Fuel retention in W as function of dpa level of radiation damage Task B. Tyburska

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 2 Motivation Neutron irradiation: Defect production new traps for tritium Transmutation effects Mechanical properties changes ITER divertor [1] Dpa (E th =90 eV [18]) 0.27 Neutron wall loading [MW/m 2 ] 0.4 Operation time [s] Temperature [K] Flux [(DT)/(m 2 s)]

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 3 Heavy ions as a surrogate for neutrons Large clusters, dense cascades Large energy transfer Lack of radioactivity Short implantation time–damage rate 10 4 higher Potential chemical composition changes–avoided by self- implantation Good temperature control–water cooling Low cost Peaked damage profile, short depth of penetration Difference in recoil spectra No transmutation effects

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 4 Defect morphology MethodNeutronW self-implantation FIM (Field Ion Microscopy) Vacancies (V), interstitials (I), vacancy clusters (VC), no voids [2-8] V, I, VCs, no voids [9-10] TEM (Transmission Electron Microscope) ? PA (Positron Annihilation) V, I, VCs, no voids [11-13] TDS (Thermal Desorption Spectroscopy) ~800 K- D desorption from the ion-induced defects (VCs) [14] Recovery temperature K [2-5] 1200 K [15-16]

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 5 1. experiment Material: Rolled W from Goodfellow, outgassed 1200 K, 2h D retention dependence on dpa (undamaged, damaged, and recovered W) : Number of traps produced by displacement damage NRA Characterization of ion-induced defects TDS Dpa value given at its peak, calculated for E th = 90 eV

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 6 Deuterium depth profiles

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 7 TDS spectra

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 8 Trapped concentration

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 9 Conclusions Deuterium depth profiles – D is trapped in irradiation-induced defects, with a trapped concentration ~1.3 %, – D concentration up to 6 m was saturated at 0.27 dpa, TDS measurements – D was trapped at the radiation-induced defects associated with peak at ~820K Effect of annealing – Annealing at 1200 K almost fully removes ion-induced defect. Deuterium depth profiles – D is trapped in irradiation-induced defects, with a trapped concentration ~1.3 %, – D concentration up to 6 m was saturated at 0.27 dpa, TDS measurements – D was trapped at the radiation-induced defects associated with peak at ~820K Effect of annealing – Annealing at 1200 K almost fully removes ion-induced defect.

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention experiment Material: Rolled W from Goodfellow, thick targets outgassed 1200 K, 2h D retention dependence on temperature: Number of traps produced by displacement damage NRA Dpa value given at its peak, calculated for E th = 90 eV

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 11 Deuterium depth profiles

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 12 Temperature dependence Front side: D plasma-defect synergetic effect

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 13 Prediction for Iter [17] Higher trap density but diffusion slower Max. T retention at ~500 K At higher temperatures T desorption and defect recovery lower the total T inventory

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 14 Current work and plans 1)Effective diffusion coefficient: Different W ion incident energies and fluences Deuterium fluences: D/m 2 = – D/m 2 2) D retention dependence on the post-annealing temperature– defects responsible for trapping Different W ion incident energies and fluences – flat damage profiles Post-annealing at different recovery temperatures D plasma exposure

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 15 Current work and plans 3) Transmutation effects: Investigation of the W samples containing Re Re implantation of W 4) D retention as a function of dpa – various materials: Goodfellow Iter grade Japanese Iter grade 5) TEM investigation of defects: ? 6) PALS investigations of the tungsten single crystal

, Garching, EU TF PWI Special Expert Working Groups on Gas balance and fuel retention 16 Literature [1]H.Iida at al., 2004 ITER Nuclear Analysis Report G 73 DDD 2 W 0 [2]L. K. Keys, J. Moteff, J. Nucl. Mater. 34 (1970) 260–280 [3]M. Attardo, J. M. Galligan, Phys. Stat. Sol 16 (1966) 449–457 [4]M. J. Attardo, J. M. Galligan, J. G. Y. Chow, Phys. Rev. Lett. 19 (1967) 73–74 [5]D. Jeannotte, J. M. Galligan, Phys. Rev. Lett. 19 (1967) 232–233 [6]L. K. Keys, J. P. Smith, J. Moteff, Phys. Rev. 176 (1968) 851–856 [7]T. Terao, Y. Hayashi, H. Yosida, Y. Yashiro, Scr. Metall. 12 (1978) 827–829 [8]K. Lacefield, J. Moteff, J. P. Smith, Philos. Mag. 13 (1966) 1079–1081 [9]A. F. Bobkov, V. T. Zabolotnyi, L. I. Ivanov, G. M. Kukavadze, N. A. Makhlin, A. L. Suvorov, Energ. 48 (1980) 326–327, translation to English and published by Springer, New York [10]K. L. Wilson, D. N. Seidman, NBS, Gaithersburg, in: Proc. Conf. on Defects and Defect Clusters in bcc Metals and Their Alloys. Ed. R. J. Arsenault, 216–239, 1973 [11]Z. Shengyun, X. Yongjun, W. Zhiqiang, Z. Yongnan, Z. Dongmei, D. Enpeng, Y. Daqing, M. Fukuda, M. Mihara, K. Matsuta, T. Minamisono, J. Nucl. Mater. 343 (2005) 330–332 [12]T. Troev, E. Popov, P. Staikov, N. Nankov, T. Yoshiie, Nucl. Instrum. Methods Phys. Res. B 267 (2009) 535–541 [13]B. Zgardzińska, B. Tyburska, Z. Surowiec, Proc. Conf. 39th Polish Seminar on Positron Annihilation, Mat. Sci. Forum, to be published [14] B. Tyburska, Ph.D. thesis, University of Maria Curie-Sklodowska, Lublin 2010 [15]B. Tyburska, V. Kh. Alimov, O. V. Ogorodnikova, K. Schmid, K Ertl, J. Nucl. Mater. 395 (2009) [16]B. M. Oliver, R. A. Causey, S. A. Maloy, J. Nucl. Mater (2004) 977–981 [17]O. V. Ogorodnikova, B. Tyburska, V. Alimov, K. Ertl, 19th PSI, San Diego 2010 [18]Standard Practice for Neutron Radiation Damage Simulation by Charge-Particle Irradiation, E521-96, Annual Book of ASTM Standards, Vol , American Society for Testing and Materials, Philadelphia, 1996, p. 1.