ML102500614
| ML102500614 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 09/07/2010 |
| From: | Electric Power Research Institute |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| Shared Package | |
| ML102500610 | List: |
| References | |
| 50-282-LR, 50-306-LR, ASLBP 08-871-01-LR-BD01, RAS 18571 | |
| Download: ML102500614 (3) | |
Text
NRC000001 Boric Acid Corrosion Guidebook, Revision 1 Managing Boric Acid Corrosion Issues at PWR Power Stations WARNING:
Please read the License Agreement on the back cover before removing the Wrapping Material.
Effective December 6. 2006. this report has been made publicly available in accordance with Section 734.3(b)(3) and published in accordance with Section 734.7 the U.S. Export Administration Regulations. As a result of this publication, this is subject to only copyright protection and does not require any license from EPRI. This notice supersedes the export control restrictions and any proprietary licensed material notices embedded in the document prior to publication.
Technical Report
NRC000001 EPRI Licensed Material Boric Acid Corrosion Tests Test Ref.:
A Test Type:
Immersion Aerated and Deaerated Boric Acid Org/Date:
Westinghouse (1967)
References:
"Materials Behavior Related Issues for Bolting Applications in the Nuclear Industry." Conference: Improved Technology for Critical Bolting Applications, Chicago, Ill., July 20-24, 1986. MPC-Vol. 26 [22].
Absorption o/Corrosion Hydrogen by 302B Steel at 70F to 500F.
Westinghouse Electric Corporation, 1967, WCAP-7099 [23].
Test Configuration, Procedure, and Results Westinghouse conducted a series of tests on electrically isolated coupons of A-302 Grade B low-alloy steel in both aerated and deaerated environments. Some experiments involved cases where the low-alloy steel test coupons were coupled to 304 stainless steel. Tests were conducted at 2500 ppm boron at several different temperatures.
Table 4-3 gives the average corrosion rate for long periods of time (40-160 days) for each of the test conditions. The test results plotted in Figure 4-8 show the effect of test duration.
Table 4-3 Average Corrosion Rates in Aerated and Oeaerated Water - Westinghouse Tests Temperature in Corrosion Rate Oeaerated in Corrosion Rate Aerated in OF eC)
IncheslYear (mm/yr)
IncheslYear (mm/yr)
Isolated Coupled to 304 Isolated Coupled to 304 70 (21) 0.0002 (0.005) 0.002 (0.05) 0.002 (0.05) 100 (38) 0.00005 (0.0013) 0.00005 (0.0013) 0.007 (0.18) 0.007 (0.18) 140 (60) 0.00007 (0.0018) 0.00011 (0.0028) 0.015 (0.38) 0.015 (0.38) 500* (260) 0.24 (6.1)
- Provided at meeting with Westinghouse.
Key observations from these tests are:
In deaerated water at temperatures less than 140°F (60°C), the corrosion rates are very low.
In aerated water, the corrosion rates increase with temperature from 70°F to 140°F (21°C to 60°C) with the long-term corrosion rate at 140°F (60°C) being about 0.0 IS in/yr (0.38 mrnlyr).
The galvanic couple between low-alloy steel and stainless steel has little effect on the corrosion rates of low-alloy steel in borated water.
4-25
EPRI Licensed Material Boric Acid Corrosion Tests Initial corrosion rates can be much higher than long-term corrosion rates.
The corrosion rate in aerated borated water at 500°F (260°C) is 0.24 inlyr (6.1 mdyr).
Conclusions Corrosion rates in low-temperature deaerated water are very low. Corrosion rates in aerated water at temperatures less than 140°F (60°C) are acceptably low to not pose a serious problem with leakage of borated water.
o A3028 Isolated Coupons A3029 Coupled to 304SS ACJO A3028 Isolated Coupons 1
A3028 Coupled to 304SS I
I Test lime, Days Test lime. Days Corrosion as measured in weight loss of A3026 in air-saturated borlc acid solution containing 2500 pprn boron Corrosion as A3028 in deaerated boric acid solution containing 2500 ppm boron Figure 4-8 Corrosion Rate in Aerated and Deaerated Water - Westinghouse Tests [22]
NRC000001 EPRI Licensed Material Boric Acid Corrosion Tests Initial corrosion rates can be much higher than long-term corrosion rates.
The corrosion rate in aerated borated water at 500 0 P (260°C) is 0.24 inlyr (6.1 mrnlyr).
Conclusions Corrosion rates in low-temperature de aerated water are very low. Corrosion rates in aerated water at temperatures less than 1400 P (60°C) are acceptably low to not pose a serious problem with leakage of borated water.
N E
~
E c:-
.2 CI) g
° U
18000 16000 14000 12000 10000 8000 6000 4000 o A302B Isolated Coupons
- A302B Coupled to 30488 2000 21 'C ~ 4.77 X 10" mm/yr (70'F ~ 0.002 In/yr) o~~~=
o 20 40 60 80 100 120 140 160 Test Time, Days Corrosion as measured in wei~ht loss of A302B in air-saturated bOriC acid solution containing 2500 ppm boron Figure 4-8 E
~
E c'
.g
'" g
° U
200 ACO A3028 Isolated Coupons 180
.... A3028 Coupled to 30488 160 140 120 i\\\\
!.~
100 1-
,r;)
80 60 40 A
O~--~~~--~--~--~--~ __ ~~
o 20 40 60 80 100 120 140 160 Test Time. Days Corrosion as A3028 in deaerated boric acid solution containing 2500 ppm boron Corrosion Rate in Aerated and Deaerated Water - Westinghouse Tests [22) 4-26