ML18004B938
| ML18004B938 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 09/14/1987 |
| From: | Cutter A CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| IEB-87-001, IEB-87-1, NLS-87-189, NUDOCS 8709180426 | |
| Download: ML18004B938 (7) | |
Text
REGUL(
INFORMATION DISTRIBUTI STEM (RIDS>
- CQ:SSION NBR: 8709180426 DOC. DATE:. 87/09/14 NOTARIZED:
YES FACIL: 50-400 Shearon Harris Nuclear Poujer Planti Unit 1I Carolina AUTH. NAME AUTHOR AFFILIATION CUTTER> A. B.
Carolina Poeer 5 Light Co.
RECIP. NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
DOCKET ¹ 05000400
SUBJECT:
Responds to NRC Bulletin 87-001 re licensee programs for maintaining thickness of pipe mails in high energy single" 8.
two-phase carbon steel piping sos.
DISTRIBUTION CODE:
IEIID COPIES RECEIVED: LTR I
ENCL J SIZE:
TITLE: Bulletin Response (50 DKT)
NOTES: Application for. permit reneuJal filed.
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~g Carolina Power 8 Light Company EP g 4 )987 SERIAL: NLS-87-189 United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NO. 50-000/LICENSE NO. NPF-63 NRC BULLETINNO. 87-01: THINNINGOF PIPE WALLS IN NUCLEAR POWER PLANTS Gentlemen:
Carolina Power R Light Company hereby submits information requested by NRC Bulletin No. 87-01, dated 3uly 9, 1987.
The subject bulletin required the submission of information concerning a licensee's programs for maintaining the thickness of pipe walls in high-energy single-phase and two-phase carbon steel piping systems.
This submittal provides the requested information regarding the SHNPP program for monitoring the wall thickness of pipes in the condensate, feedwater, steam, and connected high energy piping systems.
Should you have any questions concerning this
- response, please contact Mr. A. W. Schmich at (919) 836-8759.
Yours ery truly, ABC/AWS/pp (5278AWS)
Attachment A. B. Cutter - Vice Presid nt Nuclear Engineering cc:
Mr. B. C. Buckley Dr. 3. Nelson Grace Mr. G. F. Maxwell A. B. Cutter, having been first duly sworn, did depose and say that the information contained herein is true and correct to the best of his information, knowledge and belief; and the sources of his information are officers, employees, contractors, and agents of Carolina Power R Light Company.
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CAROLINAPOWER R LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT Response to NRC Bulletin No. 87-0l, Thinning of Pipe Walls in Nuclear Power Plants
~Summar:
Following the Surry incident, SHNPP began developing an erosion/corrosion program intended to provide a conservative means of monitoring components/piping systems, both two-phase and single-phase, that may be susceptible to erosion/corrosion.
Prior to the Surry incident, SHNPP had an erosion/corrosion program intended to monitor two-phase flow only. Since SHNPP commenced commercial operation on May 2, l987, in-service inspections for neither the previous program nor the current program have been implemented.
Based on additional erosion/corrosion problems now surfacing throughout the utility industry and CPRL study of such problems, it is anticipated that our current program willbe revised as necessary for improvement.
Implementation of our erosion/corrosion program willoccur during our first refueling outage scheduled for fall 1988.
The following provides specific information for each of the bulletin action items.
ACTION l:
Identify the codes or standards to which the piping was designed and fabricated.
Applicable Class I, 2, and 3 piping was designed an4 fabricated to ASME Section IIIcode.
Nonsafety-related piping was designed and fabricated to ANSI B3l.l code.
Specific information on code classes of piping systems is described in the applicable sections an4 flow drawings contained in the SHNPP FSAR.
ACTION 2:
Describe the scope and extent of your programs for ensuring that pipe wall thicknesses are not reduced below the minimum allowable thickness. 'nclu4e in the description the criteria that you have establishe4 for:
ae b.
Cs ds selecting points at which to make thickness measurements determining how frequently to make thickness measurements selecting the metho4s used to make thickness measurements making replacement/repair decisions The design of the SHNPP erosion/corrosion program is intended to develop and implement a conservative means for monitoring components and piping systems that may be susceptible to erosion/corrosion based on plant 'conditions.
Through examinations and inspections, the program will provide preventive measures to enhance plant reliability and safety to the public and plant employees.
(5278AWS/Jeh) r vQ
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The selection of thickness measurement data points is based on the following parameters:
temperature; velocity; geometry; and flow disturbances.
For each of these factors, a rating scale is developed based on susceptibility.
For a given component, the sum of these factor
'atings are obtained and used to identify the susceptibility to erosion/corrosion and establish an inspection priority with the larger value indicating a greater susceptibility.
Selection of specific thickness measurement data points for a given component (i.e., grid pattern) is based on component geometry, size, outside diameter, and direction of flow.
