Information Notice 1988-17, Summary of Responses to NRC Bulletin 87-01, Thinning of Pipe Walls in Nuclear Power Plants.

Summary of Responses to NRC Bulletin 87-01, Thinning of Pipe Walls in Nuclear Power Plants.

ML031150317
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
Issue date:	04/22/1988
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
BL-87-001 IN-88-017, NUDOCS 8804180039
Download: ML031150317 (11)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 April ??, 1988 NRC INFORMATION NOTICE NO. 88-17: SU MARY OF RESPONSES TO NRC BULLETIN 87-01,

"THINNING OF PIPE WALLS IN NUCLEAR POWER

PLANTS"

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is being provided to inform addressees of the results of

the NRC staff review of responses to NRC Bulletin 87-01, "Thinning of Pipe Walls

in Nuclear Power Plants." It is expected that recipients will review the informa- tion for applicability to their facilities and consider actions, as appropriate, to prevent erosion/corrosion-induced piping degradation. However, suggestions

contained in this notice do not constitute NRC requirements; therefore, no

specific action or written response is required.

Background:

On December 9, 1986, Unit 2 at the Surry Power Station experienced a catastrophic

failure of a main feedwater pipe, which resulted in fatal injuries to four workers.

During the 1987 refueling outage at the Trojan plant, it was discovered that at

least two areas of the straight sections of the main feedwater piping system had

experienced wall thinning to an extent that the pipe wall thickness would have

reached the minimum thickness required by the design code (American National

Standards Institute (ANSI) Standard B31.7, "Nuclear Power Piping") during the

next refuelina cycle. These two straight-section areas are in safety-related

portions of the Class 2 piping inside containment. In addition, numerous elbows

and piping sections in the non-safety-related portion of the feedwater lines were

replaced because of wall-thinning problems.

Because of the immediate concern about hich-energy carbon steel systems in

operating nuclear power plants, NRC Bulletin 87-01 was issued on July 9, 1987.

The staff requested all licensees to provide the following information within

60 days of receiving the bulletin:

- the code or standard to which the high-energy, carbon steel piping

was designed and fabricated

88480039\

IN 88-17 April 22, 1988 - the scope, extent, and sampling criteria of inspection programs to

monitor pipe wall thinning of safety-related and non-safety-related

high-energy, carbon steel piping systems

- the results of all inspections that have been performed to identify

pipe wall thinning

- plans for revising existing pipe monitoring procedures or developing

new or additional inspection programs

Discussion:

The staff review of licensee responses to the bulletin showed that before the

rules for piping, pumps, and valves in Section III of the American Society of

Mechanical Engineers Boiler and Pressure Vessel Code (ASME Codel were revised

in 1971, the secondary coolant systems in nuclear power plants were designed

and fabricated in accordance with ANSI B31.1. Fifty-seven percent of the

licensed units belong to this category. After 1971, safety-related portions of

the secondary coolant systems were designed and fabricated in accordance with

ASME Code Section III, while non-safety-related portions of the secondary

coolant systems continued to be designed and fabricated in accordance With

ANSI R31.1. Forty-three percent of the licensed units belong to this category.

For two-phase, high-energy carbon steel piping systems, the responses to the

bulletin indicated that programs for inspecting pipe wall thinning exist at all

plants. Inspection locations are generally established in accordance with the

1985 guidelines in Electric Power Research Institute (EPRI) Document NP-3944,

"Erosion/Corrosion in Nuclear Plant Steam Piping: Causes and Inspection

Program Guidelines." However, because implementation of these guidelines

is not required, the scope and the extent of the programs vary significantly

from plant to plant.

Responses to the bulletin indicated that limited inspections of the single- phase feedwater-condensate systems were conducted in most plants after the

Surry Unit 2 incident. Most plants developed their single-phase pipe wall

thinning monitoring programs because of the events at Surry Unit 2 and at

the Trojan plant. Some plants developed programs after NRC Bulletin 87-01 was issued. The responses to NRC Bulletin 87-01 show that 23 units, of a

total of 110, still have not established an inspection program for monitoring

pipe wall thinning in single-phase lines. Of these 23 units, 17 are operating

and 6 are under construction.

The inspection frequency for pipe wall thickness measurements and replacement/

repair decisions is based on a combination of predicted and measured erosion/

corrosion rates. In general, the pipe wall thickness acceptance criteria use

measured wall thicknesses and an erosion/corrosion damage rate to predict when

the pipe wall thickness will approach its Code-allowable minimum wall thick- ness. The acceptance criteria provide guidance for determining if a piping

component needs to be replaced or repaired immediately or for projecting when

a piping component should be replaced.

