U-601016, Responds to IE Bulletin 87-001, Thinning of Pipe Walls in Nuclear Power Plants. Util Currently Implementing Action Plan to Determine Insp Criteria & Perform Baseline Insps

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Responds to IE Bulletin 87-001, Thinning of Pipe Walls in Nuclear Power Plants. Util Currently Implementing Action Plan to Determine Insp Criteria & Perform Baseline Insps
ML20238D106
Person / Time
Site: Clinton Constellation icon.png
Issue date: 09/04/1987
From: Hall D
ILLINOIS POWER CO.
To: Davis A
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-87-001, IEB-87-1, U-601016, NUDOCS 8709100562
Download: ML20238D106 (5)
v • d • e


Text

r U-601016-L30 - 87 (09-04 )-L 1A.110 ILLINOIS POWER COMPANY September 4, 1987 Docket No. 50-461 A. B. Davis Regional Administrator Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road

-Glen Ellyn, Illinois 60137

Subject:

Clinton Power Station Response to NRC Bulletin No. 87-01

Dear Mr. Davis:

This letter is in response to NRC Bulletin Number 87-01,

" Thinning of Pipe Walls in Nuclear Power Plants."

The Attachment provides information about Illinois Power Comaany's program for monitoring the thickness of pipe walls in high-energy single-phase and two-phase carbon steel piping systems.

I hereby affirm that the information in this letter is correct to the best of my knowledge.

Sincerely yours,

. Hall Vice President

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REL/ckc Attachment B. L. Siegel, NRC Clinton Licensing Project Manager cc:

NRC Resident Inspector NRC Document Control Desk, Washington, D.C.

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Illinois Department of Nuclear Safety l

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Attachment Introduction Clinton Power Station is a newly licensed nuclear power generating station. As such, Clinton is in the favorable position of being able to perform baseline thickness measurements early in plant life at locations determined to be most susceptible to erosion / corrosion.

Illinois Power has conducted a review of an associated report, Significant Operating Event Report (SOER) 87-3 on Pipe Failures in High-Energy Systems Due to Erosion / Corrosion. The following information is provided in response to NRC Bulletin No. 87-01 concerning the thinning of pipe walls in nuclear power plants.

Question 1.

Identify the codes or standards to which the piping was designed and fabricated.

Response

The systems which will be reviewed for susceptibility to erosion / corrosion, the corresponding pipe design wall thickness, and the design / erection codes and standards are listed in Table 1.

The. piping was designed and erected in accordance with ASME Section III requirements for class 1,2, or 3 piping or ANSI B31.1 requirements as appropriate.

Question 2.

Describe the scope and extent of your programs for ensuring that pipe wall thicknesses are not reduced below the ninimum allowable thickness.

Include in the description the criteria that you have established for:

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

Illinois Power (IP) has developed an action plan which outlines steps to be taken to perform a baseline inspection during the first refueling outage for the purpose of monitoring erosion / corrosion.

The inspection criteria have not been developed. After the baseline inspection is completed, the follow on inspection plans will be developed. When the program is developed, a report will be forwarded to the NRC which addresses criteria for selection of sample points.

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Question-

- 3.

For liquid-phase' systems, state specifically whether the following

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factors have been. considered,in establishing your criteria.for

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selecting points at which to monitor piping: thickness (Item 2a):

t a.

piping material (e.g., chromium content)

.b.

piping configuration (e.g., fittings less than 10 spipe diameters apart) c.- pH of water in the system (e.g., pH 1ess.than 10)

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system temperature (e.g.. between 190 and 500*F)

'e.'

fluid' bulk-veloclty (e.g., greater than 10 ft/s)

'f.

Oxygen content in the system (e..g., oxygen content less than 50 ppb)

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' Response The inspection criteria are to be developed by Nuclear Station Engineering by November-1, 1987 per the approved action plan-for INPO. item SOER 87-3.

IP will consider items a through.f when selecting points.

Question

' 4.'

Chronologically'11st 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.

Briefly describe the inspection program and indicate whether a.

it was specifically intended to measure wall thickness or whether wall thickness measurements were an incidental determination.

b.

Describe what piping was examined and how (e.g., describe the inspection instrument (s), test method, reference thickness,

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locations examined, means for locating measurement point (s) in subsequent inspections).

j Report thickness measurement results and note those that were c.

identified as unacceptable and why, d.

