ML20028C629
| ML20028C629 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 01/07/1983 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Tucker H DUKE POWER CO. |
| References | |
| NUDOCS 8301110621 | |
| Download: ML20028C629 (4) | |
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DISTRIBUTION:
e W 7 IN3 Docket No. 50-369 LB #4 r/f
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NRC PDR
. Local..PDR Docket No 50-369 System C
EAdensam RBirkel Mr. H. B. Tucker, Vice President' g M)uncan Nuclear Production Department dei senhut/RPurple Duke Power Company Attorney, OELD P.O. Box 33189 ELJordan, DEQA: I&E
' Charlotte, North Carolina - 28242 JMTaylor, DRP:I&E ACRS(16)
Dear Mr. Tucker:
Subject:
Operation of Unit 1 at' 75% Power (McGuire Nuclear Station, Unit 1) sy letter dated November 19, 1982, we infomed you that your McGuire Unit 1 oper-ating program at a power level of 50 percent for a period extending from December 1982 to February 1983 was acceptable.
Your letter dated December 15, 1982,' pro-vided a summary of the results of the November 1982 eddy current testing (ECT).
performed on the Unit 1 steam generators and an outline of a proposed operating j
plan for the unit.
As a result of your steam generator tube inspection you con-clude that the unit could be operated at 75 percent power for an additional 30 j
days (720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br />).
You also state that the unit would continue to operate at 50 percent power until the steam generator modification is ready for installation but would be shut down no later than April 1,1983, for the next ECT.
ds a result of our review of the infomation provided as well as discussions with your staff, we conclude and find acceptable your McGuire Unit 1 operating program 1
for a period extending from February 1983 to April 1,1983, including operation at 75 percent power for a maximum of 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> (30 days).
We require that the staff be immediately notified in the event there is any indica-tion of steam generator behavior contrary to the infomation which was provided in your' August 3 and December 15, 1982, l etters.
A sinmary of the results of our review is presented in the enclosure.
Sincerely, 0"tir.m signec ty; Chc: x. ;;. i,m Thonas M. Novak, Assistant Director for Licensing
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t McGuire Mr. H. B.- Tucker, Vice President Nuclear Production Department Duke Power Company 422 South Church Street Charlotte, North Carolina 28242 cc: Mr. A. Carr Duke Power Company P.O. Box 33189 422 South Church Street Charlotte, North Carolina 28242 Mr. F. J. Twogood Power Systems Division Westinghouse Electric Corp.
P.O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. G. A. Copp Duke Power Company Nuclear Production Department P.O. Box 33189 Charlotte, North Carolina 28242 J. Michael McGarry, III, Esq.
Debevoise & Liberman 1200 Seventeenth Street, N.W.
Washington, D. C.
20036 Mr. Paul Semis Senior Resident Inspector c/o U.S. Nuclear Regulatory Commission Route 4, Box 529 Hunterville, North Carolina 28078 James P. O'Reilly, Regional Administrator U.S. Nuclear Regulatory Commission, Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 a
Encitsura REVIEW 0F McGUIRE UNIT 1 EDDY CURRENT RESULTS OF OPERATION AT 75". P0rJER AND PROPOSED OPERATING PROGRAri EXTENDING TO NO LATER THAM APRIL 1, 1983 REF: DUKE POWER COMPANY LETTER REPORT DATED DECEMBER 15, 1982 INTRODUCTION By letter dated December 15, 1982, Duke Power Company submitted results of the November 1982 eddy current inspection (ECT) of their steani generators, and based on these results proposes an operational plan for McGuire Unit 1 until the next planned shutdown for implementation of the steam generator modifications, cur-rently scheduled for no later than April 1,1983.
The licensee proposes to oper-ate McGuire Unit I during this period at a power level no greater than 75 percent.
The operating time above 50 percent power will be restricted to 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> during this period of operation.
The licensee's technical justification for operation of McGuire 1 for a limited time at 75% includes the eddy current results which established wear rates at 75%
power, and a conservative upper bound of the amount of additional tube wear, which when applied to the two largest existing tube defects during the next period of operation at 75% power, will not exceed the safety limits for those tubes.
DISCUSSION In their December 15, 1982, letter, Duke Power Company provided the following infor-mation regarding the most recent eddy current inspection.
Eddy current testing of Rows 47, 48, and 49 in all four steam generators was perfomed.
Additionally, in steal generator A, Row 46 was inspected due to the fact that more indications were observed in the previous inspections in steam generator A.
Based on this ECT exam-ination, a total of six tubes were plugged, five in steam generator A and one tube in steam generator C.
The tube plugged in steam generator C (R49-C40) had the 1argest observed wear scar ( 20 percent) at the July 1982 inspection and was expected to be plugged during the November outage.
This tube had worn to approx-imately 40 percent through wall when inspected in November 1982.
The five tubes plugged in steam generator A all exhibited indications of 25 per-cent through wall. These tubes were plugged since their projected wear rates would increase the indications to greater than 40 percent through wall with another operating cycle sinilar to the August 1982 to November 1982 cycle.
No tubes were plugged in stea*n generators B and D.
A detailed tube by tube listing of the ECT results, including those of the March 1982 and July 1982 inspections, were provided in the December 15, 1982, submittal.
The November 1982 inspection data indicated that the total number of tubes showing indication of wear is 67, including 41 which showed no indication of wear at the M y 1r' i n =ti^r.
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EVALUATION An examination of the data. from the July 1982, inspection showed nine tubes with -
10-' cubic These nine tubes now have wear indications wear:indicationsgfbetween2.6x10-.and3.4x10jnches.
cubic i Accordingly,-an upper bound for tubewearmaybeestablishedas3.4-x10gchas.
cubic inches per 30 day period at 75%
- volume of 2 x:10 gith the highest wear, tube 49-40 in steam generator C. has a wear power.. The tube cubic inche The measured vol me based on the most recent inspection is 5 2 x 10 pin July 1992.
cubic inches.. It was, therefore, concluded that a wear rate of 3.4 x 10-3 cubic inches per 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> operating period is consistent with the data from all worn tubes.
Once the wear rate was calculated based on the previous operating period, it was Ltube wear. - All of these tubes showed wear volmes of =3.4 x 10 g progression of decided that five tubes should be preventively plugged due to th cubic inches, or 23-25% through wall.
It was noted that these tubes would grow beyond the plugging limit (to approximately 56% through wall) during a subsequent 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> operating period at' 75% power.
The wear rates.for these five tubes were equal to or less than the wear rate discussed above.
It was also noted that after 720 more hours at 75% power operation twenty-three tions of =3.5 x 10-}y have wear indication of ' 10-4 tubes which current cubic inches will have indica-cubic inches.
This wear volume corresponds' to a_ through wall depth of less than 25%.
Using maxime wear projection, it is estimated that two additional tubes may require plugging based on the plugging limit of 40% through wall.
These two tubes should have indications less than 50% through wall and will
.be available for wear evaluation at the next inspection.
1 CONCLUSION We find that McGuire Unit 1 may be operated at power levels above 50 percent but no greater than 75 percent power for 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> until the next planned shutdown, tenta-tively scheduled for no later than April 1,1983, without undue risk to public health and safety.
This finding is based upon evaluation of the ECT results of the November 1982 inspections, preventive plugging and estimated additional wear on tubes with wear indications.
i Upon shutdown Duke Power Company should conduct an eddy current inspection of the first three rows of the preheater section of all steam generators.
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