ML19323C275
| ML19323C275 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 04/25/1980 |
| From: | Baer R Office of Nuclear Reactor Regulation |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 8005150241 | |
| Download: ML19323C275 (4) | |
Text
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o UNITED STATES Eh)#c 3
NUCLEAR REGULATORY COMMISSION
.. C WASHINGTON, D. C. 20555 3 J-S S~
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April 25,1980 Docket Nos.:
50-369 and 50-370 Mr. William 0. Parker, Jr.
Vice President, Steam Production Duke Power Company P. O. Box 2178 422 South Church Street Charlotte, North Carolina 28242
Dear Mr. Parker:
SUBJECT:
STEAM GENERATOR MODIFICATIONS AND CONTROL R0D GUIDE PIN REPLACEMENT (McGuire Nuclear Station, Units 1 and 2)
The steam generators of the McGuire Nuclear Station are of a design having carbon steel supporting plates with drilled tube and flow holes.
Steam generators of this design in operating plants have experienced denting and cracking. Although an effective secondary water chemistry control program can reduce the rate of steam generator degradation there is no assurance that a 40 year steam generator lifetime can be obtained.
For some forms of steam generator degradation which have occurred, eddy current testing and tube gauging alone are not sufficient to assess and monitor tube and support plate degradation.
In order to perform adequate i
assessment and monitoring of these areas, we require that inspection ports be installed in each McGuire steam generator. These ports should be installed just above the upper support plate, and between the tube sheet and the lower support plate, with both ports in line with the tube lane.
Under the ALARA concept we are requesting that all possible steam generator modifications be made prior to the start of operations. However, based upon experience we have determined that these ports can be installed in the gen-erators after start of operations at a personnel exposure of 7.5 man-rem.
We have determined that this exposure is not significant enough to justify the delay of start-up of the plant to permit the lsstallation of inspection ports. However, since the probability of secondary sMe contamination will increase as the operating time increases, we require that these ports be installed prior to start-up after the first refueling. The McGuire operating license will therefore be so conditioned, if necessary.
n da Mr. William 0. Parker, Jr. April 25,1980 Experience has also shown that the small bend radius of the Rcw 1 tubes in the steam generators of Westinghouse manufacture leads to early onset of cracking. We require that the Row 1 tubes of each McGuire steam generator be plugged prior to the start of operation. This should forestall the need for early shutdowns due to leaking tubes since these tubes are the ones most susceptible to the development of cracks.
Regarding your secondary water chemistry monitoring and control program, we require that the control of the condenser leakage be based upcn the water chemistry of the discharge of the hot well pump. Out-of-limit water chemistry indicating condenser leakage, monitored at the hot well pump, would be a better indicator of condenser leakage affecting the steam generator than the proposed hot well sampling. The McGuire program indicates that the discharge from the hot well pump will be continuously monitored. When a condenser leak is con-firmed, the leak should be repaired or plugged within 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />, as stated in the Branch Technical Position MTEB 5-3 appended to Standard Review Plan 5.4.2.1.
Although not relatee to secondary water materials consideration, we a e concerned about the McGuire control rod guide tube support pins. On March 13, 1980, Westinghouse reported to the NRC that Inconel 750 control rod guide support pins that were given a low temperature solution heat treatment may be susceptible to 1
stress corrosion cracking. This followed recent support pin inspections at a foreign plant which revealed stress corrosion cracks in Westinghouse supplied pins. We believe that the existing guide support pins in the McGuire 1 and 2 internals should be replaced with new pins that have been given a heat treatment which produces a condition that is highly resistant to stress corrosion cracking.
We requesi, that you inform us no later than May 9,1980, as to how you plan to implement the above requirements.
Sincerely,
.&.. j j.. -
Robert L. Baer, Chief Light Water Reactors Branch No. 2 Division of Project Management ec: See next page I
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Db" Mr. William 0. Parker, Jr.
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.Vice President, Steam Production
- - Duke Power Company P. O. Box 2178 422 South Church Street Charlotte, North Carolina 28242 cc:
Mr. W. L.' Porter Duke Power Company P. O. Box 2178 422 South Church Street Charlotte, North Carolina 28242 Mr. R. S. Howard Power Systems Division Westinghouse Electric Corporation P. O. Bcx 355 Pittsburgh, Pennsylvania 15230 Mr. E. J. Keith
,EDS Nuclear inco;porated 220 Montgomery Street San Francisco, California 94104 Mr. J. E. Houghtaling 5'.
NUS Corporation 2536 Countryside Boulevard Clearwater, Florida 33515 Mr. Jesse L. Riley, President
.The Carolina Environmental Study Group 854 Henley Place Charlotte, North Carolina 28207 1r.
J. Michael McGarry, III, Esq.
$tr.
Debevoise & Liberman
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1200 Seventeenth Street, N. W.
Washington, D. C.
20036 Rober t M. Lazo, Esq., Chairman Atomic Safety and Licensing P ard U. S. Nuclear Regulatory Comission Washington, D. C.
20555 Dr. Emmeth A. Luebke Atomic Safety and Licensing Board
't U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Dr. Cadet H. Hand, Jr., Director Bodega Marine Lab of California P. O. Box 247 Bodega Bay, California 94923
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Mr. !41111am 0. Parker, Jr.
cc: David Flesichaker, Esq.
1735 Eye Street, N. W.,
Suite 709
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Washington, D. C.
20006 Richard P. Wilson, Fq.
Assistant Attorr.ey General State of SoutF. Carolina r
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2600 Bull Street Columbia, South Carolina 29201 t' s l
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