B12545, Informs NRC of Actions Taken to Date Re Piping Insp Programs to Detect Erosion/Corrosion Wear.Work Will Begin w/1987 Outage to Devise Effective Pipe Wall Thickness Measurement Program to Eliminate Potential Piping Sys Concerns

Informs NRC of Actions Taken to Date Re Piping Insp Programs to Detect Erosion/Corrosion Wear.Work Will Begin w/1987 Outage to Devise Effective Pipe Wall Thickness Measurement Program to Eliminate Potential Piping Sys Concerns

ML20215C986
Person / Time
Site:	Millstone, Haddam Neck, 05000000
Issue date:	06/10/1987
From:	Mroczka E CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
B12545, NUDOCS 8706180324
Download: ML20215C986 (3)

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NORTHEAST UTILITIES cenerai Ofvices seiden street. Berlin. Cone ecticut l sIYU = NcUU P.O. BOX 270 ww *m eom a a**** HARTFORD, CONNECTICUT 06141-0270 L L 7 j ((' ]'l,['j ",,,, (203) 66s-5000 I

June 10,1987 Docket Nos. 50-213 50-245 50-336 50-423 B12545 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Haddam Neck Plant Millstone Nuclear Power Station, Unit Nos.1,2 & 3 Piping Inspection Programs to Detect Erosion / Corrosion Wear As a result of the catastrophic failure of the carbon steel feedwater system piping at Surry Unit 2, Connecticut Yankee Atomic Power Company (CYAPCO) and Northeast Nuclear Energy Company (NNECO), licensees for the Haddam ,

Neck Plant and Millstone Unit Nos.1, 2 and 3, respectively, have initiated actions to upgrade their inspection programs to determine whether significant ,

pipe wall thinning due to single-phase erosion / corrosion in secondary high-energy piping systems is occurring and to take appropriate corrective measures, as required. The purpose of this letter is to inform the NRC Staff of some of the actions we have taken to date to address this issue, recognizing that further regulatory guidance is not a prerequisite for us to proceed in this important area.

We are evaluating the ability of current inspection programs to detect wall thinning in secondary side piping. The current programs will be confirmed adequate or will be augmented such that pipe wall thinning at any of our plants can be detected before it becomes critical. The program also involves a systematic review of all secondary side systems to determine the locations which may be susceptible to single-phase, flow-assisted erosion / corrosion. The basis for this evaluation are the results of a three year research program funded by Northeast Utilities (NU) at the Massachusetts Institute of Technology (l) and available EPRI data on the subject. In this regard, NU has been and continues to be actively involved in the NUMARC Working Group on Piping Erosion / Corrosion. We intend to meet or exceed the guidelines established by this group for all our plants when they become available.

I (1) PhD Thesis; " Prediction and Mitigation of Erosive - Corrosive Wear in Extraction Piping Systems"; Richard G. Keck; Peter Griffith (Thesis Supervisor), January,1987. J o\ l jFoS"$8S$SNh3 ,o G

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U. S. Nuclear Regulatory Commission B12545/Page 2

, June 10,1987 l

Parameters which are being considered in the evaluation are piping material, {

oxygen content, temperature, pH, bulk flow velocity, and adverse geometry giving rise to localized high turbulence. Empirical and theoretical correlations between these parameters will be used to estimate wear rates. Using these wear I predictions, susceptible system locations will be ranked and ultrasonically 1 inspected according to the ranking. The results of these inspections will be. N analyzed and used as the basis for follow up or corrective actions, which may include pipe replacement, increased inspection frequency or maintenance of the current inspection frequencies. The inspection results will also give an indication of the accuracy of the predicted wear rates and will provide useful data for reevaluation of the ranking scheme, the wear prediction methodology, and the erosion / corrosion screening criteria, ,

It is iour intent to continue this work over several years during plant outages beginning with the Summer 1987 outages - at the Haddam Neck plant and l Millstone Unit No. 1, the end result being an effective pipe wall thickness  ;

measurement program to eliminate potential structural integrity concerns m applicable secondary high-energy piping systems.  !

We wish to point out that while we have initiated these actions as a result of the Surry incident, .we have had effective secondary piping wall thickness j measurement programs, which include single-phase flow areas, in place at our plants. We believe that our current efforts will serve to further improve these programs. It sho"'d be noted that ultrasonic inspections of the Millstone Unit No. I condensate scoster pump suction and discharge lines and portions of the Millstone Unit No. 2 feedwater system piping having configurations similar to Surry, ~ detected negligible, if any, pipe wall thinning. The feedwater system piping at Millstone Unit No. 3 has not yet been inspected for erosion / corrosion I wear due to the newness of the plant and since the feedwater system piping  !

arrangement at Millstone Unit No. 3 is significantly different than the Surry ]

plant. Nevertheless, we intend to apply the results of our work in this area to  !

the development of an appropriate pipe wall thickness measurement program for Millstone Unit No. 3 and willimplement it during the first refueling outage. ]

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We hope that the Staff will find this information useful in their study of this issue and we look forward to continued cooperation with the NRC and the nuclear industry on this subject. If you have any questions, please contact my staff directly. 4 I

l Very truly yours, 4 CONNECTICUT YANKEE ATOMIC POWER COMPANY  ;

NORTHEAST NUCLEAR ENERGY COMPANY '

l M &

E. J./dr'oczka / i Senior Vice President

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.U. S. Nuclear Regulatory Commission - .

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B12545/Page-3

- June 10,1987- .l J.

. cct . W. T. Russell, Region I Administrator i

. M. L. Boyle, NRC Project Manager, Millstone Unit No.1 - l D. H. Jaffe, NRC Project Manager, Millstone . Unit No. 2 -

R. L. Ferguson, NRC Project Manager, Millstone Unit No. 3'

- F. M. Akstulewicz, NRC Project Manager, Haddam Neck Plant T. Rebelowski, Resident Inspector, Millstone Unit Nos.'l and 2

'3. T. Shediosky,' Resident Inspector,' Millstone Unit No. 3 P. D Swetland, Resident Inspector, Haddam Neck Plant .

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