Information Notice 1987-10, Potential for Water Hammer During Restart of Residual Heat Removal Pumps

Potential for Water Hammer During Restart of Residual Heat Removal Pumps
	ML031140526
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, 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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill, Crane
Issue date:	02/11/1987
From:	Jordan E; NRC/IE
To:	;
References
	IN-87-010, NUDOCS 8702100126
	Download: ML031140526 (5)
	v • d • e

SSINS No.:

6835 IN 87-10

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C.

20555

February 11, 1987

IE INFORMATION NOTICE NO. 87-10:

POTENTIAL FOR WATER HAMMER DURING RESTART

OF RESIDUAL HEAT REMOVAL PUMPS

Addressees

All boiling water reactor (BWR) facilities holding an operating license or a

construction permit.

Purpose

This information notice is to alert addressees of the potential for water

hammer in the residual heat removal (RHR) system of BWRs during a design basis

loss of coolant accident (LOCA) coincident with a loss of offsite power (LOOP)

if the RHR system is aligned to suppression pool cooling.

Recipients are

expected to review the information for applicability to their facilities and

consider actions, if appropriate, to preclude similar problems occurring at

their facilities.

However, suggestions contained in this information notice do

not constitute NRC requirements; therefore, no specific action or written

response is required.

Description of Circumstances

On December 11, 1986, the Susquehanna nuclear power plant reported that based

on results of an ongoing review of the potential effects of water hammer

events, the RHR system could be susceptible to water hammer loads that would

exceed the allowable stresses in the RHR system and piping.

The specific

condition of concern involves a design-basis LOCA coincident with a LOOP, while

one or one RHR loops are in the suppression pool cooling mode. During the

power loss and subsequent valve realignment, portions of the RHR system will

void because of the drain down to the suppression pool as a result of elevation

differences. A water hammer may occur in those RHR loops that were in the

suppression pool cooling mode when the RHR pumps restart after the diesel

generators reenergize the buses.

The core spray system also may be subject to such a water hammer if it is lined

up in the suppression pool mixing mode full flow test.

The Susquehanna design basis for LOCA/LOOP assumes that the suppression pool

cooling flow path valves are initially closed in the standby lineup. The

potential duration factor used in the consideration of the coincident LOCA/LOOP

with the RHR in suppression pool cooling mode was one percent, or roughly 90

hours per year.

7

87A

IN 87- February , 1987 Contrary to the design basis assumption, a licensee review of operating

found that the worst case RHR system usage factor approached 25% during

in which significant safety relief valve weeping was experienced.

hi story

cycles

For interim corrective action, the licensee has modified operating procedures

to allow, at a time, only one loop of RHR to operate in suppression pool

cooling.

In addition, the licensee will revise plant procedures to address the

restart of an RHR pump if it trips while operating in the suppression pool

cooling mode.

The core spray system is currently prohibited from being

operated in the suppression pool mixing mode, except for required surveillance

testing.

Discussion:

The NRC discussed the potentia'

Evaluation No. AEOD/E309, "The

RHR Pumps at BWR Nuclear Power

I for this general type of event in Engineering

Potential for Water Hammer During the Restart of

Plants," dated April 1983.

In the type of scenario discussed in AEOD/E309, the line most likely to drain

and experience a water hammer is the drywell spray line because it has the

largest elevation difference between it and the suppression pool.

RHR system

pipes less than 33 feet above the suppression pool will not usually drain

because atmospheric pressure will support a column of water that high.

A water

hammer in the drywell spray line could endanger RHR system integrity, and thus

jeopardize all modes of RHR including low-pressure coolant injection.

The analysis performed by the licensee of the Susquehanna nuclear power plant

goes beyond AEOD/E309 In that detailed site-specific computer modeling was

performed which shows that piping system integrity could be challenged.

Besides Susquehanna, other plants may have high usage factors for suppression

pool cooling mode and large elevations differences in the RHR system, making

those plants potentially subject to water hammer in the RHR system.

No specific action or written response is required by this information notice.

If you have questions about this matter, please contact the Regional Adminis- trator of the appropriate NRC regional office or this office.

