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

19.07.2010, 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 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

19.07.2010, Garching, EU TF PWI Special Expert Working Groups on “Gas balance and fuel retention 4

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]

19.07.2010, 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 Eth = 90 eV

19.07.2010, Garching, EU TF PWI Special Expert Working Groups on “Gas balance and fuel retention 6

Deuterium depth profiles

19.07.2010, Garching, EU TF PWI Special Expert Working Groups on “Gas balance and fuel retention 7

TDS spectra

19.07.2010, Garching, EU TF PWI Special Expert Working Groups on “Gas balance and fuel retention 8

Trapped concentration

19.07.2010, 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.

19.07.2010, Garching, EU TF PWI Special Expert Working Groups on “Gas balance and fuel retention 10

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

19.07.2010, Garching, EU TF PWI Special Expert Working Groups on “Gas balance and fuel retention 11

Deuterium depth profiles

19.07.2010, Garching, EU TF PWI Special Expert Working Groups on “Gas balance and fuel retention 12

Temperature dependence

Front side: D plasma-defect synergetic effect

19.07.2010, 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

19.07.2010, 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: 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

19.07.2010, 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

19.07.2010, 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

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[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.