Information Notice 1992-71, Partial Plugging of Suppression Pool Strainers at a Foreign BWR

Partial Plugging of Suppression Pool Strainers at a Foreign BWR

ML031200327
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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	09/30/1992
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-92-071, NUDOCS 9209290014
Download: ML031200327 (7)

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 September 30, 1992 NRC INFORMATION NOTICE 92-71: PARTIAL PLUGGING OF SUPPRESSION POOL

STRAINERS AT A FOREIGN BWR

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

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

notice to alert addressees to the potential-for loss of emergency core cooling

systems (ECCS) that was identified as a result of an event at a Swedish

boiling water reactor (BWR). It is expected that recipients will review thel

information for applicability to their facilities and consider actions, as

appropriate, to avoid similar problems. However, suggestions contained in

this information notice are not NRC requirements; therefore, no specific

action or written response is required.

Description of Circumstances

On July 28, 1992, Sydkraft AB, the utility licensed by the Swedish regulatory

agency for the BarsebAck nuclear power plant, was restarting Unit 2 after the

annual outage. While the reactor was at 1 or 2 percent power and at 435 psi, a leaking pilot valve caused a safety valve for the reactor vessel to open.

This valve discharges directly to the drywell. Reactor scram, high pressure

safety injection, core spray, and containment spray systems initiated

automatically in response to the event. Steam from the open safety valve, impinging on thermally-insulated equipment, dislodged 440 pounds of metal- jacketed, mineral wool. An estimated 220 pounds of insulating material was

washed into the suppression pool. Two of five strainers on the suction side

of the ECCS pumps were in service and became partially plugged with mineral

wool. Plugging caused pressure to decrease significantly across the strainers

and caused indications of cavitation in one pump in about an hour after the

event began. The operators successfully back flushed the strainers and shut

down the reactor without additional problems.

Discussion

In the safety analysis for Unit 2 of the Barsebdck plant, the licensee

concluded that the strainers would not require back flushing during the first

10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> after a loss-of-coolant accident. Because of the event of July 28, the Swedish regulatory agency required Barseback Unit 2 and four other units

of similar design to remain shut down until this problem is resolved.

9209290014 e

III

IN 92-71 September 30, 1992 This event at BarsebAck is directly applicable

by the NRC. That study evaluated the potential to an earlier study conducted

insulation to form debris and to be drawn to for displaced thermal

the study are documented in "Containment Sump the sump screen. The results of

Revision 1, dated March 1984. The NRC concluded Performance," NUREG-0897, that the risk associated with

the sump clogging concern did not warrant backfitting

However, based on the Barsebdck event, this of domestic plants.

conclusion is being reevaluated.

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

Reactor Regulation (NRR) project manager. Office of Nuclear

(arles si, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact: Robert L. Dennig, NRR

(301) 504-1156 Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 92-71 September 30, 1992 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

92-70 Westinghouse Motor-Operated 09/25/92 All holders of OLs or CPs

Valve Performance Data for nuclear power reactors.

Supplied to Nuclear Power

Plant Licensees

92-69 Water Leakage from Yard 09/22/92 All holders of OLs or CPs

Area Through Conduits for nuclear power reactors.

Into Buildings

91-29, Deficiencies Identified 09/14/92 All holders of OLs or CPs

Supp. 1 During Electrical Dis- for nuclear power reactors.

tribution System Func- tional Inspections

92-68 Potentially Substandard 09/10/92 All holders of OLs or CPs

Slip-On, Welding Neck, for nuclear power reactors.

and Blind Flanges

92-67 Deficiency in Design 09/10/92 All holders of OLs or CPs

Modifications to Ad- for nuclear power reactors.

dress Failures of

Hiller Actuators Upon

A Gradual Loss of

Air Pressure

92-66 Access Denied to NRC 09/01/92 All holders of OLs or CPs

Inspectors at Five Star for nuclear power reactors

Products, Inc. and and all recipients of

Construction Products NUREG-0040, "Licensee, Con- Research, Fairfield, tractor and Vendor Inspec- Connecticut tion Status Report" (White.

Book).

92-65 Safety System Problems 09/03/92 All holders of OLs or CPs

Caused by Modifications for nuclear power reactors.