IN 88-17 April 22, 1988 The primary method of inspection reported was ultrasonic testing, supplemented

by visual examination and, in a few cases, by radiography. Measurements of

pipe wall thickness were either made by or verified by certified level 2 or

level 3 inspectors. The NRC staff considers this an adequate inspection

technique.

The systems and components reported as experiencing pipe wall thinning in the

responses to Bulletin 87-01 are listed in Attachment 1. Pipe wall thinning

problems in single-phase piping occurred primarily in the feedwater-condensate

system; the problems in two-phase piping, although varied in extent, have been

reported in a variety of systems in virtually all operating plants. Plants

that were reported to have pipe wall thinning in feedwater-condensate systems

are listed in Attachment 2. Although inspection of single-phase lines is not

scheduled until the next refueling outage for a number of plants, the available

results from plants already inspected indicate a widespread problem.

The staff's review also showed that wall thinning in feedwater-condensate systems

is more prevalent in pressurized-water reactors (PWRs) than boiling-water reactors

(BWRs). At the present time, licensees of 27 PWRs and 6 BWRs have identified

various degrees of wall thinning in feedwater piping and fittings.

The staff's review further indicated that of the feedwater-condensate systems, the recirculation-to-condenser line (minimum-flow line) has experienced wall

thinning degradation most frequently. The line is used to protect the pump

during low-power operation and is isolated by a minimum-flow valve during

high-power operation. Specific information regarding a minimum-flow line

degradation incident at the LaSalle County Station is provided for recipients

to review for applicability to their facilities and consider actions, if

appropriate, to preclude similar problems occurring at their facilities.

Description of Circumstances

of a Recent Event:

On December 10, 1987, at LaSalle County Station Unit 1, when the unit was at

approximately 100 percent power, an increased floor drain input from the heater

bay was observed. This prompted a search of that area by the plant Operating

Department. Feedwater leakage was found immediately downstream of the IR

turbine-driven reactor feedwater pump (TDRFP) minimum-flow line control valve

(IFWO11B). This valve discharges immediately into a 45-degree elbow that is

welded to an 8-inch by 14-inch expander, which is connected to piping that feeds

directly to the main condenser. The 45-dearee elbow (schedule 160, 5% chrome,

1/2% molybdenum alloy steel) was found to have throuoh-wall pinhole leaks in it.

Further investigation identified the cause of the leakage to be internal piping

erosion.

A visual inspection and ultrasonic testing of the other feedwater pump minimum- flow lines at both Unit 1 and Unit 2 revealed the following:

(1) The PA TDRFP had wall thinning in the 8-inch by IA-inch expander (schedule

80, 5% chrome, 1/2% molybdenum steel), and a 1/4-inch diameter hole in the

expander was located 1 inch downstream from the elbow/reducer weld.

IN 88-17 April 22, 1988 (2! The 1A and 2B TDRFPs had localized wall thinning in the elbow downstream

of the flow control valve similar to that found on the 1B minimum-flow

line. This metal loss did not result in a through-wall leak.

(3) The 1C and 2C feedwater pumps are motor-driven pumps with smaller minimum- flow lines (10 inches rather than 14 inches), and no degradation of the

wall thickness downstream of the flow control valves was noted.

The erosion pattern was thought to be caused by the design of the minimum-flow

control valves and the geometry of the downstream piping. The valves were manu- factured by Control Components, Inc., and were pressure breakdown "drag!'

The valves have a cone-shaped disk and are not designed to be leak tight. valves.

Any

feedwater leaking past the seat flashes to steam because of a vacuum pulling

the water from the condenser. With a cone-shaped disk, the steam is then di- on

rected, like a Jet, immediately onto the opposing wall of the elbow or reducer, causing the erosion (see Attachment 3).

The feedpump minimum-flow lines are not considered to have a safety-related

function and, therefore, this failure did not affect the ability to achieve

a safe shutdown. However, this could present a plant personnel safety concern

in the event of a catastrophic failure. The licensee did a weld overlay repair

of the wall thinning areas of all four minimum-flow lines. The lines will be

replaced during the next refueling outage. The licensee is evaluating a modi- fication to the control valve disk to prevent flow or leakage through the line

from being focused onto the downstream piping because of the conical shape of

the disk.

Past Related Generic Communications:

TE Information Notice 82-22, "Failure in Turbine Exhaust Lines," dated July 9,

1982, provides additional information on erosion/corrosion in wet steam piping.

