Information Notice 1995-16, Vibration Caused by Increased Recirculation Flow in a Boiling Water Reactor

Vibration Caused by Increased Recirculation Flow in a Boiling Water Reactor

ML031060310
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:	03/09/1995
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
IN-95-016, NUDOCS 9503030302
Download: ML031060310 (11)

.7 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION .

WASHINGTON, D.C. 20555 March 9, 1995 NRC INFORMATION NOTICE 95-16: VIBRATION CAUSED BY INCREASED RECIRCULATION

FLOW IN A BOILING WATER REACTOR

Addressees

water

All holders of operating licenses or construction permits for boiling

reactors (BWRs).

PurDose

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

notice to alert addressees to the potential for resonance vibration causedthat

an increase in reactor coolant recirculation flow rates. It is expected

facilities

recipients will review the information for applicability to their However, and consider actions, as appropriate, to avoid similar problems.

suggestions contained in this information notice are not NRC requirements;

therefore, no specific action or written response is required.

Description of Circumstances

Unit 2 On June 21, 1994, the operators at Susquehanna Steam Electric Station rate of

raised the reactor coolant recirculation flow rate from the normal

Mlb/hr] as part of a testing

about 45 Mkg/hr [100 Mlb/hr] to 49 Mkg/hr [108 with the

program for an approved uprate in reactor power. The following day, noted

recirculation pump speed at 1570 to 1580 rpm (95 percent), the operators

These included

a number of abnormal indications of significant vibration. and

vibration of the containment instrument gas piping outside the containment

in the Lontrol

vibration of the suppression pool hatch covers. The operators

from the

room noted a low-frequency pulsating hum, which appeared to be coming

primary containment structure.

of the

The licensee attributed the excessive vibration to the increased speed

recirculation pumps. Consequently, on June 23 the operators systematically

speed of both

lowered the pump speed while monitoring the vibration. When the and noise

of the recirculation pumps was lowered to 1515 rpm, the vibration

had

levels returned to normal. The licensee estimated that the vibration at what

persisted for approximately 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br />, although it was not clear then

a

time and flow rate the vibration actually started. The licensee performed and concluded

thorough evaluation of the effects of the vibration on the plant

that

that it had not caused any damage. The licensee also concluded flow rate of

maintaining the recirculation pumps at 1515 rpm, with a resulting

limited the

46.7 Mkg/hr [103 Mlb/hr], was acceptable and administratively

recirculation pumps to this speed.

9503030302 a

IN 95-16 March 9, 1995 The licensee conducted a second increased reactor recirculation flow test

program on Unit 2 during the second week in December 1994, increasing the flow

rate in steps from 46.7 Mkg/hr [103 Mlb/hr] to 49 Mkg/hr [108 Mlb/hr]. At

each pump speed plateau, the licensee deliberately varied the speed difference

between the two pumps from 0 to 2 percent of the average pump speed. When the

flow rate reached 47.6 Mkg/hr [105 Mlb/hr], the vibration noise phenomena

reappeared with the most pronounced effect occurring with a difference in

speed between the two pumps of 2 percent.

Discussion

The licensee has concluded that the vibration was caused by pressure pulses

emitted from the recirculation pumps as the pump impeller vanes passed the

pump openings. These pulses were amplified by an as yet undefined resonating

mechanism. The pumps are manufactured by Byron Jackson. They are of the

centrifugal type and have five vane impellers. The 1570-rpm to 1580-rpm pump

speed when multiplied by the number of vanes corresponds to the measured

131 Hz frequency of the vibration that was measured at the suppression pool

hatch covers. This frequency also correlates well with the natural frequency

of the hatch covers, which was measured to be 133 Hz. The low-frequency

modulation is caused by a slight difference in the frequency of the two

recirculation pumps, causing the two pumps to alternately go in and out of

synchronization with respect to vane passage of the respective pump openings.

As this occurs, the vane-generated pressure pulses tend to alternately

reinforce and cancel each other, resulting in a modulation of the frequency.

The licensee has established a working group to identify the vibration- amplifying mechanism. It is coordinating this investigation with General

Electric, the reactor supplier. The NRC staff will continue to monitor the

investigation.

Vibration attributable to high recirculation fl w-has been noted at several

nuclear power plants in the past. Hope C has experienced excessive

vibration on several occasions when the reactor recirculation flow was above

47.4 Mkg/hr [104.5 Mlb/hr]. On September 18, 1987, excessive vibration caused

two leaks from the recirculation flow instruments. The Hope Creek licensee

now monitors the recirculation system for excessive vibration during end-of- cycle coastdown periods and, if excessive vibration is detected, reduces

recirculation flow.

