Information Notice 1986-99, Degradation of Steel Containment

Degradation of Steel Containment

ML031250248
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, 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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date:	12/08/1986
From:	Jordan E NRC/IE
To:
References
IN-86-099, NUDOCS 8612050463
Download: ML031250248 (4)

SSINS No.: 6835 IN 86-99 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 December 8, 1986 IE INFORMATION NOTICE NO. 86-99: DEGRADATION OF STEEL CONTAINMENTS

Addressees

All nuclear power reactor facilities holding an operating license or a con- struction permit.

Purpose

This notice is to provide recipients with current information of a potentially

significant safety problem regarding the degradation of a steel containment

resulting from corrosion. It is expected that recipients will review this

information for applicability to their facilities and consider actions, as

appropriate, to promptly recognize or prevent a similar problem from occurring.

However, suggestions contained in this notice do not constitute NRC requirements;

therefore, no specific action or written response is required.

Description of Circumstances

The Oyster Creek Nuclear Generating Station first discovered water in the gap

between the boiling-water-reactor drywell and the concrete shield in 1980 and

began investigation of the cause in 1983. It appeared that the collection of

water varied from a few drops to 2 gallons per minute, depending on whether

the unit was in operation or an outage for refueling. During the spring and

summer of 1986, the licensee planned work to identify and eliminate this water

problem. The bellows at the drywell to cavity seal was repaired and a gasket

was replaced, thus stopping the leakage. Since the bellows is located at the

top of the drywell and the region above the bellows is flooded during refueling, it would explain why leakage was high during refueling and low during operation.

To determine if the water in the gap had caused damaged to the steel contain- ment, the licensee measured the wall thickness, using an ultrasonic testing (UT)

technique at two elevations. The 51-ft level near the drywell seal was sound, but there appeared to be loss of metal on the gap side at the 11-ft 3-in. level

immediately above the concrete floor. In this area, the gap is packed with

sand and contains five equally spaced drain pipes (see attached Figure 1). A

total of 143 measurements were made at this level and 60 indicated a reduction

in thickness of more than 1/4 in. from the drawing thickness of 1.154 in.

These readings were found throughout seven of the ten downcomer bays. The

licensee plans to cut the steel containment and remove about 12 samples to

confirm and evaluate the corrosion damage.

8612050463

IN 86-99 December 8, 1986 The licensee plans to remove a section of the drain pipe to perform a visual

examination of the outside of the drywell. Wipe samples will be taken from

several areas and a chemical analysis will be performed. Sand samples will

be taken adjacent to the core holes and will be analyzed for chemicals, bac- teria, and water composition. Some channels are being cut in the concrete

floor that is inside the drywell to provide access for further UT examination

of the containment-sand interface.

Discussion:

The purpose of the sand is to act as a cushion and allow expansion of the

drywell during operation. The steel containment is in contact with sand in

those areas where corrosion has been detected. The containment material is

ASTM A-212 Grade B carbon steel plate. The licensee stated that the outside

surface was protected with a red lead coating from above the drywell down to

about the 10-ft. level, which means that the interface between the lead paint

and the unprotected steel was in contact with wet sand. Red lead protects

steel by providing a stable and impenetrable surface, but the steel is sacri- ficial with respect to the lead in dilute, acidic water conditions.

It is possible that condensation during initial construction, moisture pickup

through the drain line during operation, and the leaking bellows wetted the

sand, thereby causing corrosion of the containment steel plates. During con- struction, water was seen running down the outside of containment into the

sand. The five drain lines, as well as other penetrations in the concrete

shield, are open during operation and would allow moist air to enter and rise

up the gap and later cool and condense as water. Water also was able to enter

the gap through the holes in the bellows during refueling until repairs were

made.

A related matter is discussed in IE Information Notice 86-35, "Fire in Com- pressible Material at Dresden Unit 3," where a large amount of water was used

to extinguish the slowly burning fire between the drywell and the concrete

shield. Oyster Creek uses different filler material.

The NRC is continuing to obtain and evaluate pertinent information. If spe- cific actions are required, an additional notification will be made.

No specific action or written response is required by this information

notice. If you have any questions about this matter, please contact the

Regional Administrator of the appropriate regional office or this office.

1dwardLJordan, Director

Division f Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Paul Cortland, IE

(301) 492-4175 Attachments:

1. Figure 1, Sketch of Possible Degraded Area

2. List of Recently Issued IE Information Notices

y

Attachment 1 IN 86-99 December 8, 1986 Sketch of Possible Degraded Areas

3 IN. ANNULAR SPACE

WITH FILLER MATFRtI&

pRYWELL

1.154 IN. DESIGN

THICKNESS

ELEVATION 11 FT.

ELEVATION 10 FT. 3

• CONCRETE. * *

OFLOORel

e4 *4 CONCRETEoo * 8 Oo

• uau°uo 0 *~ U,^ D ° /

4 DRAINAGE CHANNEL 4 A U(/ -v

4 / ,a q0

.

A WITH 4 IN. DIA. 00. ,04 SSAND FILLED DRAINkh o

a PIPE (EVERY OTHERW A <

DRYWELL VENT) & 4 Figure 1

Attachment 2 , . . . .

IN 86-99 December 8. 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information - Date of

Notice No. Subject Issue Issued to

86-21 Recognition Of American 12/4/86 All power reactor

Sup. 1 Society Of Mechanical facilities holding

Engineers Accreditation an O or CP

Program For N Stamp Holders

86-98 Offsite Medical Services 12/2/86 All power reactor

facilities holding

an OL or CP

86-97 Emergency Comaunications 11/28/86 All power reactor

System facilities holding

an OL or CP and fuel

facilities

86-96 Heat Exchanger Fouling Can 11/20/86 All power reactor

Cause Inadequate Operability facilities holding

Of Service Water Systems an OL or CP

86-95 Leak Testing Iodine125 11/14/86 All NRClicensees

Sealed Sources In ilx, Inc. authorized to use

Imaging Devices and Bone Lia1 Inc. imaging

Miners Analyzers devices

86-94 Hilti Contrete Expansion 11/6/86 All power reactor

Anchor Bolts facilities holding

an OL or CP

86-93 IE3 85-03 Evaluation Of 11/3/86 All power reactor

Motor-Operators Identifies facilities holding

Improper Torque Switch an OL or CP

Settings

86-82 Failures Of Scram Discharge 11/4/86 All power reactor

Rev. 1 Volume Vent And Drain Valves facilities holding

an OL or CP

86-92 Pressurizer Safety Valve 11/4/86 All PiR facilities

Reliability holding an OL or CP

OL

• operating License

CP

• Construction Permit

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