ML19207C453
| ML19207C453 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/05/1979 |
| From: | Herbein J METROPOLITAN EDISON CO. |
| To: | Reid R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19207C454 | List: |
| References | |
| GQL:-1141, NUDOCS 7909110641 | |
| Download: ML19207C453 (2) | |
Text
.
L Metropolitan Edison Company 0
Post CMfice Box 480
~
Middletown, Pennsylvania 17057 717 9444 041 Septem'er 5, 1979 o
GQL: 1141 Director of Nuclear Reactor Regulations Attention:
R.W. Reid, Chief Operating Reactors Branch #4 U.S. Nuclear Regulatory Commission Washington, D.C.
20555
References:
a) GQL 1059 dated August 15, 1979 b) IE Bulletin No. 79-17 dated July 26, 1979 Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR - 50 Docket No. 50-2d9 ICSCC Investigation
Dear Sir:
Background:
In the previous status report (reference a above) Metropolitan Edison referred to the use of a highly-sensitive, state of the art, ultrasonic inspection technique (UT) which was capable of identifying an IGSCC which extended only.006" into the heat affected zone of the pipe ID.
This previous report also recognized the fact that many of the indications identified by this highly sensitive UT technique were reflections from weld geometry and other welding related anomalies. The development of a screening procedure capable of classifying UT indications as to their probable cause has been recently completed. The attached procedure identified as UrL-UT-SP10 revision 4 embodies the results of this development.
The verification of this screening technique's ability to differentiate between geometric reflectors and IGSCC in an advanced state of growth is based on the following:
- 1) The evaluation technique has identified IGSCC in three samples which have been determined by metallography to have varying degrees of through wall crack growth (*25%, =50%, 100% of wall thickness).
- 2) The screening technique has identified IGSCC in two weld joints, still in the Spent Fuel Cooling System, which have been confirmed using extremely sensitive radiography. These lines were drained specifically for this radiographic i
inspection.
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- 3) The screening technique has determined that seven weld joints previously identified under the Phase I (sensitive) procedure were not IGSCC. The absence of IGSCC in these welds has subsequently been confirmed by Liquid Penetrant Examination of the pipe ID after these joints were removed from the system.
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- L eid September 5, 1979 US Nuclear Regulatory Commission Further corroborative evidence will be collected and documented with further radiographic inspections and when more samples are removed from the system. Presently an extensive re-examination of welds in 2 " diameter or larger piping in all engineered safeguard systems is under way.
Status:
The following matrix describes the 8/28/79 status of screened indications:
Total No.
Total No.
Total No.
No.
of UT with all Indications of UT of Indications UT Inspec-Using Indications Thru Evaluated Total No.
tions Sensitive after Wall to be Geometric Systems of Welds Comoleted Technique Screening Leaks Reflectors Spent Fuel 566 521 138 19 5
119 Decay Heat 408 277 99 10 1
89 Bldg. Spray 241 208 56 8
0 48 Make-Up 697*
693 96 1
0 95 Core Flood 31 31 1
0 0
0 RC Pzr. Surge 11 0
0 0
0 0
RC Pzr. Spray 28 28 1
0 0
1
(*Does not include 354 2 " welds in high radiation areas.)
At this point it is important to ncte that of the thirty-eight (38) screened indications, thirty-one (31) of them were welded in the field and of these thirty-one (31) field welds eleven (11) were repaired once.
Also note that none of the thirty-eight(38) screened indications are in deoxygenated lines. Presently it is expscted to take approximately two (2) weeks to complete all scheduled ultrasonic testing.
Met-Ed considers this report as a part of our continuing response to IE Bulletin 79-17.
The rext status report will be submitted by September 30, 1979.
f-Vtry truly yours, h'./
/
Q t M it cx J.G. Herbein Vice President Nuclear Operations JGH/CDR/gme b
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