ML042520211
| ML042520211 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/26/2004 |
| From: | Kidwell R TXU Electric |
| To: | Thadani M NRC/NRR/DLPM/LPD4 |
| Thadani M, NRR/DLPM, 415-1476 | |
| Shared Package | |
| ML042640118 | List: |
| References | |
| Download: ML042520211 (10) | |
Text
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Subject:
Comanche Peak draft RAI responses - RE: Alloy 800 sleeves Creation Date:
2/26/04 6:20PM From:
<rkidwell@txu.com>
Created By:
rkidwell@txu.com Recipients nrc.gov owf4_po.OWFN_DO MCT (Mohan Thadani) txu.com rmaysl CC obaidb CC dbuschbl CC Post Office Route owf4_po.OWFNDO nrc.gov txu.com Files Size Date & Time MESSAGE 559 02/26/04 06:20PM T04045.pdf 878145 Mime.822 1204205 Options Expiration Date:
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i Mohan Thadani -Comanche Peak draft RAI responses - RE! Alloy 800 sleeves Page 1 1
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__ _ tJ1 Mohan Thadani - Comanche Peak draft RAt responses - RE: Alloy 800 sleeves Pacie 1
From:
<rkidwell@txu.com>
To:
<mct~nrc.gov>
Date:
2/26/04 6:25PM
Subject:
Comanche Peak draft RAI responses - RE: Alloy 860 sleeves Gentlemen, Attached is the draft CPSES response to the latest RAls associated with our LAR 03-03 on Alloy 800 S/G tube sleeves. I believe the modifications made to these should address the questions and underlying concerns clarified during our 2/23/04 conference call. The markups of the Tech Spec pages are still roughly formatted, but should be adequate to see our proposed text changes.
Please contact me if you have any questions or need further information.
- Thanks, Bob Kidwell TXU Regulatory Affairs (254) 897-5310 (See attached file: T04045.pdf)
CC:
<dbuschbl @txu.com>, <obaidb@txu.com>, <rmaysl @txu.com>
I Moban-Thidani - T04045.pdf Page _
MobariThakiani - T04045.pdf Page 1 N Attachment I to TXX-04045 Page I of 3 toTXX-04045 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) UNIT 1 LICENSE AM ENDM ENT REQUEST 03-03 TAC No.MC0197
F Mohan Thiadan! - T04045.pdf
~Page 2 1 Mohan Thadani - T04045.pdf Page 21 Attachment I to TXX.04045 Page2of3
- 1.
In your response to NRC staff Question 9 in your [[letter::CPSES-200302528, Response to RAI Related to License Amendment Request 03-03, Revision to Technical Specification (TS) 5.5.9, Steam Generator Tube Repair Using Leak Limiting Alloy 800 Sleeves|letter dated January 8, 2004]], it was stated that the qualification program included sixteen sleeve/tube assemblies with laboratory-grown stress corrosion cracks.
A.
Discuss whether any of these laboratory-grown stress corrosion cracks were situated in the portion of the tube that is adjacent to (i.e., behind) the sleeve's nickel band.
B.
If some of the cracks were situated behind the nickel band, (I) discuss the size and location of these cracks (i.e., were some of the cracks situated in a manner that would require the eddy current signal to pass through the nickel band in order for the cracks to be detected); (2) discuss the orientation of the cracks (e.g., axial, circumferential, etc.);
(3) discuss the effectiveness of the eddy current inspection method in detecting these cracks, and (4) if the eddy current technique is not effective at detecting these cracks, discuss which method will be used for this inspection and the technical basis for this method.
C.
If some of the cracks were not situated behind the nickel band, provide a methodology (and technical basis) for addressing the structural and leakage integrity for the sleeve/tube assembly, assuming that degradation (e.g., a 360/, 100% through-wall circumferential flaw) could be occurring in the portion of the tube that is adjacent to (i.e.,
behind) the sleeve's nickel band.
TXU Energy Response:
L.A None of the laboratory-grown stress corrosion cracks were situated in the portion of the tube that is adjacent to (i.e., behind) the sleeve's nickel band. Further, a review of the WCAP-15918 was performed.
