Information Notice 1990-61, Potential for Residual Heat Removal Pump Damage Caused by Parallel Pump Interaction

Potential for Residual Heat Removal Pump Damage Caused by Parallel Pump Interaction

ML031130267
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, 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, 05002490, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	09/20/1990
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-90-061, NUDOCS 9009140260
Download: ML031130267 (9)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 September 20, 1990

NRC INFORMATION NOTICE NO. 90-61: POTENTIAL FOR RESIDUAL HEAT REMOVAL PUMP

DAMAGE CAUSED BY PARALLEL PUMP INTERACTION

Addressees

nuclear power

All holders of operating licenses or construction permits for

reactors.

Purpose

the potential for

This information notice is intended to alert addressees to pumps in residual heat

flow stoppage caused by the interaction of the parallel

valves located upstream of the recir- removal systems that have discharge check the information for

culation lines. It is expected that recipients will review

appropriate, to

applicability to their facilities and consider actions, as in this information

avoid similar problems. However, suggestions contained

requirements; therefore, no specific action or

notice do not constitute NRC

written response is required.

Description of Circumstances

Power Plant found

In December 1989, the staff at Unit 1 of the Sequoyah Nuclear flow

that one of the residual heat removal pumps was running without

of both pumps, a condi- (deadheading) during simultaneous surveillance testing test, both residual heat

tion that can damage a pump from overheating. In this

to draw water from

removal pumps, operating in the safety injection mode, were it back through

the refueling water storage tank suction lines and discharge

residual heat

the uminimum flow' recirculation lines (see Figure of the system at Sequoyah, removal system, attached). In the residual heat removal

a check Valve located on the discharge side of the

each of the two trains has crossover line

pumps and upstream of the recirculation lines. A normally open Because one of

connects the two trains downstream of the recirculation lines. the pressure of the

the pumps had a higher discharge pressure than the other, the discharge check

stronger pump acting through the crossover line forced from the weaker pump.

valve of the weaker pump to close. This stopped the flow

Tennessee Valley Authority (the

In its analysis of the event at Sequoyah, the than 11 minutes

licensee) found that operating a pump with no flow for longer

may cause pump damage.

90~

IN 90-61 September 20, 1990 The NRC Office of Analysis and Evaluation of Operational Data has published a

study of this issue entitled "Potential for Residual Heat Removal System Pump

Damage," AEOD/E90-06. This study reviewed the RHR designs of nineteen randomly

selected plants and.found five of them with system piping configurations

similar to that of the RHR system at the Sequoyah plant. The study indicates

that the potential for the adverse pump-to-pump interaction, which can cause the

discharge check valve to close, may not be detected during a surveillance test

in which one pump is tested at a time.

Discussion of Safety Significance

In addition to providing core cooling when the reactor is shut down, the

residual heat removal system provides low-pressure coolant injection (safety

injection) during an accident. If a loss-of-coolant accident followed by 'the

actuation of the safety injectin system were to occur, both pumps would start

running. However, until the primary system pressure has decreased to a level

that.is below the.pump shutoff head of 184 psi, the pumpscould'not inject into

the. reactor.. For a small break, the amount of time required to decrease the

reactor pressure to the 'low-pressure injection point could cause deadheaded

pumps to'overheat. For this reason,.the minimum flow bypass line valves are

designed to open during this phase to permit sufficient flow through'"the pumps

to cool them. During normal operation, the crossover line between the two

residual.heat removal trains is kept open. This is to assure a cooling water

supply to the reactor from either of the RHR pumps under adverse conditions, such as a break in one of the lines to the reactor cold legs. Consequently, the conditions identified in the.Sequoyah test would probably exist during a

small break accident and could cause the failure of the weaker pump.

NRC Bulletin 88-04, *Potential Safety-Related Pump Loss," previously addressed

the.issue of the deadheading of a weaker pump during two-pump minimum flow

operation.In its analysis that was performed in response to this bulletin, the Sequoyah staff concluded that the deadheading problem-did not exist'at

Sequoyah. 'This conclusion was based on the use of a value of 11.1 psi'for the

differential pressure between the two pumps, which had been derived from the

averagevalues from-several tests. This value was considered to be too low to

cause the deadheading-problem. Following the discovery of the deadheading'

problem in 1989,. the Sequoyah staff recalculated the differential pressure

between the two pumps based on' individual pump pressures and concluded that the

actual value was 17 psi, which was sufficient to block the flow from the weaker

pump, The staff at Sequoyah has made an interim change in its emergency operating

procedures to prevent the damaging of a residual heat removal pump during a

safety injection actuation. This change requires that one of the pumps be

stopped and placed in the standby mode if the reactor coolant system pressure

remains above 180 psi for longer than a specified time after the initiation of

safety injection. However, this procedure has the disadvantage of requiring

operator action within a short time during an emergency situation. As a

permanent corrective action, the Sequoyah staff will install check valves .in0

each train downstream of the recirculation lines. With these valves in place,

IN 90-61 September 20, 1990 any backflow resulting from crossover from a stronger pump would close the new

check valve in the lower pressure train and isolate the weak pump's recirculation

line from the stronger pump.

