ML102500614

NRC000001-Boric Acid Corrosion Guidebook, Revision 1

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: ML102500612 ML102500614 ML102500615 ML102500616 ML102500617 ML102500618 ML102500619 ML102500620
References
50-282-LR, 50-306-LR, ASLBP 08-871-01-LR-BD01, RAS 18571
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Text

NRC000001 Boric Acid Corrosion Guidebook, Revision 1 Managing Boric Acid Corrosion Issues at PWR Power Stations 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 WARNING: from EPRI. This notice supersedes the export control restrictions and any Please read the License Agreement proprietary licensed material notices embedded in the document prior to publication.

on the back cover before removing the Wrapping Material.

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

NRC000001 EPRI Licensed Licensed Material Corrosion Tests Boric Acid Corrosion Tests

• corrosion rates Initial corrosion rates cancan be much higher than long-term corrosion corrosion rates.

rates.

• The corrosion The corrosion rate rate in aerated aerated borated water at 500 500°F 0 (260°C) is P (260°C) is 0.24 0.24 inlyr (6.1 (6.1 mrnlyr).

mdyr).

Conclusions Conclusions Corrosion rates in low-temperature de deaerated aerated water are are very low.

low. Corrosion rates rates in aerated water at temperatures less than 140 140°F 0

(60°C) are P (60°C) are acceptably low to not pose a serious serious problem with leakage of borated water. water.

18000 200 oo A302B A3028 Isolated Coupons Isolated Coupons Coupons Isolated Coupons ACJO A3028 Isolated ACO 1 16000 A3029 Coupled to

• A302B to 30488 304SS 180 .... A3028 A3028 Coupled toto 30488 304SS I I

14000 160 12000 140 N

E E

~ ~

E 10000 E 120 c:- c'

.g

.2 i\\

g'"

CI) g 8000 100

!.~

,r;)

U° U° 1-6000 80 4000 60 21 'C ~ 4.77 X 10" mm/yr 2000 (70'F ~ 0.002 In/yr) 40 A o~~~=

o 20 40 60 80 100 120 140 160 O~--~~~--~--~--~--~

o 20 40 60 80 100 120

__ ~~

140 160 lime, Days Test Time, Days lime. Days Test Time. Days Corrosion as measured Corrosion measured in in wei~ht weight loss loss Corrosion as A3028 in Corrosion in deaerated deaerated of A3026 A302B in in air-saturated air-saturated bOriCborlc acid acid boric boric acid acid solution solution containing containing solution containing solution containing 2500 ppm pprn boron boron 2500 ppm ppm boron boron Figure 4-8 Corrosion Rate in Aerated and Deaerated Deaerated Water - - Westinghouse Tests [22] [22) 4-26