Information Notice 1986-39, Failures of RHR Pump Motors and Pump Internals: Difference between revisions

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{{#Wiki_filter:SSINS No.: 6835IN 86-39UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF INSPECTION AND ENFORCEMENTWashington, DC 20555May 20, 1986IE INFORMATION NOTICE NO. 86-39: FAILURES OF RHR PUMP MOTORS ANDPUMP INTERNALS
{{#Wiki_filter:SSINS No.: 6835 IN 86-39 UNITED STATES NUCLEAR REGULATORY
 
COMMISSION
 
OFFICE OF INSPECTION
 
===AND ENFORCEMENT===
Washington, DC 20555 May 20, 1986 IE INFORMATION
 
NOTICE NO. 86-39: FAILURES OF RHR PUMP MOTORS AND PUMP INTERNALS


==Addressees==
==Addressees==
:All nuclear power reactor facilities holding an operating license (OL) or aconstruction permit (CP).
:
All nuclear power reactor facilities
 
holding an operating
 
license (OL) or a construction
 
permit (CP).


==Purpose==
==Purpose==
:This notice is provided to alert licensees to serious damage which has occurredat a licensed nuclear power plant to residual heat removal (RHR) pumps manufac-tured by Bingham-Willamette with motors supplied by General Electric. The damageidentified at the Philadelphia Electric Co. (PECO), Peach Bottom facility involvedfailure of motor bearings and/or failure of pump impeller wear rings.It is expected that recipients will review this notice for applicability totheir facilities and consider actions, if appropriate, to preclude a similarproblem occurring at their facilities. However, suggestions contained in thisnotice do not constitute requirements; therefore, no specific action or writtenresponse is required.
: This notice is provided to alert licensees
 
to serious damage which has occurred at a licensed nuclear power plant to residual heat removal (RHR) pumps manufac-tured by Bingham-Willamette
 
with motors supplied by General Electric.
 
The damage identified
 
at the Philadelphia
 
Electric Co. (PECO), Peach Bottom facility involved failure of motor bearings and/or failure of pump impeller wear rings.It is expected that recipients
 
will review this notice for applicability
 
to their facilities
 
and consider actions, if appropriate, to preclude a similar problem occurring
 
at their facilities.
 
However, suggestions
 
contained
 
in this notice do not constitute
 
requirements;  
therefore, no specific action or written response is required.Description
 
of Circumstances:
On November 2, 1985, during core reload of PECO's Peach Bottom Unit 3, a fire occurred in the 3C RHR pump motor which totally engulfed the motor and rendered the pump inoperable.
 
A lower guide bearing high temperature
 
alarm had been received for 3 days prior to the pump failure, but this warning of potential pump failure went unnoticed
 
by personnel
 
because of the large number of other alarms that were received during the shutdown.
 
The motor, a 2000 HP GE verti-cal induction
 
model 5K6348XC29, and pump, a Bingham-Willamette
 
single stage centrifugal
 
model 18x24x28 CVIC (Figure 1), were uncoupled, disassembled
 
and inspected
 
for damage. Results of the inspection
 
identified
 
that the motor lower guide bearing was destroyed, the rotor bars were gouged and scorched, and the stator windings were burned and gouged. The pump internals
 
were found to have sustained
 
internal damage. Specifically, the lower impeller wear ring (Figure 1) was separated
 
from the impeller and fused to the casing wear ring.No other wear surfaces indicated
 
wear or damage. On November 16, 1985, while replacing
 
the lower pump casing gasket on the 3A RHR pump, PECO personnel discovered
 
that the lower pump impeller wear ring was separated
 
from the impeller and cracked in three places. Subsequent
 
inspections
 
of the remaining two unit 3 RHR pumps and two unit 2 pumps (2A and 2C) revealed similar wear ring failures in three of the pumps inspected.
 
8605150473 IN 86-39 May 20, 1986 On December 22, 1985, after several overcurrent
 
alarms with pump 20 from Unit 2, PECO inspected
 
this pump and discovered
 
the lower pump impeller wear ring separated
 
and cracked, a 6-inch piece of wear ring missing, and the impeller vanes damaged. Not all failures noted above were as severe as the ones identified
 
on pumps 3C and 2D. However, the similarity
 
was evident.The RHR pump impeller wear rings are press fit to the impeller and attached with eight dowel pins. The wear rings provide a wearing surface on the pump impeller.
 
