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{{#Wiki_filter:ENCLOSURE UNIT 3 STEAM GENERATOR TUBE INSPECTION PLAN 9403100195 940302 PDR ADOCK 05000530 Q PDR  
{{#Wiki_filter:ENCLOSURE UNIT 3 STEAM GENERATOR TUBE INSPECTION PLAN 9403100195 940302 PDR ADOCK 05000530 Q             PDR
~~~~1 UNIT 3 STEAM GENERATOR TUBE INSPECTION PLAN The Unit 3 steam generators will be inspected for tube defects using Eddy Current Testing (ECT)technology as opposed to ultrasonic or other non-destructive examination methods.The initial inspection scope and criteria for scope expansion are described'elow: INITIAL SCOPE~100%of the tubes in steam generator 31 and 32 will be inspected full length with bobbin coil.~MRPC 20%at the top of the hotleg tubesheet (includes sludge pile area)in steam generator 31.MRPC at the top of the hotleg tubesheet sludge pile area in steam generator 32.MRPC from the 08H support to the first vertical support in steam generator 31 and 32 (within the arc of 1800 tubes)a sample size of 369 tubes.This number is based on the recommended EPRI inspection sample of 20%, and is a conservative course of action given that previous inspections in these steam generators have not identified any axial cracking occurring in the arc region.Bases: 100%full length bobbin coilECT provides assurance that a widespread pattern of flaws does not exist.The MRPC sample at the top of the hotleg tubesheet and sludge pile area assures circumferential cracks are identified.
 
The'1800 tube arc was empirically determined to be the highest risk area from Unit 2 eddy current test data, and if cracks are developing due to the same phenomenon seen in Unit 2 this is where they are expected to be found.CRITERIA FOR EDDY CURRENT EXPANSION MRPC~For each tube with a hotleg non-quantifiable bobbin indication (NQI, DSI, DTI, and ADR)," conduct MRPC of the indication area.Bases: MRPC is required to resolve non-quantifiable indications.
~ ~ ~ ~
NQI-Non-Quantifiable Indication; DSI-Distorted Support Signal with Indication; DTI-Distorted Top of Tubesheet with Indication; ADR-Absolute Drift Response.Page 1 of 3  
1
~~~~F ,t I I Jl li I Treat the arc of 1800 tubes as the area of interest.o If less than 1%of the initial MRPC sample has NBI axial midspan flaws, conduct a 6%(108 tubes)expansion with MRPC from the 08H support to the first vertical support.In all cases a five tube buffer will be maintained from the NBI tube.o, If 1%or more of the initial MRPC sample has NBI axial midspan flaws, MRPC the entire area of interest from the 08H support to the first vertical support.Bases: The Unit 2 ECT data has shown empirically that the Unit 2 failure mechanism to be limited to an arc of approximately 1,800 tubes within an area where thermal-hydraulic conditions can create an aggressive chemical environment.
 
By treating the susceptible area separately, APS can apply Technical Specification methodology to MRPC and establish expansion criteria that zeroes in on the area at risk.~Any circumferential crack outside the sludge pile area at the hotleg tubesheet triggers a 100%MRPC examination of the hotleg tubesheet area in that steam generator.
UNIT 3 STEAM GENERATOR TUBE INSPECTION PLAN The Unit 3 steam generators will be inspected for tube defects using Eddy Current Testing (ECT) technology as opposed to ultrasonic or other non-destructive examination methods. The initial inspection scope and criteria for scope expansion are described
                                                                                          'elow:
INITIALSCOPE
~     100% of the tubes in steam generator 31 and 32 will be inspected full length with bobbin coil.
~     MRPC 20% at the top of the hotleg tubesheet (includes sludge pile area) in steam generator 31.
MRPC at the top of the hotleg tubesheet sludge pile area in steam generator 32.
MRPC from the 08H support to the first vertical support in steam generator 31 and 32 (within the arc of 1800 tubes) a sample size of 369 tubes. This number is based on the recommended EPRI inspection sample of 20%, and is a conservative course of action given that previous inspections in these steam generators have not identified any axial cracking occurring in the arc region.
