ML20065N354
| ML20065N354 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/07/1990 |
| From: | Skolds J SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | George Wunder NRC |
| References | |
| NUDOCS 9012120083 | |
| Download: ML20065N354 (3) | |
Text
._ - _____-
th Car ime flettric & Gis Comptny John
- old, uo,nw r, m.s twi* owes (bXh 345 4340 "SCE&G
. w.,
m DrT i7 man Document Control Desk U. S. Nuclear Regulatory Commission Washingtan, DC 20555 Attention: Mr. G. F. Wunder Gentleman:
Subject:
VIRGIL C. SUMMER NUCLEAR STATION DOCKET NO. 50/395 OPERATING LICENSE NO. NPF-12 TECHNICAL SPECIFICATION CHANGE - TSP 880015-4 L* ALTERNATE PLUGGING CRITERIA As discussed during a telephane conversation on December 3, 1990, by Mr. H.
F. Conrad of your staff Mr. C. V. Dodd, your consultant, and several members of my staff, the following responses address the NRC questions relative to the data acquisition and analyses capabilities for implementing the L*
criteria:
NRC Question 1 - Can we get a comitment that the scan will encompass 100 points around the circumference taken with a pitch of 0.050 inch?
SCELG Response - Impicmentation of the L* criteria at the Virgil C. Summer Nuclear Station (VCSNS) requires the use of the rotating pancake coil (RPC) eddy current technique to characterize anomelies inside the tube sheet region of the steam generator % The RPC system, hardware and software, will facilitate graphics display of each scan of each tube at a minimum of 100 points per tube circumference. The rate of probe withdrawal and probe RPM shall be such that a pitch of.050 inch or less will be maintained during data acquisition.
NRC Question 2 - Discuss the need for a standard addressing cracks at an engle to the tube axis, not just those that are either parallel or perpendicular to the axis.
SCELG Response - An eddy current tube standard shall be used for analysis set-up and calibration. This standard will contain at least two electric discharge machined (EDM) notches, at angles other than 0 to 90 degrees from center line. The enclosed drawing shows a proposed typical standard for use with L* implementation. The standard shows two E0h notches, one at 20 degrees and onc at 45 degrees from center line as well as other machined anomalies to be contained in the set-up standard.
This standard shall provide set-up of the inspection system and demonstratica of sensitivity of the system to flaws originating on both the inside diameter and outside diameter of the tube wall.
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e Document Control Desk TSP 880015-4 Page 2 NRC Question 3 - What assurance will be provided that data analyst's training is itself qualified?
SCELG Response - In addition to the vendor's qualification and certification program, the eddy current data analysis staff at VC$NS will be required to attend and successfully pass a site specific familiarization course prior to being allowed to analyze eddy current data. The site specific familiarization course and examination to be used to test analysis personnel meets or exceeds the recommendations outlined in EPRI document 6201, "PWR Steam Generator Examination Guidelines, Revision 2."
This course and the site specific guidelines document used for analysis activities will be revised, upon the approval of L* by the USNRC, to include the approach and logic used for L* implementation at VCSNS. Practical examinations to be given at the conclusion of the course will include eddy current data from the standards described above, as well as data from actual tube examinations.
Should you have any questions concerning this issue, please call Mr. M. W.
Gutierrez of my staff at (803) 345-4392 at your convenience.
Very truly yours,
/
John L. Skolds MWG:REK:JLS: led Enclosure c:
- 0. W. Dixon, Jr.
E. C. Roberts R. J. White S. D. Ebneter G. F. Wunder General Managers NRC Resident inspector J. B. Knotts, Jr.
H. G. Shealy R. E. Kelso NSRC NPCF RTS TSP 880015)
File 813.20)
NUCLEAR EXCELLENCE - A SUMMER TRADITION!
s I
Enclosure to Document Control Desk Letter T S P-880015-4 Eddy Current EDM Notch Standard E-360/MRPC Calibration For L+ Implementation
~~
0' Axial ID 20%
40%
60%
00%
0
- EDM notches are 90* apart arc-und circumference 40%
f 20
- ID 3*
40%
/-
46' ID
_~_
m Machined anomalies are square 40%
bottom EDM notches 90
- OD All notches are.6' In length 1 006' All notches are.006' in width t.0 01*
Angularity of notches is +_
2*
_