Describe actions already taken or planned for piping that has been found 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 mater 1als.

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'ResponseE 7;

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f Clinton Power Station has.just_recently. started operations.

'Therefore, inspections.have nbtibean: conducted specificallylfor the" purposeiof identifying pipe' wall' thinning resulting from operationalferosion/ corrosion. While performing routine y

maintenance, two incidents'of. wall thinning vere discovered.. In 1

both instances, the' wall. thinning is attribu' fed to acid be concentration (from p,ipe' flushing residue) in low energy piping..

The phenomena exhibited inLthese two incidents are unrelated to the concerns expressed in'this; bulletin.

is Question

'5.

Describe any plans,either for revising the present or for developing new or additional programs for monitoring pipe wall thickness.

' Response Illinois Power?s Clinton Power Sta' tion is currently in the. process of implementing.an action plan to determine. inspection criteria and perform baseline inspections.."Chexal-Horowitz Erosion Corrosion" j' '

(CHEC),Ja computer program available.through' Electric Power.

Research Institute,'is being evaluated for'use as'a basis for the pipe. wall monitoring program.1 Baseline wall thickness measurements will be ' performed during the first refueling outage.- Measurement locations will be selected as the~most susceptible pipe elements of

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the systems identified in Table 1, based on piping material, piping

configuration, pH of water in'the system, system temperature, fluid

-bulk velocity and oxygen content in the system.

Future pipe wall thickner.s measurements will be compared to the: baseline measurements to predict remain 1ng service life of'the pipe or to initiate more extensive pipe wall measurements.

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Table 1 1

Pipe Systems to be Reviewed for Susceptibility to Erosion / Corrosion Fabrication / Erection

  • Codes and Standards Pipe

Pipe

  • Material System CL1 CL2 CL3 B31.1(inches)

Wall Specification

  • Condensate Booster (CB)

X 8-24 SCH.60 A106 Gr. B X

36 1 in.

A155 Gr. KC70 C1.1 p

Feedwater Heater Miscellaneous X

6-10 SCH.40 A106 Gr. B 4

Drains and Vents (DV)

Extraction Steam and X

6-10 SCH.40 A106 Gr. B Cross-Around (ES)

X 12-24 1/2 in.

A106 Gr. B X

24-30 3/8 in.

A155 Gr. KC65 C1.2 X

24-30 1/2 in.

A155 Gr. KC65 C1.2 X

42 5/8 in.

A155 Gr. KC55 h

Feedwater (FW)

X 8-18 SCH.100 SA106 Gr. E or SA333 Gr. G X

18-20 SCH.160 SA106 Gr. B or SA333 Gr. G X

20 SCH.160 SA106 Gr. B X

12 SCH.80 A106 Gr. B i

X 12-24 SCH.160 A106 Gr. B

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X 30 2 in.

A b5 Gr. KC70 C1.1 Feedwater Heater Drains, X

6-24 SCH.40 A106 Cr. B Turbine Cycle (HD)

X 6-24 SCH.80 A106 Gr. B X

16-24 3/8 in.

A106 Gr. B X

6 SCH.40 A335 Gr. PS

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X 14 & 18 SCH.80 A335 Gr. PS Main Stearn (MS)

X 24 SCH 80 SA106 Gr. B X

10 & 12 SCH.40 SA106 Gr. B X

6-12 SCH 40 A106 Gr. B i

12-24 3/8 in.

A106 Gr. B X

6-24 SCH.80 A106 Gr. B X

36 1.452 A106 Gr. B min.

X 30 3/8 in.

A155 Gr. KC65 C1.2 Residual Heat Removal (RH)

X 8-18 SCH,100 SA106 Gr. B or SA333 Gr. 6 X

6-10 SCH.40 SA106 Gr. B X

12-20 3/8 in.

SA106 Gr. B X

6-24 SCH.80 SA106 Gr. B X

10 SCH.160 SA106 Gr. B Reactor Water Cleanup (RT)

X 6

SCH.120 SA106 Gr. B or SA333 Gr. G X

6 SCH.120 SA106 Gr. B Grade Class 1 Gr.

  • CL1 CL2 - Class 2 Sch.- Schedule CL3 - Class 3 in. - inches Dia. - Diameter min - minimum

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