Bases:     100% full length bobbin coilECT provides assurance that a widespread pattern of flaws does not exist. The MRPC sample at the top of the hotleg tubesheet and sludge pile area assures circumferential cracks are identified. The'1800 tube arc was empirically determined to be the highest risk area from Unit 2 eddy current test data, and if cracks are developing due to the same phenomenon seen in Unit 2 this is where they are expected to be found.
CRITERIA FOR EDDY CURRENT EXPANSION MRPC
~     For each tube with a hotleg non-quantifiable bobbin indication (NQI, DSI, DTI, and ADR)," conduct MRPC of the indication area.
Bases:   MRPC is required to resolve non-quantifiable indications.
NQI-Non-Quantifiable Indication; DSI-Distorted Support Signal with Indication; DTI-Distorted Top of Tubesheet with Indication; ADR-Absolute Drift Response.
Page 1 of 3
 
    ~ ~   ~ ~
F
,t I
I Jl li I
 
Treat the arc of 1800 tubes as the area of interest.
o     If less than 1% of the initial MRPC sample has NBI axial midspan flaws, conduct a 6% (108 tubes) expansion with MRPC from the 08H support to the first vertical support. In all cases a five tube buffer will be maintained from the NBI tube.
o,     If 1% or more of the initial MRPC sample has NBI axial midspan flaws, MRPC the entire area of interest from the 08H support to the first vertical support.
Bases: The Unit 2 ECT data has shown empirically that the Unit 2 failure mechanism to be limited to an arc of approximately 1,800 tubes within an area where thermal-hydraulic conditions can create an aggressive chemical environment. By treating the susceptible area separately,     APS can apply Technical Specification methodology to MRPC and establish expansion criteria that zeroes in on the area at risk.
~     Any circumferential crack outside the sludge pile area at the hotleg tubesheet triggers a 100% MRPC examination of the hotleg tubesheet area in that steam generator.
SECONDARY SIDE INSPECTION A visual examination of one steam generator secondary side will be conducted by looking through the manway with further actions being based on the results of that inspection.
SECONDARY SIDE INSPECTION A visual examination of one steam generator secondary side will be conducted by looking through the manway with further actions being based on the results of that inspection.
During the upcomirig Unit 3 refueling outage, APS will be installing handholes in the secondary side of the steam generators.'n inspection will be conducted in the accessible areas of the tubesheet in each steam generator in conjunction with the handhole installation.
During the upcomirig Unit 3 refueling outage, APS will be installing handholes in the secondary side of the steam generators.'n inspection will be conducted in the accessible areas of the tubesheet in each steam generator in conjunction with the handhole installation.
STEAM GENERATOR TUBE PULLING Preparations will be made for tube pulling as a contingency.
STEAM GENERATOR TUBE PULLING Preparations will be made for tube pulling as a contingency. However, the decision to pull tubes from Unit 3 steam generators will depend on the ECT results. The plans regarding this contingency are presented below:
However, the decision to pull tubes from Unit 3 steam generators will depend on the ECT results.The plans regarding this contingency are presented below:~Tube pulls will only be done to determine the root cause of failure for significant failure mechanism not consistent with known phenomenon.
~     Tube pulls will only be done to determine the root cause of failure for significant failure mechanism not consistent with known phenomenon.
Page 2 of 3  
Page 2 of 3
~~~~0 A p If tube pulls occur, up to two tubes will be selected that satisfy as many of the following objectives as possible: 0 Tubes which appear to show failure to comply with Regulatory Guide 1.121 o Confirm burst test correlation o Gather ECT detectability data o Gather growth rate data o Support MRPC flow sizing effort Page 3 of 3  
 
~ ~ ~ ~ 0 A
p
 
If tube pulls occur, up to two tubes will be selected that satisfy as many of the following objectives as possible:
0     Tubes which appear to show failure to comply with Regulatory Guide 1.121 o     Confirm burst test correlation o     Gather ECT detectability data o     Gather growth rate data o     Support MRPC flow sizing effort Page 3 of 3
 
~'}}
~'}}

Latest revision as of 09:26, 29 October 2019

SG Tube Insp Plan.
