Environmental Engineering Reference
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(a)
Zry-2 Channel, 43 MWd/kgU
Oxide
20
μ
m
In shadow area
120
μ
m, 150 ppm H
2
(b)
Oxide
20
μ
m
Away from shadow area
20
μ
m, 300 ppm H
2
4.46
Zirconium oxides (a) away from and (b) near a stainless steel
control blade bundle (Adamson
et al
., 2000).
dissolution during irradiation. This was noted by Cheng and Adamson
(1987) and then by Yang and Adamson (1989), in reference to thick uni-
form oxide observed in welded regions of Zircaloy-4 having totally dis-
solved SPPs. A clear correlation between SPP size and increased corrosion
at high fl uence was given by Garzarolli
et al
. (1994) (Fig. 4.47) where it was
shown that 'small SPP sizes' resulted in relatively thick corrosion fi lms after
3 or 4 cycles in-reactor but not after 1 or 2 cycles. Huang
et al
. ( 1996 ) showed
that when SPPs virtually 'disappeared' (within the resolution of STEM at
that time) corrosion increased, as did hydrogen pickup. Similar results were
reported by T ä gtstr ö m
et al
. ( 2002 ), Takagawa
et al
. ( 2004 ) and Ishimoto
et al
. (2006). It is clear that loss of SPPs affects corrosion performance, and
even earlier in fl uence, hydrogen pickup.
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