The wear rings are 410 stainless
 
steel, A 182 grade F6 with a Rockwell C hardness of 33 to 39. Metallurgical
 
examinations
 
of the wear ring fracture surfaces indicate the presence of intergranular
 
stress corrosion cracking (IGSCC). PECO has classified
 
the wear ring failures as IGSCC. On November 26, 1985, PECO made an INPO Network notification
 
regarding
 
these RHR pump failures.
 
PECO has repaired all affected pumps by replacement
 
of damaged motors and pump internals.
 
Tennessee
 
Valley Authority's
 
Browns Ferry Units 1, 2, and 3 utilize the identical
 
pumps for RHR service. Similar motor and pump impeller wear ring failures have occurred at these facilities, but not to the extent identified
 
at Peach Bottom. Pumps of similar design, but different
 
size, are utilized for core spray service both at Peach Bottom and Browns Ferry.However, these pumps use the "integral" impeller wear ring design, i.e., extended impeller part replaces separate wear ring and forms a single unit, and therefore
 
are not susceptible
 
to the type of wear ring failure previously
 
described.
 
Discussion:
These multiple events are of concern because of the potential
 
for common-mode failures of all pumps in the same system. At Peach Bottom, six of eight pumps inspected
 
exhibited
 
degraded pump impeller wear rings and internals.
 
These flaws could lead to pump hydraulic
 
degradation
 
and, under the worst conditions, complete pump failure. The motor guide bearing failures are signi-ficant because they could cause failure of the pump motors and pump internal damage.The full extent to which this type of pump may be used in safety-related
 
services at other facilities
 
is not known with complete certainty.
 
According to information
 
ascertained
 
from Bingham-Williamette
 
records and confirmed
 
by contact with affected sites, other plants utilizing
 
this type of pump in the RHR system include the following:
Cooper, Pilgrim 1, and Vermont Yankee.The exact cause of the pump internal failures has not been fully determined, except that there is evidence that IGSCC has contributed
 
to the impeller wear ring failures.
 
Operating
 
pumps with inadequate
 
flow and lubrication, whereby high internal temperatures
 
develop, is also a likely contributor, e.g., pump cavitation.
 
PECO is continuing
 
to pursue root causes and wear ring redesigns to prevent such occurrences
 
in the future.
 
IN 86-39 May 20, 1986 No specific action or written response is required by this information
 
notice.If you have any questions
 
regarding
 
this matter, please contact the Regional Administrator
 
of the appropriate
 
NRC regional office or the technical
 
contact listed below.r Jordan, Director Division of Emergency
 
===Preparedness===
and Engineering
 
Response Office of Inspection
 
and Enforcement
 
Technical
 
Contact: Ronald M. Young (301) 492-8985 Attachments:
1. Figure 1 -Typical CVIC RHR Pump Sectional
 
Assembly 2. List of Recently Issued IE Information
 
Notices
 
Attachment
 
1 IN 86-39 May 20, 1986 Casing Wear Ring Lower Impeller Wear Ring FIGURE 1 -Typical CVIC RHR Pump Sectional
 
Assembly
 
Attachment
 
2 IN 86-39 May 20, 1986 LIST OF RECENTLY ISSUED IE INFORMATION
 
NOTICES Information
 
Date of Notice No. Subject Issue Issued to 86-38 86-37 86-36 86-35 86-34 Deficient
 
Operator Actions 5/20/86 Following
 
Dual Function Valve Failures Degradation
 
Of Station 5/16/86 Batteries Change In NRC Practice 5/16/86 Regarding
 
Issuance Of Confirming
 
Letters To Principal
 
Contractors
 
Fire In Compressible
 
Material 5/15/86 At Dresden Unit 3 Improper Assembly, Material 5/13/86 Selection, And Test Of Valves And Their Actuators Information
 
For Licensee 5/6/86 Regarding
 
The Chernobyl Nuclear Plant Accident Request For Collection
 
Of 5/2/86 Licensee Radioactivity
 
Measurements
 
Attributed
 
To The Chernobyl
 
Nuclear Plant Accident Unauthorized
 
Transfer and 5/6/86 Loss of Control of Industrial
 
Nuclear Gauges Design Limitations
 
of 4/29/86 Gaseous Effluent Monitoring
 
Systems All power reactor facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All power reactor facilities


