Investigation of cobalt buildup behavior and suppression by zinc injection on stainless steel under HWC conditions using simultaneous continuous measurements of corrosion and cobalt buildup

Figures & data

Figure 1. Schematic drawing of immersion test apparatus.

Table 1. Water chemistry conditions.

Components	Without Zn	In the presence of Zn
O2	<5 μg kg^−1
H2	50 μg kg^−1
Zn	0 μg kg^−1	5 μg kg^−1
Co	0.1 μg kg^−1
^60Co	6.7 Bq kg^−1

Figure 2. Schematic drawing of PDM part.

Table 2. Parameters of PDM system.

Applied current	1 mA
Resistivity of 316 SS	1.17 × 10^−2 Ω m
Collection time	0.5 s
Repetition number	50
Measurement interval	10 min

Figure 3. Schematic drawing of T.P. part.

Figure 4. Comparison of corrosion amounts for (a) the entire immersion time and (b) initial 50 h.

Table 3. Total amounts of metals and oxygen, and amounts of Zn and ⁶⁰Co in each separated layer.

	Outer layer			Inner layer
	Total	Zn	^60Co	Total	Zn	^60Co
Conditions	(μg m^−2)	(μg m^−2)	(MBq m^−2)	(μg m^−2)	(μg m^−2)	(MBq m^−2)
Without Zn	1321	0	0.19	1343	0	0.39
In the presence of Zn	615	41	0.16	944	49	0.03

Figure 5. SEM images of surface and cross section of test pieces after 500-h immersion.

Figure 6. Comparison of ⁶⁰Co buildup amounts for (a) the entire immersion time and (b) initial 50 h.

Figure 7. Comparison of measured ⁶⁰Co buildup amounts and amounts calculated using the equations (immersion without Zn).

Figure 8. Comparison of measured ⁶⁰Co buildup amounts and amounts calculated using the equations (immersion in the presence of Zn).