ML20050E017
| ML20050E017 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 04/01/1982 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 8204120473 | |
| Download: ML20050E017 (10) | |
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' Doc ht Nosi 502369/370 LB #4 r/f Docket ilos: 50-369 DEisenhut/RPurple and 50-370 EAdensam RBirkel MDuncan bec: TERA SHanauer NRC PDR RTedesco Local PDR lir. W1111aa 0. Parker, Jr.
ZRosztoczy NSIC Vice President Stean Production RVollmer TIC Duke Power Company JKramer ACRS (16)
P.O. Dox 2178 RMattson N
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422 South Church Street RHartfield Charlotte, North Carolina 28242 D
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Dear fir. Parker:
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Subject:
Continued Operation of Unit 1 O k[8 5
(McGuire Nuclear Station Units 1 & 2) f/
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g By letter of March 12, 1982, we infomed you that operation ticGuir.cJldt' utilizing the Model D stean generator, on an interim basis at
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accep-i' table pending receipt of a detailed report describing the basis for your continued operation at power icvel of 50% and above. On !! arch 16, 1982, you filed a report which was to provide the basis for operation of Unit 1 between 50% and 75% over the next several months.
1 The staff and its consultants have reviewed the contents of the fiarch 16, 1982, report and additionally have had the benefit of telephone discussion with nenbers of your staff and Westinghouse. Based on the information provided to us we cannot conclude that it would be prudent to operate Unit 1 above 50% until a demonstrable technical basis is provided to support interin reactor operation at power levels greater than 50%.
In response to your request dated flarch 16, 1982, we conclude and find acceptable and grant permission for continued operation of Unit 1 for a period not to exceed 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> as detemined from your nid-March restart at a power level no higher i
than 50%. !!owever, should you believe that additional data need be obtained at higher power levels, you should submit a proposed testing program and justifica-tion to deal with short tem operation above 50%.
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!?r. Willian 0. Parker, Jr..
ife require that the llRC staf f he franodiately notified in the event of any informa-tion (priraary to secondary leak or internal instrunentation) which nay be indicative of severe vibrational behavior or excessive wear during the current operating node.
Further stean generator eddy current testing shall be perfomed subsequent to this period of operation and the results reported to liRR. A su cary of the results of our review is presented in the enclosure.
Sincerely,
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Robert L. Tedesco, Assistant Director for Licensing Division of Licensing
Enclosure:
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DISTRIBUTION:
Docket Nos. 50-369/370 LB #4 r/f Docket Nos: 50-369 DEisenhut/RPurple and 50-370 EAdensam RBirkel bcc: TERA Mr. Willian 0. Parker, Jr.
MDuncan NRC PDR Vice President Steam Production SHanauer Local PDR Duke Power Cor pany RTedesco NSIC P.O. Box 2178 ZRosztoczy TIC 422 South Church Street RVollmer ACRS (16)
Charlotte, North Carolina 23242 JKramer RMattson
Dear Mr. Parker:
RHartfield, MPA 0 ELD
Subject:
Continued Operation of Unit 1 OIE (McGuire Nuclear Station Units 1 & 2)
By letter of March 12, 1982, we inforted you that operation of McGuire Unit 1, utilizing the flodel D steam generator, on an interin basis at 5tt/. power was accep-table pending receipt of a dettIled report describing the basis for your continued operation at power level of 50% and above. On March 16, 1982, you filed a report which was to provide the basis for operation of Unit 1 between 50% and 75% over the next several months.
N The staff and its consultants have revleued the contents of the fiarch 16, 1982, report and additionally have had the benefit of telephone discussion with nenbers of your staff and Westinghouse. Bdsed on the information provided to us we cannot conclude that it would be prudent td operate Unit 1 above 50% until a denonstratable g
technical basis is provided to suppor interim reactor operation at power levels creater than 50%.
In response to your request dated March 6, 1982, we conclude and find acceptable and qrant permission for continued opera ion of Unit 1 for a period not to exceed g
1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> as deternined f rom your nid-Macph restart at a power level no higher than 50%. We require that the NRC staff bKirnediately notified in the event of any information (prinary to secondary leak aq internal instrumentation) which may be indicative of severe vibrational behavior or 4xcessive wear during the current oper-ating rode.
Further steam generator eddy currhnt testing shall be performed sub-sequent to this period of operation and the rashlts reported to NRR. A summary of y
the results of our review is presented in the encslosure.
