ML20086P952
| ML20086P952 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 02/17/1984 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-84 NUDOCS 8402270393 | |
| Download: ML20086P952 (4) | |
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T TENNESSEE-VALLEY-AUTHORITY CH ATTANOOGA. TENNESSEE 374C1
' 400 Chestnut Street Tower II y ( j a 22 A g : hbruary 17, 1984 BLRD-50-438/83-23 U.S. Nuclear Regulatory Commission Region II L
Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNIT 1 - WELDS ON BAFFLE PLATES IN CORE SUPPORT ASSEMBLY BY BABCOCK & WILCOX'- BLRD-50-438/83 THIRD INTERIM REPORT The subject deficiency was initially reported to NRC-0IE Inspector P. E.
Fredrickson on March 2,1983 in accordance with '10 CFR 50.55(e) as NCR 2267. - This was followed by our reports dated March 30 and October 5,1983 Enclosed is our third interim report. We spect to submit our next report by January 11, 1985. We consider 10 CFR Part 21 applicable to this 4
deficiency.
If you have any questions concerning this matter, please get in touch with R..H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills,11anager Nuclear Licensing i
Enclosures cc:
Mr. Richard C. DeYoung, Director (Enclosures)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 l-j.
Babcock & Wilcox Coripany (Enclosures)
P.O. Box 1260 l~
Lynchburg, Virginia 24505 Attention:
Mr. H. B. Barkley Records Center (Enclosures)
Institute of Nuclear Power Operations 1100 circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 l'
~ OFFICIAL COM.
$2$oo$ON $
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An Equal Opportunity Employer t-
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ENCLOSURE 1 4
BELLEFONTE NUCLEAR PLANT UNIT 1 WELDS ON BAFFLE PLATES IN CORE SUPPORT ASSEMBL7 BY B&W 10 CFR 50.55(e)
BLRD-50-438/83-23 NCR 2267 THIRD ILTERIM REPORT Description of Deficiency While performing onsite modifications to the unit 1 reactor internals (B&W field change package 194), defects were noticed in 12 of 20 wide baffle plates adjacent to the narrow baffle plates being modified. Former bolts are used to hold the baffle plates together. Nine of the twelve affected baffle plates have 24 bolts each and the other three have 48 bolts each, for a total of 360 bolts. The former bolts are prevent 3d from backing out by the use of locking pins, which are secured by tack welding each end to its baffle plate. At 26 of the 360 locations, tack welds were found to be cracked. One of the 26 locking pins had cracked tack welds at each end.
Additionally, three pins were welded to bolts, there was a lack of fusion indication on one pin, and one pin had a tungsten inclusion. The apparent cause of these defects is poor workmanship during fabrication at B&W.
Interim Progress TVA has inspected the remaining reactor pressure vessel internal bolted joints as identified in the second interim report on this construction deficiency report (CDR). The results of these inspections appear in enclosure 2.
As noted in Table 3 of our second interim report (dated October 5,1983), TVA initially intended to inspect only the 81 lower elevation brazement set screws. However, due to the number of identified discrepancies, TVA has determined that it will also inspect the middle and upper elevation set screws (162 additional screws). Our next report will discuss the results of this additional inspection.
TVA has also inspected the 81 brazement positioning dowel pins and has reported the results in enclosure 2.
B&W has submitted corrective action for defective welds in all of the bolted joints with the following exceptions: column weldment flange to upper grid,_
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upper grid to plenum cylinder, and vent assembly mounting screws. TVA is currently reviewing the corrective action provided by B&W. The three groups of bolts listed above are among the internals bolts made of A286 material which are being replaced to prevent failures like those experienced at some operating plants.
EJCLOSURE 2 RESULTS OF ADDITIONAL INSPECTIONS ON LOCKING MECHANISM WELDS Number of Joint Quantity Defective Types Identification Of Bolts Bolt Welds Of Defects Upper grid pad 444 307 1,3,5,20,6,16,12,17,8 mounting screws Lower grid pad 444 352 1,3,10,20,6,16 mounting screws Column weldment 35 6 flange to upper grid Upper grid to 56 plenum cylinder Plenum cf inder 70 34 15,16,17,8,5,4,9,1 l
to plenum cover Rod guide caps 162 71 18,7,12,4,10,1,9,8,6,19, to plenum cover 5,11,3 Vent assembly 64 mounting screws "affle to former 576 bolts Support post to 52 51 10,2,8,9,3,14,5,7,15 lower grid Flow distributor 134 134 to lower grid Former to core 992 992 barrel Brazement set 81 47 3,4,8,12,13,7,1,9,11
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- Brazement 81 16 1,10,6,3,7,12,9 positioning dowel pins b
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ENCLOSURE 2 (Continued) a Codes for Types of Defects 1.
Crack 2.
Bolt head welded 3
Insufficient weld metal 4.
Crater crack 5.
Corrosion 6.
Splatter 7.
Unacceptable contour 8.
Arc strike 9
Overlap
- 10. Lack of fusion 11. Undercut 12.
Welds not 1800 apart 13 Need brushing
- 14. Irregularities in hex slot
- 15. Loss of shield gas
- 16. Inclusion
- 17. Washing
- 18. Cup off center
- 19. No bolt
- 20. Porosity
'These bolts are to be replaced as the material they are made of ( A286) has been shown to be suspect when used for RPV internals bolting.
- This information was provided by the second interim report on this CDR.
- All looking pin welds for these connections were rejcoted since they were not in accordance with vendor drawings.
- The remaining 162 brazement set screw locations are to be inspected.
Results will be provided later.
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