ML20045A034
| ML20045A034 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 06/01/1993 |
| From: | Denton R BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9306090276 | |
| Download: ML20045A034 (4) | |
Text
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BALTIMORE GAS AND ELECTRIC 1650 CALVERT CtJFFS PARKWAY. LUSBY, MARYLAND 20657-4702 PoBERT E. DENTON Vict PRESIDENT NUCLE AR ENERGY (4po) 260-4 4 55 June 1,1993 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Non-destructive Examination Notice of Violation
REFERENCE:
(a)
Letter from Mr. J. P. Durr (NRC) to Mr. R. E. Denton (BG&E),
dated April 23, 1993, NRC Region I Inspection of Calvert Cliffs Units 1 and 2 Inservice Inspection Activities, Combined Inspection Report Nos. 50-317/93-08 and 50-318/93-08 Gentlemen:
In response to Reference (a), Attachment (1) is provided. Based on the information contained in this attachment, we ask that you reconsider the violation.
Should you have any further questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours,
[
I RED /DWM/dwm/bjd/rej Attachment 9306090276 930601 r
PDR ADOCK 05000317 i{
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'4 Document Control Desk I
June 1,1993
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D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC D. G. Mcdonald, Jr., N RC T. T. Martin, NRC P. R. Wilson, NRC R. I. McLean, DNR J. H. Walter, PSC f
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g ATTACIIMENT m 4
NOTICE OF VIOI ATION 50-318/93 08-01 Notice of Violation 50-318/93-0841 states that contrary to Technical Specification (TS) 4.0.5, which requires Inservice Inspection (ISI) of ASME Code Class 1,2, and 3 components to be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code, rejectable magnetic particle indications on main steam system welds 34-MS-2001-6 and 36-MS-2001-3 were examined and accepted using an ultrasonic examination method that failed to establish the dimensions of the flaws as required by ASME Section XI.
Baltimore Gas and Electric Company disagrees with this violation. Our understanding of the Code is that the purpose of determining the dimensions ofindications is to determine whether they are or are not of sufUcient size to be rejectable. Once this determination is made, further dimensioning of indications is unnecessary. We believe that the technique used in this case was sufficient to verify that the indications found were not of sufficient size to be rejectable. We have asked the Electric Power Research Institute's (EPRI's) Non-destructive Examination (NDE) Center to verify that this is in fact the case. We have also written to the ASME Code Committee requesting an interpretation regarding our use of the technique.
On March 2,1993, we discovered, via magnetic particle examination, a 3/8" linear indication on weld 3 of the main steam line (36-MS-2001). On the same day, a similar indication was found on weld 6 of the same line. Both flaws were rejectable due to their length per ASME Code Section XI, IWB-3514.7 and Table IWB-3514.4. On March 3,1993 we performed an Ultrasonic Examination of both welds per ASME Code Section XI, IWB-3514.2(b). The method used was a 45 degree full vec shear wave described in Appendix III of the Code. The Ultrasonic Examination failed to find any indications in either weld. The location and orientation of the surface indications were known and accounted for during performance of the examination. We documented our conclusion that since the flaws were not deep enough to be detected by ultrasonic examination, they could not be deep enough to be rejectable. Given the calibration sensitivity and pipe size we were examining, a 14.6 percent throughwall crack would have been acceptable. We therefore accepted the welds.
We believe that the 45 degree full vec shear wave technique we used is capable of identifying rejectable indications initiating at the OD surface of a pipe in accordance with IWA-2232(b) and IWB-3514.2(b) of the Code. This is the standard technique used by our vendor to detect reflectors in ferritic piping. The examiner calibrated using 10 percent throughwall deep notches and increased the sensitivity of the instrument by increasing the gain 6,14, and 20 decibels (2,5, and 10 times the reference level sensitivity) during the course of the examination. He verified that sound was getting to the surface by creating a couplant pocket and obtaining a reficctor. He received no recordable indications even with significantly increased instrument sensitivity and concluded that the indications had no measurable throughwall dimension. The indications would have to be detectable and therefore measurable in order to be rejectable. The technique would have detected a 14.6 percent throughwall crack. Had a measurable throughwall indication been found we would have sized the indication.
L Our conclusion was conGrmed when we examined the area containing the surface flaws using a high j
angle ultrasonic sizing technique advocated in the subject inspection report as being appropriate.
j We obtained exactly the same results from this examination (no detectable throughwall indications) l as we had from the earlier one. We believe that the earlier technique found no indications because there were no throughwall indications to find, rather than because it is not an appropriate technique.
We have requested that the EPRI NDE Center verify this conclusion by demonstrating the ability of the technique to detect throughwallindications in circumstances similar to ours.
The subject inspection report discusses a demonstration at another utility in which the te.hnique failed to identify five out of seven cracks emanating from the OD surface of a pipe. We have j
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ATTACIIMENT (1)
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NOTICE OF VIOLATION 50-318/93-08-01 discussed this with the utility in question and believe that the findings of this demonstration are not applicable to our situation. The demonstration involved a blind test of a section of stainless steel I
pipe for an unknown number of indications of unknown size or orientatica. We were k>oking for a previously located indication of known orientation in a carbon steel pipe, it is more difficult to locate surface flaws in stainless steel than carbon steel. The unknown indications in the demonstration were located on the weld surface and toe of the weld while the indications we were examining were both krated on the base metal, where flaws are more easily k)cated. None of the demonstration indications were greater than five percent throughwall and the test found 40 percent of them.
Although we believe that the technique used was acceptable, we will use techniques to more exactly size indications until such time as we receive answers from the Code Committee and EPRI, at which time we will make any appropriate program changes.
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