Other erosion/corrosion events pertaining specifically to the feedwater system

(including emergency and auxiliary feedwater) have occurred in feedwater pump

minimum-flow lines, J-tubes in steam generator feedwater rings, and emergency

supplies to a helium circulator.

IE Information Notice 86-106, "Feedwater Line Break," was issued on Pecember 16,

1986. It described the then-known details of the December 9, 1986, failure of

the suction line to a main feedwater pump at Surry Power Station Unit 2. Sup- plement 1 to this information notice, which was issued on February 13, 1987, provided additional detail on the failure mechanism. Supplement 2, which was

issued on March 10, 1987, discussed the effects of the system interactions that

resulted from the line break.

NRC Bulletin 87-01, "Thinning of Pipe Walls in Nuclear Power Plants," issued on

July 9, 1987, requested that licensees submit information concernino their

programs for monitorino the thickness of pipe walls in high-energy single-phase

and two-phase carbon steel piping systems.

K)

IN 88-17 April 22, 1988 NRC Information Notice 87-36, "Significant Unexpected Erosion of Feedwater Lines,"

was issued August 4, 1987. It described a potentially generic problem pertaining

to significant unexpected erosion that resulted in pipe wall thinning in the

safety-related portions of feedwater lines and other related problems discovered

at the Trojan Plant.

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

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

contacts listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Paul C. Wu, NRR

(301) 492-0826 Michael Jordan, R11T

(312) 790-5552 Attachments:

1. Systems/Components Experiencing Pipe Wall Thinning

2. Plants Experiencing Pipe Wall Thinning in Feedwater- Condensate System

3. LaSalle Minimum-Flow Control Valve

4. List of Recently Issued NRC Information Notices

W

Attachment 1 IN 88-17 April 22, 1988 SYSTEMS/COMPONENTS EXPERIENCING PIPE WALL THINNING

Single-Phase Line Two-Phase Line

o main feedwater lines, o main steamlines

straight runs, fittings

o turbine cross-over piping

o main feedwater recirculation to

condenser, straight runs, fittings o turbine cross-under piping

o feedwater pump suction lines, o extraction steamlines

straight runs, fittings

o moisture separator reheater

o feedwater pump discharge lines, straight runs, fittings 0 feedwater heater drain piping

o condensate booster pump

recirculation line fittings

o steam generator letdown lines, straight runs, fittings

Attachment 2 IN 88-17 April 22, 1988 Page I of 1 PLANTS EXPERIENCING PIPE WALL THINNING IN FEEDWATER-CONDENSATE SYSTEM

Type of Commercial Degraded Component

Plant Unit Reactor Operation Fittings or Straight Runs

- ------ __ - __ -

Dresden 2 BWR January 3970 elbows

Duane Arnold BWR March 1974 elbows, reducers, straight runs

Pilgrim I BWR June 1972 elbows

Oyster Creek BVIR May 1969 elbows

River Bend I BWR October 1985 recirculation line

Perry BWR June 1986 straight runs

Arkansas 1 PWR August 1.974 elbows, drain pump discharge

piping

Arkansas 2 PWR December 1978 undefined

Calvert Cliffs 1 PWR October 1974 elbows, reducers, straight runs

Calvert ClIffs 2 PWR November 1976 elbows, reducers, straight runs

Callaway PWR October 1984 recirculation line elbows

Diablo Canyon 1 PWR April 1984 elbows, straight runs

Diablo Canyon 2 PWR August 1985 elbows, and Y

Donald Cook 2 PWR March 1978 elbows

Ft. Calhoun PWR August 1973 elbows, straight run

Haddam Neck PWR July 1967 recirculation line

Millstone 2 PWR October 1975 elbows, heater vent piping

North Anna 1 PWR April 1978 elbows, straight runs

North Anna 2 PWR June 1980 elbows, straight runs

H. B. Robinson 2 PWR September 1970 recirculation lines

San Onofre 1 PWR June 1967 reducers, heater drain piping

San Onofre 2 PWR July 1982 heater drain piping

San Onofre 3 PWR August 1983 heater drain piping

Salem 1 PWR December 1976 recirculation line

Salem 2 PWR August 1980 recirculation line

Shearon Harris PWR October 1986 recirculation line

Surry 1 PWR July 1972 fittings

Surry 2 PWR March 1973 fittings

Sequoyah 1 PWR July 1980 elbows, straight runs

Sequoyah 2 PWR November 1981 elbows

TroJan - PWR December 1975 elbows, reducers, straight runs

Turkey Point 3 PWR October 1972 feedwater pump suction line

fittings

Fort St. Vrain HGTR* January 1974 straight run in emergency

feedwater line

Rancho Seco PWR September 1974 straight runs downstream of

MFW loop isolation valve

or MFPs miniflow valves

• High Temperature-Gas Peactor

~Area Where

Wall is Thinning.

