Information Notice 1996-10, Potential Blockage by Debris of Safety System Piping Which Is Not Used During Normal Operation or Tested During Surveillances

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Potential Blockage by Debris of Safety System Piping Which Is Not Used During Normal Operation or Tested During Surveillances
ML031060270
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, 03500354, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date: 02/13/1996
From: Crutchfield D
Office of Nuclear Reactor Regulation
To:
References
IN-96-010, NUDOCS 9602070259
Download: ML031060270 (11)
v • d • e


14 UNITED STATES

NUCLEAR REGULATORY COMMISSION

  • ' OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 February 13, 1996 NRC INFORMATION NOTICE 96-10: POTENTIAL BLOCKAGE BY DEBRIS OF SAFETY SYSTEM

PIPING WHICH IS NOT USED DURING NORMAL

OPERATION OR TESTED DURING SURVEILLANCES

Addressees

nuclear power

All holders of operating licenses or construction permits for

reactors.

Purpose

information

The U.S. Nuclear Regulatory Commission (NRC) is issuing this by debris, of

notice to alert addressees to the potential for the blockage, safety system piping in boiling-water reactors (BWRs) or pressurized-water

the information

reactors (PWRs). It is expected that recipients will review as appropriate, to

for applicability to their facilities and consider actions, this information

avoid similar problems. However, suggestions contained in or written

notice are not NRC requirements; therefore, no specific action

response is required.

notice was the

The source of the information--contained in this information Economic Cooperation

incident reporting system (IRS) of the Organization for

Agency. The Spanish regulatory staff

and Development Nuclear Energy

authorized public dissemination of this information.

Description of Circumstances

are usually

During refueling outages at PWRs in Spain, containment sumps inlet pipes

inspected visually to ensure that the sump, screens, and suction

and that the

in the emergency core cooling system (ECCS) are free of debris, sumps screens are not corroding.

its containment

In November 1993, the licensee of a PWR in Spain inspected it unusual

sumps during outage surveillance. The licensee did not consider to the sump

for the sumps to contain water because there is some leakage the ECCS borated

during functional testing of a three-way valve which connects the individual

tanks with the containment sumps. However, in this case, dirty, so he had it

inspecting the sump believed that the water was unusually that three of the

siphoned off. Once the water had been removed, he could seefor the ECCS. A

four sumps had debris in the bottom below the suction pipe two of the four

closer examination of the ECCS suction lines revealed that

960pt70259

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iLR I

fi

IN 96-10

February 13, 1996 ECCS lines taking suction from the sumps were partially blocked by debris.

One of the two partially blocked lines had almost half the flow area of the

pipe blocked off; the other was blocked less. It is believed that the debris

had been there since the plant was commissioned, and that this event demon- a

strated a significant failure of the surveillance program. Figure 1 shows

cross-sectional view of the sump and indicates where the debris was found.

Upon further review, the Spanish regulators noted that there are no technical

specification requirements to inspect the piping from the containment sumps to

the ECCS to ensure that it is clear of any obstruction by debris. It was also

noted that many sections of piping on safety systems in both PWRs and BWRs are

only called upon to function during accident conditions, and are not used

during normal operation or tested during functional surveillance tests.

Confidence in the operability of these pipes was based on the fact that they

had not been used since they were tested before plant startup.

In response to the event, Spanish regulators issued a generic letter which

asked their licensees to take four actions. First, they were requested to

establish administrative controls, including a locking device, on the sump

hatch and on any other removable sump parts (PWRs only). Second, they were

requested to inspect the containment sump and the piping between the sump and

the first ECCS valve which separates the part of the system that is

functionally tested from the part that is not (PWRs only). Third, they were

requested to inspect the sump every refueling outage. If more than 1 kilogram

of debris was found in the sump, licensees were then requested to reinspect

the piping between the sump and the functionally tested portion of the ECCS

(PWRs only). And fourth, licensees were requested to identify piping segments

of safety systems through which flow does not occur, either during normal

operation or during surveillance testing, and to analyze whether there are

reasonable guarantees that no obstruction exists (BWRs and PWRs). Examples of

the piping segments that would require this analysis are crossover piping from

the essential service cooling system to the auxiliary feedwater system (PWRs),

relief valve discharge piping (PWRs), low-pressure coolant injection suction

piping from the condensate storage tank (BWRs), and crossover connections

between low-pressure coolant injection trains (BWRs).

