ML20078G217
| ML20078G217 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 11/08/1994 |
| From: | Saccomando D COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9411150544 | |
| Download: ML20078G217 (5) | |
Text
_-___-_______ - _____________________
[CN)
Comm:nwrith Ediscn c
1400 Opus Piace i
I O'
Downers Grove. Ilknois 60515
\\j November 8, 1994 Office' of Nuclear Reactor Regulation U..S.
Nuclear Regulatory Commission Washington, D.C.
20555 Attention:
Document Control Desk
Subject:
Braidwood Station Unit 2 Flaw Evaluation Report for Residual Heat Removal Heat Exchanger Nozzle to Shell Welds NRC Docket No 50-457
References:
1)
Teleconference between Commonwealth Edison Company and the Nuclear Regulatory Commission dated November 8, 1994, Regarding the Unit 2 RHR Heat Exchanger Nozzle Inspection Results 2)
H.
Pontious letter to NRC dated November 8, 1994, transmitting WCAP 13454, " Fracture Mechanics Evaluation Byron and Braidwood Units 1 and 2 Residual Heat Exchanger Tube Side Inlet and Outlet Nozzles" 3)
R.
Pulsifer letter to T.
Kovach dated November 21, 1991, transmitting Safety Evaluation on Flaw Evaluation for Residual Heat Removal Heat Exchanger Nozzle to Shell Welds for Braidwood Unit 2 During Braidwood Station's 1994 Unit 2 Refueling Outage (A2R04) a volumetric examination of the Residual Heat Removal (RHR) Heat Exchanger nozzle to shell welds was conducted in accordance with the NRC approved Braidwood Inservice Inspection program.
This examination disclosed indications on the RHR Heat Exchanger which exceed the acceptance criteria as approved by a Safety Evaluation transmitted in reference 3. As a result of the inspection results, several teleconferences were held in which the appropriateness of including the fillet weld in the available wall thickness. During the reference teleconference, Comed ctrmitted to providing the Staff with the following documentation to clarify this issue:
1) 1994 Braidwood Unit 2 RHR Heat Fxchanger Inservice Inspection Results j
2)
WCAP 13454, " Fracture Mechanics Evaluation Byron and Braidwood Units 1 and 2 Residual Heat Exchanger Tube Side Inlet and Outlet Nozzles," dated August 1992, and L ; n l a s bwd i f 1 t r e s 9411150544 941108 DR ADOCK 05000457
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Document Control Desk November 8, 1994 3)
Finite Element Analyses for the Byron and Braidwood Units 1 and 2 RHR Heat Exchanger Nozzle to Shell Welds Attached is item 1.
Item 2 was transmitted in reference 2. Item 3 will be provided to the Staff for their review by November 10, 1994.
Comed believes that the information/ analyses that will be docketed, provides adequate justification that the fillet weld thickness can be credited when performing limit load structural margin assessment of the nozzle to shell weld. Comed understands that this topic may warrant further discussions, and would be happy to address any questions concerning this topic.
Please address any questions concerning this correspondence to this office.
Comed appreciates the Staff's efforts towards expedited resolution of this issue.
Sincerely,
/Ql'f.
e ~Au Denise M.
Saccomando Nuclear Licensing Administrator Attachment cc:
R. Assa, Braidwood Project Manager-NRR S. Dupont, Senior Resident Inspector-Braidwood J. Martin, Regional Administrator-RIII Office of Nuclear Safety-IDNS I
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Attachment 1994 Braidwood Unit 2-l Residual Heat'Remova'A (RHR)
Heat Exchanger Inservice Inspection Results h
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The fo.llowing summarizes, for each nozzle, the recordable indications detected during ultrasonic examinations in 1994.
All indications are subsurface flaws, not open to the internal and external surfaces.
Both the ultrasonic examinations and visual inspections of the repair cavities points to slag inclusions, porosity, and lack of fusion due to fabrication rather than service induced flaws.
Following the methodology of ASME Section XI, IWA-3310 (b), several flaws have been considered as surface flaws and are so reported in these tables.
The "a/t w/o fillet" column values have been developed using the actual nozzle wall thickness, as measured by ultrasonic examinations.
The "a/t with Fillet" column values have been developed using a conservative effective throat distance based on the location of the indication L
from the heat exchanger shell wall. Please note that all dimensions are in inches. Due to differences in ultrasonic examination techniques the 1991 submitted data is not easily correlatable to the 1994 examination results.
In addition, an independent Level III review and comparison of the 1993 and 1994 automated ultrasonic data did not reveal any evidence of flaw propagation.