That Were Not Adequately

Reviewed and Tested

92-64 Nozzle Ring Settings 08/28/92 All holders of-OLs or CPs

on Low Pressure Water- for nuclear power reactors.

Relief Valves

OL = Operating License

CP = Construction Permit

K> <YIN 92-71 September 30, 1992 This event at Barseback is directly applicable to an earlier study conducted

by the NRC. That study evaluated the potential for displaced thermal

insulation to form debris and to be drawn to the sump screen. The results of

the study are documented in "Containment Sump Performance," NUREG-0897, Revision 1, dated March 1984. The NRC concluded that the risk associated with

the sump clogging concern did not warrant backfitting of domestic plants.

However, based on the BarsebAck event, this conclusion is being reevaluated.

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 Office of Nuclear

Reactor Regulation (NRR) project manager.

Original Signed by

Charles E. Rossi

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical con itact: Robert L. Dennig, NRR

(301) 504-1156 Attachment: List of Recently Issued NRC Information Notices

Document Name: 92-71.IN

• SEE PREVIOUS CONCURRENCES

DO *C/OGCB:DOEA:NRR*RPB:ADM

C GHMarcus TechEd

09/; 92 09/28/92 09/24/24

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NRCIN 92-XX

September xx, 1991 documented in "Containment Sump Performance," NUREG-0897, Revision 1, dated March

1984. The NRC concluded that the risk associated with the sump clogging concern

did not warrant backfitting of domestic plants. However, based on the Barseback

event and NUREG-0897, Revision 1, this conclusion is being reevaluated.

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

have any question about the information in this notice, please contact the

technical contact listed below or the appropriate Office of Nuclear Reactor

Regulation project manager.-

Charles E. Rossi, Director

Division of Operational

Events Assessment

Office of Nuclear Reactor Regulation

Technmical Contact: Robert L. Dennig, NRR

(301) 504-1156 Attachment:

1. List of Recently Issued Information Notices

• See previous page for concurrence.

CONCURRENCE:

OEAB TECH EDITORS SC:OEAB :SPLB BC:OEAB BC:OGCB

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V- IN 92-71 September 29, 1992 This event at Barseback is directly applicable to an earlier study conducted

by the NRC. That study evaluated the potential for displaced thermal

insulation to form debris and to be drawn to the sump screen. The results of

the study are documented in "Containment Sump Performance," NUREG-0897, Revision 1, dated March 1984. The NRC concluded that the risk associated with

the sump clogging concern did not warrant backfitting of domestic plants.

However, based on the Barsebdck event and NUREG-0897, Revision 1, this

conclusion is being reevaluated.

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 Office of Nuclear

Reactor Regulation (NRR) project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical con tact: Robert L. Dennig, NRR

(301) 504-1156 Attachment: List of Recently Issued NRC Information Notices

Document Name: 92-71.IN

• SEE PREVIOUS CONCURRENCES

DOEA:NRR C/OGCB:DOEA:NRR*RPB:ADM

CERossi GHMarcus)GLK- TechEd

09/ /92 09/,S/92 &o 09/24/24

• OEAB:DOEA:NRR*SC/OEAB:DOEA:NRR *C/OEAB:DOEA:NRR*C/SPLB:DST:NRR CEP/OIP

RWWoodruff RLDennig AChaffee CEMcCracken AKenneke

09/24/92 09/24/92 09/ /92 09/ /92 09/ /92

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NRCIN 92-XX

September xx, 1991 technical contact listed below or the appropriate Office of Nuclear Reactor

Regulation project manager.

Charles E. Rossi, Director

Division of Operational

Events Assessment

Office of Nuclear Reactor Regulation

Robert L. Dennig, NRR

(301) 504-1156 Attachment:

1. List of Recently Issued Information Notices

CONCTRRENCE:

OEAB W' TECH EDITOR BC: SPLU BC: OEKB BC: KCB

RWWoodruff irgaln Pl CEMcCracken AEChaffee GHMarcus

09 5/92 09/2,1/92 09/; f92 09/ /92 09/ /92 09/ /92 D: DOEA

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