The frequency for taking thickness measurements willbe based on a series of calculations including: erosion/corrosion, erosion/corrosion rate, wear rate, wall thickness remaining, life remaining, and inspection interval: Thickness measurements taken on a perceritage of selected erosion/corrosion susceptible components during our first and second refueling outages willthen be input into these calculations and a monitoring frequency determined.
The primary method used for taking thickness measurements willbe by the manual UT, contact, pulse-echo type.
When performed by qualified
- individuals, this method was determined to be superior in reliability, time efficiency, and cost effectiveness over other methods considered.
However, secondary methods such as automated UT, radiography, and visual exams utilizing fiberoptics/borescopes willbe considered when deemed appropriate.
The criteria used to determine the necessity for component replacement or repair is based on design minimum wall requirements.
Each component willbe evaluated on an individual basis, i.e.,
(I)
If a component is found to be below the design minimum wall, that component shall be repaired/replaced.
(2)
If a component is found to be above the design minimum wall but through erosion/corrosion rate calculations we would project wall thickness to be reduced below design minimum wall before the next scheduled outage, that component will be monitored more frequently to ensure minimum wall is not exceeded or repaired/replaced to assure its integrity.
(3)
The components found to be above design minimum wall and erosion/corrosion rate calculations project acceptable minimum wall willbe assigned a monitoring frequency for examination on a periodic basis.
For liquid-phase systems, state specifically whether the following factors have been considered in establishing your criteria for selecting points at which to monitor piping thickness (Item 2a):
(5278AWS/jeh)
a.
piping material (e.g., chromium content) b.
piping configuration (e.g., fittings less than 10 pipe diameters apart) c.
pH of water in the'system (e.g., pH less than 10) d.
system temperature (e.g., between 190 and 500'F) e.
fluid bulk velocity (e.g., greater than 10 ft/s) f.
oxygen content in the system (e.g., oxygen content less than 50 ppb)
~CP 6 The factors described in Action 3a through 3f above were considered in the development of criteria for the selection of data points to monitor.
The applicable liquid phase systems contain carbon steel piping material and are included in the program.
Since the pH and oxygen content are controlled, these factors are considered to not be driving variables and were not a priority in the selection of inspection locations.
The factors determined to be important in selecting inspection locations are discussed further in our response to Action 2a.
Chronologically list and summarize the results of all inspections that have been performed which were specifically conducted for the purpose of identifying pipe wall thinning, whether or not pipe wall thinning was discovered, and any other inspections where pipe wall thinning was discovered even though that was not the purpose of that inspection.
ao b.
Co Briefly describe the inspection program and indicate whether it was specifically intended to measure wall thickness or whether wall thickness measurements were an incidental determination.
Describe what piping was examined and how (e.g., describe the inspection instrument(s), test method, reference thickness, locations examined, and means for locating measurement point(s) in subsequent inspections).
Report thickness measurement results and note those that were identified as unacceptable and why.
d.
Describe actions already taken or planned for piping that has been fo'und to have a nonconforming wall thickness.
If you have performed a failure analysis, include the results of that analysis.
Indicate whether the actions involve repair or replacement including any change of materials.
(5278AWS/Jeh)
C~PR R
SHNPP commenced commercial operation on May 2, 19S7.
As a newly operating plant, in-service inspection (ISI) of piping systems has not yet been performed.
A detailed inspection program for examining pipe components susceptible to erosion/corrosion, both two-phase and single-phase, is scheduled for implementation during our first refueling outage.
Prior to fuel load during pre-service inspections (PSI), 37 elbows on the extraction steam system were spot checked to verify wall thickness and develop baseline data for subsequent inspections.
The thickness readings taken were within the manufacturers'olerances.
This inspection was completed December 30, 1935.
During plant start-up testing, a piping configuration deficiency was identified within the feedwater pump recirculation lines. This configuration led to excessive and accelerated erosion due to cavitation and turbulance.
Action to correct the deficiency, including the development of a plant modification, has been initiated.
'I Describe any plans for revising the present or for developing new or additional programs for monitoring pipe wall thickness.
~CR R
Prior to the Surry incident, our erosion/corrosion program consisted of monitoring two-phase flow only. A detailed study of industry-updated, erosion/corrosion-related information is currently underway by plant Technical Support personnel.
Based on the erosion/corrosion data now being reported throughout the utility industry, CPRL (SHNPP) is taking a conservative approach in our efforts to monitor carbon steel components and piping, both two-phase and single-phase, susceptible to erosion/corrosion to assure pipe design minimum wall requirements are maintained.
Revisions to our existing program, as appropriate, willbe implemented upon completion of this study.
In addition, CPRL will evaluate the EPRI Erosion Corrosion Matrix (CHEC Program).
The results of this evaluation willbe used to validate the adequacy of the current plant erosion/corrosion program.
(5278AWS/jeh
)