Information Notice 1987-63, Inadequate Net Positive Suction Head in Low Pressure Safety Systems

Inadequate Net Positive Suction Head in Low Pressure Safety Systems

ML031180034
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, Crane
Issue date:	12/09/1987
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-87-063, NUDOCS 8712030052
Download: ML031180034 (7)

IN P7-63

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555

December 9, 1987

NRC INFORMATION NOTICE NO. 87-63:

INADEQUATE NET POSITIVE SUCTION HEAD

IN LOW PRESSURE SAFETY SYSTEMS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is being provided to alert addressees to problems which

could result in inadequate net positive suction head (NPSH) at the inlet to the

low pressure pumps following a loss-of-coolant accident (LOCA). It is expected

that recipients will review the information for applicability to their facili- ties and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice do not constitute NRC reauire- ments; therefore, no specific action or written response is required.

Description of Circumstances

A Nuclear Regulatory Commission review has identified several similar reported

problems related to excessive flow rates in low pressure safety systems that

could occur following a LOCA. Higher than expected flow rates in the pump

discharge lines can lead to lower than calculated suction line pressures and

consequently to inadequate pump NPSH.

On.May 19, 1987, Turkey Point, Unit 3, personnel reported that during a reexam- ination of the containment spray (CS) system the hydraulic resistance of the CS

system was found to be less than that assumed in the design calculations.

Furthermore, they reported that adequate NPSH for the CS pumps could not be

assured during the injection phase following a LOCA when the CS system was

drawing water from the refueling water storage tank. This deficiency was

caused by missing flow orifices in the pump discharge lines that were assumed

in the system design but never installed. The licensee corrected the problem

by installing the missing flow orifices and reported the event in Licensee

Event Report 250-87-014.

On December 12, 1986, while designing modifications for the facility residual

heat removal (RIR) system, the Haddam Neck licensee discovered that pump

cavitation could occur in the low pressure pumps during the recirculation phase

ERA05

--,IN 87-63 December 9, 1987 following a LOCA (in a narrow range of break sizes). A combination of break

flow, a system arrangement where the high pressure pumps are downstream of the

low pressure pumps, and a certain volume of water in the containment sump at

the time of switchover from the injection to the recirculation phase all

contributed to the scenario in which inadeauate NPSH would exist at the low

pressure pump inlet. The licensee corrected the problem by throttling the RHR

system control valves to balance the flowpaths and effectively increase the

system hydraulic resistance on the low pressure pump discharge line while

maintaining minimum flow requirements.

On March 31, 1986, the Trojan licensee discovered that there would be inade- quate NPSH at the inlet to the low pressure pumps of the emergency core cooling

system (ECCS) at Trojan under certain accident conditions. During the recircu- lation phase following a LOCA, two low pressure pumps feed the charging pumps, the safety injection pumps, and the cold leg injection paths. If only one low

pressure pump is operating (accounting for a single failure) and the cross-tie

between ECCS trains is open, the low pressure pump NPSH would be deficient by

about 10 feet. The licensee corrected the problem by modifving procedures to

(1) isolate the cross-tie between trains prior to entering the recirculation

phase and (2) secure ell other pumps in the same-train as the inoperable low

pressure pump.

In July 1977, the Farley, Unit 1, licensee reported that the residual heat

removal (RHR) pump flow rate at that facility would be significantly above the

expected flow rate during the cold leg recirculation mode of operation follow- ing a LOCA.

Investigations by the licensee revealed that the high flow rates

were due to lower than expected hydraulic resistances in the RHR pump discharge

piping. The actual roughness of the installed piping was less than the stan- dard commercial steel roughness assumed in the calculations, and the hydraulic

resistance of installed check valves was less than estimated. Consequently, the licensee installed orifices in the pump discharge piping to reduce the flow

to a rate that would provide adequate NPSH at the low pressure pumps under all

post-LOCA conditions.

Discussion:

Inadequate FPSH can cause pump cavitation and lead to pump unavailability.

