ML20058C076
| ML20058C076 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 07/09/1982 |
| From: | Wells D DETROIT EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| EF2-58747, NUDOCS 8207260248 | |
| Download: ML20058C076 (3) | |
Text
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Donald A. Wells m
mm ~~
Edison EiE!==
July 9,1982 EF2-58747
./
Mr. James G. Keppler, Regional Administrator Region III U.S. Nuclear Regulatory Comtission 799 Roosevelt Road Glen Ellyn, Illinois 60137
Subject:
Final Report of 10CFR50.55(e) Item on RHR Service Water Piping Design Deficiency (#57)
I
Dear Mr. Keppler:
l This is Detroit Edison's final report on the RHR service water piping design deficiency problem. This problem was originally reported to Mr.
J. Konklin of NRC Region III by Detroit Edison's Mr. H.A. Walker, Super-visor-Construction Quality Assurance, on February 18, 1982.
During Februar,f 1982, Edison Start-Up at Fermi 2 requested authority to perform a hydrostatic test of the RHR service water piping system at ambient temperatures, which were well below 320 F (OcC) at the time. A review of the material specifications revealed the piping had been made to the SA106, Grade B Specification, which could fail in a brittle mode if stressed at low temperature. The RHR service water system was designed to operate as low as 400 F, so a ccuplete analysis of the system was undertaken to determine if the system is safe to operate at the pressures and temperatures for which it was designed.
Impact testing of steels has become routine for steels designed for use at low temperatures since the Liberty ship failures during World War II.
Many specifications have been developed to incorporate restricted chemistries and sugplenentary tests to assure safe operation when the design temperatures are 32 F or less. Specification SA106 does not have these limitations, and s
material made to this specification may be subject to brittle failure if stressed sufficiently at low temperatures.
The heat numbers and analyses of all the piping, lugs and fittings in the system were collated fran the documents on file in. site OC Records. The analyses were divided into "more susceptible" or "less susceptible" materials based on the Mn:C ratio, whether the material had been normalized, and whether Charpy V-notch testing had been perforned. When the Mn:C ratio was less than 3:1, and the material was neither normalized nor had impact tests run, a stress analysis was conducted on the piping in accordance with Equation 9, of sub-section NC 3650 of the ASME Code. Stresses developed during an earthquake were considered during the evaluation, as were the dead weight and pressure induced stress. All of the above data is on file.
8207260248 820709 PDR ADOCK 05000341 S
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Mr. James G. Keppler, Regional Administrator July 9, 1982 Page 'IWo EF2-58747 The stress analyses were further separated into "over 8000 psi" and "less than 8000 psi" ranges. The literature indicates 8000 psi is the
" lower stress limit for fracture propagation", and " represents the stress level below which fracture propagation is not possible because the minimum, small amount of elastic strain energy relcase required for continued propa-gation of brittle fracture is not attained".
Nine pieces of pipe and three fittings still were suspect after this dis-tinction was made. These were subjected to fracture mechanics analysis.
The results of this analysis indicated an initial crack of k inch deep through the pipe thickness and inch circumferential dimension can be tolerated during the hydrostatic test. A defect this large was not cred-ible since the welds were surface examined on this piping.
The analyses reported above indicated the piping would not fail in a brittle manner at 400 F either during a hydrostatic test or during operation. There-fore, no corrective action nor special precautions during the hydrostatic test were deemd necessary. The structure should operate safely as designed and built.
If you have questions concerning this matter, please contact Mr. H.A. Walker, Supervisor-Construction Quality Assurance.
Very truly yours, llVff DAW / HAW /cp t/
cc: Mr. Richard DeYoung, Director Office of Inspection and Enforcem nt Division of Reactor Inspection Programs U.S. Nuclear Regulatory Ccnmission Washington, D.C. 20555 Mr. Bruce Little, Resident Inspector U.S. Nuclear Regulatory Ccmnission 6450 North Dixie Highway Newport, Michigan 48166 I
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Mr. James G. Keppler, Regional Administrator July 9, 1982 Page Three EF2-58747 bec:
T.A. Alessi J.C. Ard, Jr.
C.R. Bacon W.F. Colbert W.M. Everett W.J. Fahrner E.P. Griffing C.M. Heidel W.H. Jens E. Lusis P.A. Marquardt/ Docket File (2)
E.H. Newton S.H. Noetzel J.W. Nunley J.D. Ryan L.E. Schuerman II. Tauber G.M. Trahey R.A. Vance/L.E. Eix H.A. Walker A.E. Itgele Site Document Control NRC Follow-Up Book /NRC File Chron File
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