ML022390598
| ML022390598 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/31/2002 |
| From: | FirstEnergy Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML022390598 (47) | |
Text
Docket Number 50-346 License Number NPF-3 Serial Number 2744 Page 1 of 1 Davis-Besse Nuclear Power Station Results of Visual Examination of Reactor Head CRDM Nozzle Penetrations Performed in 1996, 1998, and 2000 (46 Pages Follow)
Davis-Besse NPS Results of Visual Examination of Reactor Head CRDM nozzle penetrations Performed in 1996, 1998, and 2000
- Nozzle Arrangement-69.CRDM Nozzles W
LIFTING LUGS (3 GUIDE STUD LOCATIONS 0 NODS.
is5&45 84-1
.JIfA.
BOLT HOLES ON 144'/z-DIA. BC.
(NOT PRESSURE RETAINING BOLTING)
Y KEY PLAN FENOC RESTRICTED INFORMATION "GUIDE STUD REACTOR VESSEL CLOSU.EREAD
Nozzle Core Quadrant No.
Locat.
1 2
3 4
5 6
7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 H8 G7 G9 K9 K7 F8 H10 L8 H6 F6 Fl10 L1 0 L6 E7 E9 Gll Kll M9 M7 K5 G5 D8 Hi12 N8 H4 E5 Eli mil M5 D6 010 F12 i 12 NlO N6 L4 F4 07 C9 G13 Ki 13 09 07 K3 G3 D4 D12 1996 Inspection results *1998 Inspection results See Note 1.0 Flange Leak Evident
> Flange Leak Evident SFlange Leak Evident Flange Leak Evident SFlange Leak Evident Flange Leak Evident Flange Leak Evident No Leak Observed SNo Leak Observed No Leak Observed SFlange Leak Evident SNo Leak Observed SNo Leak Recorded Flange Leak Evident Flange Leak Evident Flange Leak Evident 6 No Leak Observed No Leak Recorded KNo Leak Observed SNo Leak Observed K No Leak Observed Flange Leak Evident I No Leak Observed
.,.No Leak Recorded No Leak Recorded SNo Leak Recorded g Flange Leak Evident SNo Leak Recorded 1"No Leak Recorded tNo Leak Observed Flange Leak Evident
' Flange Leak Evident
- No Leak Recorded
.No Leak Recorded
> No Leak Recorded SNo Leak Recorded SNo Leak Recorded SNo Leak Recorded Flange Leak Evident
- 1 Flange Leak Evident FNo Leak Recorded SNo Leak Recorded No Leak Recorded SNo Leak Recorded iiNo Leak Recorded SNo Leak Recorded SFlange Leak Evident 2000 Inspection results Flange Leak Evident
'Flange Leak Evident Flange Leak Evident Flange Leak Evident Flange Leak Evident Flange Leak Evident Flange Leak Evident No Leak Observed No Leak Observed No Leak Observed Flange Leak Evident No Leak Observed No Leak Observed Flange Leak Evident Flange Leak Evident Flange Leak Evident No Leak Observed No Leak Observed No Leak Recorded No Leak Observed No Leak Observed Flange Leak Evident No Leak Observed No Leak Recorded No Leak Observed No Leak Observed Flange Leak Evident No Leak Observed No Leak Observed No Leak Observed Flange Leak Evident Flange Leak Evident No Leak Observed No Leak Observed No Leak Recorded No Leak Observed No Leak Observed Flange Leak Evident Flange Leak Evident Flange Leak Evident No Leak Observed No Leak Recorded No Leak Recorded No Leak Observed No Leak Observed No Leak Observed Flange Leak Evident FENOC RESTRICTED INFORMATION
Nozzle Core Quadrant 1996 Inspection results 1998 Inspection results No.
48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 Locat.
N12 N4 C5 cil E 13 M13 O11 05 M3 E3 B8 H14 P8 H2 B6 B1 0 Fl14 L14 Plo P6 L2 F2 Filed as h/RCS leakage issues/nozzle review Table Notes:
1 In 1996 during 10 RFO, 100% of nozzles were inspected by visual examination.
Since the video was void of head orientation narration, each specific nozzle view could not be correlated by nozzle number.
Nozzles 1,2,3, and 4 which do not have sufficient interference gap were excluded.
