of specimens (tT ). Experiment
N
t (h)
tT (h)
Static tensile (3 temperature levels) Hardness Fracture toughness Fracture toughness (DBTT) (4 temperature levels) Charpy impact Fatigue (RT and irradiation temperature) Fatigue crack growth (RT, irradiation temperature) Creep Stress crack corrosion (RT, irradiation temperature)
9 (12)
0.5 (RT)–5
31.5
5 6 (2) 28 (0)
0.1 0.5 (RT)–5 0.5 (RT)–5
0.5 16.5 140
8 (12) 10 (6)
1 1–104
8 22222
6 (3)
103 –104
3 (16) 6 (0)
3
4
10 –10 103 –104
28000 14000 28000
RAF/M steels; 750 ◦ C for ODS steels; 800 ◦ C for V-alloys; 1100 ◦ C for SiC/SiC composites; and 1200 ◦ C for W-alloys [3,4].
2523
The HT-HFTM consisting on cast-like capsules being able to achieve higher temperatures will have a reduced volume for specimens. The HT-HFTM is arranged in 9 independent capsules arranged horizontally in three rows. Being the design of the HTHFTM still in its first stage we can assume [11] that about 40–60 specimens can be hosted in each capsule. For the irradiation schedule and delivery to the PIE Facility we will assume also two different options: (1) three capsules are able to host 2 bundles as described in Table 1 or (2) each capsule can host one bundle as described in ref. [2]. In addition to the HFTMs there will be in IFMIF several test modules used to perform in situ experiments under irradiation. Following the irradiation campaign a number of experiments will be also required in the PIE Facility. Materials to be tested include Li-based ceramics, beryllium alloys, insulating coatings (SiC, Al2 O3 , etc.), insulators, optical materials, radiofrequency windows or superconductors. The experiments to be performed in the PIE Laboratories are well described in [3,4]. The number of specimens expected from these modules is relatively low as compared with the HFTM where hundreds of specimens will be packed together.
2. PIE tests and number of specimens
3. Irradiation programme
The tests to be performed in the irradiated specimens with in the PIE Laboratories according to IFMIF specifications are: tensile, hardness, fracture toughness, fatigue, charpy impact and creep. It is assumed that microstructure analysis will be performed in more specialized laboratories with specific instrumentation [3,4]. A more complete material characterization should include crack growth experiments as proposed in [2] and fatigue corrosion as proposed in [6]. Furthermore material characterization will require several testing temperature levels. The number of specimens required for each test can be controversial. On one hand higher number of specimens would provide higher reliability but on the other hand data on irradiated material at different damage levels is required as soon as possible and available volume in the HFTM is limited. Optimization of the available time and volume will require further discussions among materials experts. As an example, Table 1 reports the required PIE tests in IFMIF together the number of specimens required for each test for the creation of the materials database to the authors understanding. Minimum number of specimens reported in Table 1 includes all the specimens required for each temperature level. High flux test modules (HFTMs) will be used to irradiate specimens at controlled temperature in the highest neutron flux volume. In addition to the reference HFTM (ref-HFTM) whose conceptual design was part of IFMIF conceptual design already in the 90s [10] a high temperature (HT) HFTM will be used to irradiate specimens up to 1000 ◦ C [11]. The ref-HFTM is composed by 12 capsules, each hosting 80 specimens. The temperature can be controlled inside each capsule in the range from 250 ◦ C to 550 ◦ C. Capsules are vertically arranged in 3 rows each row being exposed to a different neutron flux. This configuration can provide 12 different material conditions (damage and temperature). The specimens’ configuration in each capsule can be arranged according to the irradiation needs. According to ref. [2] two specimens sets representing two different materials can be hosted in each capsule containing enough number of specimens for a complete PIE characterization. The number of specimens reported in Table 1 almost doubles the number of specimens proposed in [2]. Each capsule in the ref-HFTM may include one material bundle as described in Table 1 or two material bundles as described in [2]. These two options are analyzed below as representative examples dealing to different irradiation and PIE schedules.