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ATTACHMENT J_RAJDWOOD UNIT 2 RHR HEATER EXCHANGER NOZZLE WELD UT EXAM DATA November 8,1994 EFFECTIVE NOZZLE FILLET o/t a/t IND SURFACE /
THICKNESS THROAT W/O WITH.
LOCATION SUBSURFACE LENGTH a(20) a/l i
tc FILLET FILLET i
2A RHR HEAT EXCHANGER INLET NOZZLE 1
23 7 to 24 4 Subsurface 0700
(.160) 0.114 0.390 n/a 21%
n/a 2
9.3 to 10.5 Subsurfcce 1.200
(.240) 0.100 0.390 n/a 31%
n/a 3
41.1 to 417 Subsurface 0.600
(.220) 0.183 0.390 n/a 28%
n/a i
2A RHR HEAT EXCHANGER OUTLET NOZZLE 1
18.4 fo 18.9 Surface 0.500 0.100 0.200 0.365 n/a 27%
n/a 2
19 8 to 231 Surface 3.300 0.280 0.085 0 365 0.132 77%
56%
3 30 4 to 30 5 Subsurface 0.100 (0 030) 0.150 0.365 n/a 4%
n/a 2B RHR HEAT EXCHANGER INLET NOZZLE 1
O to 0.32 Subsurface 0.320
(.180) 0 281 0.394 n/a 23%
n/a 2
0 76 to 1.20 Subsurface 0440
(.440) 0.500 0 394 n/a 56%
n/a 3
4 9 to 5.7 Surfoce 0800 0.300 0.375 0.394 0.132
'76%
57%
4 8.4 to 9.9 Surface 1.500 0.240 0.160 0.394 0.132 61 %
46%
5 8.4 to 9 8 Subsurface 1.400
(.C80) 0 029 0.394 n/a 10%
n/a 6
13 2 to 14.6 Subsurface 1.400
(.060) 0.021 0.394 n/a 8%
n/a 7
15 0 to 15.1 Subsurface 0100
(.040) 0.200 0 394 n/a 5%
n/a 8
16 2 to 16 3 Subsurface 0.100
(.030) 0.150 0.394 n/a 4%
n/a 9
23 0 to 23 2 Subsurface 0.200
( 160) 0400 0.394 n/a 20%
n/a 10 25 4 to 25 5 Subsurface 0.100
(.040) 0200 0.394 n/a 5%
n/a 11 29.I to 29 5 Subsurface 0.400
(.100) 0.125 0.394 n/a 13%
n/a 12 36 0 to 36.3 Subsurface 0.300
( 080) 0.133 0.394 n/a 10%
n/a 13 41.7 to 41.75 Subsurface 0.050
(.020) 0.200 0.394 n/a 3%
n/a 14 42.3 to 42 4 Subsurface 0.100
(.060) 0.300 0.394 n/a 8%
n/a 15 44 6 to 44.7 Subsurface 0100
(.140) 0.700 0.394 n/a 18%
n/a l
l 2B RHR HEAT EXCHANGER OUTLET NOZZLE 1
O to l.9 Surface 1 900 0500 0263 0.385 n/a 130%
Removed 2
2.5 to 2 8 Subsurface 0300 (0 140) 0233 0.385 n/a 18%
n/a 3
3 2 to 3 25 Subsurfaco 0 050
( 040) 0.400 0.385 n/c 5%
n/a 4
4 0 to 4 2 Subsurface 0200
(.120) 0300 0.385 n/a 16%
n/a 5
5 0 to 9.9 Surfoce 4.900 0.440
'D90 0.385 n/a 114%
Removed 6
131to135 Subsurface 0400
(.180) 0225 0 385 n/a 23 %
n/a 7
216 to 23 6 Subsurface
?.000 (240) 0.060 0.385 n/a 31%
Removed 8
24 6 to 25.0 Subsurface A400
( 060) 0.075 0.385 n/a 8%
n/a 9
26 3 to 26 4 Subsurface L100
( 030) 0.150 0.385 n/a 4%
n/a 10 27 0 to 27.1 Subsurface 0.100
(.030) 0.150 0.385 n/a 4%
n/a 11 28 3 to 28 4 Subsurface 0.100
(.030) 0.150 0.385 n/a 4%
n/a 12 30.I to 30 2 Subsurfaco 0.100
(.040) 0200 0.385 n/a 5%
n/a 13 32.3 to 32 9 Subsurfcce 0600
(.180) 0.150 0.385 n/a 23%
n/a 14 3531o387 Subsurface 3 400
( 480) 0 071 0.385 n/a 62%
Removed 15 41.5 to 41.6 Subsurfaco 0100
(.120) 0600 0.385 n/a 16%
n/a 16 42 2 to 44 6 Subsurface 2 400
(.440) 0.0V2 0.385 n/a 57%
Ramoved j
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