ML20138R010
| ML20138R010 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 10/30/1985 |
| From: | Miosi A COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 0840K, 840K, NUDOCS 8512300208 | |
| Download: ML20138R010 (3) | |
Text
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October 30, 1985 Mr. James G. Keppler Regional Administrator Region III U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, 11 60137 SUUJECT:
draidwood Station Units 1 and 2 Supplemental Response to Inspection Reports Nos.
50-456/84-34 and 50-457/84-32 NRC Docket No'i. 50-4S6 and 50 457 HEFERENCE (u):
H.F.
narnick letter to Cordell Reed dated December 31, 1984 (b)
O. L. Farrar letter to J. G. Keppler dated February 13, 1985
Dear Mr. Keppler:
This letter supplements our Reference (b) respanuu to the Reference (a) Inspection Report.
The enclosure detuils additional corrective action to be taken in the area or silicon Dronzu welds.
Should you or your starf have any questions regarding this matter please contact this office.
Very truly yours, 0 ;it f Y A. O toni Nuclear Licensing Administrutor
/klj Enclosure Iraidwnod cc:
NRC Resident Inspector 0840K U312300200 05:03o PDff ADOCK 05000456 j
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l Enclosure Commonwealth Edison Company Supplemental Responso to Inspection Report 50-450/84-34 and 50-457/84-32 Item 456/84-34-01 and 457/84-32-01 1
Rusponse Commonwonlth Edison's February 13, 1985 response to item 456/04-34-01 and 457/04-32/01 stated we had initiated NCR 701 to address the concurns identified in the breaking of silicon bronzu shop wolds between companion unglos and shout metal.
NCR 701 identified uluvun (11) companion anglo joints containing brokun i
wolds.
Sargent & Lundy porformed calculations for those 11 casus to take into account the of fect of the brnkun welds, and have duturmined that the existing installation can be accommodated within codu ruquirements, and that the design loud carrying requirements havu buon mot.
Although it has boun shown that thosu broken welds arenotdesirhnsignificant, ullman Shout Metal procedures, the brokun welds have been rupnired por ustablinned t
The specific cause for thu broken welds is induturminatu at this point in time.
For opproximately 2000 duct sections inspucted thru August 1985, 2.M of tne duct sections had 1 or more broken welds.
Thu frequency of brokun wuld occurrunce is 0.1% for thu 2000 duct sectionu int.pucted.
,The separations occurred randomly ovur many weldurs implying that this situation is not related to woldur tuchniquo for an individual wolder.
du buliuvo that thu silicon bronze wolds suparated from thu companion nnglu as a result of uxcussivo loudu boing imposud during uruction and othur construction nctivities in thu vicinity of thu ductwork.
- Howevur, wo have buon unable to duplicatu thu fulluru muchanismb in the field when subjecting other ductwork suctions to excessivo construction lands.
As stated in our initial runponnu, Pullman Proceduru 010.3F
" Installation Inspection Procuduru" has been revised to inspect for brokun silicon bronzo shop wulds betwoon companion nnglou and sheet metal.
This inspection will unsure that brokun silicon bronze shop wolds aru corrected upon complution of ductwork oruction activities.
Commonwon1th Edison Company also proposes to conduct a tunting program for 9111 con bronzo wuldu.
This tunting program will confirm that thu final visual wuld inspect!cn of thu silicon bronzo shop nnd field welding is aduqunto to ust4Dll sh quality of thu work und thus provido additional assurance that the instulled hVAC silicon bronzu wolds are aduquatu.
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The following guidelines establish the test program of shop and field silicon bronze welding for the HVAC duct construction for the Braidwood Station.
1.
A total of 75 individual silicon bronze welds will be tested.
2.
Of the 75 weld samples, 15 samples will be taken f rom han jer-to-duct (HTD) welds from duct and hanger pieces wni:h have been removed from the plant as a result of the test program on hanger welding from Inspection Report 83-09.
3.
Sixty (60) samples shall be taken from companion angle to duct welds selected from duct pieces which have been removed from the plant and comprise a representative population of gages and fabrication dates.
4.
Duct pieces shall be sorted into groups by gage thickness and date of fabrication.
Duct pieces will be selected ut random representing each gage (22 guge, 20 gage, 18 gage, and 16 gage), and from each of 3 time frames for the project (1978, 1979, 1960).
5.
After 60 duct pieces have been selected, a companion angle weld on each duct piece shall be selected at random.
Corner welds shall be excluded from this selection due to the difficulty of testing in a tensile machine.
6.
Specimens shall be prepared for testing in a tensile machine.
Weld maps shall be prepared prior to testing each wold.
7.
Tent louds shall be compared to required design vnlues to establish acceptability.
Where required, the companion angle welds adjacent to the initially selected companion angle weld muy be tested and averaged with the first tested weld to establish acceptability.
8.
The assigned fikC Inspector will review for acceptability, sample selection and tout results on an as-completed banis.
0840K
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