Different irradiation conditions will be required for material characterization. Three dose levels and three temperature levels are proposed in ref. [1]. Four temperature levels and eight dose levels are proposed in [2]. Other possibilities can be considered indeed depending on the needs. Since data at 30–50 dpa and 100 dpa are to be provided as soon as possible we will take into account only these two damage levels as the priority and the 150 dpa level for a second step [1]. Four different temperatures as proposed in ref. [2] for the refHFTM is assumed for this analysis. These temperature levels could be for example 250 ◦ C, 350 ◦ C, 450 ◦ C and 550 ◦ C. M-ODS are considered as primary candidates to be operated up to 750 ◦ C and therefore the HT-HFTM will be required to provide data above 550 ◦ C. Taking into account the smaller volume available in this module using the ref-HFTM at lower temperatures even for the M-ODS would optimize the irradiation programme. Three temperature levels are assumed, for example: 600 ◦ C, 700 ◦ C and 750 ◦ C for the HT-HFTM. For the assessment of the time required to complete these irradiation campaigns the following assumptions were taken into account: (1) The radiation damage in the HFTM will be around 45 dpa/fpy, 35 dpa/fpy and 25 dpa/fpy in the first, second and third rows respectively as described in refs. [2,12] for both the ref-HFTM and the HT-HFTM; (2) Availability of IFMIF will be 70% including one month maintenance following 11 months of operation. (3) During the first three years of operation only one accelerator will be available. Additional replacements of the target assembly in this first period may be required until reliable data on the back plate are available. For this analysis we will assume that the first three years will provide the radiation damage corresponding to 1 year of normal operation with two accelerators. Changes in the extension of this first period would not alter the main conclusions of this paper. Damage accumulated in specimens irradiated for one year in the first row and one more year in the third row would amount 49 dpa. The same damage level would be accumulated in the second row specimens in the same period. 49 dpa-irradiation campaigns (2 years) for a first period and 98 dpa-irradaition campaigns (4 years) for a second period are assumed in this paper to complete priorities (1) and (2) described in Section 1.2 for primary candidates. Different configurations are indeed possible. Some of them and the consequences for the PIE workload are discussed below.
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J. Molla et al. / Fusion Engineering and Design 86 (2011) 2522–2525
3.1. Irradiation programme: option 1 We will assume first that the specimens bundle described in Table 1 is required for each irradiation condition. Each capsule would represent in that case one material at one irradiation condition. The complete ref-HFTM is able to irradiate 3 materials (two grades of RAF/M steel and one grade of M-ODS), at four different temperature levels simultaneously. Regarding the HT-HFTM, we will assume three capsules kept at the same temperature hosting two specimens’ bundles (M-ODS and one additional material). The complete HT-HFTM will be able to irradiate 2 materials at 3 temperature levels. Following a first 4-year (3 + 1) irradiation campaign to achieve 49 dpa, M-ODS should be irradiated at high temperature for two additional years to complete the 49 dpa (the first priority). The foreseen delivery of specimens to the PIE would be: End of year 4: 12 bundles: RAF/M-A, RAF/M-B and M-ODS @ 49 dpa @ 250 ◦ C – 350 ◦ C – 450 ◦ C – 550 ◦ C End of year 6: 3 bundles for M-ODS and 3 more bundles for an additional material @ 49 dpa @ 600 ◦ C – 700 ◦ C – 750 ◦ C End of year 10: 12 bundles: RAF/M-A, RAF/M-B and M-ODS @ 98 dpa @ 250 ◦ C – 350 ◦ C – 450 ◦ C – 550 ◦ C End of year 14: 3 bundles for M-ODS and and 3 more bundles for an additional material @ 98 dpa @ 600 ◦ C – 700 ◦ C – 750 ◦ C 3.2. Irradiation programme: option 2 If only 40 specimen/bundles would be enough for material characterization as proposed in [2] then each capsule in the ref-HFTM could host two bundles. Six materials (for example two grades of RAF/M, two grades of M-ODS and two additional materials) at four temperature levels could be irradiated simultaneously. The HTHFTM capsules would be able to host one complete specimen’s bundle. Three materials (for example two grades of M-ODS and one additional material) can be irradiated at three temperature levels. Following the same schedule to achieve 49 dpa and 98 dpa as in option 1, the delivery to the PIE would be: End of year 4: 16 bundles for RAF/M-A, RAF/M-B, M-ODS-A and M-ODS-B and 8 more bundles for an additional material (two grades) @ 49 dpa @ 250 ◦ C – 350 ◦ C – 450 ◦ C – 550 ◦ C End of year 6: 6 bundles for the M-ODS-A and M-ODS-B and 3 more bundles for an additional material @ 49 dpa @ 600 ◦ C – 700 ◦ C – 750 ◦ C End of year 10: 16 bundles for RAF/M-A, RAF/M-B, M-ODS-A and M-ODS-B and 8 more bundles for an additional material (two grades) @ 98 dpa @ 250 ◦ C – 350 ◦ C – 450 ◦ C – 550 ◦ C End of year 14: 6 bundles for the M-ODS-A and M-ODS-B and 3 more bundles for an additional material @ 98 dpa @ 600 ◦ C – 700 ◦ C – 750 ◦ C 3.3. Irradiation programme: option 3 There are indeed many other combinations. One option is to irradiate the same material(s) in the three rows without exchanging. Damage levels of 62 dpa, 49 dpa and 35 dpa would be available following the first four years in the first material, for example RAF/M. Two additional years would be required for the same damage levels in a second material. In this case all the specimens in the HFTM would be delivered to the PIE every two years in the first irradiation period to complete 30–50 dpa and every 4 years in the second irradiation period to reach 100 dpa.
