ML20009A934
| ML20009A934 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 07/02/1981 |
| From: | Mazur D WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Faulkenberry B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, GO-1-81-194, NUDOCS 8107140512 | |
| Download: ML20009A934 (3) | |
Text
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50.55(e) Report
./
Docket Nos. 50-460/513 Washington Public Power Supply System P.O. Box 968 3000 GeorgeWashitc onWay Richland,Washini, ton 99352 (509) 372-5'X)0 Nuclear Regulatory Commission July 2, 1981 Region V G0-1-81-194 Suite 202 Walnut Creek Plaza 4
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k[f7/(Ig h 1990 N. California Boulevard Walnut Creek, California 94596
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Attention:
Mr. B. H. Faulkenberry Chief, Reap.or Construction Projects Branch T
Subject:
PROJECTS 1 AND 4 DOCKET NOS. 50-460 AND 50-513 P0TENTIALLY REPORTABLE CONDITION 10CFR50.55(e)
(
DECAY HEAT REMOVAL HEAT EXCHANGER TUBING Referenct.:
1)
Telecon TJ Houchins, Supply System to DF Kirsch, Region V Nuclear Regulatory Commission dated January 17, 1981 2)
G0-1-81-25, dated January 30, 1981, DW Mazur to RH Engelken, Director In reference 1) the Supply System informed your office of the potentially reportable deficiency under 10CFR50.55(e) and reference 2) was an interim report in the subject condition.
Attachment A includes a brief description as to how the potential deficiency was discovered, and the investigation methodology used to evaluate the possible deficiency. Project Engineering has reviewed all the pertinent test data derived from our investigation and determined that the seam welded tubing used in the decay heater removal heat exchangars manufactured by Ametek, Schutte and Koerting Division, Whitlock and Bethayres plants for Babcock & Wilcox meet the applicable ASME code requirements. Based on the information provided in Attachment A it has been concluded that the originally reported " Potential" deficiency does not satisfy the necessary criteria of 10CFR50.55(e) to be considered reportable, therefore this is a final report and no further action will be taken by the Supply System.
If you have any questions or desire further information, please advise.
N g ery truly yours, c
1, 2
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a (bJ t2 D. W. Maz e
's JUL 131981* T3 Program Director i
v.s. wuam uaum WNP-1/4 common DWM:MER:lm 3,
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Attachment m,
9 cc: CR Bryant, Bonneville' Power Administration /399 fl g
8107140312 810702
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ATTACHMENT A WNP-1/4 Docket Nos: 50-460 and 50-513 Reportable Condition 10 CFR 50.55(e) (Potentiall Decay Heat Removal Heat Exchanger Tubing Final Report EACKGROUND The Supply System had en experience at its WM?-3/5 site which icentified a potential problem that could have been generic to certain types of seam walded heat exchanger tubing.
For this reason it was decided to investigate the integrity of seam welded tubing used in the decay heat removal heat exchangers supplied to UNP-1/4 by Babcock
& Wilccx Company.
These heat exchangers were manufactured for Babcock & Wilcox by Ametek, Schutte and Koerting Division, Whitlock and Bethayres Plants.
Preliminary examinution of selected tubes had shown indications of imperfections along the saam weld area. The results cf thi.s preliminary inspection were the basis for.the Supply System informing your office of a potentially reportable deficiency under 10 CFR 50.55(e)
(Telecon dated January 17, 1981, and letter dated January 30, 1931)..
ACTION TAKEN ine zu;p.y System requested Babcock & Wilcox's par ici:atitn in tne evaluation program and in March 1,1981, an inspection was ccqducted cn prs-selected tubes to demonstrate the Supply System's testing rethocciogy that was used in detecting the tubing impe' fections. To formally characterize the type of defects that were r
- being detected, it was de:ided to perform 'a destructive examination.
One representative tube from each of the tube nanufactures (Trent Tubing and Greenville Tubing) was removed from the heat exchancers on April 1,1931.
The evaluation program at this
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D6 Mt was secarated into the following three areas of fnvestigation:
(1 ) Were the indications in the tubing not being picked up by the tubing manufacturer as a result of the tubing ranufacturer violating the ASME requirements for non-destructive examination?
(2) Were the indications really there anc hr.1 accurate was the Su; ply System eddy current testing methodology?
