Information Notice 1992-35, Higher than Predicted Erosion/Corrosion in Unisolable Reactor Coolant Pressure Boundary Piping Inside Containment at a Boiling Water Reactor

Higher than Predicted Erosion/Corrosion in Unisolable Reactor Coolant Pressure Boundary Piping Inside Containment at a Boiling Water Reactor

ML031200365
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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	05/06/1992
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-92-035, NUDOCS 9205010009
Download: ML031200365 (5)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 May 6, 1992 NRC INFORMATION NOTICE 92-35: HIGHER THAN PREDICTED EROSION/CORROSION IN

UNISOLABLE REACTOR COOLANT PRESSURE BOUNDARY

PIPING INSIDE CONTAINMENT AT A BOILING

WATER REACTOR

Addressees

power

All holders of operating licenses or construction permits for nuclear

reactors.

Purpose

notice

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

to alert addressees to erosion/corrosion rates that could be higher

piping inside

predicted in certain unisolable reactor coolant pressure boundary that recip- the containment drywell at boiling water reactors. It is expected

and

ients will review the information for applicability to their facilities sugges- consider actions, as appropriate, to avoid similar problems. However, therefore, tions contained in this information notice are not NRC requirements;

no specific action or written response is required.

Description of Circumstances

performed

The Pennsylvania Power and Light Company (the licensee) recently Station, Unit

erosion/corrosion inspections at the Susquehanna Steam Electric

unexpectedly high rate of erosion/corrosion in

1, and may have identified an 1). Erosion

certain main feedwater (FW) piping inside containment (Attachment portion

of this portion of FW piping is of particular concern since this

cannot be isolated from the reactor vessel, and erosion/corrosion inspection

strategies may not direct attention to that part of the FW system.

the

When the licensee began operating the unit commercially in June 1982, current

nominal wall thickness for the pipe was about 0.688 inch. During the

refueling outage, wall thinning was found in one of the 20 inch by 12 inch 12 reducing tee risers approximately 10 inches downstream from the tee During in the

pipe weld. the

inch pipe section, immediately above a circumferential

had measured the pipe

previous refueling outage (18 months ago) the licensee

wall as 0.619 inch thick at that location. During the current refueling

outage, the licensee measured a thickness of 0.521 inch at the same location. of that

The licensee measured a thickness of 0.482 inch within about 2 inches of 0.440

location. The licensee calculated a minimum allowable wall thickness

indicated

inch for that portion of FW pipe. Previous experience and models had the most

an erosion wear rate of no more than 0.085 inch each cycle. However,

9205010009 Ar& EC 9 / /JA J20'o

/i'-'-

IN 92-35 May 6, 1992 recent measurement indicates a higher wear rate that may be greater than 0.100

inch each cycle.

The licensee evaluated the data for the FW system and determined that continued

operation could not be justified for another fuel cycle. Therefore, the

licensee repaired, rather than replaced, the FW pipe in accordance with Section

XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure

Vessel Code.

Discussion

The licensee determined that although it had expected to find erosion/corrosion

at this location, the magnitude of wall thinning exceeded expectations. The

licensee is continuing its investigation to determine the root cause of the

unexpected erosion/corrosion rate.

Related Generic Communications

Following a pipe rupture at the Surry Power Station in 1986, the NRC issued

Bulletin 87-01, "Thinning of Pipe Walls in Nuclear Power Plants," July 9, 1987.

In this bulletin, the staff requested licensees and applicants to inform the

NRC about their programs for monitoring the wall thickness of carbon steel

piping in both safety-related and nonsafety-related high energy fluid

systems.

In 1989, following an audit of the erosion/corrosion programs at 10 plants, the NRC issued Generic Letter (GL) 89-08, "Erosion/Corrosion-Induced Pipe Wall

Thinning," May 2, 1989. In this generic letter, the staff requested licensees

and applicants to implement long term erosion/corrosion monitoring programs.

The staff made this request to obtain assurances that the addressees had imple- mented procedures or administrative controls to maintain the structural integrity

of all carbon steel systems carrying high energy fluids.

The NRC also issued several information notices on the subject of erosion/

corrosion.

IN 92-35 May 6, 1992 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 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 contacts: K. I. Parczewski, NRR S. Barber, Region I

(301) 504-2705 (717) 542-2134 David Gamberoni, NRR John White, Region I

(301) 504-1171 (215) 337-5114 Attachments:

1. Feedwater System Erosion/Corrosion Location

2. List of Recently Issued NRC Information Notices

II*

REACTOR REACTOR

REACTOR

VESSEL VESSEL VESSEL

24' X 12- FLOW

l -

20 X 12'

REDUCING

REDUCING

TEE

o- I A -

r--,

1, I I--O l lI 7

20- 24 X 20- 24-

12- 20- X 12'

REDUCER REDUCER

"BP

FEEDWATER

LINE

EROSION/

CORROSI ON

ZONE

1 I FLOW

20" X 12"

REDUCING

TEE

FLOW (D 'OOb

co rr

'0 r-%.

FEEDWATER SYSTEM EROSION/CORROSION LOCATION "-I"

Attachment 2 IN 92-35 May 6, 1992 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

92-34 New Exposure Limits for 05/06/92 All licensees whose opera- Airborne Uranium and tions can cause airborne

Thorium concentrations of uranium

and thorium.

92-33 Increased Instrument 04/30/92 All holders of OLs or CPs

Response Time When for nuclear power reactors.

Pressure Dampening

Devices are Installed

92-32 Problems Identified with 04/29/92 All holders of OLs or CPs

Emergency Ventilation for nuclear power reactors.

Systems for Near-Site

(Within 10 Miles) Emer- gency Operations Facili- ties and Technical Support

Centers

92-31 Electrical Connection 04/27/92 All holders of OLs or CPs

Problem in Johnson for nuclear power reactors.

Yokogawa Corporation

YS-80 Programmable Indi- cating Controllers

92-30 Falsification of Plant 04/23/92 All holders of OLs or CPs

Records for nuclear power reactors

and all licensed operators

and senior operators.

92-21, Spent Fuel Pool Re- 04/22/92 All holders of OLs or CPs

Supp. 1 activity Calculations for nuclear power reactors.

92-29 Potential Breaker Mis- 04/17/92 All holders of OLs or CPs

coordination Caused by for nuclear power reactors.

Instantaneous Trip

Circuitry

OL = Operating License

CP = Construction Permit