Discussion

The licensee in this case concluded that the safety significance of this event

was small because the partial blockage of the lines would not prevent the ECCS

from providing sufficient core cooling. However, it was also noted that some

of the debris could have been entrained in the water flow and could have

detrimental effects on other parts of the system (e.g., pump and valve

components and heat exchangers). The licensee initial corrective actions

(prior to issuance of the generic letter) included cleaning up the sumps and

. -. . 4 v>

IN 96-10

February 13, 1996 suction lines, locking sump hatches, and establishing administrative controls.

These corrective actions address the root cause of the presence of debris in

the sump and suction line.

It has been noted in previous NRC generic communications that debris could

prevent such safety systems as the ECCS from functioning reliably throughout a

design-basis accident. These previous NRC communications have dealt with the

potential for debris to clog the ECCS strainers (operational debris, loss-of- coolant-accident-generated debris, or a combination of both). The debris

described in this information notice is another example of the potential

fordebris to impair the operation of safety systems. Although the licensee in

this case has determined that the debris found in its sump was insufficient to

prevent the ECCS from performing its safety function, such debris could damage

individual components of the safety system (e.g., pumps), degrade system

performance, or (in combination with the debris generated during a loss-of- coolant accident) could accelerate a loss of net positive suction head for the

ECCS pumps.

Related Generic Communications

Cooling Suction Strainers," dated May, 11, 1993, and February 18, 1994.

Cooling Systems Caused by Foreign Material Blockage," dated

December 23, 1992.

Strainers at a Foreign BWR," dated September 30, 1992.

and Incorrect Screen Configurations," dated November 21, 1989.

Piping Systems," dated November 16, 1988.

Recirculation Capability Due to Insulation Debris Blockage," dated

May 19, 1988.

K>

IN 96-10

February 13, 1996 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.

e s .Crut r

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Eric J. Benner, NRR

(301) 415-1171 Internet:ejbl@nrc.gov

Robert B. Elliott, NRR

(301) 415-1397 Internet:rbe@nrc.gov

Attachments:

1. Figure 1: Scheme of Containment Sump

2. List of Recently Issued NRC Information Notices

4~N 5ZJ*4 rj

.I

FIGURE 1. Scheme of containment sump

Strainer Inspection hatch Concrete

.

- A A -- A

A _

A A A

a CO D (Dl

03 CD C+(

- n al :t

-a),

(D I a)

to :r '

  • -1I

a 01-= o

'-< 0 CD

(0)

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Attachment 2 IN 96-10

February 13, 1996 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

96-09 Damage in Foreign Steam 02/12/96 All holders of OLs or CPs

Generator Internals for pressurized water

reactors

96-08 Thermally Induced Pres- 02/05/96 All holders of OLs or CPs

sure Locking of a High for nuclear power reactors

Pressure Coolant Injec- tion Gate Valve

96-07 Slow Five Percent Scram 01/26/96 All holders of OLs or CPs

Insertion Times Caused for boiling water reactors

By Viton Diaphragms in

Scram Solenoid Pilot

Valves

96-06 Design and Testing 01/25/96 All holders of OLs or CPs

Deficiencies of Tornado for nuclear power reactors

Dampers at Nuclear Power

Plants

96-05 Partial Bypass of Shutdown 01/18/96 All holders of OLs or CPs

Cooling Flow from the for boiling water reactors

Reactor Vessel

96-04 Incident Reporting Require- 01/10/96 All radiography licensees

ments for Radiography and manufacturers of radio- Licensees graphy equipment

96-03 Main Steam Safety Valve 01/05/96 All holders of OLs or CPs

Setpoint Variation as a for nuclear power reactors

Result of Thermal Effects

OL = Operating License

CP = Construction Permit

<I

IN 96-10

February 13, 1996 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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Eric J. Benner, NRR

(301) 415-1171 Internet:ejbl@nrc.gov

Robert B. Elliott, NRR

(301) 415-1397 Internet:rbe@nrc.gov

Attachments:

1. Figure 1: Scheme of Containment Sump

2. List of Recently Issued NRC Information Notices

Reviewed and concurred on by tech editor 12/18/95 IN faxed to Jose Villadoniga of Consejo De Seguiridad on 2/6/96.

