Information Notice 1994-63, Boric Acid Corrosion of Charging Pump Casing Caused by Cladding Cracks
- 7'Q
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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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>
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Attachment 1
August 30, 1994 PACIFIC PUMP
SHOP ORDER
B46-617 B46-617 B46-617 B46-617 B46-617 B46-617 B46-617 B46-617 B46-617 B46-617 B47-096 B47-096 B47-096 B47-096 B47-096 B47-096 SERIAL NO.
45603/04
45605/06
45607/08
45609/10
45611/12
45613/14
45615/16
45617/18
45619/20
45621/22
46352/53
46354/55/56
46357/58/59
46360/61
46362/63/64
46365/66/67 USER
Public Service Electric
& Gas
Electric Co.
Electric Co.
Commonwealth Edison Co.
Pacific Gas & Electric
Co.
Public Service Electric
& Gas
Commonwealth Edison Co.
Pacific Gas & Electric
Co.
Tennessee Valley
Authority
Tennessee Valley
Authori .y
Duquesne Light Co.
Southern Nuclear Co.
Virginia Electric and
Power Co.
Portland General
Electric Co.
Virginia Electric and
Power Co.
Kansai Electric &
Power Co.
Salem #1 D.C. Cook #1 D.C. Cook #2 Zion #2 Diablo Canyon #1 Salem #2 Zion #1 Diablo Canyon #2 Sequoyah #1 Sequoyah #2 Beaver Valley #1 J. M. Farley #1 North Anna #1 Trojan
North Anna #2 Takahama #1
Attachment 2
August 30, 1994 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
94-62
94-61
94-60
94-30,
Supp. 1
94-59
Operational Experience
on Steam Generator Tube
Leaks and Tube Ruptures
Corrosion of William
Powell Gate Valve Disc
Holders
Potential Overpressuriza- tion of Main Steam System
Leaking Shutdown Cooling
Isolation Valves at
Cooper Nuclear Station
Accelerated Dealloying of
Cast Aluminum-Bronze
Valves Caused by Micro- biologically Induced
Corrosion
Reactor Coolant Pump
Lube Oil Fire
Debris in Containment
and the Residual Heat
Removal System
Inaccuracy of Safety Valve
Set Pressure Determinations
Using Assist Devices
Problems with Copes-
Vulcan Pressurizer
Power-Operated Relief
Valves
08/30/94
08/25/94
08/22/94
08/19/94
08/17/94
08/16/94
08/12/94
08/11/94
08/04/94
All holders of OLs or CPs
for pressurized water
reactors.
All holders of OLs or CPs
for nuclear power reactors.
All holders of OLs or CPs
for pressurized-water
reactors.
All holders of OLs or CPs
for nuclear power reactors.
All holders of OLs or CPs
for nuclear power reactors.
All holders of OLs or CPs
for pressurized water
reactors.
All holders of OLs or CPs
for nuclear power reactors.
All holders of OLs or CPs
for nuclear power reactors.
All holders of OLs or CPs
for nuclear power reactors.
94-58
94-57
94-56
94-55 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
j
DTaylor
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
1 I
/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 nson
W
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
_