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Wolsong NPP1 1
Steam Generator Tube Inspection and Foreign Object Retrieval
in Wolsong NPP
Lee, Jeong Uk ( [email protected] )
Wolsong NPP1 Chemistry Dep’t KOREA HYDRO & NUCLEAR POWER
CO., LTD.
South Korea
NDT in Canada 2016 & 6th International CANDU In-Service
Inspection Workshop, Nov 15-17, 2016, Burlington, ON (Canada)
www.ndt.net/app.NDTCanada2016
mailto:[email protected]
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Wolsong NPP1 2
Recently, To enhance integrity of secondary side tube of steam
generator(S/G) is strengthening the requirements of non-destructive
inspection • ECT • FOSAR(Foreign Object Search and Retrieval)
CANDU type steam generator tube is hardly defective But results
of a diagnostic program may be affected by
• Structural characteristics of S/G model • Retention of
optimized equipment, Operation period • Inspection evaluation •
Foreign substance characteristics (Especially)
Diagnostic Program for S/G Reliability
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Wolsong NPP1
Foreign Object Effect in S/G
3
In steam generator with many years of operation, • Equipment
access restriction due to hard sludge • Difficult to access for
foreign objects inspection • ECT Detectivity effect : Co-existence
of non-contact non-magnetic
foreign objects and sedimentary sludge
Effect of Foreign Object remaining between tubes • Increase the
tube defects probability by flow, vibration
Complementary relationship for Foreign Object detection • ECT •
FOSAR
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Wolsong NPP1 4
Item Unit 1 (1) Unit 2, 3, 4
Manufacturer Foster Wheeler Bobcock & Wilcox
Quantity 4 4
Tube 3,558 3,530
Tube Material Alloy 800 Alloy 800
2nd Side Handhole 3 (2” 1ea, 4” 2ea) 4 (2” 1ea, 4” 2ea)
2nd Side Manway 1 1
Tube Gap 4.74mm 5.02mm
Sludge Lancing No (2) Yes (4)
In-Bundle FOSAR Yes (3) Yes (4)
Tube ECT Yes Yes
(1) Continued Operation after license extension (2) No sludge
lancing after first by B&W in 2001 (3) First In-Bundle FOSAR in
2016(After Equipment Development) (4) Sludge lancing & FOSAR(2
S/G) for Every outage since 2008
Wolsong NPP Condition
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Wolsong NPP1
NDT Requirement : Performance for S/G
Inspection Methods
Item SGMP
Requirement
Performance Remarks
S/G #1 #2 #3 #4
Bobbin Full Length 100% / 60EFPM - 100% - 100%
MRPC H/L 100% / 60EFPM 10.5% 100% 10.5% 100%
C/L - - 9.6% - 9.6% 3 Col. of Annulus
Sludge Depth H/L
Once / 5 period - 100% - 100%
C/L - 20% - 20%
Sludge Lancing H/L Once / 4 period - - - - No equipment
FOSAR H/L Once / 4 period 50% 50% 50% 50% Hard sludge effect
Inspection Methods
Item SGMP
Requirement
Performance Remarks
S/G #1 #2 #3 #4
Bobbin Full Length 100% / 60EFPM 100% - 100% -
MRPC H/L 100% / 60EFPM 50.7% - 50.3% -
- C/L - - - -
Sludge Depth H/L
Once / 5 period 100% - 100%
C/L 20% - 20%
Sludge Lancing H/L, C/L Once / 4 period 100% - 100% Once / 2
period
FOSAR H/L, C/L Once / 4 period 100% 100% 100% 100% Once / 2
period
Unit 1 (24th Outage,
’16.3)
Unit 2 (15th Outage,
’15.11)
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Wolsong NPP1 6
(Monitoring) MVIQ by GE
(Inspection) 2.95mm Sword probe
by GE
Development of FOSAR equipment
FOSAR Mock-Up Simulation and Training • Moving magnetized Rail
assembly to the annulus area of S/G • 2.95mm Sword video probe(GE
custom application) inspection
Guide Tube