Edward L. Jordan, Director

Division of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Technical Contacts:

Eric Weiss, 1E

(301) 492-9005

George Lanik, IE

(301) 492-9007 Attachment: List of Recently Issued IE Information Notices

by phone

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01/30/87

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Attachment 1

IN 87-10

February 11, 1987

LIST OF RECENTLY ISSUED

1E INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issue

Issued to

87-09

87-08

87-07

87-06

87-05

87-04

87-03

87-02

87-01

86-110

Emergency Diesel Generator

Room Cooling Design

Deficiency

Degraded Motor Leads in

Limitorque CD Motor

Operators

Quality Control of Onsite

Dewatering/Solidification

Operations by Outside

Contractors

Loss of Suction to Low-

Pressure Service Water

System Pumps Resulting From

Loss of Siphon

Miswiring in a Westinghouse

Rod Control System

Diesel Generator Fails

Test Because of Degraded

Fuel

Segregation of Hazardous

Inadequate Seismic Quali- fication of Diaphragm

Valves by Mathematical

Modeling and Analysis

RHR Valve Misalignment

Causes Degradation of

ECCS in PWRs

Anomalous Behavior of

Recirculation Loop Flow

in Jet Pump BWR Plants

2/5/87

2/4/87

2/3/87

1/30/87

2/2/87

1/16/87

1/15/87

1/6/87

12/31/86

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 Westinghouse

power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All NRC licensees

All power reactor

facilities holding

an OL or CP

All PWR facilities

holding an OL or CP

All BWR facilities

holding an OL or CP

OL = Operating License

CP = Construction Permit

IN 87- February , 1987 Contrary to the design basis assumption, a licensee review of operating history

found that the worst case RHR system usage factor approached 25% during cycles

in which significant safety relief valve weeping was experienced.

For interim corrective action, the licensee has modified operating procedures

to allow, at a time, only one loop of RHR to operate in suppression pool

cooling. In addition, the licensee will revise plant procedures to address the

restart of an RHR pump if it trips while operating in the suppression pool

cooling mode.

The core spray system is currently prohibited from being operated

in the suppression pool mixing mode, except for required surveillance testing.

Discussion:

The NRC discussed the potential for this general type of event in Engineering

Evaluation No. AEOD/E309, "The Potential for Water Hammer During the Restart of

RHR Pumps at BWR Nuclear Power Plants," dated April 1983.

In the type of scenario discussed in AEOD/E309, the line most likely to drain

and experience a water hammer is the drywell spray line because it has the

largest elevation difference between it and the suppression pool.

RHR system

pipes less than 33 feet above the suppression pool will not usually drain

because atmospheric pressure will support a column of water that high. A water

hammer in the drywell spray line could endanger RHR system integrity, and thus

jeopardize all modes of RHR including low-pressure coolant injection.

The analysis performed by the licensee of the Susquehanna nuclear power plant

goes beyond AEOD/E309 in that detailed site-specific computer modeling was

performed which shows that piping system integrity could be challenged.

Besides Susquehanna, other plants may have high usage factors for suppression

pool cooling mode and large elevations differences in the RHR system, making

those plants potentially subject to water hammer in the RHR system.

No specific action or written response is required by this information notice.

If you have questions about this matter, please contact the Regional Adminis- trator of the appropriate NRC regional office or this office.

Edward L. Jordan, Director

Division of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Technical Contacts:

Eric Weiss, IE

(301) 492-9005

George Lanik, IE

(301) 492-9007 Attachment: List of Recently Issued IE Information Notices

by phone

LPlisco for

L

SEE PREVIOUS CONCURRENCE

EAB:DEPER:IE Region I *IE

// EAB:DEPER:IE

EGCB:DEPER:IE

DD:DEPER:IE

D:DEPER:IE

EWWeiss:ew

JWiggins DGable

JRosenthal

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ELJordan

01/14/87

01/20/87 01/15/87 01 t/87

01/3Q/87

01/ /87

IN 87- February , 1987 Contrary to the design basis assumption, a licensee review of operating history

found that, during cycles in which significant safety relief valve weeping was

experienced, the worst case RHR system usage factor approached 25%.

For interim corrective action, the licensee has modified operating procedures

to allow only one loop of RHR to operate in suppression pool cooling or one

loop of core spray in suppression pool mixing mode at a time. In addition, the

licensee will revise plant procedures to address the restart of an RHR pump if

it trips while operating in the suppression pool cooling mode.

The core spray

system is currently prohibited from being operated in the suppression pool

cooling mode, except for requited surveillance testing.

Discussion:

The NRC discussed the potential for this general type of event in Engineering

Evaluation No. AEOD/E309, "The Potential for Water Hammer During the Restart of

RHR Pumps at BWR Nuclear Power Plants," dated April 1983.

In the type of scenario discussed in AEOD/E309, the line most likely to drain

and experience a water hammer is the drywell spray line because it has the

largest elevation difference between it and the suppression pool.

RHR system

pipes less than 33 feet above the suppression pool will not usually drain

because atmospheric pressure will support a column of water that high. A water

hammer in the drywell spray line could endanger RHR system integrity, and thus

jeopardize all modes of RHR including low pressure coolant injection.