(3)
If the indications vere there, were they injurious to the tubes?
The tubing manufacturers were aisc visited in April,1981.
The tub.ing manufacturers utilized Eddy Current Standards that comply with the minimum recuirements of the ASME Boiler and Pressure Yessel Code, Section Ill.
The standard utilized by Greenville contained indications 1 inch long,1/16 inch wide and.004 inch deep on the 0.D. and 1.D. and a 1/16 inch diameter through wall hole..
The 1971 Edition, Winter 1972 Addenda of the ASME Boiler and Pressure Vessel Code, to which the heat exchangers were manufactured, required an I.D. and 0.D. notch as above and the 1/16 inch diar,eter through wall hole.
Greenville could detect the indications i'n their
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s ta ndard.
The indications in the standard utilized by Trent Tubing were smaller m
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. s1-also meeting the requirements of the AS"E Code.
The Trent Tubing eddy current exa-inaf Cn was therefore more strir. gent thar is required by AI".E.
The fir.ii result of tne aucits at Trent and Greenville confirmed the tube vendors dio conform t; the.inimum requirements of the A5"E Eoiler and Pressure "essei C:de for inscecticn of the SA-249 tubing.
The tubes removed from the heat exchanger were eddy current examined at Babcock's and Wilcox's Lynchburg Research Center (LRC) utilizing an I.D. coil and an 0.0.
coil.
Tre eddy current equipment was set up utilizing an ASME ninimum standard and util' zing an LEC standard that closely a;proximates a lack of fusien in the weld.
'l hen using the AS"E standaro it :as fcund that the previously icentified indications (utilizing Supply Syster rethodo'cgy.' fell uithin the acce;tatie lirits of the standard and therefore the tubing ins;ecticn at the tubing vendcr, c;ic n:t aave detected any rejectable conditions either.
A metallographic examination of tube areas ccntaining the ir.dications was perforr.ed for the purpose of: (1) icentifying the existence and type of ;hysical concitions a t the site of the indication previously identified by the Supply System and Babcock and Wilcox eddy current testing and, ('2) determining the character and size of any pnysical conditions.
The sectioning results yielded real features of interrittent 0.0. and 1.D. weld centerline porosity and a condition which is described as I.D.
weid corner undercut with a round bottom configuration.
The depths associated with the centerline porosity appeared to be considerably traller than the evaluated eddy current sicnal.
The size of the '; eld c:rrer.nde cut </as si# ar :: t"3 c:-resznding
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'.-Ma l l U nO.ere.-;as no case ich Z.e :: LS.
m fe?th e>CeeGeC 'ne eddy Current ir.cicatec ce:.h.
~'is Su;;lj $ ster's es ti'; i7.odLicgy 7
.;as capable of Edecuateiy identifying tnis t..pe of suail vcice ce:ects in. ics are not in excess of the acceptable range of the applicable AS"E Ctde stanc!-d.
' An ASME Code stress analysis (per Article bB-3200) vas performed to address any potentially injurious characteristics arisin; frc the identified indications.
This e mMis shc'.;ed that all stresses, at cesign conditions and ::e ating c:nii: ions are i:hin the Code ailcuable limits.
Secondary cerfo mance the ai ccnditicns < tere ap?tiec to the analysis for added conservatism in.the assessme t of nor al cperation.
A Code fatigue analysis was not necessary since the ceneral stress state anc the projected load cycles are relatively low.
In addition, an analysis assessing the stress corrosion cracking and fatigue crack pror?.qution potential of the type c' flacs detected in the tubing cas perferred.
F e s ul 5-4 f I' : analysis sP:xsd that the deri.ed f racture stress intensities do not enceed ass sec activatico threshold intensity levels; therefore, stress corrosion cracking ar.d fatigue crack propagation are not active failure mechanisms for axial flaws in these heat exchanger tubes that are less thar 75S of the tube uali thickness.
C0.lCLUSION The program undertaken by the Supply System and Babcock & Wilccx to investigate the potential ceficiency concludes that the Decay Heat Per: oval Heat Exchan;ers 'urnished for WNP-i/4 are capable of performing their intended function without presenting a threat to the safety of the plant or without a threat to public health and safety.
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On tnis basis, this condition is not considered reportable.
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