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Wolsong NPP1 7
Development of FOSAR equipment
S/G Structural characteristic and FOSAR Equipment
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Wolsong NPP1 8
ECT & FOSAR • Unit 1&2 : No signal of degradation
mechanism besides DSI(1) • Unit 1 : A number of ECT PLP signal
Detection : ECT 81(404 signals) + FOSAR 146 = Total 227 Removal
: FOSAR 108 Residue : 119
Access restriction area of FOSAR equipment because of sludge
Prevention Maintenance according to the evaluation results
Tube plugging : 1 tube (Remaining lifetime : 1.2 yr) • ECT PLP
evaluation was proved as FOSAR performance
In previous outages it was evaluated as deposit After
development of FOSAR equipment, it was confirmed
foreign objects
• Unit 2 : ECT PLP (1) but FOSAR result was a hard sludge
Inspection Results
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Wolsong NPP1 9
ECT & FOSAR • Unit 1 : Foreign object 108(73.9%) of 146 were
removed
Most foreign objects were thin plate type, Processing chip (Mn
0.38%, Si 0.60% : Corroded carbon steel)
Applying the development(R&D) of FOSAR Equipment
Influx Route : S/G moisture separator remodeling work in
1984
Inspection Results
S / G Location Detection Removal Non Removal
#1 In bundle 30 25 5 Annulus 0 0 0
No tube lane 2 2 0
#2 In bundle 50 38 12 Annulus 0 0 0
No tube lane 0 0 0
#3 In bundle 48 34 14 Annulus 1 1 0
No tube lane 1 1 0
#4 In bundle 14 7 7 Annulus 0 0 0
No tube lane 0 0 0
소계 In bundle 142 104 38 Annulus 1 1 0
No tube lane 3 3 0
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Wolsong NPP1 10
ECT : DSI(Distorted Support Indication) of Unit 1 • +Point MRPC
performance for Anti-Vibration Bar 6th • Result : Wear defect 8%
(Plugging Criteria : 40%)
[23th Outage] [24th Outage]
Inspection Results
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Wolsong NPP1 11
Sludge Depth & Sludge Lancing • Unit 1 : Steadily increase
& distribution around hot leg center
Inspection Results
Date S/G Sludge Depth(inch) Sludge Lancing
(kg) Remarks Max Avg
15th(’01.09)
#1
30 B&W Canada
#2 #3 #4
: : : : : :
21th(’10.06)
#1 6.25 2.46 Refurbishment (’09.4~’11.7)
#2 6.73 3.20 #3 7.36 2.85 #4 7.96 3.00
22th(’12.07) #2 7.49 3.13 #4 8.61 3.33
23th(’15.03) #1 8.56 3.13 #3 9.93 3.51
24th(’16.03) #2 8.33 3.00 #4 9.19 3.24
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Wolsong NPP1 12
Sludge Depth & Sludge Lancing • Unit 2 : Slightly
increase
Inspection Results
Date S/G
Sludge Depth(inch) Sludge Lancing
(kg) Remarks Max Avg
12th(’12.02) #2 2.94 1.00 4.3
#4 2.02 1.08 1.7
13th(’13.05) #1 1.29 0.68 2.6
#3 2.02 0.76 2.5
14th(’14.07) #2 3.12 1.04 2.6
#4 2.27 0.99 2.4
15th(’15.10) #1 1.72 0.87 3.0
#3 2.32 0.77 1.9
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In Unit 1, many foreign objects present inside S/G were removed
through the FOSAR • S/G Reliability was proved by performing the
residue evaluation
Developed FOSAR system was identified the performance • Field
test was successful and some improvement is needed
ECT signal evaluation should be cautious if it’s an old plant
and FOSAR has not been performed for a long time
For next, to overcome the access restriction area of FOSAR
system • Development of Sludge Lancing system required(proceeding,
~’17.9) • (First) Sludge Lancing (later) FOSAR
Conclusions
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Wolsong NPP1
( [email protected] )
14
Thank you
mailto:[email protected]
