9.5 Fuel Retention in Tungsten (W)
175
Depth/ m
~10 -5
H/W
0.1
H +
Recrystallized
regions
H 2
Hydrogen
saturated zone
Original
structure
Fully saturated
Grain surface
saturated
Penetraon by diffusion
+ grain boundary diffusion
and trapping by intrinsic defects,
impuries and grain boundaries
Blistering
by accumulaon of bubbles by exfoliaon of grain boundaries
Fig. 9.8 Schematic drawing for retention of H injected in W. Top surface and subsurface are
saturated with H. A few to several μm from the top surface should be recrystallized owing to highpower load, and surface and subsurface regions should be saturated with H. Hydrogen diffuses into
bulk to make exponentially decaying concentration profile and without appreciable grain boundary
diffusion
Fig. 9.9 Schematic depth
profile of H injected into W
with estimated areal or
volume densities [20] based
on Fig. 9.8
10 18
10 22
H atoms /cm 3
10 19
10 20
10 17
H atoms /m 2 /nm
10 16
10 19
10 21
10 18
10 15
10 17
10 23
10 20
aμP
aPP
10 24
~ 2 x 10 23 /m 2
Dissolved within 10mm
~ 5 x 10 23 /m 2
Trapped in near surface
10 22
H/W
1.0
10 -3
10 -6
a[ P
0RQR/D\HU
10 25
N-irradiation
enhance this part
~ 0.1