ML20031D326
| ML20031D326 | |
| Person / Time | |
|---|---|
| Site: | Cherokee  |
| Issue date: | 10/01/1981 |
| From: | Dail L DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8110130250 | |
| Download: ML20031D326 (3) | |
Text
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i DUKE POWER COMPANY a.o. eon :
GENERAL OFFICES
"' a'r's."$N 43: 30uf M ANORCN STREtt CHARLO' RTE. N. C. 28242 m
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October 1, 1991 0
5 UDT131981= 2
-8 Mr. J. P. O'Reilly Director
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j U.S.NuclearRegulatoryCommission
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101 Marietta Street, Suite 3100
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Atlanta, GA 30303 b qQ[
Re: Cherokee Nuclear Station, Unit 1 Docket No. 50-491 IE 81/01-5PS-491 NSSS-Shutdown Heat Exchanger Duke Files: P81-1201.00, P81-1201.06
Dear Mr. O'Reilly:
Attached is Duke's final report on the referenced 10CFR50.55(e) reportable item.
Initial notification was made by telephone to Mr. Rausch of your office on Decenber 17,1980 An interim report was submitted to your office on January 15, 1981. A pro.:ress report was submitted to your office on July 14, 1981.
Very truly yours, REGIONAL DIRECTOR
/7 DEPUTY DIRECTOR
/
t_
ASSISTANT TC DIRECTOlt IL. C. Dail, Vice President DIRECTOR, RRPI i
l Design Engineering Department DIRECTOR, EPOS DIRECTOR, ENF/INV i
l GDR/pam DIRECTOR, ETI PUBLIC AFFAIRS OFFICER Attachnent cc: Director of Inspection &. Enforcement
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U. S. Nuclear Regulatory Commission Washington, DC 20555 si 8110130250 811001 DR ADOCK 05000 g-e
-e.,
DUKE POWER CO.
CHEROKEE NUCl. EAR STATION Report Number:
IE 81/01-5PS-491,(Final Report)
Report Date: January 15. 19t. ~ (Initial)
Facility: Cherokee Nuclear Station - Unit #1 IEestatenent of Deficiency:
Apparent breakdowns in manufacturing, cleaning, and inspection processes on Shutdown Heat Exchangers (SOHX's).
Description of Deficiency:
On December 17, 1980 Mr. R. E. Miller and Mr. W. H. Bradley infonned Mr. John Rausch, NRC of potential deficiencies in the Shutdown Heat Exchangers, supplied by Combustion Engineering as part of the NSSS contract, along the following lines.
1.
Due to problems encountered on the WPPSS Unit #3 and #5 SDHX's, and since the Duke SDHX's were manufactured by the same vendor (Ametek),
CE advised Duke that heat exchangers were suspect of similar deficiencies.
2.
Duke Unit #1 SDHX's were inspected c.t the site, and were found to have problems with the stainless steel cladding and contamination of tube side material surfaces.
Analysis of Safety Implications:
Refer to initial report.
Corrective Actions:
50HX Units lA (serial number 79358, Ametek shop number N80-45650) and 1B (serial number 79359, betek shop number N80-45651) were shipped back to Amstek in Bethayres, PA fc: repairs in February,1981.
The following problem areas were identified after snop inspection:
Unit lA: Dirty tuces, cladding PT indications and unacceptable stainless steel clad (SAW-Supplemental Metal Powder)
Unit 18: Dirty tubes and cladding PT indications.
A.
Un_it 1A The cover and tubesheet face of SDHX 79358 had two areas that were clad with a SAW-supplemental metal powder technique.
It was detennind fror,i metallurgical tests on the WPPSS 3 SDHX that cladding done by Anttek's specific procedure by this method produced an unacceptable hard martensitic' microstructure'.
Consequently, the cladding on these two parts was completely removed and reciad with an acceptable two layer strip clad technique.
In order to remove the old clad and reclad the tubesheet, the tubes were removed.
As the tubes could not be reused, they were replaced.
Cladding PT indications of the tubeside plenum (channel) were repaired.
Replacement tubes were cleaned with nonnal shop procedures.
Cleanliness was checked using dry felt plugs.
Any unacceptabic l
tubec were cleaned withmtane snaked felt nluas.
All weld serrlay cled.oma
h3d the clad thickness measured by UT; and all measurements wero found ts be ll acccptablo. The.. channel area was cican:dt. channel cover installed; and.the l
shell and tube sides hydrostatically tested and &cepted. The heat exchanger l
was drained, dried and a nitrogen purge was placed on both the tube and shell sides of the unit prior to shipment back to the site.
B.
Unit 18 Cladding PT indications were repaired. All weld overlay cladding was measured i
to determine if mininnan required thicknesses were met; a UT measurement technique was used. Ten Measurements were unacceptable; i.e.,1/8" (.125") mininnan i
thickness was not met. Nine were on the channel flange face, one was on the L
channel flange ID, and the thinnest of these areas was 0.10S". It sas detemined by C-E that this thickness was sufficient-to provide corrosion protection for forty ' years and therefore considered acceptable.
l The tube ID's were cleaned by detergent / wire brush method. Cleanliness was verified by blowing dry felt plugs through the tubes and visually examining the plugs. Degree of plug discoloration was established for acceptance criteria; i.e., a slight grayish discoloration was acceptable. The channel area was cleaned; the channel'cever was installed and the tube side was hydro-3 statically tested and accepted. The heat exchanger was drained, dried and a nitrogen purge was placed on both the tube and shell sides of the unit prior to shipment back to the site.
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C. Units TA and 1B i
As part of the repair plan, both Unit I SDHX's tubes received supplementary examination in the form of Eddy Current Testing (ECT) tu a C-E developed pro-cedure. This testing was done because of metallurgical findings on a piece of WPPSS'3 tubing. Although the Unit 1 tubing was supplied by different vendors, t
it was decided to perfom this test, to ensure the tube quality. This ECT in addition to metallurgical examination of representative tubes found them to l
be acceptable.
I D. _Geaerat In addition to the above repairs a thorough review of Amatek's re ords relative l
to these heat exchangers was made.by C-E.
The NRC also perfomed an audit at Ametek. As the result of the NPC audit, the Certified Mill Test-Reports from two lots of weld wire / flux combination used on SDHX's were found to be incomplete.
The incomplete information was detemined from existing test data / additional testing, and accepted by C-E via a " Deviation of Contract Requinment" fom.
The repairs of the Unit 1 SDHX's were done under the provisions of Section III of the ASME B & PY Codes N-1 data foms were revised and missued for the heat 1
exchangers.
Following receipt of the Unit 1 SDH1's at Cherokee, an inspection was conducted to detemine if the deficiencies inttially identified had been corrected. As a result of this. inspection..it was concluded that all previous findings had been
' corrected to an acceptabo conditt an. Deficiencies covered under this report are not applicable to subsequent Cherokee Units or other Duke Prefects.
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