Sincerely, Robert L. Tedesco, Assistant Director for Licensing i Division of Licensin9 AD:SA AD:L/DL
Enclosure:
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Docket Hos. 50-369/370 LB #4 r/f DEisenhut/RPurple EAdensam Docket Hos: 50-369 RBirkel and 50-370 MDuncan 1
i SHanauer bec: TERA 3
ffr. Hillian O. Parker, Jr.
RTedesco NRC PDR Vice President Stqam Production ZRosztoczy Local POR Duke Power Companv\\
RVollmer NSIC P.O. Fox 2178
Charlotte, florth Caroli 1 28242 RHartfield, MPA 0 ELD
Dear ffr. Parker:
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Subject:
Continued Operatio, of Unit 1 (McGuire Nuclear Sta fon Units 1 A 2)
By letter of l' arch 12, 1982, we forned you that operation of ficCuire !! nit 1, utilizing the Model D stean genero r, on an interim basis at 50% power was accep-table pending receipt of a detailed eport describing the basis for your continued operation at power level of 507. and al ove. On March 16, 1932, you filed a report which was to provide the basis for ope ition of Unit 1 between 50". and 757. over the next several months.
j The staff and its consultants have reviewe the contents of the Itarch 16, 1982, report and additionally have had the beneft of telephone discussion with menbers of your staff and tfestinghouse. Based on the infonnation provided to us we cannot conclude that it would be prudent to operate U it I above 50% until a demonstratable technical basis is provided to support interin actor operation at power level arcater than 50%.
In response to your request dated March 16, 1982, w conclude and find acceptable and grant pernission for continued operation of Unit for a period not to excocd i
1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> as deternined fron your nid-f tarch restart a power level no higher than 50%. Further stean eenerator eddy current testin shall be perforned sub-sequent to this period of operation. A sunmary of the
.sults of our review is presented in the enclosure.
Sincerely, Robert L. Tedesco, Aspistant Director for Licensing i
Division of Licensing
Enclosure:
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McGuire Mr. William 0. Parker, Jr..
Vice President - Steam Production Duke Power Company P.O. Box 2178 3
422 South Church Street Charlotte. North Carolina 28242 cc:
Mr. A. Carr James P. O'Reilly, Regional Administrator Duke Power Company U.S. Nuclear Regulatory Commission, P.O. Box 2178 Region II 422 South Church Street 101 Marietta Street, Suite 3100
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Charlotte, Nort.h Carolina 28242 Atlanta, Georgia 30303
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Mr. F. J. Twogood Power Systems Division Westinghouse Electric Corp.
P.O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. E. J..Keith EDS Nuclear Incorporated 220 Montgomery Street San Francisco, California 94104 Mr. J. E. Houghtaling 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 J. Michael McGarry, III, Esq.
DeBevoise & Liberman 1200 Seventeenth Street, N.W.
Washington, D. C.
20036 Shelley Blum, Esq.
1716 Scales Street Raleigh, North Carolina 27608 Mr. Paul Bemis Senior Resident Inspector c/o U.S. Nuclear Regulatory Commission P.O. Box 216 Cornelius, North Carolina 28013 O
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Enclosure REVIEV 0F PROPOSED GPEP.ATIONAL PROGRAM FOR McCulRE UNIT HO. I UTILIZING MODEL D STEAM GENERATORS Ref: buke power Company Letter Report Dated March 16, 1982 INTRODUCTION By letter dated March 16, 1982, Duke Power Conpany sutsitted its proposed operating program for McGuire 1 for a period extending to July 4,1982. The proposed program includes operation up to and including 75% power. Operation between 50 and 75%
power would be limited to 60 days from the date of restart following the February 1982 steam generator inspection outage. McGuire would be shutdown for additional inspections at the first practical opportunity following this 60 days above 50%
power, but no later than July 4,1982. The licensee's submittal includes its tech-nical justification for the proposed operating progran, which includes what they consider to be an upper bound on the amount of tube wear which will occur during the proposed operating period.
BACKGROUND McGuire 1 had accunulated the following operating history at the time it was shut-down on February 26, 1982:
Power Level Hours at or above this power level
- 507, 1500 75%
324 901 72 100%
23 The total number of ef fective full power hours to date is 1093.
Eddy current (ECT) inspections of the McGuire stean generators during the February outage revealed four tubes with 0.0. indications in stean generator C.
