Information Notice 1994-63, Boric Acid Corrosion of Charging Pump Casing Caused by Cladding Cracks

Boric Acid Corrosion of Charging Pump Casing Caused by Cladding Cracks

ML031060393
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	08/30/1994
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
IN-94-063, NUDOCS 9408240172
Download: ML031060393 (10)

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 30, 1994 NRC INFORMATION NOTICE 94-63: BORIC ACID CORROSION OF CHARGING PUMP CASING

CAUSED BY CLADDING CRACKS

Addressees

All holders of operating licenses or construction permits for pressurized

water reactors.

Purgose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information

notice to alert addressees to the potential for significant damage that could

result from corrosion of reactor system components caused by cracking of the

stainless steel cladding. It is expected that recipients will review the

information for applicability to their facilities and consider actions, as

appropriate, to avoid similar problems. However, suggestions contained in

this information notice are not NRC requirements; therefore, no specific

action or written response is required.

Description of Circumstances

During July and August 1993 the Virginia Electric Power Company discovered

severe corrosion damage of the carbon steel casing of a high head safety

injection pump at North Anna Unit 1. The damage was caused by cracks through

the stainless steel cladding in the pump that allowed corrosive attack by the

boric acid coolant. The cracks were discovered when the pump was disassembled

for maintenance and rust was observed on the otherwise shiny surface of the

cladding in the discharge section of the pump.

When the licensee ground out the cracked ar'ea to repair the pump by welding, it discovered that the boric acid corrosion had penetrated to within about

3 mm [0.125 inch] of the outside surface of the pump. The licensee then

ground out the corroded material, producing a cavity that was approximately

64 mm long by 38 mm wide by 13 mm deep [2.5 by 1.5 by 0.5 inches].

Discussion

The damaged pump, designated the IC pump, is one of three such pumps designed

for both emergency high head safety injection and normal charging to the

reactor vessel of each North Anna unit. In September 1989, the licensee

discovered cladding cracking in the suction section of the Un 1 A pump.

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9408240172 Y//e o9

IN 93-63 August 30, 1994 This cracking resulted in boric acid attack of the carbon steel base metal.

However, the extent of the damage is not known for this pump because the

licensee replaced the pump casing with an all stainless steel casing and did

not make a detailed examination of the old casing. In August 1993, the

licensee inspected the Unit 1 B charging pump cladding but did not discover

any deterioration in this pump.

The discovery of cladding cracks in the iC charging pump prompted the licensee

to visually inspect the remaining stainless steel clad charging pumps at North

Anna. In January 1994, the licensee found eight cracks that extended through

the cladding of the Unit 2 B charging pump. Six were located in the pump

suction section and two in the pump discharge section. Although the licensee

did not measure the damaged volume of the base metal, rust on the surface of

the stainless steel cladding indicated that base metal corrosion attack had

occurred. After an unsuccessful attempt to repair the 2B charging pump

casing, the licensee replaced it with one made entirely of stainless steel.

In May 1994, the licensee found numerous cracks through the cladding of the

end of the Unit 2 A charging pump. The licensee also found a large hole

(approximately 2.5 cm [1 inch] in diameter) through the cladding in the

discharge end of the pump. The licensee decided that repairing the 2A

charging pump casing was not practical and replaced the casing with one made

of solid stainless steel.

Corrosive attack by boric acid coolant resulting from small cracks in charging

pump cladding generally proceeds relatively slowly due, apparently, to the low

temperature of the charging coolant. However, as the experience discussed in

this notice shows, such attack can eventually lead to significant thinning of

the pump casing and possibly substantial leakage. Since these pumps are

normally relied on for high head emergency injection, as well as normal

charging, this type of attack, if not identified, could eventually result in

the inability of the pump to perform a vital safety function in an emergency.

This experience also shows that the corrosion of the base metal due to

cladding cracks is usually relatively easy to identify through visual

inspection.

Related Generic Communications

On October 29, 1980, NRC issued Information Notice 80-38, "Cracking in

Charging Pump Casing Cladding", in which it discussed cracking at the

transition between the pump casing barrel and the pump suction end plate in a

Zion Unit 1 charging pump. The cracking allowed localized boric acid attack

in the base metal to a maximum depth of 1.6 mm [0.0625 inch]. The Zion

licensee replaced this pump with one that had a solid stainless steel casing.