Table 2 Number of testing machines for each experiment in the PIE Facility depending on the irradiation programme. Property
Option 1
Option 2
Option 3
Tensile, hardness, fracture toughness and charpy Fatigue Fatigue crack growth Stress crack corrosion Creep
1
1
1
8 8 8 4
12 12 0 6
34 34 0 17
should be tested at least at the same rate they are delivered to the PIE Facility. In option 1, 15 bundles should be tested in 6 years being each bundle composed of the specimens reported in Table 1. In option 2, 22 bundles each bundle being composed of only 40 specimens [2] should be tested in the same time. We are assuming that additional materials are not primary candidates and will not need to be tested immediately. The time required for each experiment can range in a very wide scale. Fatigue, creep and crack growth experiments can last up to several thousand hours while tensile or fracture toughness experiments may last a few hours. One testing machine for each of the short experiments – Static tensile, hardness, fracture toughness and charpy impact – would be enough to test all the specimens in around one year for any of the options described above. On the other hand time for long lasting experiments is spread in a logarithmic time scale. Fatigue experiments for example require 5 specimens to be tested during 1 h, 10 h, 102 h, 103 h and 104 h. The number of required testing machines will be determined by the longest one. Furthermore fatigue, crack growth and stress corrosion should be tested at the irradiation temperature and at room temperature. Creep should be measured only at irradiation temperature. Fatigue testing experiment is taken as an example in the analysis below. 5. PIE Facility testing machines 5.1. Option 1 According to the irradiation schedule described in option 1, 15 specimens (one per bundle) should be tested for 104 h and testing temperature. Three testing machines working in parallel would be able to finish 12 times 104 h tests in 56 months starting at the beginning of 5th year and finalizing before the end of 9th year. One more testing machine would be able to finish all the shorter (1–103 h) tests before the end of 6th year and then start the remaining three tests for the high temperature M-ODS specimens at the beginning of 7th year and finalizing before the end of 10th year. PIE for the 98 dpa specimens would start at the beginning of 11th year. With this schedule, four testing machines per temperature would be enough to finish all the PIE on 49 dpa specimens before the end of 10th year what is in agreement with the schedule approach in ref. [1] and [3,4]. Table 2 reports the required instrumentation in the PIE laboratories in this case. 5.2. Option 2 Option 2 irradiation schedule would deliver 22 bundles to the PIE Facility what means that two more testing machines would be required for each property and each testing temperature (see Table 2). Stress corrosion test is not included in this bundle configuration.
4. Discussion on the PIE workload
5.3. Option 3
For this discussion we assume that the accumulation of specimens should be avoided in the PIE Laboratories [6]. The specimens
In this case if the irradiation capsules are considered to be loaded as in option 2 (the most demanding case). 24 bundles from the
J. Molla et al. / Fusion Engineering and Design 86 (2011) 2522–2525
ref-HFTM and 9 more from the HT-HFTM would be delivered to the PIE Facility every 4 years during the 50 dpa irradiation campaigns. The only way to avoid accumulation of specimens in the PIE Laboratories would be with 17 testing machines working in parallel per testing temperature (see Table 2). Very long lasting experiments – up to 105 h – for fatigue and creep could be recommended for the assessment of components lifetime. If these very long lasting experiments (around 12 years) were required 60 additional testing machines for fatigue and 30 testing machines for creep would be needed in the less demanding case (option 1) to test all the 50-dpa and 100-dpa specimens in parallel up to 105 h; otherwise the time for testing would be excessively long.In addition to the testing machines described in Table 2 several experimental setup will be required: laser profilometry on creep tubes, thermal conductivity, electrical conductivity, etc. The number of specimens to be tested in these cases will be low and only one experimental setup will be required in each case. 6. Conclusions Different irradiation matrices for IFMIF operation will impose different requirements to the PIE Facility in IFMIF. Some of these options and the consequences for the PIE Facility have been analyzed. Requirements for short experiments like tensile or fracture toughness are independent of the irradiation matrix. Number of testing machines for long lasting experiments like fatigue or crack growth depends very much on the irradiation matrix. For the three options analyzed in this paper the number of testing machines varies between 4 and 34 depending also on the desired number of