Identification of deficiencies in system design, installation, or operation

that could result in inadequate WPSH can occur in any type of pump system

arrangement and may require more than a review of the original design calcula- tions, as noted by the above mentioned events. In general, pump availability

may also be affected by sudden suction pressure oscillations durina pump starts

that may cause unexpected pump trips. This is discussed in NRC Information

Notice 87-53, "Auxiliary Feedwater Pump Trips Resulting From Low Suction

Pressure".

IN 87-63 December 9, 1987 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.

arles E.R oss

Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Sanford Israel, AEOD

(301) 492-4437 Attachment: List of Recently Issued NRC Information Notices

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Attachlent 1

IN 17.63 December to ItS?

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES 1I7 snTcnnasan

Notice No.

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Failure of Westinghouse

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Cell Stches.

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Depressurlzation of Reactor

Coolant Systems in

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C6-108

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Coolant System Pressure

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Boric Acid Corrosion

87-59

Potential RHR Pump Loss

S7-58 continuous Ctiniou~cationa

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Notifications

87-57

Less of EWrgency Boration

Capability Due to Nitrogen

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87.56 improper IPydraulic Control

Unit Installation at *WR

Plants.

Dte oa

Mssuance

Issued to

17/S/87

All holders of OLe

or CPs for nuclear

power reactors

12/7/67

All holders of OLs

or CPs for nuclear

power reactors.

12/4/87

All holders of OLs

or CPS for MWRs.

11/19J/7

All holders of OLs

or CPe for nuclear

power reactors.

11/17/87

All holden of OLe

or CPS for nuclear

power reactors.

11/16/87

All nuclear PMwer

reactor facilities

holding an OL and

the following fuel

facilities that have

Emergency Notification

Systes: Nuclear

Fuel Services. Erwin.

TN; general Atomics, San Diego, CAI UNC,

Nontvillle CTI and

• A V LRC and I &£

Navy, Lynchburg. VA.

11/6/87

All holders of OLs

or CPs for nuclear

power reactors.

11/4/87

All holders of OLs

or CPS for boiling

water reactors (BWRs).

OL

• Operating Licensa

CP

• Construction Permit

UNITED STATES

UCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, $300

FIRSTCLASSMAF1

IP0STA8t & Fasa PAID

USNRCJ

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IN 87-63 December 9, 1987 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

Sanford Israel, AEOD

(301) 492-4437 Attachment:

List of Recently Issued NRC Information Notices

CA E S)

T.M.NOVAK DATED OCTOBER 7, 1987)

(TRANSMITTED BY MEMORANDUM TO C.E.ROSSI FROM

• SEE PREVIOUS CONCURRENCES

• OGCB:DOEA:NRR *ROAB:DSP:AEOD

JGuillen

SIsrael

11/06/87

11/06/87

• PPMB:ARM

TechEd

11/06/87

• C/OGCB: DOEA:NRR

CHBerlinger

11/17/87

4'12

12/B5/81

4

IN 87-XX

November xx, 1987 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

Sanford Israel, AEOD

(301) 492-4437 Attachment: List of Recently Issued NRC Information Notices

OA ache

• SEE PREVIOUS CONCURRENCES

• OGCB:DOEA:NRR *ROAB:DSP:AEOD

JGuillen

SIsrael

11/06/87

11/06/87

• PPMB:ARM

TechEd

11/06/87 C/OGCB2E:NRR

CHBerlinger

11/7/187 D/DOEA:NRR

CERossi

11/ /87

IN 87-XX

November xx, 1987 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

Sanford Israel, AEOD

(301) 492-4437 Attachment: List of Recently Issued NRC Information Notices

OGC

A~RR

JGu i~

II/L I7 Abk SP :AEOD

SIsrael

II/V /87 PPMB:ARM4/

TechEdaU

11/(1/87 C/OGCB:DOEA:NRR

CHBerlinger

11/ /87 D/DOEA:NRR

CERossi

11/ /87