Information Notice 1989-08, Pump Damage Caused by Low-Flow Operation
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
January 26, 1989
NRC INFORMATION NOTICE NO. 89-08:
PUMP DAMAGE CAUSED BY LOW-FLOW OPERATION
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
This information notice is being provided to alert addressees to potential
problems that may result from operation of centrifugal pumps at flows that
can cause severe pump component damage. 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 do not constitute NRC requirements;
therefore, no specific action or written response is required.
Description of Circumstances
Two events which resulted in pump damage are described below.
Operations for
extended periods at low-flow conditions apparently created hydraulic instability, resulting in pump damage from cavitation, pressure pulsation, and/or vibration.
These events occurred at the Haddam Neck Plant and Susquehanna Steam Electric
Station, Unit 1 (Susquehanna 1).
The pump damage at the Haddam Neck plant was
attributed to pressure pulsation and pump vibration, while at Susquehanna 1 it
was the result of cavitation.
Haddam Neck Plant Event:
On February 4, 1988, an electric-driven fire pump was declared inoperable
during a routine surveillance test when a high-amperage condition was noted.
The normal indication of 200 amps initially increased to between 340 and 360
amps. The indication further increased to 1000 amps during a subsequent
manual restart.
The cause of the high amperage was attributed to physical
damage to the stuffing box brass bushing in the upper shaft area.
On the
basis of the licensee's evaluation and its discussions with the manufacturer, the licepsee concluded that prolonged operation of the pump at low flow may
have caused the problem.
Operation of the pump at or near the shut-off head
had occurred during the containment integrated leak rate test.
During the
test, the fire pump operated in a low-flow mode, providing cooling water to
the air compressors.
8901190418 Zfr
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AS_
-IN
89-08 January 26, 1989 Susquehanna 1 Event:
While the plant was operating at full power on May 22, 1986, an over-current
alarm for an emergency service water (ESW) pump was received in the control
room.
The pump was declared inoperable, placing the plant in a limiting
condition for operation. Subsequent disassembly of the pump revealed that
the bottom portion of the pump suction bell had separated from the pump body
and fallen into the pump pit. In addition, the pump's impeller vanes were
eroded through.
Similar, but less severe, damage was found on the three
other ESW pumps. A subsequent inspection of the residual heat removal
service water (RHRSW) pumps found similar damage.
The licensee determined
that the damage to the ESW and RHRSW pumps was caused by recirculation
cavitation, caused by operation of the pumps at flows significantly below
their design flow rates.
The ESW pumps are normally operated at 60 percent or less of their design flow
of approximately 6,000 gallons per minute (gpm) per pump. When the loop sup- plying cooling water to the diesels is run with two operating pumps, each pump
delivers approximately 3500 to 3900 gpm.
The other loop, that does not serve
the diesels is normally run with only one pump providing approximately 1000
to 1500 gpm. Operation at these conditions is believed by the pump vendor
to cause recirculation cavitation. In addition, the RHRSW pumps are believed
to have been operated at less than 50 percent of design flow most of the time.
The licensee indicated that the cavitation damage can be avoided by operating
the pumps at higher flows; specifically, operation at 75 to 100 percent of
design flow is desirable.
Discussion:
These events illustrate that pump damage, caused by operating pumps at flows
significantly below their design flow rates, has resulted, with slow deteri- oration of pump internals occurring over a long period. During the early
phases of degradation, the pumps were still functional and remained operable.
The pumps had to be disassembled before damage to the pump internals could be
seen.
Therefore, the routine pump surveillance tests, provided in the plant
inservice test programs, may not be capable of detecting early component de- gradation. In addition, while operating the pumps in their normal, specified
system operating ranges, plant personnel were not aware of a problem until
actual failure of a pump occurred. It is most likely that pump degradation
caused by low-flow operation will go undetected until total failure of the
pump occurs, preventing the associated system from performing its safety
function.
IN 89-08 January 26, 1989 No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
aLzi
l orj
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Chuck Hsu, AEOD
(301) 492-4443 Attachment: List of Recently Issued NRC Information Notices
IN 89-08 January 26, 1989 No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the techntcal
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Chuck Hsu, AEOD
(301) 492-4443 Attachment:
List of Recently Issued NRC Information Notices
The draft of this information notice was transmitted to DOEA
memorandum from Thomas M. Novak dated October 18, 1988.
by AEOD in a
The results of the review and recommendation for issuance of this draft infor- mation notice was transmitted to OGCB In a memorandum from M. Wayne Hodges
dated November 17, 1988.
- SEE PREVIOUS CONCURRENCES
- C/OGCB: DOEA:NRR*PPMB:ARM
CHBerlinger
TechEd
01/11/89
12/22/88 D *ROAB:DSP:AEOD *C/ROAB:DSP:AEOD
MChiramal
JERosenthal
10/18/88
10/18/88
- OGCB:DOEA:NRR
RJKiessel
12/06/88
- DSP:AEOD
VBenoroya
10/18/88
- AD/SAD:DEST:NRR
ACThadani
12/09/88
- D/DSP:AEOD
TMNovak
10/18/88 CHsu
10/18/88
IN 89-XX
January xx, 1989 No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Chuck Hsu, AEOD
(301) 492-4443 Attachment:
List of Recently Issued NRC Information Notices
The draft of this information notice was transmitted to DOEA
memorandum from Thomas M. Novak dated October 18, 1988.
by AEOD in a
The results of the review and recommendation for issuance of this draft infor- mation notice was transmitted to OGCB in a memorandum from M. Wayne Hodges
dated November 17, 1988.