2525
testing temperature levels. 30 additional testing machines would be needed -even in the least demanding case- if very long lasting experiments (up to 105 h) were required. References [1] L. Cook, N. Taylor, D. Ward, L. Baker, T. Hender, Accelerated development of fusion power, UKAEA FUS 521 (2005). [2] A. Moeslang, Development of a Reference Test Matrix for IFMIF Test Modules, Final Report on the EFDA Task TW4-TTMI-003 D4, 2006. [3] P. Garin, E. Diegele, A. Moeslang, Y. Poitevin, R. Heidinger, A. Ibarra, et al., IFMIF Users Specifications and Proposals, BA D 224ERJ Report, March 2010. [4] P. Garin, E. Diegele, R. Heidinger, A. Ibarra, S. Jitsukawa, H. Kimura, et al., IFMIF specifications from the Users point of view, these proceedings. [5] Report on International Fusion Irradiation Facility, in: J.E. Leiss, K. Ehrlich, A.N. Goland, A. Miyahara, H. Ohno, P. Schiller (Eds.), Workshop, San Diego, USA, February 1989. [6] IFMIF-CDA Team, M. Martone (Ed.), Int.Fusion Materials Irradiation Facility—Conceptual Design Activity, Final Report, ENEA-Frascati Report RT/ERG/FUS/96/17, 1996. [7] K. Noda, K. Ehrlich, S. Jitsukawa, A. Moeslang, S. Zinkle, User’s requirements for IFMIF, Journal of Nuclear Materials 97 (1998) 258–263. [8] H. Nakamura, M. Ida, M. Sugimoto, M. Takeda, T. Yutani, H. Takeuchi (Eds.), IFMIF Key Element Technology Phase (KEP) report, JAERI-TECH 2003-005, 2003, http://jolissrch-inter.tokai-sc.jaea.go.jp/pdfdata/JAERI-Tech-2003-005.pdf. [9] IFMIF Comprehensive Design Report (CDR), IFMIF International Team, 2004, IEA online publication, http://www.iea.org/techno/technologies/fusion/IFMIFCDR PartA.pdf. [10] K. Ehrlich, A. Moeslang, IFMIF – an international fusion materials irradiation facility, Nuclear Instrumentation and Methods in Physics Research B 139 (1998) 72. [11] S. Ebara, S. Nagata, H. Irisa, T. Yokomine, A. Shimizu, Feasibly study on cast-like IFMIF HFTM, Fusion Engineering and Design 81 (2006) 887. [12] U. Fischer, Y. Chen, S.P. Simakov, P.P.H. Wilson, P. Vladimirov, F. Wasastjerna, Overview of recent progress in IFMIF neutronics, Fusion Engineering and Design 1195 (81) (2006).
Contents lists available at ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Workload foreseen for the IFMIF Post Irradiation Examination Facility J. Molla a,∗ , M. Yamamoto b , A. Polato c , M. Soldaini d , H. Takeuchi b , E. Wakai e a
EURATOM-CIEMAT Association, IFMIF/EVEDA Project Team, Rokkasho, Japan JAEA, IFMIF/EVEDA Project Team, Rokkasho, Japan INFN-LNL, IFMIF/EVEDA Project Team, Rokkasho, Japan d CEA, IFMIF/EVEDA Project Team, Rokkasho, Japan e JAEA, Fusion Research and Development Directorate, Ibaraki, Japan b c
a r t i c l e
i n f o
Article history: Available online 13 April 2011 Keywords: IFMIF Materials Mechanical properties Irradiation Post Irradiation Examination
a b s t r a c t The workload for the Post Irradiation Examination Facility during the operation of IFMIF is evaluated in this paper based on the users’ specifications. The foreseen irradiation and Post Irradiation Examination programmes presented in this paper are based on the IFMIF specifications proposed by IFMIF users’ community, available irradiation volumes in the test modules and materials properties required to compile the materials database needed for design of DEMO reactors. Candidate materials to be tested, number of specimens, temperature range or radiation damage levels are the main parameters used as input for this assessment. The main assumptions made to draw a realistic scenario for the irradiation campaigns and post irradiation experiments are also described in this paper. An assessment of the required test machines is done. Long lasting experiments like fatigue test or crack growth test will determine the time required to complete the characterization of each set of specimens. In these cases several test machines working in parallel will be required. © 2011 Elsevier B.V. All rights reserved.