The remaining 65 nozzles did not show any evidence of leakage.
Bold letters indicate leaking CRDM bolting flanges discovered and repaired during 12 RFO ( April 2000).
No Leak Observed = Visual Inspection Satisfactory, No Video Record Required.
No Leak Recorded = Nozzle inspection recorded on videotape Italicized text indicates nozzles that are not expected to show leakage due to insufficient gap.
FENOC RESTRICTED INFORMATION No Leak Recorded
,.No Leak Recorded 0 No Leak Recorded M Flange Leak Evident No Leak Recorded
,"No Leak Recorded
,No Leak Recorded SNo Leak Recorded No Leak Recorded No Leak Recorded
'M No Leak Recorded
ý1 No Leak Recorded M
gNo Leak Recorded No Leak Recorded SNo Leak Recorded No Leak Recorded No Leak Recorded No Leak Recorded No Leak Recorded No Leak Recorded No Leak Recorded No Leak Recorded 2000 Inspection results No Leak Observed No Leak Observed No Leak Observed Flange Leak Evident Flange Leak Evident No Leak Observed No Leak Observed No Leak Recorded No Leak Observed No Leak Observed Flange Leak Evident No Leak Observed No Leak Recorded No Leak Observed No Leak Observed Flange Leak Evident Flange Leak Evident No Leak Observed No Leak Recorded No Leak Recorded No Leak Observed No Leak Observed
IPY& IUI & 12 1F Ins.pecWio Riesmlts
- No leakage identified
- Evaluated not to have sufficient gap to exhibit leakage
- Insufficient gap with leaking flange
- Nozzle obscured by boron
- Nozzle obscured by boron with leaking flange
- Newly affected, since 11 RFO, by leaking flange(s)
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0 0
d00
Spring 1996 Inspection FENOC RESTRICTED INFORMATION
1996 Inspections The following pictures are representative of the head in the Spring 1996 Outage. The head was relatively clean and afforded a generally good inspection.
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1996 Inspections FENOC RESTRICTED INFORMATION
1996 Inspections Some boron piles were observed at the top of the head in the vicinity of previous leaking flanges. Because of its location on the head, it could not be removed by mechanical cleaning but was verified to not be active or wet and therefore did not pose a threat to the head from a corrosion standpoint. Additionally, since these drives are not credited with leaking, that further ratifies that the boron is from previous flange leakage. The boron was heaviest beneath the mirror insulation seams.
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1996 Inspections FENOC RESTRICTED INFORMATION
1996 Inspections FENOC RESTRICTED INFORMATION
1996 Inspections n
4*
S A
oH FENOC RESTRICTED INFORMATION llý
1996 Inspections FENOC RESTRICTED INFORMATION "XI
1996 Inspections Hole 44-45 FENOC RESTRICTED INFORMATION
1996 Inspections Hole 37-38 FENOC RESTRICTED INFORMATION
1996 Inspections Hole 33-34 FENOC RESTRICTED INFORMATION
1996 Inspections FENOC RESTRICTED INFORMATION
1996 Inspections The boron deposits uphill of the CRDM drive below and to the right was reviewed from several angles and definite trails of born could be seen streaming from above the mirror insulation. This coupled with no boron on the bottom (downhill) edge of the CRDM penetration and the fact that boron will grow but not flow uphill allowed us to call this penetration as a non-leaker.
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Spring 1998 Inspection FENOC RESTRICTED INFORMATION
SPYe11sf 11 RF lnsAectiOn Results (9 - No leakage identified o
- Evaluated not to have sufficient gap to exhibit leakage
- Insufficient gap with leaking flange 0
- Nozzle obscured by boron
Q7.
No.53 The following pictures are from access hole #9. They were clipped from video taken in the Spring of 1998.
Although much more boron dusting 2C A was present in 1998 than in 1996, a
- good video inspection was able to be performed for those 50 drives that were not obscured by boron from leaking CRDM flanges.
Although much more video can be viewed, these attached pictures are representative of the condition of the drives and the heads. We attempted to capture in still photographs all of the outer most drives since they are the most susceptible to circumferential cracking based upon finite element analysis which showed them to have the highest stresses on the uphill and downhill slopes of the penetration.