K I II

A-o 2 ->

C+

to- r ZO

CD -- 030D

c 0

LaSalle Minimum-Flow Control Valve 7~

• 03:

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Attachment 4 IN 88-17 April 22, 1988 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

88-16 Identifying Waste Generators 4/22/88 Radioactive waste

in Shipments of Low-Level collection and

Waste to Land Disposal service company

Facilities licensees handling

prepackaged waste, and licensees operating

low-level waste

disposal facilities.

88-15 Availability of U.S. Food 4/18/88 Medical, Academic, and Drug Administration and Commercial

(FDA)-Approved Potassium licensees who possess

Iodide for Use in Emergencies radioactive iodine.

Involving Radioactive Iodine

88-14 Potential Problems with 4/18/88 All holders of OLs

Electrical Relays or CPs for nuclear

power reactors.

88-13 Water Hammer and Possible 4/18/88 All holders of OLs

Piping Damage Caused by or CPs for nuclear

Misapplication of Kerotest power reactors.

Packless Metal Diaphragm

Globe Valves

88-12 Overgreasing of Electric 4/12/88 All holders of OLs

Motor Bearings or CPs for nuclear

power reactors.

88-11 Potential Loss of Motor 4/7/88 All holders of OLs

Control Center and/or or CPs for nuclear

Switchboard Function Due power reactors.

to Faulty Tie Bolts

88-10 Materials Licensees: Lack 3/28/88 All NRC licensees

of Management Controls Over authorized to use

Licensed Programs byproduct material.

.87-44, Thimble Tube Thinning in 3/?S/88 All holders of OLs

Supp. 1 Westinchouse Reactors or CPs for nuclear

power reactors that

employ a Westinghouse

NSSS.

---

OL = Operating License

CP = Construction Permit

IN 88-17 April 22, 1988 NRC Information Notice 87-36, 'Significant Unexpected Erosion of Feedwater Lines,"

was issued August 4, 1987. It described a potentially generic problem pertaining

to significant unexpected erosion that resulted in pipe wall thinning in the

safety-related portions of feedwater lines and other related problems discovered

at the Trojan Plant.

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

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

contacts listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Paul C. Wu, NRR

(301) 492-0826 Michael Jordan, RIII

(312) 790-5552 Attachments:

1. Systems/Components Experiencing Pipe Wall Thinning

2. Plants Experiencing Pipe Wall Thinning in Feedwater- Condensate System

3. LaSalle Minimum-Flow Control Valve

4. List of Recently Issued NRC Information Notices

• Tranmitted by memorandum to C. E. Rossi from L. C. Shao dated March 31, 1988

• C/OGCB: DOEA:NRR*PPMB:ARM *RTII *RIII

CHBerlinger TechEd MJordan EGreenman

04//7/88 04/14/88 04/6/88 04/7/88 04/7/88

• OGCB:DOEA:NRR *ECEB:DEST:NRR *C/ECEB:DEST:NRR *EAD/DEST:NRR *D/DEST:NRR

RJK1iessel PCWu CEMcCracken JRichardson LCShao

04/6/88 04/ /88 04/ /88 04/ /88 04/ /88

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IN 88-XX

April xx, 1988 No specific action or written response is required by this information notice.

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

contacts listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Paul C. Wu, NRR

(301) 492-0826 Michael Jordan, RIII

(815) 357-8611 Attachments:

1. Systems/Components Experiencing Pipe Wall Thinning

2. Plants Experiencing Pipe Wall Thinning in Feedwater-Condensate System

3. LaSalle Minimum-Flow Control Valve

4. List of Recently Issued NRC Information Notices

• Tranmitted by memorandum to C. E. Rossi from L. C. Shao dated March 31, 1988 D/DOEA:NRR

CERossi

C/OGC DOEA :NRR PPMB:ARM

CHBerlinger TechEd

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MJordan

RIII k

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04/ /88 04/l_4/88 04/& /88 04/7'/88 04/ 7/88 OGCB:DOEA:NR, *ECEB:DEST:NRR *C/ECEB:DEST:NRR *EAD/DEST:NRR *D/DEST:NRR

RJKiessel A PCWu CEMcCracken JR ichards on LCShao

04/6 /88 04/ /88 04/ /88 04/ /88 04/ /88