1. Introduction 1.1. Objective IFMIF and ITER define nowadays the reference international fusion programme required for the design of DEMO. The main role of IFMIF is to provide a database on material properties irradiated under radiation fields similar to Fusion reactors. Although important in situ experiments will be performed in IFMIF directly in the test modules under irradiation, most of the information will be provided by post irradiation experiments (PIE). Nearly 1000 small specimens can be irradiated simultaneously to be tested afterwards in the PIE Facility. Currently the irradiation programme in IFMIF and the examination programme in the PIE Facility are still under definition. A first proposal can be found in ref. [1] and more recently new approaches were proposed according to the test module performances [2]. The engineering design of the PIE Facility – to be performed during the IFMIF – EVEDA in the framework of the BA Agreement – requires as a first step to transform the expected workload into technical specifications. IFMIF specifications and irradiation performances in the test modules are the basis to foresee in this paper
∗ Corresponding author. Tel.: +34 91 346 6580; fax: +34 91 346 6068. E-mail address: [email protected] (J. Molla). 0920-3796/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.fusengdes.2011.03.037
the irradiation schedule, the workload in the PIE Facility and the requirements in terms of testing machines to accomplish with the expectations for IFMIF.
1.2. The role of IFMIF The latest specifications for IFMIF are summarized in the “IFMIF Users Specifications and Proposals” [3,4] which is intended to be the input requirements for the IFMIF-EVEDA project. These specifications are an updating of the needs for an intense neutron source for testing materials as described in a number of papers along the last two decades [5–9]. Information to be provided by IFMIF is structured according to its urgency in three packages [3,4]: (1) data up to 30–50 dpa for the engineering design of DEMO; (2) data up to 100 dpa for DEMO lifetime evaluation and (3) data up to 150 dpa for application to commercial power plants. Regarding the materials to be investigated in IFMIF two groups of materials are considered: (a) primary candidate materials and (b) candidate structural materials for advanced blanket concepts. Within the first group, only Reduced Activation Ferritic/Martensitic (RAF/M) steels including Martensitic Oxigen Dispersion Strengthened (M-ODS) Steels are considered. Ferritic-ODS steels, V-alloys, W-alloys and SiC/SiCf composites are candidate materials for advanced blanket concepts. The priority should be given to primary candidates. The irradiation temperatures should be up to the maximum expected operation temperature in DEMO, i.e. 550 ◦ C for
J. Molla et al. / Fusion Engineering and Design 86 (2011) 2522–2525 Table 1 Experiments to be performed in the PIE Facility for each specimens’ bundle representing one irradiation condition (temperature and damage level); number of specimens required for each test (and recommendation in [2]); time required per specimen (t) and total time for the minimum number of specimens (tT ). Experiment
N
t (h)
tT (h)
Static tensile (3 temperature levels) Hardness Fracture toughness Fracture toughness (DBTT) (4 temperature levels) Charpy impact Fatigue (RT and irradiation temperature) Fatigue crack growth (RT, irradiation temperature) Creep Stress crack corrosion (RT, irradiation temperature)
9 (12)
0.5 (RT)–5
31.5
5 6 (2) 28 (0)
0.1 0.5 (RT)–5 0.5 (RT)–5
0.5 16.5 140
8 (12) 10 (6)
1 1–104
8 22222
6 (3)
103 –104
3 (16) 6 (0)
3
4
10 –10 103 –104
28000 14000 28000
RAF/M steels; 750 ◦ C for ODS steels; 800 ◦ C for V-alloys; 1100 ◦ C for SiC/SiC composites; and 1200 ◦ C for W-alloys [3,4].
2523
The HT-HFTM consisting on cast-like capsules being able to achieve higher temperatures will have a reduced volume for specimens. The HT-HFTM is arranged in 9 independent capsules arranged horizontally in three rows. Being the design of the HTHFTM still in its first stage we can assume [11] that about 40–60 specimens can be hosted in each capsule. For the irradiation schedule and delivery to the PIE Facility we will assume also two different options: (1) three capsules are able to host 2 bundles as described in Table 1 or (2) each capsule can host one bundle as described in ref. [2]. In addition to the HFTMs there will be in IFMIF several test modules used to perform in situ experiments under irradiation. Following the irradiation campaign a number of experiments will be also required in the PIE Facility. Materials to be tested include Li-based ceramics, beryllium alloys, insulating coatings (SiC, Al2 O3 , etc.), insulators, optical materials, radiofrequency windows or superconductors. The experiments to be performed in the PIE Laboratories are well described in [3,4]. The number of specimens expected from these modules is relatively low as compared with the HFTM where hundreds of specimens will be packed together.