==Description of Circumstances==
holding an OL or CP Fuel cycle licensees and Priority 1 material licensees All power reactor facilities
:On November 2, 1985, during core reload of PECO's Peach Bottom Unit 3, a fireoccurred in the 3C RHR pump motor which totally engulfed the motor and renderedthe pump inoperable. A lower guide bearing high temperature alarm had beenreceived for 3 days prior to the pump failure, but this warning of potentialpump failure went unnoticed by personnel because of the large number of otheralarms that were received during the shutdown. The motor, a 2000 HP GE verti-cal induction model 5K6348XC29, and pump, a Bingham-Willamette single stagecentrifugal model 18x24x28 CVIC (Figure 1), were uncoupled, disassembled andinspected for damage. Results of the inspection identified that the motorlower guide bearing was destroyed, the rotor bars were gouged and scorched,and the stator windings were burned and gouged. The pump internals were foundto have sustained internal damage. Specifically, the lower impeller wear ring(Figure 1) was separated from the impeller and fused to the casing wear ring.No other wear surfaces indicated wear or damage. On November 16, 1985, whilereplacing the lower pump casing gasket on the 3A RHR pump, PECO personneldiscovered that the lower pump impeller wear ring was separated from theimpeller and cracked in three places. Subsequent inspections of the remainingtwo unit 3 RHR pumps and two unit 2 pumps (2A and 2C) revealed similar wearring failures in three of the pumps inspected.8605150473 IN 86-39May 20, 1986 On December 22, 1985, after several overcurrent alarms with pump 20 from Unit 2,PECO inspected this pump and discovered the lower pump impeller wear ringseparated and cracked, a 6-inch piece of wear ring missing, and the impellervanes damaged. Not all failures noted above were as severe as the onesidentified on pumps 3C and 2D. However, the similarity was evident.The RHR pump impeller wear rings are press fit to the impeller and attachedwith eight dowel pins. The wear rings provide a wearing surface on the pumpimpeller. The wear rings are 410 stainless steel, A 182 grade F6 with aRockwell C hardness of 33 to 39. Metallurgical examinations of the wear ringfracture surfaces indicate the presence of intergranular stress corrosioncracking (IGSCC). PECO has classified the wear ring failures as IGSCC. OnNovember 26, 1985, PECO made an INPO Network notification regarding these RHRpump failures. PECO has repaired all affected pumps by replacement of damagedmotors and pump internals. Tennessee Valley Authority's Browns Ferry Units 1,2, and 3 utilize the identical pumps for RHR service. Similar motor and pumpimpeller wear ring failures have occurred at these facilities, but not to theextent identified at Peach Bottom. Pumps of similar design, but different size,are utilized for core spray service both at Peach Bottom and Browns Ferry.However, these pumps use the "integral" impeller wear ring design, i.e.,extended impeller part replaces separate wear ring and forms a single unit,and therefore are not susceptible to the type of wear ring failure previouslydescribed.Discussion:These multiple events are of concern because of the potential for common-mode failures of all pumps in the same system. At Peach Bottom, six of eightpumps inspected exhibited degraded pump impeller wear rings and internals.These flaws could lead to pump hydraulic degradation and, under the worstconditions, complete pump failure. The motor guide bearing failures are signi-ficant because they could cause failure of the pump motors and pump internaldamage.The full extent to which this type of pump may be used in safety-relatedservices at other facilities is not known with complete certainty. Accordingto information ascertained from Bingham-Williamette records and confirmed bycontact with affected sites, other plants utilizing this type of pump in theRHR system include the following: Cooper, Pilgrim 1, and Vermont Yankee.The exact cause of the pump internal failures has not been fully determined,except that there is evidence that IGSCC has contributed to the impeller wearring failures. Operating pumps with inadequate flow and lubrication, wherebyhigh internal temperatures develop, is also a likely contributor, e.g., pumpcavitation. PECO is continuing to pursue root causes and wear ring redesignsto prevent such occurrences in the future.


