ML19309G064

Submits Addl Info Re March 1980 Inservice Insp of Steam Generators & Tubes & Height of Tubesheet Sludge Pile in 1975 & 1980,in Response to NRC 800423 Telcon.No Correlation Possible for Tube Insp or Sludge Pile Height

ML19309G064
Person / Time
Site:	Point Beach
Issue date:	04/25/1980
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	Harold Denton, Schwencer A Office of Nuclear Reactor Regulation
References
NUDOCS 8005020302
Download: ML19309G064 (3)

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%fsconsin Electnc mcoww 231 W. MICHl AN. P.O. 80X 2046, MILWAUKEE. WI 53201 April 25, 1980 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. NUCLEAR REGULATORY COMMISSION Washington, D. C. 20555 Attention: Mr. A. Schwencer, Chief Operating Reactors Branch 1 Gentlemen:

DOCKET NO. 50-301 ADDITIONAL INFORMATION STEAM GENERATOR INSPECTION POINT BEACH NUCLEAR PLANT, UNIT 2 This is in response to questions from members of your Staff during telephone conversations on April 23 regarding the March 1980 inservice inspection of the Point Beach Nuclear Plant Unit 2 steam generators. In our Licensee Event Report (LER)80-003, dated March 12, 1980, and the update of that report dated April 16, 1980, we concluded that, based on all available data, the top of tubesheet indications for twenty-six of the thirty-one tubes identified in the LER had been present but undetectable since 1974. This conclusion was based upon a review of all the single frequency (400 KHZ) eddy current inspection tapes for these tubes dating from 1974. For the remaining five tubes, specifically R7C21, R13C19, R18C68, R12C73 and RllC74, the March 1980 inspection was the first time that these tubes had been inspected. Therefore, no correlation to previous inspections was possible.

The Staff also asked if recent inspection results for tubes identified as having indications above the tubesheet, but which were below plugging limits, showed any significant changes from the Spring 1979 eddy current inspection results. The 1979 inspection results were reported in our Annual Results and Data Report for 1979. We have crosschecked those indications against the results of the March 1980 inspection and have determined that the indication sizes are essentially unchanged indicating a stable condition. Table 1, attached, summarizes this determination.

The Staff also requested that we inform you of the i height of the tubesheet sludge pile in 1975 and in 1980. Up until 1977, a 25 KHZ eddy current signal was used to measure

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Mr. Harold R. Denton April 25, 1980 the height of the sludge pile. In 1976, the last year this technique was used for sludge depth determination, the recorded height of deposits ranged from 0 inches to 10 inches with an average depth of 4 to 5 inches. Beginning in 1977, a water balance method was used to determine the amount of sludge present both before and after sludge lancing. We, therefore, have no direct measurement of the present height of the sludge pile which can be related to the 1976 levels.

As you know, during the present Unit 2 refueling outage, we removed tube R18C37 from the "A" steam generator for metallurgical examination and evaluation. We are anticipating the availability of preliminary results of this exam!. nation by May 7. We shall provide these results to you at thrt time.

A report summarizing the examination results is expected to be available within four to six weeks after the preliminary results.

We trust this information is responsive to your recent questions. If you have any additional questions or comments, please contact us.

Very truly yours, h}Vl (71/.

C. W. Fay, Director Nuclear Power Department Attachment Copies to: Mr. C. F. Riederer (PSCW)

Mr. Peter Anderson (WED) .

Ms. Joan Estes (LSCFSE) l l

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TABLE 1 COMPARISON OP 1979 AND 1980 EDDY CURRENT RESULTS

. POINT BEACH NUCLEAR PLANT, UNIT 2 1979 1980 Still No Defect Increased Increased

<20% <20% Detected <10% 10-20%

"A" SG Inlet 21 10 10 0 1 "A" SG Outlet 14 9 5 0 0 "B" SG Inlet 10* 2 2 4 1 "B" SG Outlet 133 127 2 4 0 ,

Same No Defer" Decreased Increased Increased 20-29% +3% Detected >3% 3-10% 10-20%

"A" SG Inlet 5 1 0 3 0 1 "A" SG Outlet 1 0 0 1 0 0 "B" SG Inlet 3 1 1 0 0 1 "B" SG Outlet 92 66 0 18 7 1 Same No Defect Decreased Increased Increased 30-39% +3% Detected >3% 3-10% 10-20%

"A" SG Inlet 6 1 0 2 2 1 "A" SG Outlet 1 0 0 1 0 0 "B" SG Inlet 3 3 0 0 0 0 "B" SG Outlet 5 1 0 4 0 0 i

• One tube not inspected.

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