In the fall of 1989, Quad Cities Unit 2 experienced a harmonic vibration

during reactor recirculation system coastdown tests when the pump speed passed

420 rpm. The licensee attributed the vibration to the vane passing frequency

excitation phenomenon and established an administrative limit on recirculation

flow to minimize the possibility of a recurrence.

In September 1992, the Browns Ferry Unit 2 licensee increased the

recirculation pump speed in preparation for an end of cycle coastdown. The

reactor experienced a resonant vibration when the recirculation pump speed was

near 1500 rpm. The licensee administratively limited the pump speed to less

than this value.

IN 95-16 March 9, 1995 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. /7

6 Brian K. Grimes, irector

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: P. Y. Chen, NRR C. Poslusny, NRR

(301) 415-2789 (301) 415-1402 T. Greene, NRR

(301) 415-1175 Attachment:

List of Recently Issued NRC Information Notices

Add

GeV L rr-A-ell4d-

I'Atachment

IN 95-16 March 9, 1995 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Subject Issuance Issued to

Notice No.

Inadequate Logic Testing 03/07/95 All holders of OLs or CPs

95-15 for nuclear power reactors.

of Safety-Related Circuits

Susceptibility of Con- 02/28/95 All holders of OLs or CPs

95-14 for nuclear power reactors.

tainment Sump Recircula- tion Gate Valves to

Pressure Locking

Potential for Data 02/24/95 All holders of OLs or CPs

95-13 for nuclear power reactors.

Collection Equipment to

Affect Protection System

Performance

Potentially Nonconforming 02/21/95 All holders of OLs or CPs

95-12 for nuclear power reactors.

Fasteners Supplied by

A&G Engineering II, Inc.

Failure of Condensate 02/24/95 All holders of OLs or CPs

95-11 for nuclear power reactors.

Piping Because of Erosion/

Corrosion at a Flow- Straightening Device

Potential for Loss of 02/10/95 All holders of OLs or CPs

95-10 for nuclear power reactors.

Supp. 1 Automatic Engineered

Safety Features

Actuation

Potential for Loss of 02/03/95 All holders of OLs or CPs

95-10 for nuclear power reactors.

Automatic Engineered

Safety Features

Actuation

Use of Inappropriate 01/31/95 All holders of OLs or CPs

95-09 for nuclear power reactors.

Guidelines and Criteria

for Nuclear Piping and

Pipe Support Evaluation

and Design

Inaccurate Data Obtained 01/30/95 All holders of OLs or CPs

95-08 for nuclear power reactors.

with Clamp-On Ultrasonic

Flow Measurement Instruments

OL = Operating License

CP = Construction Permit

4 I

"' < IN 95-16 March 9, 1995 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.

orig /s/'d by BKGrimes

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: P. Y. Chen, NRR C. Poslusny, NRR

(301) 415-2789 (301) 415-1402 T. Greene, NRR

(301) 415-1175 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME: 95-16.IN

• See orevious concurrences

OECB:DOPS* PUB:ADM*l EMEB:DE* PDI-1:DRPE*

DKirkpatrick MMejak (Tech Ed) PYChen CPoslusny

10/12/94 10/13/94 11/8/94 10/18/94 C/EMEB:DE* D/DE* OECB:DOPS* SC/OECB:DOPS*

RWessman BSheron TGreene EGoodwin

01/29/95 02/08/95 02/13/a,5 02/21/95 OECB:DOPS* C/OECB:DOPS DA"

RKiessel AChaffee* LB 1_ __ __

02/21/95 03 & /95

02/21/95 OFFICIAL RECORD COPY

IN 95-xx

February xx, 1995 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

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: P. Y. Chen, NRR C. Poslusny, NRR

(301) 415-2789 (301) 415-1402 T. Greene, NRR

(301) 415-1175 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME: S:\DOPS_SEC\RCIRCVIB

• See previous concurrences

OECB:DOPS* PUB:ADM* EMEB:DE* PDI-1:DRPE*

DKirkpatrick MMeJak (Tech Ed) PYChen CPoslusny

10/12/94 10/13/94 11/8/94 10/18/94 C/EMEB:DE* D/DE* OECB:DOPS* SC/OECB:DOPS*

RWessman BSheron TGreene EGoodwin

01/29/95 02/08/95 02/13/95 02/21/95 OECB:DOPS* C/OECB:DOPS D/DOPS _

RKiessel AChaffee* BGrime_ _ _)_

02/21/95 02/21/95 02/ /95 OFFICIAL RECORD COPY

K> IN 95-xx

February xx, 1995 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

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: P. Y. Chen, NRR C. Poslusny, NRR