Based on review of the WCAP, industry events, and associated laboratory testing it was concluded that there is no documented report which depict that corrosion cracks have been discovered behind the Alloy 800 sleeve's nickel band. Westinghouse representatives were consulted to review the laboratory reports for the tests. No documented issues regarding the cracks behind the nickel band were noted.
L.B None of the laboratory-grown stress corrosion cracks were situated in the portion of the tube that is adjacent to (i.e., behind) the sleeve's nickel band, therefore this question is not applicable.
1.C The nickel band improves sealing of the sleeve when it is rolled into the tube. The thermally-sprayed nickel alloy band (as described in the installation procedures) results in a rough surface and enhances the rolled mechanical joint. The rolled mechanical joint now becomes a pressure boundary area. Surface and subsurface indications in the sleeve and the parent tube within the defined pressure boundary (including the Nickel band) are detectable using an eddy current probe with a 75 kHz frequency.
MohanThadani-T04045.
Page 3 Attachment I to TXX-04045 Page 3 of 3
- 2.
In your proposed technical specifications for the Plugging or Repair Limit, you indicate that the plugging limit for leak tight sleeve is equal to 20% of the nominal wall thickness (which is consistent with the definition of an imperfection) which indicates that indications below 20% of the nominal tube wall thickness may be considered as imperfections.
If it is not your intent to plug all tubes with indications in the sleeves upon detection (regardless of the depth of degradation), please provide the technical basis for this plugging limit. In your response, please describes the testing programs used in determining the growth rate and non-destructive examination uncertainty used in the determination of this plugging limit. If you do intend to plug all tubes with indications in the sleeves upon detection (regardless of the depth of degradation), please modify your technical specifications appropriately.
TXU Energy Response:
- 2.
The present statement in the Technical Specifications that 'The plugging limit for Leak Tight Sleeves is equal to 20% of the nominal wall thickness" is only applicable to the leak tight (i.e., Alloy 690) sleeves previously approved by the NRC in license Amendment 101 on 25 September, 2002 (ADAMS Accession #ML022590423). This statement does not apply to the leak limiting (i.e., Alloy 800) sleeves.
The leak limiting (Alloy 800) sleeves are addressed by the following statement added Technical Specification 5.5.9.f; "For Leak Limiting sleeves, the tube will be plugged regardless of the depth size for the degradation of the sleeve or for the parent tube behind the sleeve. The F* criteria is not applicable to Leak Limiting Sleeves installed in thetubesheet transition zone."
Mohan Thadani'-_T0405.pf age Attachmnent I to TXX-04045 Page 4 of 3
- 3.
In your January 8, 2004 response to question 2, you indicate that if a tube flaw is below the sleeve. then it is allowed to stay in service due to the F* analysis.
Please provide the technical basis for this proposal. Include in your response the test results showing that structural and leakage integrity will be maintained with just the sleeveltube joint (i.e., ignoring the non-pressure boundary portion of the parent tube since its integrity will no longer be able to be retied upon).
The staff notes that the basis for the F* criterion did not address whether the length of the parent tube at the rolled joint of a sleeve was adequate to ensure structural and leakage integrity given the assumed absence of the parent tube above this location (and spanned by the sleeve).
Alternatively, modify your proposed technical specifications to indicate that the plugging or repair limit will apply to defects located below the sleeve.
TXU Energy Response:
F* criteria wilt not be applicable to tubes with leak limiting sleeves installed in the transition zone. See markup of Technical Specifications 5.5.9.f and 5.5.9.j in Attachment 2 to this letter.
1 Mohan Thadani - T04045.pdf Page 5 Attachment I to TXX-04045 Page 5 of 3
- 4.
In your January 8, 2004 response to question 4, you indicate that operational experience to date has confirmed these calculated values to be conservative.
The intent of question 4 was to obtain any operating experience (under any condition including operating conditions) in which Alloy 800 sleeves has leaked. Please provide this information.
TXU Energy Response:
TXU Energy and Westinghouse are not aware of any reported or documented leakage of an operational steam generator tube in which an Alloy 800 sleeve has been installed. The lack of any conflicting operational data provides confirmation that the calculated maximum leakage values are conservative considering the operational experience to date.