These indications have been attributed to snall volume wear de.fects, less than EDI, in depth at the 5th support plate in the preheater section. The licensee estimates that the % through-wall penetrations of these defects is between 5 and 10%, con-pared to the Technical Specification plugging limit of 40%.
It is the staff's understanding that these tubes have not been plugged, internal instrumentation was installed in two tubes during the February outage to provide operating data regarding the dynanic response of the tubet. The instru-nentation nay also serve to identify the power level associated with the onscf. of significant vibration activity which riay lead to high rate of wear dr.cge to the tubino.
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- PcGuire has operated for approxinately 300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> since the February outage at a power level less than or equal to 50% with the exception of a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period during which power was escalated to 75% for purposes of collecting instrurentation data regarding the tube response over this range. Evaluation of this data is in pro-gress, and no prolininary findings have been reported to the staff to date.
The licensee has established its proposed operating program based on the following:
l 1.
Estinated wear rates as a function of power level. These estinates were determined on the basis of estimated wear volumes associated with the ECT indications identified in the field during the February 1992 inspection, and on the operating tires accumulated at different power levels prior to the February 1982 inspection.
2.
Allowable voar volume.
t The licensee analysis deals directly with wear volunes as opposed to depth of wear consistant with classical models which consider wear rates (in terns of volumetric removal rates) to be a constant for a critical set of parameters.
The licensee has estimated the maxinun wear volune associated with the field ECT 1.5 X 10 qs jrom the February 198? inspection to be conservatively bounded by indicatio in. This estinate appears tn be based on the fact that the maxioua I
length associated with the field indications was
.4", and that five flaws observed on the pulled tubes from Alvaraz and Ringhals which exhibited lengths rangigg jron
.15 to.5 inches in length exhibited wear volunes ranging from 1 to 7 X 10 in.
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Ilowever, we have several reservations about the conservatism of this number inclu-ding:
l l
1.
Licensee has provided no estimate of possible error associated with the length estinates of the McGuire indications, nor whether the
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1engths associated with the pulled tube examinations are based upon ECT estinates or actual measured lengths determined from the labor-a tory.
In addition, the licensee has not indicated whether the length estinate wern hased upon differential or absolute ECT read-i ings.
If based on differential signals, taper of the wear flaws could lead to underestimates of the wear length. Even a small underestimation of the flaw length could lead to a large under-estination of the flaw volume using this rethodology. '4e note that t
length, the corresponding volune is 4 X 10-4the data base for Ringhals indic L
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The licensee's estimate is based upon a total of.five data points from a total of four tubes. We believe the data base to be too small to properly reflect all geometric, tvechanical, and flow paraneters which may affect the relationship between length and volune of wear defects.
3.
Most inportantly, the licensee has perfomed at least four other wear volume estimates using different nethodologies which are substantially larger than the assuned 1.5 X 10-4f n3 value.
These estinates range from 3 X 10-4 n3 to 8 X 10-4 n 3 The 1
1 licensee has not provided adequate justification for excluding any of these estinates from its analysis.
Regarding allowable defect volume, the licensee has establised 10-3fn3 as an allou-able defect volume on the basis of valueetric wear vs. wear depth data from the Ringhals and Almaraz pulled tube exaninations (Figure 14 of submittal). For defect cating flaw volunes from 4.5 to 7 X 10-3 n. gh wall, three data points exist indi-penetrations ranging between 20 and 50% throu i
f 3 A begt fit regression line through all the data indicates a wear vglume of 4 X 10-31n associated with the plugging limit depth of 40%. The 10-3fn criterion was selected by the licensee to reflect
-uncertainties in the method and models used and to account for any increase in wear rate which might occur due to the onset of wear and the increase in the diametral gap between the tube and the baffle plate.
We }ing that the licensee has not provided adequate justification to support the 10 in estimate. Ue note that the 1.49 X 10 in volume asscciated with the wear defect which penetrated 100% through wall at Ringhals in October 1981 was not included among the data plotted in Figure 14 of the licensee's subnittal. This data point deviates sharply from the data trends and regression line pictured in this Figure, in the sense that the volume associated with the leaker is substan-e tially smaller than what would be estinated on the basis of the infomation in the Fiqure.. This data point indicates to us that actual flaw penetrations can vary i
quite substantially from the trend shown in Figure 14 'of the subittal, even from a small 4 tube sample. Considering the large number of tubes loc.,ted in the outer four rows in the prcheater section, we would expect numerous instan es of such deviations.
