Information Notice 1988-28, Potential for Loss of Post-Loca Recirculation Capability Due to Insulation Debris Blockage

Potential for Loss of Post-Loca Recirculation Capability Due to Insulation Debris Blockage

ML031150681
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:	05/19/1988
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-88-028, NUDOCS 8805130108
Download: ML031150681 (6)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555

May 19, 1988 NRC INFORMATION NOTICE NO. 88-28:

POTENTIAL FOR LOSS OF POST-LOCA

-

RECIRCULATION CAPABILITY DUE TO

INSULATION DEBRIS BLOCKAGE

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is being provided to alert addressees to potential prob- lems regarding debris that could block containment emergency sump screens in a

pressurized water reactor (PWR) or- debris that could block emergency core spray

pump or residual heat removal pump strainers in a boiling water reactor (BWR).

It is expected that recipients will review the information for applicability to

their facilities and consider actionsi as appropriate, to avoid similar problems.

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 March 14, 1988, Pennsylvania Power & Light (the licensee for Susquehanna)

notified the U.S. Nuclear Regulatory Commission of a 10 CFR Part 21 reportable

item concerning deterioration of drywell Insulation and the potential for the

aluminum foil coating of the Insulation to block emergency core cooling system

(ECCS) strainers during a loss-of-coolant accident (LOCA).

While the unit was in a refueling outage, the licensee inspected the Susquehanna

Unit 2 drywell.

The licensee observed extensive delamination of the aluminum

foil coating on the surface of the fiberglass insulation used on valve bodies

and pipe hangers and in other areas that are awkward or difficult to Insulate.

The aluminum foil covering is i-mil thick and is bonded to the outer covering of

Alpha Maritex fiberglass cloth (style #2025/9480 HT) that is used as a covering

for Temp-Mat insulation. An upper-bound estimate is that 5000 square feet of

this insulation is used in more than 300 different locations within the drywell.

The licensee estimates that 50 percent of the insulation has undergone some de- gradation.

This is the first time the licensee has observed degradation to this

extent, although some degradation had been noticed earlier. A different insu- lation material is used at Susquehanna Unit 1, and no insulation delamination

has been observed at that unit. Alpha Associates, Inc. supplied the insulation

880

V.

-

IN 88-28 May 19, 1988 to the licensee through Bechtel. However, representatives of Alpha Associates, Inc., have indicated that other companies supply the same or similar insulation

and that its use may be widespread.

After the event at Susquehanna Unit 2, the licensee for Millstone Unit 1 reported, that In a worst-case scenario, the net positive suction head margin for ECCS

pumps could be compromised because of suction strainer blockage resulting from

LOCA-generated Insulation debris. At Millstone Unit 1, Temp-Mat Insulation is

used without a foil facing. In this case, the concern was that the fiberglass

cloth covering would be freed during a LOCA and migrate to the ECCS pump suction

strainers.

The licensee Is evaluating the feasibility of replacing the existing

strainers with strainers that have a larger area as a possible solution of the

problem of transported Insulation.

Discussion:

In PWRs the containment emergency sumps provide for the collection of reactor

coolant and chemically reactive spray solutions following a LOCA, thus serving

as water sources to effect long-term recirculation for residual heat removal

and containment atmosphere cleanup. In a BWR, the suppression pool serves as

the water source for effecting long-term recirculation cooling.

Debris, transported as a result of an event, can block sump debris interceptors

and-sumpoutlets, resultingAnd gradat~onorloss-of recirculation flow marginn--

At Susquehanna, the ECCS core spray pump suction screen has a cross-sectional

area of 18.3 square feet, while each residual heat removal pump suction screen

has a cross-sectional area of 43.8 square-ft. In comparison, the Insulation

covering that could block recirculation flow covers an area of several thousand

square feet.

However, the potential effect of insulation on sump performance is

plant specific. Thus, plant Insulation surveys, methods for estimating debris

generation and transport, debris transport experiments, and other information

have shown that the effects of debris-blockage depend on the types and quantities

of insulation used, the primary system layout within the containment, and post- LOCA recirculation flow rates.

The staff addressed similar concerns in resolving

Unresolved Safety Issue A-43, "Containment Emergency Sump Performance."