2. PIE tests and number of specimens
3. Irradiation programme
The tests to be performed in the irradiated specimens with in the PIE Laboratories according to IFMIF specifications are: tensile, hardness, fracture toughness, fatigue, charpy impact and creep. It is assumed that microstructure analysis will be performed in more specialized laboratories with specific instrumentation [3,4]. A more complete material characterization should include crack growth experiments as proposed in [2] and fatigue corrosion as proposed in [6]. Furthermore material characterization will require several testing temperature levels. The number of specimens required for each test can be controversial. On one hand higher number of specimens would provide higher reliability but on the other hand data on irradiated material at different damage levels is required as soon as possible and available volume in the HFTM is limited. Optimization of the available time and volume will require further discussions among materials experts. As an example, Table 1 reports the required PIE tests in IFMIF together the number of specimens required for each test for the creation of the materials database to the authors understanding. Minimum number of specimens reported in Table 1 includes all the specimens required for each temperature level. High flux test modules (HFTMs) will be used to irradiate specimens at controlled temperature in the highest neutron flux volume. In addition to the reference HFTM (ref-HFTM) whose conceptual design was part of IFMIF conceptual design already in the 90s [10] a high temperature (HT) HFTM will be used to irradiate specimens up to 1000 ◦ C [11]. The ref-HFTM is composed by 12 capsules, each hosting 80 specimens. The temperature can be controlled inside each capsule in the range from 250 ◦ C to 550 ◦ C. Capsules are vertically arranged in 3 rows each row being exposed to a different neutron flux. This configuration can provide 12 different material conditions (damage and temperature). The specimens’ configuration in each capsule can be arranged according to the irradiation needs. According to ref. [2] two specimens sets representing two different materials can be hosted in each capsule containing enough number of specimens for a complete PIE characterization. The number of specimens reported in Table 1 almost doubles the number of specimens proposed in [2]. Each capsule in the ref-HFTM may include one material bundle as described in Table 1 or two material bundles as described in [2]. These two options are analyzed below as representative examples dealing to different irradiation and PIE schedules.
Different irradiation conditions will be required for material characterization. Three dose levels and three temperature levels are proposed in ref. [1]. Four temperature levels and eight dose levels are proposed in [2]. Other possibilities can be considered indeed depending on the needs. Since data at 30–50 dpa and 100 dpa are to be provided as soon as possible we will take into account only these two damage levels as the priority and the 150 dpa level for a second step [1]. Four different temperatures as proposed in ref. [2] for the refHFTM is assumed for this analysis. These temperature levels could be for example 250 ◦ C, 350 ◦ C, 450 ◦ C and 550 ◦ C. M-ODS are considered as primary candidates to be operated up to 750 ◦ C and therefore the HT-HFTM will be required to provide data above 550 ◦ C. Taking into account the smaller volume available in this module using the ref-HFTM at lower temperatures even for the M-ODS would optimize the irradiation programme. Three temperature levels are assumed, for example: 600 ◦ C, 700 ◦ C and 750 ◦ C for the HT-HFTM. For the assessment of the time required to complete these irradiation campaigns the following assumptions were taken into account: (1) The radiation damage in the HFTM will be around 45 dpa/fpy, 35 dpa/fpy and 25 dpa/fpy in the first, second and third rows respectively as described in refs. [2,12] for both the ref-HFTM and the HT-HFTM; (2) Availability of IFMIF will be 70% including one month maintenance following 11 months of operation. (3) During the first three years of operation only one accelerator will be available. Additional replacements of the target assembly in this first period may be required until reliable data on the back plate are available. For this analysis we will assume that the first three years will provide the radiation damage corresponding to 1 year of normal operation with two accelerators. Changes in the extension of this first period would not alter the main conclusions of this paper. Damage accumulated in specimens irradiated for one year in the first row and one more year in the third row would amount 49 dpa. The same damage level would be accumulated in the second row specimens in the same period. 49 dpa-irradiation campaigns (2 years) for a first period and 98 dpa-irradaition campaigns (4 years) for a second period are assumed in this paper to complete priorities (1) and (2) described in Section 1.2 for primary candidates. Different configurations are indeed possible. Some of them and the consequences for the PIE workload are discussed below.