(301) 415-2789 (301) 415-1402 T. Greene, NRR

(301) 415-1175 Attachment:

List of Recently Issued NRC Information Notices

OECB:DOPS* PUB:ADM* lEMEB:DE* PDI-1:DRPE*

DKirkpatrick MMeJak (Tech Ed) PYChen CPoslusny

10/12/94 10/13/94 11/8/94 10/18/94 C/EMEB:DE* D/DE* OECB:DOPS* SC/OECB:DOPS N

RWessman BSheron TGreene EGoodwin

1/29/95 2/08/95 2/13/95 2/2/5 OECB:DOPS* C/OECB:D1K9 D/DOPS

RKiessel AChaffee BGrimes

2/21/95 2/J /95 1 2/ /95

• See previous concurrences.

DOCUMENT NAME: G:\DON\RCIRCVIB

V. IN 95-xx

February xx, 1995 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

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: P. Y. Chen, NRR C. Poslusny, NRR

(301) 415-2789 (301) 415-1402 T. Greene, NRR

(301) 415-1175 Attachment:

List of Recently Issued NRC Information Notices

OECB:DOPS* PUB:ADM* EMEB:DE* PDI-1:DRPE*

DKirkpatrick MMejak (Tech Ed) PYChen CPoslusny

10/12/94 10/13/9A 11/8/94 10/18/94

• C/EMEB:DE* D/D a OECB:DOPS _SC/OECB:DOPS l 9 EGoodwin

"'2P

RWessman BShg 7 A TGreene

1/29/95 2/ /95 2//3/95 2/ /95 OECB:DOPS C/OECB:DOPS D/DOPS l

RKiessel & e AChaffee BGrimes

21/95 2/ /95 2/ /95 See previous concurrences.

.7

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K> IN 95-xx

Januray xx, 1995 This information notice requires no specific action or written response. If

you have any questions ibbut 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

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: P. Y. Chen, NRR C. Poslusny, NRR

(301) >8K-2789 (301) 50-1402

4Ar

T. Greene, NRR

(301) 9Sq-1175

4,1 Attachment:

List of Recently Issued NRC Information Notices

OECB:DOPS* PUB:ADM* EMEB:DE* PDI-1:DRPE*

DKirkpatrick lMMejak (Tech Ed) PYChen CPoslusny

- 10/12/94 10/13/94 11/8/94 10/18/94 C/EMEB:DE D/DE If yv OECB:DOPS SC/OECB:DOPS

RWessman BSheron TGreene EGoodwin

1 /95 IM I/ /95 1/ /95 I/ /95 OECB:DOPS C/OECB:DOPS D/DOPS

RKiessel AChaffee BGrimes l

1/ /95 1/ /95 1/ /95

• See previous concurrences.

1X3 V-( I IuC

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K> IN 94-xx

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

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

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

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: P. Y. Chen, NRR C. Poslusny, NRR

(301) 504-2789 (301) 504-1402 T. Greene, NRR

(301) 504-1175 Attachment:

List of Recently Issued NRC Information Notices

OECB:DOPS* PUB:ADM* EMEB:DE PDI-1:DRPE*

DKirkpatrick MMejak (Tech Ed) PYChen CPoslusny

10/12/94 10/13/94 11/8 /94 10/18/94 C/EMEB:DE D/DE OECB:DOPS SC/OECB:DOPS

RWessman BSheron TGreene EGoodwin

11/ 1// /9r 11/ /94 OECB:DOPS C/OECB:DOPS D/DOPS

RKiessel AChaffee BGrimes

11/ /94 11/ /94 11/ /94

• See previous concurrences.

I

IN 94-xx

October 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 contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: P. Y. Chen, NRR C. Poslusny, NRR

(301) 504-2789 (301) 504-1402 T. Greene, NRR

(301) 504-1175 Attachment:

List of Recently Issued NRC Information Notices

1-0

%&%-"4Q'i. 111

. V

OECB:DOPS* PUB:ADM* EMEB:DE PDI-1:DRPE d

DKirkpatrick MMejak (Tech Ed) PYChen CPoslusny

10/12/94 10/13/94 10/ /94 10/ %/94 C/EMEB:DE D/DE OECB:DOPS SC/OECB:DOPS

RWessman BSheron TGreene EGoodwin

10/ /94 10/ /94 10/ /94 10/ /94 OECB:DOPS C/OECB:DOPS DD/DOPS D/DOPS

RKiessel AChaffee BLiaw BGrimes

10/ /94 10/ /94 10/ /94 10/ /94

• See previous concurrences.