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

{{Adams
| number = ML031200365
| issue date = 05/06/1992
| title = Higher than Predicted Erosion/Corrosion in Unisolable Reactor Coolant Pressure Boundary Piping Inside Containment at a Boiling Water Reactor
| author name = Rossi C
| author affiliation = NRC/NRR
| addressee name = 
| addressee affiliation = 
| docket = 05000003, 05000010, 05000029, 05000133, 05000155, 05000171, 05000206, 05000213, 05000219, 05000220, 05000237, 05000244, 05000245, 05000247, 05000249, 05000250, 05000251, 05000254, 05000255, 05000259, 05000260, 05000261, 05000263, 05000265, 05000266, 05000267, 05000269, 05000270, 05000271, 05000272, 05000275, 05000277, 05000278, 05000280, 05000281, 05000282, 05000285, 05000286, 05000287, 05000289, 05000293, 05000295, 05000296, 05000298, 05000301, 05000302, 05000304, 05000305, 05000306, 05000309, 05000311, 05000312, 05000313, 05000315, 05000316, 05000317, 05000318, 05000320, 05000321, 05000322, 05000323, 05000324, 05000325, 05000327, 05000328, 05000329, 05000330, 05000331, 05000333, 05000334, 05000335, 05000336, 05000338, 05000339, 05000341, 05000344, 05000346, 05000348, 05000352, 05000353, 05000354, 05000361, 05000362, 05000364, 05000366, 05000368, 05000369, 05000370, 05000373, 05000374, 05000382, 05000387, 05000388, 05000389, 05000390, 05000391, 05000395, 05000397, 05000400, 05000409, 05000410, 05000412, 05000413, 05000414, 05000416, 05000423, 05000424, 05000425, 05000437, 05000438, 05000439, 05000440, 05000441, 05000443, 05000444, 05000445, 05000446, 05000454, 05000455, 05000456, 05000457, 05000458, 05000461, 05000482, 05000483, 05000498, 05000499, 05000508, 05000528, 05000529, 05000530
| license number = 
| contact person = 
| document report number = IN-92-035, NUDOCS 9205010009
| document type = NRC Information Notice
| page count = 5
}}
{{#Wiki_filter: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}}

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