In parti- cular, the staff's technical findings concluded that a single generic solution is

not possible, but rather that the effects of debris blockage are governed by

plant-specific design features and post-LOCA recirculation flow requirements.

The NRC staff has investigated the buoyancy, transport, and headloss character- istics of reflective metallic insulation and construction materials and the

results are summarized in NUREG/CR-3616, "Transport and Screen Blockage Charac- teristics of Reflective Metallic Insulation Materials." Briefly, the tests

showed that thin metallic foils could be transported at low flow velocities

and that flow blockage could occur at the lower portion of the screen.

IN 88-28 May 19, 1988 Although the exact cause of the degradation of the foil covering on the insu- lation at Susquehanna is not known, the causes may include temperature, humidity, and the effects of radiation on the neoprene-type adhesive used in the bonding

process.

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

If you have any questions about this matter, please contact the technical con- tact listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Dlrector

Division of Operational Events Assessment

L. Zerr, NRR

(301) 492-1177 Attachment:

List of Recently Issued NRC Information Notices

4 l

41."

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Attachment

TN 88-78 may 19, 1988 LIST OF RECENTLY ISSUED

NRC INFOTRATTON NOTICES

notice No.

88-27

85-35.

Supplement I

88-2e

88-25

88-2'

eP-73

88-22

88-21 Subject

Oeficient Electrical

Terminations Identified

In Safety-Related

Components

Failure of Air Ch eck

Valves to Seat

Falsified Pro-Employment

Screening Records

Ninimum Edge Distance for

Expansion Anchor Bolts

Failures of Air-Operated

Valves Affecting Safety-

Reloted Systems

Potential for Gas Binding

of H1gh-Pressure Safety

Injection Pumps During a

Loss-of-Coolant Accident

Disposal of Sludge frim

Onsite Sewage Treatment

Facilities at Nuclear

Power Stations

Inadvertent Criticality

Events at Oskarshamn

Po ert Pat s h l ar

Power Plants

Vats of

Issuance

5/18/88

5/17/88

5/16/88

5/16/88

5/13/e8 S/12188

5/12/88

5/9/88 Issued to

All holders of OLs

or CPs for nuclear

power reactors.

All holders of OLs

or CPs for nuclear

power reactors.

All holders of OLs

or CPs for nuclear

power reactors and

all major fuel

facility licensees.

All holders of OLs

or CPs for nuclear

power reactors.

All holders of OLs

or CPs for nuclear

power reactors.

All holders of OLs

or CPs for PWRs.

All holders of OLs

or CPs for nuclear

power reactors.

All holders of OLs

or CPs for nuclear

-Pow~e-ctor9.

-

-

OL

• Operating License

CP

• Construction Permit

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, $300

FIRST CLASS MAIL

POSTAGE & FEES PAIO

USNRC

PERMIT No. 0G 7

IN 88-28 May 19, 1988 Although the exact cause of the degradation of the foil covering on the insu- lation at Susquehanna is not known, the causes may include temperature, humidity, and the effects of radiation on the neoprene-type adhesive used In the bonding

process.

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

If you have any questions about this matter, please contact the technical con- tact listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Director

Division of Operational Events Assessment

L. Zerr, NRR

(301) 492-1177 Attachment:

List of Recently Issued NRC Information Notices

• EAB:NRR

LZerr:db

5/6/88

• EAB:NRR

PBaranowsky

5/12/88

• C: EAB:NRR

WLanning

5/12/88

• TECH:ED

• C:OGCB:NRR

CHBerlinger

/ /88

/

/88

5//388

IN 88-XX

May , 1988 Although the exact cause of the degradation of the foil covering on the in- sulation at Susquehanna is not known, the causes may include temperature, humidity, and the effects of radiation on the neoprene-type adhesive used in

the bonding process.

Licensees who use Alpha Maritex or similar insulation coverings inside the

containment are alerted to that delamination of exterior coatings could occur, especially if large amounts of this type of insulation have been used.

No specific

If you have

tact listed

office.

action or written response is required by this information notice.

any questions about this matter, please contact the technical con- below or the Regional Administrator of the appropriate regional

Charles E. Rossi, Director

Division of Operational Events Assessment

L. Zerr, NRR

(301) 492-1177 Attachment: List of Recently Issued NRC Information Notices

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