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3.1. Irradiation programme: option 1 We will assume first that the specimens bundle described in Table 1 is required for each irradiation condition. Each capsule would represent in that case one material at one irradiation condition. The complete ref-HFTM is able to irradiate 3 materials (two grades of RAF/M steel and one grade of M-ODS), at four different temperature levels simultaneously. Regarding the HT-HFTM, we will assume three capsules kept at the same temperature hosting two specimens’ bundles (M-ODS and one additional material). The complete HT-HFTM will be able to irradiate 2 materials at 3 temperature levels. Following a first 4-year (3 + 1) irradiation campaign to achieve 49 dpa, M-ODS should be irradiated at high temperature for two additional years to complete the 49 dpa (the first priority). The foreseen delivery of specimens to the PIE would be: End of year 4: 12 bundles: RAF/M-A, RAF/M-B and M-ODS @ 49 dpa @ 250 ◦ C – 350 ◦ C – 450 ◦ C – 550 ◦ C End of year 6: 3 bundles for M-ODS and 3 more bundles for an additional material @ 49 dpa @ 600 ◦ C – 700 ◦ C – 750 ◦ C End of year 10: 12 bundles: RAF/M-A, RAF/M-B and M-ODS @ 98 dpa @ 250 ◦ C – 350 ◦ C – 450 ◦ C – 550 ◦ C End of year 14: 3 bundles for M-ODS and and 3 more bundles for an additional material @ 98 dpa @ 600 ◦ C – 700 ◦ C – 750 ◦ C 3.2. Irradiation programme: option 2 If only 40 specimen/bundles would be enough for material characterization as proposed in [2] then each capsule in the ref-HFTM could host two bundles. Six materials (for example two grades of RAF/M, two grades of M-ODS and two additional materials) at four temperature levels could be irradiated simultaneously. The HTHFTM capsules would be able to host one complete specimen’s bundle. Three materials (for example two grades of M-ODS and one additional material) can be irradiated at three temperature levels. Following the same schedule to achieve 49 dpa and 98 dpa as in option 1, the delivery to the PIE would be: End of year 4: 16 bundles for RAF/M-A, RAF/M-B, M-ODS-A and M-ODS-B and 8 more bundles for an additional material (two grades) @ 49 dpa @ 250 ◦ C – 350 ◦ C – 450 ◦ C – 550 ◦ C End of year 6: 6 bundles for the M-ODS-A and M-ODS-B and 3 more bundles for an additional material @ 49 dpa @ 600 ◦ C – 700 ◦ C – 750 ◦ C End of year 10: 16 bundles for RAF/M-A, RAF/M-B, M-ODS-A and M-ODS-B and 8 more bundles for an additional material (two grades) @ 98 dpa @ 250 ◦ C – 350 ◦ C – 450 ◦ C – 550 ◦ C End of year 14: 6 bundles for the M-ODS-A and M-ODS-B and 3 more bundles for an additional material @ 98 dpa @ 600 ◦ C – 700 ◦ C – 750 ◦ C 3.3. Irradiation programme: option 3 There are indeed many other combinations. One option is to irradiate the same material(s) in the three rows without exchanging. Damage levels of 62 dpa, 49 dpa and 35 dpa would be available following the first four years in the first material, for example RAF/M. Two additional years would be required for the same damage levels in a second material. In this case all the specimens in the HFTM would be delivered to the PIE every two years in the first irradiation period to complete 30–50 dpa and every 4 years in the second irradiation period to reach 100 dpa.
Table 2 Number of testing machines for each experiment in the PIE Facility depending on the irradiation programme. Property
Option 1
Option 2
Option 3
Tensile, hardness, fracture toughness and charpy Fatigue Fatigue crack growth Stress crack corrosion Creep
1
1
1
8 8 8 4
12 12 0 6
34 34 0 17
should be tested at least at the same rate they are delivered to the PIE Facility. In option 1, 15 bundles should be tested in 6 years being each bundle composed of the specimens reported in Table 1. In option 2, 22 bundles each bundle being composed of only 40 specimens [2] should be tested in the same time. We are assuming that additional materials are not primary candidates and will not need to be tested immediately. The time required for each experiment can range in a very wide scale. Fatigue, creep and crack growth experiments can last up to several thousand hours while tensile or fracture toughness experiments may last a few hours. One testing machine for each of the short experiments – Static tensile, hardness, fracture toughness and charpy impact – would be enough to test all the specimens in around one year for any of the options described above. On the other hand time for long lasting experiments is spread in a logarithmic time scale. Fatigue experiments for example require 5 specimens to be tested during 1 h, 10 h, 102 h, 103 h and 104 h. The number of required testing machines will be determined by the longest one. Furthermore fatigue, crack growth and stress corrosion should be tested at the irradiation temperature and at room temperature. Creep should be measured only at irradiation temperature. Fatigue testing experiment is taken as an example in the analysis below. 5. PIE Facility testing machines 5.1. Option 1 According to the irradiation schedule described in option 1, 15 specimens (one per bundle) should be tested for 104 h and testing temperature. Three testing machines working in parallel would be able to finish 12 times 104 h tests in 56 months starting at the beginning of 5th year and finalizing before the end of 9th year. One more testing machine would be able to finish all the shorter (1–103 h) tests before the end of 6th year and then start the remaining three tests for the high temperature M-ODS specimens at the beginning of 7th year and finalizing before the end of 10th year. PIE for the 98 dpa specimens would start at the beginning of 11th year. With this schedule, four testing machines per temperature would be enough to finish all the PIE on 49 dpa specimens before the end of 10th year what is in agreement with the schedule approach in ref. [1] and [3,4]. Table 2 reports the required instrumentation in the PIE laboratories in this case. 5.2. Option 2 Option 2 irradiation schedule would deliver 22 bundles to the PIE Facility what means that two more testing machines would be required for each property and each testing temperature (see Table 2). Stress corrosion test is not included in this bundle configuration.
