arkansas nuclear one unit one steam generators tube to tube wear
TRANSCRIPT
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
1/42
ANO1 Steam Generators
NRC PresentationArkansas Nuclear One Unit One Steam Generators
Tube to Tube Wear
1
Entergy/AREVA INC.
January 2012
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
2/42
ANO1 Steam Generators
Entergy
Jaime McCoy Engineering Director
Danny Hughes EP&C Supervisor
Dan Meatheany SG Program Owner
Steve Brown Corporate SG Program Owner
2
Bob Clark - Licensing
AREVA INC.
Jeff Fleck
Jim Begley Jeff Grigsby
Mike Boudreaux
John Remark
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
3/42
ANO1 Steam Generators
Agenda
Opening Remarks Jaime McCoy
Outage Results Dan Meatheany
Damage History Mike Boudreaux
3
Questions
Closing Comments Jaime McCoy
Root Cause John Remark
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
4/42
ANO1 Steam Generators
Opening Comments
4
Engineering Director
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
5/42
EOTSG Description
15 Tube Support Plates
External FW and EFW Rings
Floating TSP/Tie Rod
ANO1 Steam Generators
5
TSP are Trefoil Broach SS Aspirating Port in 10th Span
Upper and Lower Shroud
Orifice Plate in Downcomer
FW into Downcomer
EFW Penetrates Shroud
52 Tie Rods Concentric Circles
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
6/42
ANO1 Steam Generators
ANO1 EOTSG Inspections
Generators replaced in fall of 2005 (1R19) First ISI was spring 2007 (1R20)
Second ISI was fall 2008 (1R21)
6
Third ISI was spring 2010 (1R22) Fourth ISI was fall of 2011 (1R23)
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
7/42
ANO1 Steam Generators
Inspection Scope
IR23 Inspection Scope 100% bobbin full length of tubes
X-Probe of affected tubes around tie rods
7
X-Probe of special interest (SI) locations
A similar scope of 100% Bobbin and X-Probe SI
was conducted in 1R20 and 1R21
Outage 1R22 was a limited scope of tubessurrounding tie rods for tie rod bowing
All special interest has been performed with the
X-Probe
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
8/42
ANO1 Steam Generators
Time Line for Identification of Tube-to-Tube
Wear Started ANO1 inspection on 10/20/2011
Analysis and repair complete on 10/26/2011
8
Notified by Exelon and AREVA on 11/07/2011about Tube-to-Tube wear
Re-analyzed 100% of the 1R23 data using auto
analysis and performed a review of historical data
Revised CMOA acceptable to operate for 3
cycles
Initiated root cause effort
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
9/42
ANO1 Steam Generators
Attributes of Tube-to-Tube Wear Located in the middle of the 9th span which is also the middle
of the entire tube and some (far fewer) indications in the
middle of the 8th span
Typically located in a radial pattern 30 45 from the center of
9
Present in adjacent tubes (groups of two or three) unless near
the detection threshold
In adjacent tubes the indications face one another at the same
elevation and are the same length and depth range
Indications occurring in a triangular pattern show two
indications in one tube and one indication in each of the other
two tubes
Symmetrically tapered to a maximum depth in the center
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
10/42
ANO1 Steam Generators
Reanalysis for Tube-to-Tube Wear
Diagnosis of this condition at TMI led to animmediate notification and reanalysis of the
ANO inspection data
10
automated algorithm with a reporting threshold
of 0.35 volts, which equates to 6% TW (0.50 voltsequates to 8% TW)
All identified indications were further reviewedfor the attributes defined for Tube-to-Tube wear
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
11/42
ANO1 Steam Generators
Reanalysis for Tube-to-Tube Wear
Identified tube-to-tube wear indications werereviewed in all prior inspections to concisely
define history and develop growth data
11
+Point voltages for TMI Tube-to-Tube wear, a
calibration curve was developed for the ANO1
bobbin data to estimate depth based upon
+Point voltage from EPRI 27905.3 Depths were assigned to all indications in 1R20,
1R21 and 1R23 inspections
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
12/42
ANO1 Steam Generators
Tube-to-Tube Wear Inspection Findings
A total of 126 indications in 122 tubes were identifiedwith tube-to-tube wear
EOTSG A: 48 indications in 48 tubes
12
Wear depths range from 5% to 26% through wall
Indications have initiated with time
None were present in the preservice inspection
and none have disappeared since initiation
79 were present in the first inspection