In June 1983, the Pacific Pump Division of Dresser Industries (the vendor)

issued procedure bulletin 037-0-0104-0 listing its pumps constructed with

cladding and suggesting methods for field inspection of the pumps. A list of

nuclear power plants with these pumps is attached.

IN 93-63 August 30, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director 4 Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: John York, RII

(404) 331-5536 Don Taylor, RII

(703) 894-5421 Attachments:

1. List of Power Plants with Pumps Identified by Dresser

2. List of Recently Issued NRC Information Notices

~A/61 f> f

I

Attachment 1 IN 94-63 August 30, 1994 PACIFIC PUMP

SHOP ORDER SERIAL NO. USER

B46-617 45603/04 Public Service Electric

& Gas Salem #1 B46-617 45605/06 Indiana & Michigan

Electric Co. D.C. Cook #1 B46-617 45607/08 Indiana & Michigan

Electric Co. D.C. Cook #2 B46-617 45609/10 Commonwealth Edison Co. Zion #2 B46-617 45611/12 Pacific Gas & Electric

Co. Diablo Canyon #1 B46-617 45613/14 Public Service Electric

& Gas Salem #2 B46-617 45615/16 Commonwealth Edison Co. Zion #1 B46-617 45617/18 Pacific Gas & Electric

Co. Diablo Canyon #2 B46-617 45619/20 Tennessee Valley

Authority Sequoyah #1 B46-617 45621/22 Tennessee Valley

Authori .y Sequoyah #2 B47-096 46352/53 Duquesne Light Co. Beaver Valley #1 B47-096 46354/55/56 Southern Nuclear Co. J. M. Farley #1 B47-096 46357/58/59 Virginia Electric and

Power Co. North Anna #1 B47-096 46360/61 Portland General

Electric Co. Trojan

B47-096 46362/63/64 Virginia Electric and

Power Co. North Anna #2 B47-096 46365/66/67 Kansai Electric &

Power Co. Takahama #1

Attachment 2 IN 94-63 August 30, 1994 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

94-62 Operational Experience 08/30/94 All holders of OLs or CPs

on Steam Generator Tube for pressurized water

Leaks and Tube Ruptures reactors.

94-61 Corrosion of William 08/25/94 All holders of OLs or CPs

Powell Gate Valve Disc for nuclear power reactors.

Holders

94-60 Potential Overpressuriza- 08/22/94 All holders of OLs or CPs

tion of Main Steam System for pressurized-water

reactors.

94-30, Leaking Shutdown Cooling 08/19/94 Supp. 1 All holders of OLs or CPs

Isolation Valves at for nuclear power reactors.

Cooper Nuclear Station

94-59 Accelerated Dealloying of 08/17/94 All holders of OLs or CPs

Cast Aluminum-Bronze for nuclear power reactors.

Valves Caused by Micro- biologically Induced

Corrosion

94-58 Reactor Coolant Pump 08/16/94 All holders of OLs or CPs

Lube Oil Fire for pressurized water

reactors.

94-57 Debris in Containment 08/12/94 All holders of OLs or CPs

and the Residual Heat for nuclear power reactors.

Removal System

94-56 Inaccuracy of Safety Valve 08/11/94 All holders of OLs or CPs

Set Pressure Determinations for nuclear power reactors.

Using Assist Devices

94-55 Problems with Copes- 08/04/94 All holders of OLs or CPs

Vulcan Pressurizer for nuclear power reactors.

Power-Operated Relief

Valves

OL Operating License

CP = Construction Permit

IN 93-63 August 30, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

(one of) the technical contact(s) listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

orig /s/'d by CIGrimes/for

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: John York, RII

(404) 331-5536 Don Taylor, RII

(703) 894-5421 Attachments:

1. List of Power Plants with Pumps Identified by Dresser

2. List of Recently Issued NRC Information Notices

• SFF PREVIOUS CONCURRENCE

OFFICE *OGCB:DORS *DFIPS:ADM *C/EMCB:NRR *DRP:RII *R:RII

NAME DKirkpatrick JMain JStrosnider JYork DTaylor

DATE 07/07/94 07/13/94 07/27/94 08/08/94 08/08/94 OFFICE *AD/DRP:RII *C/OGCB:NRR D/DORS:NRR

NAME JJohnson EDoolittle BGrimesrb

DATE 08/08/94 08/15/94 08/7A794 I_

DOCUMENT NAME: 94-WA.1N

IN 93-xx

August xx, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

(one of) the technical contact(s) listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: John York, RII