4. Discussion on the PIE workload
5.3. Option 3
For this discussion we assume that the accumulation of specimens should be avoided in the PIE Laboratories [6]. The specimens
In this case if the irradiation capsules are considered to be loaded as in option 2 (the most demanding case). 24 bundles from the
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ref-HFTM and 9 more from the HT-HFTM would be delivered to the PIE Facility every 4 years during the 50 dpa irradiation campaigns. The only way to avoid accumulation of specimens in the PIE Laboratories would be with 17 testing machines working in parallel per testing temperature (see Table 2). Very long lasting experiments – up to 105 h – for fatigue and creep could be recommended for the assessment of components lifetime. If these very long lasting experiments (around 12 years) were required 60 additional testing machines for fatigue and 30 testing machines for creep would be needed in the less demanding case (option 1) to test all the 50-dpa and 100-dpa specimens in parallel up to 105 h; otherwise the time for testing would be excessively long.In addition to the testing machines described in Table 2 several experimental setup will be required: laser profilometry on creep tubes, thermal conductivity, electrical conductivity, etc. The number of specimens to be tested in these cases will be low and only one experimental setup will be required in each case. 6. Conclusions Different irradiation matrices for IFMIF operation will impose different requirements to the PIE Facility in IFMIF. Some of these options and the consequences for the PIE Facility have been analyzed. Requirements for short experiments like tensile or fracture toughness are independent of the irradiation matrix. Number of testing machines for long lasting experiments like fatigue or crack growth depends very much on the irradiation matrix. For the three options analyzed in this paper the number of testing machines varies between 4 and 34 depending also on the desired number of
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testing temperature levels. 30 additional testing machines would be needed -even in the least demanding case- if very long lasting experiments (up to 105 h) were required. References [1] L. Cook, N. Taylor, D. Ward, L. Baker, T. Hender, Accelerated development of fusion power, UKAEA FUS 521 (2005). [2] A. Moeslang, Development of a Reference Test Matrix for IFMIF Test Modules, Final Report on the EFDA Task TW4-TTMI-003 D4, 2006. [3] P. Garin, E. Diegele, A. Moeslang, Y. Poitevin, R. Heidinger, A. Ibarra, et al., IFMIF Users Specifications and Proposals, BA D 224ERJ Report, March 2010. [4] P. Garin, E. Diegele, R. Heidinger, A. Ibarra, S. Jitsukawa, H. Kimura, et al., IFMIF specifications from the Users point of view, these proceedings. [5] Report on International Fusion Irradiation Facility, in: J.E. Leiss, K. Ehrlich, A.N. Goland, A. Miyahara, H. Ohno, P. Schiller (Eds.), Workshop, San Diego, USA, February 1989. [6] IFMIF-CDA Team, M. Martone (Ed.), Int.Fusion Materials Irradiation Facility—Conceptual Design Activity, Final Report, ENEA-Frascati Report RT/ERG/FUS/96/17, 1996. [7] K. Noda, K. Ehrlich, S. Jitsukawa, A. Moeslang, S. Zinkle, User’s requirements for IFMIF, Journal of Nuclear Materials 97 (1998) 258–263. [8] H. Nakamura, M. Ida, M. Sugimoto, M. Takeda, T. Yutani, H. Takeuchi (Eds.), IFMIF Key Element Technology Phase (KEP) report, JAERI-TECH 2003-005, 2003, http://jolissrch-inter.tokai-sc.jaea.go.jp/pdfdata/JAERI-Tech-2003-005.pdf. [9] IFMIF Comprehensive Design Report (CDR), IFMIF International Team, 2004, IEA online publication, http://www.iea.org/techno/technologies/fusion/IFMIFCDR PartA.pdf. [10] K. Ehrlich, A. Moeslang, IFMIF – an international fusion materials irradiation facility, Nuclear Instrumentation and Methods in Physics Research B 139 (1998) 72. [11] S. Ebara, S. Nagata, H. Irisa, T. Yokomine, A. Shimizu, Feasibly study on cast-like IFMIF HFTM, Fusion Engineering and Design 81 (2006) 887. [12] U. Fischer, Y. Chen, S.P. Simakov, P.P.H. Wilson, P. Vladimirov, F. Wasastjerna, Overview of recent progress in IFMIF neutronics, Fusion Engineering and Design 1195 (81) (2006).