ML20069D008

Interim Deficiency Rept Re Apparent Accelerated Corrosion on Reactor Bldg Svc Water Pumps Mfg by Bingham-Willamette Co. Initially Reported on 820609.First & Second Stage Impellers Experienced Corrosion & Pitting

ML20069D008
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	07/16/1982
From:	Milligan M LONG ISLAND LIGHTING CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, SNRC-732, NUDOCS 8208020337
Download: ML20069D008 (3)

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1. ! LONG ISLAND LIGHTING COMPANY l - . SHOREHAM NUCLEAR POWER STATION

_ _ _ 3 P.O. SOX 618. NORTH COUNTRY ROAD e WAOING RIVER. N.Y.11792 July 16, 1982 SNRC-732 Mr. Ronald C. Haynes Office of Inspection & Enforcement Region I 631 Park Avenue King of Prussia, PA 19406 Lcug Island Lighting Co.

Shoreham Nuclear Power tion - Unit 1 O Docket No. O

Dear Mr. Haynes:

On June 9, 1982, in accordance with 10CFR 50.55 (e) , we reported verbally to Region I a potential deficiency concerning apparent accelerated corrosion which was evident on the Shoreham Reactor Building Service Water Pumps (RBSWP). This~ letter serves as our thirty-day written report on this deficiency.

Description of the Deficiency The four pumps which are of concern were manufactured by the Bingham-Willamette Company of Portland, Oregon and are identified i

as type 16X26C-VM-two stage.

These deep draft pumps, P41*P-003A, P41*P-003B, P41*P-003C and P41*P-003D, in the Reactor Building Service Water System, are O designed to provide cooling water for multiple plant safety related systems. A scheduled inspection of RBSWP "A", which was being performed by our Startup organization to inspect the installed pump shaft keys, revealed that both the first and second stage impellers, as well as various small parts, were experiencing extensive corrosion and pitting. Subsequent inspections of RBSWP "B, C & D" have indicated that the unaccep-table rates of corrosion are also occurring on these pumps.

Although none of these pumps were degraded to the point where j their performance was adversely affected, continuation of corrosion at the rates evidenced could have impacted the pumps' ability to adequately perform their safety related function.

Therefore, we have concluded that this situation constitutes a reportable deficiency under 10CFR50.55(e).

Detailed inspections of the RBSWPs have been conducted by vendor l representatives, Stone & Webster and LILCO pump, metallurgy and I

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l SNRC-732 July 16, 1982 Page 2 I

cathodic protection specialists. As a result of field inspec- ,

tions and subsequent evaluations, it was determined that there I were two poss *ble causes of the accelerated corrosion: improper l temper annealing of the affected metal, or galvanic or stray ,

electrical currents causing an accelerated cathodic / anodic reac-  !

tion to occur. Since those components which were found to be i extremely corroded comprised a range of materials, some of which did not require temper annealing, and metallurgical analysis has provided no indication of improper temper annealing, we have concluded that the primary corrosion mechanism appears to be galvanic action. l O Testing performed to detect galvanic activity has' shown the presence of a D.C. electrical current flowing from the Monal in the pump shaft to the aluminum-bronze pump casing. It appears while the pump is running, the pump shaft and impellers become ,

electrically isolated from the pump casing and the electrical current exits through the aluminum-bronze impeller, cap screws and plate, resulting-in galvanic corrosion of these components.

In addition, berillium-copper displays a galvanic dissimilarity from Monel and this would explain the corrosion ,found on the berillium-copper retaining rings. ,

Also, when the motor is running, an AC current was found to be traveling from the motor shaft across the coupling down the Monel pump shaft, which may have contributed to the galvanic activity

already present.

Corrective Action O At present, we are actively implementing modifications which we believe will eliminate this condition. The modifications can be summarized as follows:

1. Installation of a grounding system to electrically couple the rotating pump shaft to the pump casing. This will serve to significantly alter the surface area ratios of K-Monel (shaft) to aluminum-bronze (impeller and pump casing) and thus minimize the effects due to galvanic action.

2. All small components (cap screws and plate, retaining rings, etc.) which were found to be corroded will be replaced with K-Monel, which is galvanically compatible with the shaft.

3. The motor to pump coupling will be modified to isolate the pump shaft from any stray electrical currents from the motor, which could possible excite galvanic activity in the pump.

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SNRC-732 July 16, 1982 Page 3 The engineering necessary for the implementation of these modifi-cations is presently underway and it is anticipated that all modifications will be completed by the end of September, 1982.

If during the course of performing this work, it is determined that additional modifications are necessary, we will notify your office. If you have any questions relative to this matter, please do not hesitate to contact us.

Very truly yours,

_m M. H. Milligan

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Project Engineer Shoreham Nuclear Power Station .

t WMJ/ law cc: Mr. Richard DeYoung, Director .

NRC Office of Inspection & Enforcement '

DiviEion'~of" Reactor Operating Inspection Washington, D.C. 20555 Mr. J. Higgins, Site NRC All Parties O

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