IN concurred on by Bill Upshaw of International Programs on 1/4/95 Reviewed by Mike Cullingford on 2/6/96.

  • See previous concurrence

DOCUMENT NAME: 96-1O.IN

To receive a copy of this document, Indicate In the box: AC" - Copy without enclosures 'E' - Copy with enclosures "N' - No copy

OFFICE TECH CONTS I SCSB:DSSA I PECB:DRPM I D:4PM IP

NAME EBenner* CBerlinger* AChaffee* D4 d

DATE 01/03/96 01/16/96 01/18/96 02/ /96 OFFICIAL RECORD COPY

IN 96-xx

February xx, 1996 potential for foreign material to impact operation of safety systems.

Although the licensee in this case has determined that the debris found in

their sump was insufficient to prevent the ECCS from performing its safety

function, such this debris could damage individual components of the safety

system (e.g., pumps), degrade system performance or, in combination with the

debris generated during a loss-of-coolant accident, could accelerate a loss of

net positive suction head for the ECCS pumps.

Related Generic Communications

NRC Bulletin 93-02 and Supplement 1: 'Debris Plugging of Emergency Core

Cooling Suction Strainers," dated May, 11, 1993, and February 18, 1994.

Cooling Systems Caused by Foreign Material Blockage," dated

December 23, 1992.

Strainers at a Foreign BWR," dated September 30, 1992.

and Incorrect Screen Configurations," dated November 21, 1989.

Piping Systems," dated November 16, 1988.

Recirculation Capability Due to Insulation Debris Blockage," dated

May 19, 1988.

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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Eric J. Benner, NRR

(301) 415-1171 Internet: EJBINRC.GOV

Robert B. Elliot, NRR

(301) 415-1397 Internet: RBE@NRC.GOV

Attachments:

1. Figure 1: Scheme of Containment Sump

2. List of Recently Issued NRC Information Notices

Reviewed and concurred on by tech editor 12/18/95 IN concurred on by Bill Upshaw of International Programs on 1/4/95

  • See previous concurrence

DOCUMENT NAME: G:\EJB1\FOREIGN.IN

To receive a copy of this document, Indicate hi the box: 'C' . Copy without enclosures 'E' = Copy with enclosures 'N' - No copy

OFFICE PECB:DRPM I C SC/PECB:DRPM I N C SCSB:DSSA I E C/PECB:DRPM C DRPM I

NEBenner* EGoodwin* CBerlinger* IAChaffee* DCrutchfield

DATE 1/3/96 1/4/96 01/16/96 01/18/96 01/ /96 OFFICIAL RECORD COPY hID PA..

ANr96-xx

January xx, 1996 example of the potential for foreign material to impact operation the of safety

systems. Although the licensee in this case has determined that debris

found in their sump was insufficient to prevent the ECCS from performing its

safety function, it is important to realize that this debris could damage

individual components of the safety system (e.g., pumps), degradea system loss-of- performance or, in combination with the debris generated during

coolant accident, could accelerate a loss of net positive suction head for the

ECCS pumps.

