ML19323H716
| ML19323H716 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/09/1980 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | Clark R, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8006160092 | |
| Download: ML19323H716 (3) | |
Text
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l Wisconsin Electnc ma coww 231 W. MICHIGAN. P.O. BOX 2046. MILWAUKEE, WI 53201 June 9,1980 Mr. Harold R. Denton, Director
.0ffice of Nuclear Reactor Regulation U. S. NUCLEAR REGULATORY COMMISSION Washington, D. C.
2.0555 Attention: Mr. Robert A. Clark, Chief Operating Reactors Branch #3 Gentlemen:
DOCKET NO. 50-301 STEAM GENERATOR E00Y CURRENT INDICATIONS POINT BEACH NUCLEAR PLANT UNIT 2 This is in reply to the telephone request of Mr. E. Murphy of your Staff for additional information regarding the Point Beach Nuclear Plant Steam Generator Eddy Current inspection completed in March 1980.
Mr. Murphy requested the number of eddy current indications recorded in the A and B steam generator hot legs and their distribution by size and height above the tubesheet.
This information is provided in the attached Table.
As you are aware, the March 1980 eddy current inspection utilized for the first time, in the Point Beach Unit ? steam generators, the multi-frequency eddy current technique. As discussed and documented in our previous correspondence, including the License Event Report (LER) filed on this outage dated May 16, 1980, the multi-frequency eddy current technique permits a much better resolution of indication signals which are located at the tubesheet interface, since low volume indications can be masked otherwise by the tubesheet entry signal. We are in the process of comparing the results of this inspection to the results of the previous eddy current inspections of these tubes. Thus far we have determined in general that the results of this most recent inspection are consistent with the results of previous inspections.
In the majority of the tubes, the previous eddy current inspection results have listed either distorted tubesheet notations or less than 20% eddy current indications.
The use of the multi-frequency eddy current mixing process has permitted us to differentiate such indication in this latest inspection and record them as specific percentage indications.
In a few cases, the earlier inspection results have indicated no previous eddy current indications. As repcrted
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e Mr. lHarold R. Denton, Director' June 9,1980 in our May 16 LER, we have previously compared the actual eddy current taped signals from previous inspections to the latest 400 KHZ signal for those
-tubes listed in the LER. Based on the experience from those observations, we believe these indications have been present for some time but were masked by the tubesheet entry signal and thus, not previously recordable. Overall, the results of the March 1980 inspection indicate a stable situation with very little change in the. condition of the tubes in the Unit 2 steam genera-tors.
Please note that this information is based on the field data sheets.
A final. report _on this inspection will not be available for several months.
The results of this inspection, as have previous inspections, will be report-ed in our Annual Results'and Data Report.
Very truly yours,
/
C. W. Fay, Director Nuclear Power Department Attachment Copy to: NRC Resident Inspector
- Point Beach Nuclear Plant C. F. Riederer - PSCW Peter Anderson - WED Joan Estes -'LSCFSE 9
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2 ATTACHMENT TO JUNE 9, 1980 LETTER TO MR.~HAROLO R. DENTON
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EDDY CURRENT-INDICATIONS BY SIZE AND LOCATION POINT BEACH NUCLEAR PLANT UNIT 2 MARCH 1980 INSPECTION I.
.A Hot Leg.
<20%
20-29%
30-3"
'At Top 'of Tubesheet*
226 118 80 h"~Above.TS 17
~
- 1"- Above TS 7
2" Above TS 1
TOTALS
'251=
118 80
.II.
.B-Hot Leg
<20%
20-29%
30-39%
At' Top of Tubesheet*
26 17 6
A" Above TS 19-4 1" Above TS 2
1 2
1h" Above-TS 1
1 32" Above TS TOTALS 48 23 8
- The notationI" top of tubesheet" refers to defect indications which have been
- separated from~the tubesheet entry eddy current signal using multi-frequency 1 techniques. The recent development of this. technique, which was used for the
. first time lon: Unit l2 during this ~ inspection, permits much better discrimination of' low volume defect Lindications.from the tubesheet signal. During previous inspections,.using only 400 KHZ eddy current signals, the majority of these i
stop of'tubesheet-indications were referred to as either distorted tubesheet signals or.less;than 20%. indications.
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