ML17310B091
Person / Time
Site: Palo Verde Arizona Public Service icon.png
Issue date: 03/02/1994
From:
ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:
Shared Package
ML17310B089 List:
References
PROC-940302, NUDOCS 9403100195
Download: ML17310B091 (8)
v • d • e


Text

ENCLOSURE UNIT 3 STEAM GENERATOR TUBE INSPECTION PLAN 9403100195 940302 PDR ADOCK 05000530 Q PDR

~ ~ ~ ~

1

UNIT 3 STEAM GENERATOR TUBE INSPECTION PLAN The Unit 3 steam generators will be inspected for tube defects using Eddy Current Testing (ECT) technology as opposed to ultrasonic or other non-destructive examination methods. The initial inspection scope and criteria for scope expansion are described

'elow:

INITIALSCOPE

~ 100% of the tubes in steam generator 31 and 32 will be inspected full length with bobbin coil.

~ MRPC 20% at the top of the hotleg tubesheet (includes sludge pile area) in steam generator 31.

MRPC at the top of the hotleg tubesheet sludge pile area in steam generator 32.

MRPC from the 08H support to the first vertical support in steam generator 31 and 32 (within the arc of 1800 tubes) a sample size of 369 tubes. This number is based on the recommended EPRI inspection sample of 20%, and is a conservative course of action given that previous inspections in these steam generators have not identified any axial cracking occurring in the arc region.

Bases: 100% full length bobbin coilECT provides assurance that a widespread pattern of flaws does not exist. The MRPC sample at the top of the hotleg tubesheet and sludge pile area assures circumferential cracks are identified. The'1800 tube arc was empirically determined to be the highest risk area from Unit 2 eddy current test data, and if cracks are developing due to the same phenomenon seen in Unit 2 this is where they are expected to be found.

CRITERIA FOR EDDY CURRENT EXPANSION MRPC

~ For each tube with a hotleg non-quantifiable bobbin indication (NQI, DSI, DTI, and ADR)," conduct MRPC of the indication area.

Bases: MRPC is required to resolve non-quantifiable indications.

NQI-Non-Quantifiable Indication; DSI-Distorted Support Signal with Indication; DTI-Distorted Top of Tubesheet with Indication; ADR-Absolute Drift Response.

Page 1 of 3

~ ~ ~ ~

F

,t I

I Jl li I

Treat the arc of 1800 tubes as the area of interest.

o If less than 1% of the initial MRPC sample has NBI axial midspan flaws, conduct a 6% (108 tubes) expansion with MRPC from the 08H support to the first vertical support. In all cases a five tube buffer will be maintained from the NBI tube.

o, If 1% or more of the initial MRPC sample has NBI axial midspan flaws, MRPC the entire area of interest from the 08H support to the first vertical support.

Bases: The Unit 2 ECT data has shown empirically that the Unit 2 failure mechanism to be limited to an arc of approximately 1,800 tubes within an area where thermal-hydraulic conditions can create an aggressive chemical environment. By treating the susceptible area separately, APS can apply Technical Specification methodology to MRPC and establish expansion criteria that zeroes in on the area at risk.

~ Any circumferential crack outside the sludge pile area at the hotleg tubesheet triggers a 100% MRPC examination of the hotleg tubesheet area in that steam generator.

SECONDARY SIDE INSPECTION A visual examination of one steam generator secondary side will be conducted by looking through the manway with further actions being based on the results of that inspection.

During the upcomirig Unit 3 refueling outage, APS will be installing handholes in the secondary side of the steam generators.'n inspection will be conducted in the accessible areas of the tubesheet in each steam generator in conjunction with the handhole installation.

STEAM GENERATOR TUBE PULLING Preparations will be made for tube pulling as a contingency. However, the decision to pull tubes from Unit 3 steam generators will depend on the ECT results. The plans regarding this contingency are presented below:

~ Tube pulls will only be done to determine the root cause of failure for significant failure mechanism not consistent with known phenomenon.

Page 2 of 3

~ ~ ~ ~ 0 A

p

If tube pulls occur, up to two tubes will be selected that satisfy as many of the following objectives as possible:

0 Tubes which appear to show failure to comply with Regulatory Guide 1.121 o Confirm burst test correlation o Gather ECT detectability data o Gather growth rate data o Support MRPC flow sizing effort Page 3 of 3

~'

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