IN 86-39May 20, 1986 No specific action or written response is required by this information notice.If you have any questions regarding this matter, please contact the RegionalAdministrator of the appropriate NRC regional office or the technical contactlisted below.r Jordan, DirectorDivision of Emergency Preparednessand Engineering ResponseOffice of Inspection and Enforcement
holding an OL or CP All power reactor facilities


===Technical Contact:===
holding an OL or a CP All power reactor facilities
Ronald M. Young(301) 492-8985Attachments:1. Figure 1 -Typical CVIC RHR PumpSectional Assembly2. List of Recently Issued IE Information Notices


Attachment 1IN 86-39May 20, 1986Casing Wear RingLowerImpeller Wear RingFIGURE 1 -Typical CVIC RHR PumpSectional Assembly
holding an OL or a CP 86-33 86-32 86-31 86-30 OL = Operating


Attachment 2IN 86-39May 20, 1986LIST OF RECENTLY ISSUEDIE INFORMATION NOTICESInformation Date ofNotice No. Subject Issue Issued to86-3886-3786-3686-3586-34Deficient Operator Actions 5/20/86Following Dual Function ValveFailuresDegradation Of Station 5/16/86BatteriesChange In NRC Practice 5/16/86Regarding Issuance OfConfirming Letters ToPrincipal ContractorsFire In Compressible Material 5/15/86At Dresden Unit 3Improper Assembly, Material 5/13/86Selection, And Test Of ValvesAnd Their ActuatorsInformation For Licensee 5/6/86Regarding The ChernobylNuclear Plant AccidentRequest For Collection Of 5/2/86Licensee RadioactivityMeasurements Attributed ToThe Chernobyl Nuclear PlantAccidentUnauthorized Transfer and 5/6/86Loss of Control ofIndustrial Nuclear GaugesDesign Limitations of 4/29/86Gaseous Effluent MonitoringSystemsAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPFuel cycle licenseesand Priority 1 materiallicenseesAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or a CPAll power reactorfacilities holdingan OL or a CP86-3386-3286-3186-30OL = Operating LicenseCP = Construction Permit
License CP = Construction


}}
Permit}}


{{Information notice-Nav}}
{{Information notice-Nav}}

Revision as of 12:59, 31 August 2018

Failures of RHR Pump Motors and Pump Internals
ML031250031
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, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, 05000115, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date: 05/20/1986
From: Jordan E L
NRC/IE
To:
References
IN-86-039, NUDOCS 8605150473
Download: ML031250031 (5)
v • d • e


SSINS No.: 6835 IN 86-39 UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF INSPECTION

AND ENFORCEMENT

Washington, DC 20555 May 20, 1986 IE INFORMATION

NOTICE NO. 86-39: FAILURES OF RHR PUMP MOTORS AND PUMP INTERNALS

Addressees

All nuclear power reactor facilities

holding an operating

license (OL) or a construction

permit (CP).

Purpose

This notice is provided to alert licensees

to serious damage which has occurred at a licensed nuclear power plant to residual heat removal (RHR) pumps manufac-tured by Bingham-Willamette

with motors supplied by General Electric.

The damage identified

at the Philadelphia

Electric Co. (PECO), Peach Bottom facility involved failure of motor bearings and/or failure of pump impeller wear rings.It is expected that recipients

will review this notice for applicability

to their facilities

and consider actions, if appropriate, to preclude a similar problem occurring

at their facilities.

However, suggestions

contained

in this notice do not constitute

requirements;

therefore, no specific action or written response is required.Description

of Circumstances:

On November 2, 1985, during core reload of PECO's Peach Bottom Unit 3, a fire occurred in the 3C RHR pump motor which totally engulfed the motor and rendered the pump inoperable.

A lower guide bearing high temperature

alarm had been received for 3 days prior to the pump failure, but this warning of potential pump failure went unnoticed

by personnel

because of the large number of other alarms that were received during the shutdown.

The motor, a 2000 HP GE verti-cal induction

model 5K6348XC29, and pump, a Bingham-Willamette

single stage centrifugal

model 18x24x28 CVIC (Figure 1), were uncoupled, disassembled

and inspected

for damage. Results of the inspection

identified

that the motor lower guide bearing was destroyed, the rotor bars were gouged and scorched, and the stator windings were burned and gouged. The pump internals

were found to have sustained

internal damage. Specifically, the lower impeller wear ring (Figure 1) was separated

from the impeller and fused to the casing wear ring.No other wear surfaces indicated

wear or damage. On November 16, 1985, while replacing

the lower pump casing gasket on the 3A RHR pump, PECO personnel discovered

that the lower pump impeller wear ring was separated

from the impeller and cracked in three places. Subsequent

inspections

of the remaining two unit 3 RHR pumps and two unit 2 pumps (2A and 2C) revealed similar wear ring failures in three of the pumps inspected.

