Determining factors for anodic polarization curves of typical structural materials of boiling water reactors in high temperature – high purity water

Figures & data

Table 1. Shapes and sizes of WEs.

#	Materials	Shapes	Sizes* (mm)
1	Platinum	Wire	Φ 0.5
2	316L SS	Wire	Φ 0.5
3	Alloy 182	Rod	0.5 × 0.5 × 20
4	Fe	Wire	Φ 0.5
5	Cr	Rod	0.5 × 0.5 × 20
6	Ni	Wire	Φ 0.5
Note: *Exposed surface area of all Wes was set at 0.1 cm^2.

Table 2. Chemical compositions (wt%) of WEs.

Material	C	Cr	Mn	S	P	Si	Mo	Cu	Nb + Ta	Ni	Fe	Specifications
316L SS	0.021	16.88	1.40	0.001	0.027	0.36	2.13	–	–	11.24	Bal.	SAE J 405
Alloy 182	0.043	15.94	3.12	0.003	<0.005	0.21	–	0.02	1.63	Bal.	10.79	JIS Z 3224

Figure 1. Impedance response described by the Nyquist diagram when measured using an inert WE.

Figure 2. Measured anodic polarization curves of type 316L SS, Alloy 182 and type 304 SS [1] in deaerated high temperature – high purity water.

Table 3. Characteristic parameters of anodic polarization curves of typical structural material of BWRs.

#	Parameter	Unit	Material
			304 SS [1]	316L SS	Alloy 182
1	E corr	Vvs.SHE	−0.46	−0.43	−0.44
2	E pp	Vvs.SHE	−0.36	−0.34	−0.43
3	i crit	μA·cm^−2	5.0	2.8	0.7
4	E cp	Vvs.SHE	−0.27	−0.27	−0.43
5	i ps	μA·cm^−2	1.0	0.5	0.7
6	E tp	Vvs.SHE	−0.15	0.00	−0.09

Figure 3. Measured anodic polarization curves of Fe, Cr, and Ni in deaerated high temperature – high purity water with thermodynamically stable species of Fe, Cr, and Ni.

Figure 4. Effects of sulfuric acid on anodic polarization curves of typical BWR structural materials.

Figure 5. Governing elements of anodic polarization curve of 316L SS for (a) active state, (b) passive state, and (c) transpassive state.

Table 4. The stable chemical species of Fe, Cr, and Ni in each region of both SSs.

	(a)	(b)	(c)
RegionState	Active state	Passive state	Transpassive state
Fe	Fe2O3	Fe2O3	Fe2O3
Cr	Cr2O3, Cr(OH)3	Cr2O3, Cr(OH)3	Cr2O7 ^2−
Ni	NiO	NiO	NiO

Figure 6. Governing elements of anodic polarization curve of Alloy 182 for (a) passive state and (b) transpassive state.

Table 5. The stable chemical species of Fe, Cr, and Ni in each region of Alloy 182.

Region	(a)	(b)
State	Passive state	Transpassive state
Fe	Fe2O3	Fe2O3
Cr	Cr2O3, Cr(OH)3	Cr2O7 ^2−
Ni	NiO	NiO