NO. 65 What can also be seen in many of the photos is the staining of the underside of the mirror insulation by boron trails.
This conresponds to the boron found on top of the mirror insulation in the vicinity of the leaking CRDM flanges.
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NO. 41 INO. -.
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No. 65 FENOC RESTRICTED INFORMATION
The two pictures to the left are examples of some drives where we had to view them from several angles to ascertain that the boron adjacent to the drives was actually boron that flowed or tumbled down from higher up on the head and came to rest against the uphill side of the CRDM nozzle. Sometimes this was ascertained by comparing the pictures at the left to video of the vacuuming that was performed later which showed the boron to very loose and not a crystalline mass. Additionally, there were no boron deposits on the downhill penetration seam, which is contrary, to what industry experience has shown us to be true at plants that have identified leakers.
Because of the tight tolerances of the penetrations, any leakage through the penetration will encircle the drive with the largest accumulation being on the downhill edge because of gravity flow to that location.
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No. 69 FENOC RESTRICTED INFORMATION
1NO.
56 FENOC RESTRICTED INFORMATION Note the loose boron clumps to the left which were not in the immediate vicinity of the nozzle penetrations.
These clumps appeared to have accumulated further up on the head and then rolled or tumbled to their resting spots as shown. Note also the boron traces around the mirror insulation penetrations.
INO. (xi No.35 INO. 4Z FENOC RESTRICTED INFORMATION
No. 13 No. 43 No. 60 FENOC RESTRICTED INFORMATION
NO. 24 No.43 No. 67 FENOC RESTRICTED INFORMATION
INO. OW FENOC RESTRICTED INFORMATION No. 48, -)4, Ot)
No. 56 INo. 29 No49 side FENOC RESTRICTED INFORMATION CRDM Penetrations as viewed from inspection opening #7
INO. DD No. 49 front No.36 FENOC RESTRICTED INFORMATION
No. 68 INO. 44 No. 61 FENOC RESTRICTED INFORMATION
No. 25 No. 61 FENOC RESTRICTED INFORMATION I
Ak=ft-m Ir
No. 68 iNo. o9 and iNO. 4-in tme middle on the oack FENOC RESTRICTED INFORMATION
NO. b/
No. 46 FENOC RESTRICTED INFORMATION APR-24-5 13 -.26 : 3c;'.
INO. J I No. 26 No. 48 FENOC RESTRICTED INFORMATION
N(). 04ZI Same as above No. 34 on the right No. 28 FENOC RESTRICTED INFORMATION
No. 48 No. 66 FENOC RESTRICTED INFORMATION
dJ
INJ
(.
0 zi No. 52 FENOC RESTRICTED INFORMATION
NO, b*
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Spring 2000 Inspection FENOC RESTRICTED INFORMATION
IP leuat 12 RFOI Ispoction Results S-No leakage identified o
- Evaluated not to have sufficient gap to exhibitleakage 2W - Insufficdent gap with leaking flange 0
- Nozzle obscured by boron Nozzle obscured by boron with leaking flange FENOC RESTRICTED INFORMATION
No. 67 No. 43 No. 35 These photos were taken from our 2000 spring outage videotapes.
The lighting and video camera optics created an orange coloration of all of the pictures. However, deposits of boron are visually discernable as shown by the scattered pieces of boron.
No 67 has no buildup around its penetration and the boron debris shown in the picture for No. 43 are scattered well away from the penetration.
These drives were video taped because they had boron deposits in the vicinity of the CRDMs. Completely clean drive penetrations are not depicted here.
The photo for No. 19 depicts in the background the extent of boron buildup on the head and is the reason no credit is taken for being able to visually inspect the remainder of the drives.
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No. 19 FENOC RESTRICTED INFORMATION No. 60 No. 24 The debris piled up against the uphill side of No. 66 on the next page is indicative of loose debris that has fallen down the slope of the head and came to rest on the drive. It does not resemble "popcorn" deposits witnessed at other plants. There were also no signs of boron anywhere else on the drive penetration opening.
No. 66 No. 66 No. 42 No. 19 No. 24 No. 35 No. 35 FENOC RESTRICTED INFORMATION
No. 55 No. 29 FENOC RESTRICTED INFORMATION