Related Generic Communications

Cooling Systems Caused by Foreign Material Blockage"

Cooling Suction Strainers"

Strainers at a Foreign BWRN

and Incorrect Screen Configurations"

Piping Systems"

Recirculation Capability Due to Insulation Debris Blockage"

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

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

one of the technical contacts listed below.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Eric J. Benner, NRR

(301) 415-1171 Internet: EJBINRC.GOV

Robert B. Elliot, NRR

(301) 415-1397 Internet: RBE@NRC.GOV

Reviewed and concurred on by tech editor 12/18/95 IN concurred on by Bill Upshaw of International Programs on 1/4/95

  • See previous concurrence

DOCUMENT NAME: G:\EJB1\FOREIGN.IN No copy

To receive acopy of this document. Indicate In the box: wC" - Copy without enclosures 'E' - Copy with enclosures N -

IPECB:DRPM I C SC/PECB:DRPM I N C/SCSB:DSSA I E C/PECE PM C DRPM I

OFFICE

NAME IEBenner* IEGoodwin* CBerlinger* ACha %DCrutchfield

DATE 1/3/96 1/4/96 01/16/96 01/f /96 J-% 01/ /96 OFFICiAL RECORD COPY

December xx, 1995 example of the potential for foreign material to impact operation of safety

systems. Although the licensee in this case has determined that the debris

found in their sump was insufficient to prevent the ECCS from performing its

safety function, it is important to realize that this debris could damage

individual components of the safety system (e.g., pumps), degrade system

performance or, in combination with the debris generated during a loss-of- coolant accident, could accelerate a loss of net positive suction head for the

ECCS pumps.

Related Generic Communications

Cooling Systems Caused by Foreign Material Blockage"

Cooling Suction Strainers'

Strainers at a Foreign BWRE

and Incorrect Screen Configurations"

Piping Systems"

Recirculation Capability Due to Insulation Debris Blockage"

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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Tech nical contact: Eric J. Benner, NRR

(301) 415-1171 2/s77 /B~77A.

E-mail: EJB1@NRC.GOV

Robert B. Elliot, NRR

(301) 415-1397 E-mail: RBE@NRC.GOV

Reviewed and concurred on by tech editor 12/18/95 IN concurred on by Bill Upshaw of International Programs on 1/4/95

  • See previous concurrence

DOCUMENT NAME: G:\EJB1\FOREIGN.IN

Tn rvaei a*nnv documnnt. Indlenta In the box: 'C'

nf Mthis = Coov without enclosures 'E' - Coov with enclosures 'N' - No copy

I

OFFICE

'NAME

Contacts

EEGoodwin*

.C SC/PECB:DRPM I N

}CB[I 1 CC/SCSB:gA

I EC/PECB:DRPM

AChaffee

I lC/RPM

DCrutchfield

DATE 1/3/96 1/ /96 1/4/96 96 l 017e/ /96 01/ /96 OFFICIAL RECORD COPY

\t95-xx

December xx, 1995 example of the potential for foreign material to impact operation of safety

systems. Although the licensee in this case has determined that the debris

found in their sump was insufficient to prevent the ECCS from performing its

safety function, it is important to realize that this debris could damage

individual components of the safety system (e.g., pumps), degrade system

performance or, in combination with the debris generated during a loss-of- coolant accident, could accelerate a loss of net positive suction head for the

ECCS pumps.

Related Generic Communications

Cooling Systems Caused by Foreign Material Blockage"

Cooling Suction Strainers"

Strainers at a Foreign BWR"

and Incorrect Screen Configurations"

Piping Systems"

Recirculation Capability Due to Insulation Debris Blockage"

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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Eric J. Benner, NRR

(301) 415-1171 E-mail: EJBINRC.GOV

Robert B. Elliot, NRR

(301) 415-1397 E-mail: RBE@NRC.GOV

Reviewed and concurred on by tech editor 12j18/95 Use of Spanish documentation for IN approved by Bill Upshaw of International

Programs on 1/3/95 DOCUMENT NAME: G:\EJB1\FOREIGN.IN

To receive a copy of this document, indicate Inthe box: "C" *= Copy without enclosures 'E" =Copy with enclosures 'N" - No copy

OFFICE PECB:DRPM SC/PECB:DRPM I C/SCSB:DSSA I -C/PECB:DRPM l C/DRPM Il

INAME EBenner ith5 IEGoodwink,. ICBerlinger AChaffee DCrutchfield

DATE 01/1 /96 U 01/ /96 101/ /96 01/ /96 01/ /96 OFFICIAL RECORD COPY


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