This information notice requires no specific action or written response. If

you have any questions about the Information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Chuck Hsu, AEOD

(301) 492-4443 Attachments:

1. Figure of Residual Heat Removal System - Minimum Flow Lineup

2. List of Recently Issued NRC Information Notices

Miniflow Bypass ' NOTE:

Line - A - Proposed Location For

J L9

"% The Check Valve.

A7 I%0 -- izB _ - - I -

To Cold Log

Residual Heat

R.osidual Heat Removal Exchanger

-L. Pump

10 A

_I4 PI

From RWST To Refueling

Water Storage Tank

From Containment

Recirc. Sump

Xc Residual Heat, Ii I

A

Residual Heat A

Removal Pump Exchanger A

aI - iP

To Cold Leg

I? cMt 2 From Hot Leg Miniflow Bypass 10- C1 Line $.- a In

a, 0' a

Residual Heat Removal System - Minimum Flow Lineup

t-a

10

10

- o

I \ <' Attachment 2 IN 90-61 September 20, 1990

Page 1 of I

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

90-60 Availability of Failure - 9/20/90 All holders of

Data In the Government- OLs or CPs for

Industry Data Exchange nuclear power

Program reactors.

90-59 Errors In the Use of 9/17/90 All medical

Radioactive Iodine-131 licensees.

90-58 Improper Handling of 9/11/90 All NRC medical

Ophthalmic Strontium-90 licensees.

Beta Radiation Applicators

90-57 Substandard, Refurbished 9/5/90 All holders of OLs

Potter & Brumfield Relays or CPs for nuclear

Misrepresented As New power reactors.

90-56 Inadvertent Shipment of A 9/4/90 All U.S. Nuclear

Radioactive Source In A Regulatory Com- Container Thought To Be mission (NRC)

Empty licensees.

90-55 Recent Operating Experi- 8/31/90 All holders of OLs

ence on Loss of Reactor or CPs for nuclear

Coolant Inventory While power reactors.

In A Shutdown Condition

83-44 Potential Damage to 8/30/90 All holders of OLs

Supp. 1 Redundant Safety Equip- or CPs for nuclear

ment As A Result of power reactors.

Backflow Through the

Equipment and Floor Drain

System

90-54 Summary of Requalification 8/28/90 All holders of OLs

Program Deficiencies or CPs for nuclear

power reactors.

89-18 Criminal Prosecution of 8/24/90 All holders of OLs

Supp. 1 Wrongdoing Committed by or CPs for nuclear

Suppliers of Nuclear power reactors.

Products or Services

OL = Operating License

CP = Constructier Permit

IN 90-61 September 20, 1990 any backflow resulting from crossover from a stronger pump would close the new

check valve in the lower pressure train and isolate the weak pump's recirculation

line from the stronger pump.

This information notice requires no specific action or written response. If

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

technical contact listed below or the appropriate NRR project manager.

Original Signif~b

Charles E. Rossi

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Chuck Hsu, AEOD

(301) 492-4443 Attachments:

1. Figure of Residual Hea t Removal System - Minimum Flow Lineup

2. List of Recently IssueLd NRC Information Notices

• SEE PREVIOUS CONCURRENCES

/OGCB:DOEA:NRR

i CHBerlinger

09//7/90 9/13/90

• OGCB:DOEA:NRR *ROAB:DSP:P6EOD *ROAB:DSP:AEOD *D/DSP:AEOD *RPB:ADM

DCKirkpatrick CCHsu JERosenthal TMNovak TechEd

08/29/90 08/31/90 09/06/90 09/06/90 08/29/90

Document Name: IN 90-61

IN 90-XX

September xx, 1990 backfilow resulting from crossover from a stronger pump would close the new

check valve in the lower pressure train and isolate weak pump's recirculation

line from the stronger pump.

This information notice requires no specific action or written response. If

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

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Chuck Hsu, AEOD

(301) 492-4443 Attachments:

1. Figure of Residual Heat Removal System

2. List of Recently Issued NRC Information Notices

Document Name: IN ON RHR PUMP MINIMUM FLOW

• SEE PREVIOUS CONCURRENCES

• /DOEA:NRR Cl :DOEA:NRR

CERossi CHBerlinger

09/ /90 09/13/90

• OGCB:DOEA:NRR *ROAB:DSP:AEOD *ROAB:DSP:AEOD *D/DSP:AEOD *RPB:ADM

DCKirkpatrick CCHsu JERosenthal TMNovak TechEd

08/29/90 08/31/90 09/06/90 09/06/90 08/29/90

-3 -

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 appropriate NRC regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Chuck Hsu, AEOD

(301) 492-4443 Attachments: 1. Figure of Residual Heat Removal System

2. L1st of Recently Issued NRC Information Notices

DOCUMENT NA1lE: IN ON RHR PUMP MINIMUM FLOW r

OGCB:DOEA:NRR RPD:ADM ROAB:DSP:AECD

DCKirkpatrick Tech Ed -SMot.4Q CCHsu vo4.

08/ij/90 48/11/90

/DSP:AEOD D/DOEA:NRR C/OGCB:DOEA:NRR

J#tMhovac CERossi CHBerlinger

oUs6iIG/90 08/ /90 08/ /90