(404) 331-5536 Don Taylor, RII

(703) 894-5421 Attachments:

1. List of Power Plants with Pumps Identified by Dresser

2. List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCE

OFFICE *OGCB:DORS *DFIPS:ADM *C/EMCB:NRR *DRP:RII *R:RII

NAME DKirkpatrick JMain JStrosnider JYork jDTaylor

DATE 07/07/94 07/13/94 07/27/94 08/08/94 j 08/08/94 OFFICE *AD/DRP:RII *C/OGCB:NRR D/DORS: NR _ _

NAME JJohnson EDoolittle BGrime_ _ _

DATE 08/08/94 08/15/94 082 /94 _

DOCUMENT NAME: CRACKCP.IN

IN 93-xx

August xx, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

(one of) the technical contact(s) listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: John York, R11

(404) 331-5536 Don Taylor, RII

(703) 894-5421 Attachments: 1. List of power plants with pumps identified by Dresser

2. List of Recently Issued NRC Information Notices

• FF PRFVTIOS CONCURRENCE

OFFICE *OGCB:DORS *DFIPS:ADM *C/EMCB:NRR *DRP:RII *R:RII

NAME DKirkpatrick JMain JStrosnider JYork DTaylor

DATE 07/07/94 07/13/94 07/27/94 08/08/94 08/08/94 OFFICE *AD/DRP:RII C :NRR D/DORS:NRR

NAME JJohnson I itle BGrimes

DATE 08/08/94 1I /94 08/ /94 DOCUMENT NAME: CRACKCP.IN tAd VO

. 1.

Related Generic Communications

Information Notice number 80-38, titled "Cracking in Charging Pump Casing

Cladding", was issued on October 29, 1980. This notite discussed cracking

that had occurred in a Zion Unit 1 charging pump at the transition between the

pump casing barrel and the pump suction end plate. The cracking allowed

localized boric acid attack in the base metal that extended to a maximum depth

of 1.6 mm [1/16 inch]. The licensee replaced this pump with a one that had a

solid stainless steel casing.

In June, 1983, the Pacific Pump Division of Dresser Industries, the vendor, issued a procedure bulletin (designated No 037-0-0104-0) identifying their

pumps that were constructed with cladding and suggesting methods for field

inspection of the pumps. A list of nuclear power plants with these pumps is

attached.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

(one of) the technical contact(s) listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: John York, RII

(404) 331-4198 Don Taylor, RII

(703) 894-5421 Attachments: 1. List of power plants with pumps identified by Dresser

2. List of Recently Issued NRC Information Notices

OFFICE OGCB:DORS DFIPS:ADM C/EMCB:NRR I P II R:RII

NAME DKirkpatrick JMain JStrosnider JYot'I4 DTaylorA PA

DATE 07/ /94 j07/ /94 j07/ /94 .1 /8 /94/

OFFICE AD/D P:RII X C/OGCB:NRR D/DORS:NRR

NAME JJo nsonW Dool ittle BGrimes

DATE OJ/C 94 07/ /94 07/ /94

I I 11 Related Generic Communications

Information Notice number 80-38, titled "Cracking in Charging Pump Casing

Cladding", was issued on October 29, 1980. This notice discussed cracking

that had occurred in a Zion Unit 1 charging pump at the transition between the

pump casing barrel and the pump suction end plate. The cracking allowed

localized boric acid attack in the base metal that extended to a maximum depth

of 1.6 mm [1/16 inch]. The licensee replaced this pump with a one that had a

solid stainless steel casing.

In June, 1983, the Pacific Pump Division of Dresser Industries, the vendor, issued a procedure bulletin (designated No 037-0-0104-0) identifying their

pumps that were constructed with cladding and suggesting methods for field

inspection of the pumps. A list of nuclear power plants with these pumps is

attached.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

(one of) the technical contact(s) listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: John York, RII

(404) 331-4198 Don Taylor, RII

(703) 894-5421 Attachments: 1. List of power plants with pumps identified by Dresser

2. List of Recently Issued NRC Information Notices

OFFICE OGCB:DORS DFIPS:ADM DRP:RII R:RII

NAME DKirkpatrick JMain JYork DTaylor

DATE 07/1/94Uoi St 07H/?/94 07 r/9 07/ /94 107/ /94 OFFICE AD/DRP:RII C/OGCB:NRR D/DORS:NRR

NAME JJohnson EDoolittle BGrimes

DATE 07/ /94 107/ /94 107/ /94 _ 1_