Apart from the methods used to estinate allowabic operating tines as a function of power level, ~we have concerns regarding the operation at power levels exceeding 50%.
Westinghouse analysis of Ringhal/Almaraz data indicates significant increase in vibration activity and consequent tube wear at power levels a50ve 50% to 75% (Ref.
Vestinghouse recting of February 19, 1982, at Bethesda). Cur independent analysis and review of plant operating experience support this conclusion. The RMS spectra omcep sunmaue >......................
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NRC FORM 318 (10-80) NRCM 024o OFFIClAL RECORD COPY usam mi-mm
. of time varying data are used to indicate the characteristics of the transducer out-puts. The increase in tube activity level is indicated by the growth and broadening of the spectral peaks in descrete frequency intervals. A qualitative assessment of the spectra for one of the accelerometers in tube row 49, column 51 fran Alnaraz indicates that vibration activity represents a power curve (screwhere between a square and cube curve) and activity increases significantly above 50% power levels.
The definition of the tube excitation nechanism in terns of flow rate, tube motion (node / frequency) and acolitude of notion has not been established. The excitation mechanism appears to be of a ' threshold type' - probably a type of fluid-clastic ins tabili ty.
However, turbulent buffeting or sone conbination of turbulent buffet-ing and fluid-elastic instability cannot be ruled out as a forn of the excitation nechanisn. If turbulent buffeting is the doninant mechanism, wear can be expected at all power icvels and there would be no increase in wear at a certain power level or as the report refers ' onset of wear'.
If the excitation nechanism is predomin-antly of the fluid-elastic instability type, there will be threshold values assoc-iated with it. The objective of the licensee's progran should be to identify these threshold valves and avoid these instabilities by operating at power levels suffi-ciently removed from these critical values. The subject report does not address the tube excitation phenomena in sufficient detail instead an attempt has been nade to use wear neasurement data to determine threshold power levels (flow rates) for the onset of large amplitude vibration which would be responsible for rapid wear and tube failures.
In our opinion, the threshold values can easily and accurately be determined by tube vibration neasurencnts from internally nounted accelerometers. This vital informa-tion is unavailable at this time.
EVAL.UATION AHO COHCt.llSIOMS The available evidence to date suggest that the potential for significant vibration activity and high wear rates becomes significant for power levels exceeding 50 to 75% power. To justify operation beyond 50% power requires that wear rates and allowabic wear volu~es be firmly established on a conservative basis. As noted in our earlier discussion, we have a number of questions and concerns about the con-servatism of the licensee estinates as developed in their Harch 16, 1982, subnit-tal. Unless these concerns can be resolved to our satisfaction, operation beyond 50% power can only be approved after the licensee has submitted sufficient data (including data from internal instrumentation) to indicate that significent vibration activity which nay lead to high wear rates will not occur, or af ter stean generator nodifications have been installed to correct the problen.
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, In the interin, we find that f*cGuire may be operated at power levels not to exceed 50% for a maximum of 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> from the date of restart following the most recent steam generator inspection, without undue risk to public health or safety. This
. finding is based upon the following:
1.
McGuire has operated for 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> at power levels at and above 50%
power, including 324 hours0.00375 days <br />0.09 hours <br />5.357143e-4 weeks <br />1.23282e-4 months <br /> at and above 75% power, while incurring only minor degradation (<20% through-wall penetration) on four tubes.
2.
Preliminary results of Westinghouse analyses and tests, and preliminary data from the internal instrumentation at Alnaraz 1 indicate that the onset of significant vibration of the tubing does not occur until power has been escalated beyond 50% power. Thus, we expect any further pro-gression of wear during the current 1500 hour0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> operating period would be small.
3.
Restrictive limits on allowable prirary to secondary leakage in the Technical Spectfications provide added assurance of adequate tube integrity.
The staff will consider an extension to this 1500 bcur authorization to July 4,1982, provided the licensee submits its analyses of the internal instrurentation data, which is currently in progress, by April 30, 1982.
Finally, we are requiring that the flRC staff be innediately notified in the event of any infornation (prinary to secondary leakage or internal instrumentation) which may be indicative of severe vibrational behavior or excessive wear during the current
' operating mode.
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