11 new indications were in the second inspection
36 new indications were in the fourth inspection
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
13/42
ANO1 Steam Generators
13
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
14/42
ANO1 Steam Generators
14
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
15/42
ANO1 Steam Generators
Tube-to-Tube Wear Inspection Findings
Average Depth
of New
Indications at
Average
Depth
Repeat
Largest
1R23 New
Indication
Largest
1R23
Indication
15
at 1R23SG A 9%TW 8%TW 16%TW 16%TW
SG B 8%TW 10%TW 11%TW 26%TW
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
16/42
ANO1 Steam Generators
16
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
17/42
ANO1 Steam Generators
17
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
18/42
ANO1 Steam Generators
18
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
19/42
ANO1 Steam Generators
Growth History for Two Largest Indications
19
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
20/42
ANO1 Steam Generators
Condition Monitoring Satisfied
Utilized maximum depth and conservative lengthfor 3 delta P conditions
Substantial margin against accident leakage and
20
LBLOCA loading conditions evaluated and also
satisfied, conservatively assuming 180 degree
circumferential extent of wear
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
21/42
ANO1 Steam Generators
21
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
22/42
ANO1 Steam Generators
Operational Assessment Summary
Mixed arithmetic/monte carlo method utilized
Cycle length 4.13 EFPY (three fuel cycles)
Used maximum growth over previous cycle
22
Significant margin to leakage and burst(>10%TW margin)
LBLOCA evaluation also demonstrates
significant margin
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
23/42
ANO1 Steam Generators
ANO Unit 1 Inspection History
23
Mike Boudreaux
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
24/42
ANO1 Steam Generators
Absolute Drift Indications
Absolute Drift Indications (ADI) are eddy current
signals from the bobbin probe which have only
an absolute channel response and are caused
24
, ,
MBMs and material property changes Historically service related degradation in PWR
Steam Generators have produced both
differential and absolute channel responses andMBMs and material property changes have
produced only an absolute channel response
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
25/42
ANO1 Steam Generators
25
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
26/42
ANO1 Steam Generators
26
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
27/42
ANO1 Steam Generators
ADI Reporting Process (Bobbin Probe)
The reporting process for ADIs has been
consistent since 1R20 to support historical review
The reporting criteria for absolute indications is
27
. .
the most common source MBMs
The analysis rules allow reporting below this
threshold if the indication is flaw-like
Resolution analysts review the production calls aswell as evaluate the indications for change using
a criteria of 10 degree phase shift and > 0.50
volt increase in amplitude
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
28/42
ANO1 Steam Generators
Reporting Process (X-Probe)
The reporting process has been consistent since
1R20
The analysis requirements are prescriptive
28
e repor ng cr er a nvo ves no par cu ar
thresholds and there are reporting codes for linear
and volumetric indications otherwise No
Degradation Found (NDF)
Resolution analysts review the production callsand assign a final call as they deem appropriate
with concurrence
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
29/42
ANO1 Steam Generators
Reporting History for Tube-to-Tube Wear
SG A Tube-to-Tube Wear Indications Reported by Outage
Category 1R20 1R21 1R23
Primary Not available 4 17
Secondary Not available 3 22
Resolution 1 1 17
29
o a resen
Not Reported 0.49 volts 11 18 23 0.50 volts 3 0 2
SG B Tube-to-Tube Wear Indications Reported by Outage
Category 1R20 1R21 1R23
Primary Not available 26 27
Secondary Not available 25 41
Resolution 15 18 23
Total Present 64 67 78
Not Reported 0.49 volts 40 31 28
0.50 volts 9 7 6
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
30/42
ANO1 Steam Generators
Analysis Process Review
An average of 21% of the Tube-to-Tube wear indications
have been reported over the past inspections
An average of 57% of the Tube-to-Tube wear indications
were below the ADI re ortin threshold over the ast
30
inspections This total of 78% means that, on the average, 20% of the
