Fuel retention in W as function of dpa level of radiation damage Task 01-08 B. Tyburska

Fuel retention in W as function of dpa level of radiation damage

Task 01-08

B. Tyburska

19.07.2010, 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 (Eth=90 eV [18]) 0.27

Neutron wall loading [MW/m2] 0.4

Operation time [s] 2107

Temperature [K] 500-1200

Flux [(DT)/(m2s)] 1020-1022

CW C

Be

WW

CW C

Be

CW C

Be

WW


Heavy ions as a surrogate for neutrons

Large clusters, dense cascades Large energy transfer Lack of radioactivity Short implantation time–damage rate 104 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


Defect morphology

Method Neutron W self-implantationFIMFIM(Field Ion Microscopy)

Vacancies (V), interstitials (I), vacancy clusters (VC), no voids[2-8]

V, I, VCs, no voids

[9-10]

TEMTEM(Transmission Electron Microscope)

― ?

PAPA(Positron Annihilation)

―V, I, VCs, no voids[11-13]

TDSTDS(Thermal Desorption Spectroscopy)

―~800 K- D desorption from the ion-induced defects (VCs) [14]

Recovery temperature 1200-1350 K [2-5] 1200 K [15-

16]


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 Eth = 90 eV


Deuterium depth profiles


TDS spectra


Trapped concentration


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.


2. 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 Eth = 90 eV


Deuterium depth profiles


Temperature dependence

Front side: D plasma-defect synergetic effect


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


Current work and plans

1) Effective diffusion coefficient:

Different W ion incident energies and fluences

Deuterium fluences: 1023-51026 D/m2

= 1023–51026 D/m2

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


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


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) 150-155

[16] B. M. Oliver, R. A. Causey, S. A. Maloy, J. Nucl. Mater. 329-333 (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. 12.02, American Society for Testing and Materials, Philadelphia, 1996, p. 1.

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Fuel retention in W as function of dpa level of radiation damage Task 01-08 B. Tyburska