- SEE PREVIOUS CONCURRENCES
D/DOEA:NRR
- C/OGCB:DOEA:NRR*PPMB:ARM
CERossi
CHBerlinger
TechEd
01/
/89
01/11/89
12/22/88
- ROAB:DSP:AEOD *ROAB:DSP:AEOD *C/ROAB:DSP:AEOD
MChiramal
JERosenthal
10/18/88
10/18/88
10/18/88
- OGCB:DOEA:NRR
RJKiessel
12/06/88
- DSP:AEOD
VBenoroya
10/18/88
- AD/SAD:DEST:NRR
ACThadani
12/09/88
- D/DSP:AEOD
TMNovak
10/18/88
IN 89-XX
January xx, 1989 Discussion:
These events illustrate that pump damage, caused by operating pumps at flows
significantly below their design flow rates, has resulted with slow deteriora- tion of pump internals occurring over a long period.
During the early phases
of degradation, the pumps were still functional and remained operable. The
pumps had to be disassembled before damage to the pump internals could be seen.
Therefore, the routine pump surveillance tests, provided in the plant inservice
test programs, may not be capable of detecting early component degradation. In
addition, while operating the pumps in their normal, specified operating
ranges, plant personnel were not aware of a problem until actual failure of the
pump occurred.
It is most likely that pump degradation caused by low-flow
operation will go undetected until total failure of the pump occurs, preventing
the associated system from performing its safety function.
The information herein is being provided as an early notification of a poten- tially significant matter that is under further consideration by the NRC staff.
If NRC evaluation so indicates, further licensee action may be requested.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Chuck Hsu, AEOD
(301) 492-4443 Attachment: List of Recently Issued NRC Information Notices
The draft of this information notice was transmitted to DOEA by AEOD in a
memorandum from Thomas M. Novak dated October 18, 1988.
The results of the review and recommendation for issuance of this draft infor- mation notice was transmitted to OGCB in a memorandum from M. Wayne Hodges
dated November 17, 1988.
- SEE PREVIOUS CONCURR
- PPMB:ARM
C/OGCB D~t4NRR D/DOEA:NRR
TechEd
CHBerl hIer
CERossi
12/22/88
01/1//89
01/ /89
- OGCB:DOEA:NRR *AD/SAD:DEST:NRR*C/SRXB:DEST:NRR
- SRXB:DEST:NRR*SRXB:DEST:NRR
RJKiessel
ACThadani
MWHodges
TECollins
MMcCoy
12/06/88
12/09/88
12/17/88
12/17/88
12/17/88
- ROAB:DSP:AEOD *ROAB:DSP:AEOD *C/ROAB:DSP:AEOD
- DSP:AEOD
- D/DSP:AEOD
MChiramal
JERosenthal
VBenoroya
TMNovak
10/18/88
10/18/88
10/18/88
10/18/88
10/18/88
IN 88-XX
December xx, 1988 during which the pumps were still functional and remained operable at early
degradation. Damage indication on the pumps' internals can only be observed by
disassembly of the pumps. The routine surveillance tests of the pumps provided
in the plant inservice test programs may not be capable of detecting early
component degradation. In addition, since the pumps operated in the specified
operating ranges, the plants were not aware of the problem until the occur- rences of pump failure. There is the potential that pump degradation due to
low flow operation could go undetected until total failure of the pump occurs.
Such failures could prevent the associated system from performing its safety
function.
The information herein is being provided as an early notification of a possibly
significant matter that is still under consideration by the NRC staff.
Recipi- ents should review the information for possible applicability to their facili- ties. If NRC evaluation so indicates, further licensee action may be
requested.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Chuck Hsu, AEOD
(301) 492-4443 Attachment: List of Recently Issued NRC Information Notices
The draft of this information notice was transmitted to DOEA by AEOD in a
memorandum from Thomas M. Novak dated October 18, 1988.
The results of the review and recommendation for issuance of this draft infor- mation notice was transmitted to OGCB in a memorandum from M. Wayne Hodges
dated November 17, 1988.
- SEE PREY
CONCURRENCES
PPMB:ARMitiv
C/OGCB:DOEA:NRR D/DOEA:NRR
TechEd
CHBerlinger
CERossi
12/fe/88
12/
/88
12/ /88 OGCB:DOEA:IRI
AD/SAD:DESI:PRR *C/SRXB:DEST:NRR
- SRXB:DEST:NRR*SRXB:DEST:NRR
RJKiessel
ACThgdani /
MWHodges
TECollins
MMcCoy
12/6/88
12/ 1/88
12/17/88
12/17/88
12/17/88
- ROAB:DSP:AEOD *ROAB:DSP:AEOD *C/ROAB:DSP:AEOD
- DSP:AEOD
- D/DSP:AEOD
MChiramal
JERosenthal
VBenoroya
TMNovak
10/18/88
10/18/88
10/18/88
10/18/88
10/18/88