reportable ADIs were not reported over the past
inspections
The absence of a differential channel response, to
indicate a flaw-like condition, coupled with a reporting
threshold of 0.50 volts are the primary contributing factors
to the percentage of indications reported
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
31/42
ANO1 Steam Generators
Analysis Process Review
A review of the indications shows that both the
production, resolution and IQDA analysts have
mischaracterized the indications in one fashion or
31
Production - either by not reporting them ormischaracterizing them
Resolution either by deleting them or
mischaracterizing them IQDA either by not questioning deleted
indications or agreeing with the
mischaracterization
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
32/42
ANO1 Steam Generators
Review of Tube R116-T029 Reporting History
1R20
Reported as an NQI on bobbin and VOL on X-Probe
1R21
32
Reported by production as ADI on bobbin and SVI and
MBM on X-Probe
Resolution stated it was anomaly or geometry and
changed call to NDF with IQDA agreement
1R23 Reported by production as ADI on bobbin and
changed to NQS based on history and did not receive
an X-Probe test
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
33/42
ANO1 Steam Generators
Review of Tube R117-T029 Reporting History
1R20
Not reported on bobbin though signal was present
1R21
33
Reported by production as ADI on bobbin and SVI and
MBM on X-Probe
Resolution stated it was anomaly or geometry and
changed call to NDF with IQDA agreement
1R23 Reported by production as ADI on bobbin and
changed to NQS based on history and did not receive
an X-Probe test
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
34/42
ANO1 Steam Generators
Summary for R116-T029 and R117-T029
Hindsight review would indicate that these indications
should have been investigated further
34
The indications are at the same elevation
The bobbin voltage was > 2 volts
The X-Probe signal was volumetric in nature
Voltage change was > 0.5 volts from 1R20 outage
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
35/42
ANO1 Steam Generators
Resolution Analysis Team Structure (1R23)
The primary and secondary resolution teams were
from different companies
The IQDA was from the secondary analysis
35
There were 5 primary & 6 secondary resolution
analysts and 2 IQDA all certified Level III QDA
The resolution process requires a minimum of two
resolution and one IQDA analysts to deletedegradation
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
36/42
ANO1 Steam Generators
Resolution Analysis Team Experience (1R23)
PositionExperience
(# Jobs)
Primary Resolution 1 16
Primary Resolution 2 5
Primary Resolution 3 25
36
Primary Resolution 4 11
Primary Resolution 5 9
Secondary Resolution 1 2
Secondary Resolution 2 4
Secondary Resolution 3 7
Secondary Resolution 4 5
Secondary Resolution 5 9
Secondary Resolution 6 3
Independent QDA 1 8
Independent QDA 2 14
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
37/42
ANO1 Steam Generators
Potential to Mask Other Degradation
As the steam generators age there is a possibility for
another form of degradation to initiate at a Tube-to-Tube
wear site
It is unlikel that the absolute si nal from the wear scar
37
will mask other degradation since that degradation islikely to produce a differential signal and differential
channels are unaffected by Tube-to-Tube wear signals
New degradation will result in a change in the signal
which will require the indication to be further tested
No other attributes of the Tube-to-Tube wear scar are
likely to affect eddy current signal response for bobbin,
X-Probe or RPC
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
38/42
ANO1 Steam Generators
ANO Unit 1 1R24
38
Dan Meatheany
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
39/42
ANO1 Steam Generators
Purpose of Inspections
Confirm apparent cause and analysis inputs
Determine magnitude of tie rod bow
Determine if free-span wear exists on tubes
39
Determine if denting exists on tubes around tie
rods
Evaluate the Tube-to-Tube wear
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
40/42
ANO1 Steam Generators
Current Scope of 1R24 Inspection Plans
Bobbin test of surrounding tubes for all 52 tie
rods in both steam generators
Inspect all previously identified Tube-to-Tube
40
.
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
41/42
ANO1 Steam Generators
Questions ?
41
-
8/3/2019 Arkansas Nuclear One Unit One Steam Generators Tube to Tube Wear
42/42
ANO1 Steam Generators
Closing Comments Jaime McCoy
42