ML20237K846

Forwards Info Re Programs for Monitoring Thickness of Pipe Walls in High Energy single-phase & two-phase Carbon Steel Piping Sys,Per 870709 NRC Bulletin 87-001, Thinning of Pipe Walls in Nuclear Power Plants

ML20237K846
Person / Time
Site:	Summer
Issue date:	09/01/1987
From:	Nauman D SOUTH CAROLINA ELECTRIC & GAS CO.
To:	Grace J NRC, NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20237K848	List: ML20237K846 ML20237K857
References
IEB-87-001, IEB-87-1, NUDOCS 8709080065
Download: ML20237K846 (5)

Text

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o th Ca na Electric & Gas Company n n Nuclear Operations gumga.g29218 sceaa

_,, September 1, 1987 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTN: Dr. J. Nelson Grace

SUBJECT:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 NRC Bulletin No. 87-01 Thinning of Pipe Walls in Nuclear Power Plants l

Dear Sir:

In a letter dated July 9, 1987, South Carolina Electric & Gas Company (SCE&G) l received NRC Bulletin No. 87-01, " Thinning of Pipe Walls in Nuclear Power l Plants." This bulletin requested licensees to submit information concerning their programs for monitoring the thickness of pipe walls in high energy single-phase and two-phase carbon steel piping systems. The attachments to this letter provide SCE&G's respcase to this request.

The information contained in this letter and its attachments are true and correct to the best of my knowledge, information and belief.

. If you have any questions, please advise.

t#Ul y yours, hVer.)h

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1 A>Nauman AMM/ DAN:bjh Attachment l pc: 0. W. Dixon, Jr./T. C. Nichols, Jr. C. L. Ligon (NSRC) i E. C. Roberts R. M. Campbell, Jr.

l 0. S. Bradham K. E. Nodland 1 0. R. Moore J. C. Snelson l W. A. Williams, Jr. G. O. Percival J. Nelson Grace R. L. Prevatte l Group Managers J. B. Knotts, Jr.

W. R. Baehr INP0 Records Center W. R. Higgins Marsh & McLennan R. B. Clary ANI Library G. G. Soult RTS C. A. Price NPCF l W. T. Frady File T, L. Matlosz 8709000065 870901 l PDR ADOCK 05000395 PDR 6lk

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Attachments to NRC Bulletin 87-01 September 1,1987 Page l of 2 ATTACHMENT I REQUEST 1: i l

Identify the codes or standards to which the piping was designed and  !

fabricated. '

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Response

1. Main Steam System (Nuclear): ASME Boiler and Pressure Vessel Code Section III,1971 edition, addendu m through Summer 1973.

2. Main Steam System (Noa-Nuclear): ANSIB31.1.0 and B16.5,1967 issue with addendum through Summer 1973.

3. Feedwater System (Nuclear): ASME Boiler and Pressure Vessel Code Section Ill,1971 edition, addendum through Summer 1973.

4. FeedwaterSystem (Non-Nuclear): ANSIB31.1.0 and B16.5,1967 issue with addendum through Summer 1973.

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5. Condensate System: ANSIB31.1.0 and B16.5,1967 issue with addendum through Summer 1973.

6. Extraction Steam System: ANSIB31.1.0 & B16.5,1967 issue with addendum )

through Summer of1973.

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7. High Pressure Heater Drips: ANSIB31.1.0 & B16.5,1967 issue with addendum through Summer of1973. The High Pressure Heaters are ASME Boiler and Pressure Vessel Code Section III,1971 edition addendu m through Summer 1973.

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8. Steam Generator Blowdown System: Safety Related section, ASME Boiler and Pressure Vessel Code Section !II,1971 edition addendum through Summer 1973. Non-safety related section, ANSIB31.1,0 and B16.5,1967 issue with i addendum through Summer 1973.

9. Feedwater Reverse Flush: ASME Boiler and Pressure Vessel Code Section Ill, 1971 edition, addendum through Summer 1973.

10. Scavenging Steam System: ANSIB31.1.0 & B16.5,1967 issue with addendum through Summer of1973,

11. Crossover and Crossunder Turbine Piping: ANSIB31.1.0 & B16.5,1967 issue with addendum through Summer of1973.

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Attachments to NRC Bulletin 87-01 September 1,1987 Page 2 of 2 Prior to Jan uary 1987, the SCE&G program for monitoring wall thickness in pipes was limited to two-phase flow systems most susceptible to erosion degradation (items 6 through 11 above)*. The areas in these systems identified in the current program are for the most part various high energy fittings and connectingpiping containing steam / water mixtures. As described in response to question 5, various changes to the \

program are being evaluated and incorporated. See question 5 for a more thorough discussion on revisions to the program.

• NOTE: The above list identifies codes and standards to which various potentially applicable piping systems are designed and fabricated. Tlte current l SCE&G inspection program does not include allparts ofall of the above listed systems. Responses to subsequent questions will clarify the current and future SCE&G program plans.

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AttachmentII to NRC Bulletin 87-01 September 1,1987 Page l of 2 1

4 ATTACHMENT II REQUEST 2:

Descrihe the scope and extent of your programs for ensuring that pipe wall  !

thicknesses are not reduced below the minimum allowable thickness. 1 Include in the description the criteria that you have established for:

a. selecting points at which to make thickness measurements i

b. determining how frequently to make thickness measurements i

c. selecting the methods used to make thickness measurements

d. making replacement / repair decisions l

Response

I A copy ofGeneral Test Procedure (GTP) 308, " Detection and Evaluation of l Erosion / Corrosion in Steam Systems,"is included as Enclosure I to this Attachment. i This procedure governs the current program for monitoring piping erosionicorrosion at the Virgil C. Summer Nuclear Station. A summary of the scope and the extent of this program follows.

Normally ultrasonic examination is used to detect erosion or corrosion of the internal surfaces ofpipe fittings and connecting piping. The inspection points selected for examination in the SCE&G program are based on engineeringjudgment considering the following factors:

a. piping material

b. pipingconfiguration

c. pH of the water contained in the system

d. system temperature

e. fluid velocity i

f. Oxygen content offluid

g. relative moisture content The piping configuration, fluid velocity and moisture content have generally been considered the most critical factors in determining inspection points for the two-phase flow systems included in the currentprogram.

All inspection points in the originalprogram were examined during the first two refueling outages (Fall 1984 and Fall 1985) to establish baseline data. The measurement frequency is determined by comparing baseline data with design data and establishing a projected erosion rate. Generally, subsequent examinations of a specific area will be performed each 8-10 years. By the end of the first 15 years of operation,100% of the inspection points will have been examined at least once (in addition to the initial baseline examination). Should an examination reveal a pipe wall thickness less than the established acceptable limit, an additional 10% of the inspection points within the same system shall be examined. If these additional areas exhibit through wall degradation below minimum requirements, then allpoints in that system wili be examined.

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..AttachmentII to NRC Bulletin 87-01 September 1,1987 -

Page 2 of 2 Acceptance criteria forpipes and fittings are as follows:

1. Thickness measurements below Tmf .2 Tm (forfittings)or Tmp .2 Tm (forpipes) are unacceptable.*

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2. Thickness measurements below Tmf or Tmp, as applicable, covering an area greater than 20% of the total examination area are unacceptable.  ;

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• NOTE: See Sections 7.8.1, 7.8.2 and 7.8.3 ofGTP 308 for definitions of Tmf and

[ Tmp.

Fittings and/orpiping shall be repaired or replaced when the affected area falls outside of the acceptance criteria stated above, or when the projected thickness is expected to be unacceptableprior to the next refueling outage.

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