ML20196D658
| ML20196D658 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 09/11/1988 |
| From: | George Thomas PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | Russell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-87-001, IEB-87-1, NYN-87106, NUDOCS 8812090155 | |
| Download: ML20196D658 (5) | |
Text
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George S. Thomas Vee he9derd Nucleot heduc+on Put2c SeMoe of New Hampshire
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New Hampshire Yankoo DMsion NYN-87106 September 11, 1987 United States Nuclear Regulatory Commission Regton 1 631 Par; Avenue King of Prussia, PA 19406 Attention: Mr. William T. R90 sell Regional Admiaistrator Subj ect Response to NRC Bulletin No. 87-01 Dear Sir As requested by NRC Bulletin No. 87-01, Enclosure 1 provides information pertirent to the pipe wall erosion / corrosion monitoring program currently being developed for Seabrook Station.
Shou'.d you require further information regarding this matter, please contact Mr. G. Kann at (603) 474-9574 extension 2503.
Very truly yours, George /. Thomas 3
Enclosure cc: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Mr. A. C. Cerne NRC Senior Resident Inspector Seabrook Station Seabrock, N.H.
03874 88120VOlbb 880911
{DR ADOCK 05000443 PDC Ill P.O. Box 300. Seabrook, NH 03874. Telephone (603) 474 957A
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STATE OF NEW HAMPSHIRE Rockingham, ss.
September 11, I A7 Then personally appeared before me, the above-named George S. Thomas who, being duly sworn, did state that he is Vice President - Nuclear Production of Public Service Company of New Hampshire, that he is duly authorized to execute and file the foregoing information in the name and on behalf of Public Service Company of New Hampshire, and that the statements therein are true to the best of his knowledge and belief.
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b Doris 7./ Patterson, Notary Public My ComMssion Expires October 29, 1991 i
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5 ENCLOSURE 1 70 NYN-87106 Response to NRC Bulletin No. 87-01 Action Requested:
1.
Identify the codes or standards to which the piping was designed and fabricated.
Responset The piping to be considered for inclusion in the erosion / corrosion monitoring program was designed and fabricated in accordance with either the ASME Boiler and Pressure Vessel Code,Section III (for safety class 1, 2 and 3 piping) or ANSI B31.1 (for non-nuclear safety class piping).
Action Requested:
2.
Describe the scope and extent of your programs for ensuring that pipe wall thickness are not reduced below the minimum allowable thickness.
Include in the description the criteria that you have established fort a.
selecting points at which to make thickness measurements b.
determining how frequently to make thickness measurements c.
selecting the methods used to make thickness measurements d.
making replacement / repair decisions
Response
The Seabrook Station piping erosion / corrosion monitoring program is currently under development, utilizing for the most part the methodology and technical guidance described in the Final Summary Report of the NUMARC Technical Subcommittee Working Group on Piping Erosion /Cc.Losion dated June 15, 1987. Specific comments relating to items 2.a through 2.d above f)11owt a.
The key tool for selecting piping locations for thickness measurements is the Chexal-Forowitz-Erosion-Corrosion (CHEC) personal computer program now being deseloped by EPRI.
Specific information (e.g., pipe diameter, material and schedule, fluid chemistry, velocity, temperature and pressure) utilized to select piping locations to be monitored will be determined by the input requirements of the CHEC computer program.
Selection of specific measurement points within the piping location identified by the CHEC computer pror, ram will be made by use of a grid system described in the NUHARC Subconcittee Working Group Report, b.
The f requency of thickness measurements will initially be established based on a predetermined likelihood of er aion/ corrosion. The sample lot determined to be most susceptible wila be examined prior to the second fuel cycle.
Subsequent measurements will be scheduled based on calculated rates of wall thickness redoetion such that minimum allownble wall thickness requirements will not be violated.
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c.
Manual ultrasonic testing techniques will normally be used to measure wall thickness.
This will be coupled with a grid marking system to ensure adequate area coverage and repeatability.
d.
Replacement / repair decisions will be made based on calculated time-to-f ailure (violatien of minimum allowable wall thickness), outage schedules and planned work on a particular system or portion of a system. Areas found to have already violated sinimum allowable thickness, or that will reach minimum allowable thickness before the next scheduled outage, will be immediately evaluated and replaced / repaired accordingly. A plan to tie time-to-minimum-wall thickness to examination cycles wil? be developed prior to implementation of this program.
Action Requested 3.
For liquid phase systems, state specifically whether the following factors have been considered in establishing your criteria for selecting points at which monitor pioing thickness (1 tem 2a):
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)
Response
Since the NUMARC Working Group methodology and technical guidelines are not finalized and the EPRI CHEC computer program has not been released, final decisions regarding the inclusion of the above and other factors in our program have not been made. However, it is expected that each of the above factors will be considered in the CHEC program in establishing the criteria for piping locations to be monitored for thickness.
Action Requested:
4.
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.
Responset Since Seabrook Station's piping systems have not yet experienced significant durations of fluid flow, no pipe wall thinning inspection have been performed to date.
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5.
Describe any plans either for revising the present or for developing new or additional programs for monitoring pipe wall thickness.
Response
The initial pipe wall thickness monitoring program will be developed for implementation when Seabrook Unit 1 begins commercial operation.
At this time we plan to use the NUMARC Working Group guidelines, including the Chexal-Horowitz-Erosion-Corrosion (CHEC) program, to help establish the scopw and content of this monitoring program.
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