8605150473 IN 86-39 May 20, 1986 On December 22, 1985, after several overcurrent

alarms with pump 20 from Unit 2, PECO inspected

this pump and discovered

the lower pump impeller wear ring separated

and cracked, a 6-inch piece of wear ring missing, and the impeller vanes damaged. Not all failures noted above were as severe as the ones identified

on pumps 3C and 2D. However, the similarity

was evident.The RHR pump impeller wear rings are press fit to the impeller and attached with eight dowel pins. The wear rings provide a wearing surface on the pump impeller.

The wear rings are 410 stainless

steel, A 182 grade F6 with a Rockwell C hardness of 33 to 39. Metallurgical

examinations

of the wear ring fracture surfaces indicate the presence of intergranular

stress corrosion cracking (IGSCC). PECO has classified

the wear ring failures as IGSCC. On November 26, 1985, PECO made an INPO Network notification

regarding

these RHR pump failures.

PECO has repaired all affected pumps by replacement

of damaged motors and pump internals.

Tennessee

Valley Authority's

Browns Ferry Units 1, 2, and 3 utilize the identical

pumps for RHR service. Similar motor and pump impeller wear ring failures have occurred at these facilities, but not to the extent identified

at Peach Bottom. Pumps of similar design, but different

size, are utilized for core spray service both at Peach Bottom and Browns Ferry.However, these pumps use the "integral" impeller wear ring design, i.e., extended impeller part replaces separate wear ring and forms a single unit, and therefore

are not susceptible

to the type of wear ring failure previously

described.

Discussion:

These multiple events are of concern because of the potential

for common-mode failures of all pumps in the same system. At Peach Bottom, six of eight pumps inspected

exhibited

degraded pump impeller wear rings and internals.

These flaws could lead to pump hydraulic

degradation

and, under the worst conditions, complete pump failure. The motor guide bearing failures are signi-ficant because they could cause failure of the pump motors and pump internal damage.The full extent to which this type of pump may be used in safety-related

services at other facilities

is not known with complete certainty.

According to information

ascertained

from Bingham-Williamette

records and confirmed

by contact with affected sites, other plants utilizing

this type of pump in the RHR system include the following:

Cooper, Pilgrim 1, and Vermont Yankee.The exact cause of the pump internal failures has not been fully determined, except that there is evidence that IGSCC has contributed

to the impeller wear ring failures.

Operating

pumps with inadequate

flow and lubrication, whereby high internal temperatures

develop, is also a likely contributor, e.g., pump cavitation.

PECO is continuing

to pursue root causes and wear ring redesigns to prevent such occurrences

in the future.

IN 86-39 May 20, 1986 No specific action or written response is required by this information

notice.If you have any questions

regarding

this matter, please contact the Regional Administrator

of the appropriate

NRC regional office or the technical

contact listed below.r Jordan, Director Division of Emergency

Preparedness

and Engineering

Response Office of Inspection

and Enforcement

Technical

Contact: Ronald M. Young (301) 492-8985 Attachments:

1. Figure 1 -Typical CVIC RHR Pump Sectional

Assembly 2. List of Recently Issued IE Information

Notices

Attachment

1 IN 86-39 May 20, 1986 Casing Wear Ring Lower Impeller Wear Ring FIGURE 1 -Typical CVIC RHR Pump Sectional

Assembly

Attachment

2 IN 86-39 May 20, 1986 LIST OF RECENTLY ISSUED IE INFORMATION

NOTICES Information

Date of Notice No. Subject Issue Issued to 86-38 86-37 86-36 86-35 86-34 Deficient

Operator Actions 5/20/86 Following

Dual Function Valve Failures Degradation

Of Station 5/16/86 Batteries Change In NRC Practice 5/16/86 Regarding

Issuance Of Confirming

Letters To Principal

Contractors

Fire In Compressible

Material 5/15/86 At Dresden Unit 3 Improper Assembly, Material 5/13/86 Selection, And Test Of Valves And Their Actuators Information

For Licensee 5/6/86 Regarding

The Chernobyl Nuclear Plant Accident Request For Collection

Of 5/2/86 Licensee Radioactivity

Measurements

Attributed

To The Chernobyl

Nuclear Plant Accident Unauthorized

Transfer and 5/6/86 Loss of Control of Industrial

Nuclear Gauges Design Limitations

of 4/29/86 Gaseous Effluent Monitoring

Systems All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP Fuel cycle licensees and Priority 1 material licensees All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or a CP All power reactor facilities

holding an OL or a CP 86-33 86-32 86-31 86-30 OL = Operating

License CP = Construction

Permit


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