IMohan Thadani - T04045.Ddf Pagel Mohari Thadani -TO4O45ndf Paae6
ATTACHM ENT 2 to TXX-04045 PROPOSED TECHNICAL SPECIFICATION CHANGES(MARK-UP)
Pages 5.0-16 and 5.0-17
I MohaqThadai'fli-T04045.pdf Page 7 Programs and Manuals 5.5 5.5 Programs and Manuals 5.5.9 Steam Generator (SG) Tube Surveillance Program (continued) t)
Plugging or Repair Limit means the imperfection depth at or beyond which the tube shall be removed from service by plugging or (for Unit 1 only) repaired by sleeving and Is equal to 40% of the wall thickness. The plugging limit for laser welded sleeves Is equal to 43% of the nominal wall thickness. The plugging limit for Leak Tight sleeves is equal to 20% of the nominal wall thickness. This definition does not apply to that portion of the Unit 1 tubing that meets the definition of an Fi tube. This definition does not apply to tube support plate intersections for which the voltage-based plugging criteria are being applied. Refer to 5.5.9e.1 m) for the repair limit applicable to these intersections. All tubes repaired with Leak Limiting sleeves shall be plugged upon detection of degradation in the sleeve and/or pressure boundary portion of the original tube wall In the sleeve/tube assembly (i.e., the sleeve-to-tube joint) regardless of depth. The F-criteria is not applicable to the parent tube located behind the Leak Limiting sleeves installed in the tubesheet transition zone; g) Unserviceable describes the condition of a tube if It leaks or contains a detect large enough to affect its structural integrity In the event of an Operating Basis Earthquake, a loss-of-coolant accident, or a steam line or feedwater line break as specified in Specification 5.5.9d.3, above; h) Tube Inspection means an Inspection of the steam generator tube from the tube end (hot leg side) completely around the U-bend to the top support of the cold leg. For a tube repaired by sleeving (for Unit 1 only) the tube inspection shall include the sleeved portion of the tube; i)
Preservice Inspection means an Inspection of the full length of each tube in each steam generator performed by eddy current techniques prior to service to establish a baseline condition of the tubing. This Inspection shall be performed prior to initial POWER OPERATION using the equipment and techniques expected to be used during subsequent Inservice Inspections; i)
F Distance (Unit 1 only) is the distance of the hardroll expanded portion of a tube which provides a sufficient length of non-degraded tube expansion to resist pullout of the tube from the tubesheet. The F-distance is equal to 1.13 inches, plus an allowance for eddy current measurement uncertainty, and is measured down from the top of the tubesheet, or the bottom of the roll transition, whichever Is lower In elevation.
The F-criteria is not applicable to the parent tube located behind the Leak Limiting sleeves installed in the tubesheet transition zone; k) F-Tube (Unit 1 only) is that portion of the tubing In the area of the lubesheet region below the F-distance with a) degradation below the F-distance equal to or greater than 40%, b) which has no Indication of degradation within the F-distance, and c) that remains inservice; (continued)
COMANCHE PEAK - UNITS 1 AND 2 5.0-16 Amendment No. =n
~'Mo-ha n-Th-a-d an i - T04045.pdf_ __ ' _Page 8.
Programs and Manuals 5.5 5.5 Programs and Manuals 5.5.9 Steam Generator (SG) Tube Surveillance Program (continued)
- 4. Certain intersections as Identified In WPT-15949 will be excluded from application of the voltage-based repair criteria as it is determined that these Intersections may collapse or deform following a postulated LOCA + SSE event.
- 5. If an unscheduled mid-cycle Inspection Is performed. the following mid-cycle repair limits apply Instead of the limits Identified In 5.5.9e.l.m)l.. 5.5.9e.l.m)2., and 5.5.9e.l.m)3.
The mldcycle repair limits are determined from the following equations:
VMURL
.S CL M~
1.0 NDE Gr___
CL VMLRL VMURL VURL VLRL C
where:
VURL
=
upper voltage repair limit VLFIL
=
lower voltage repair limit VMURL
=
mid-cycle upper voltage limit based on time Into cycle VMLRL
=
mid-cycle lower voltage repair limit based on VMALRL and time Into cycle
=
length of time since last scheduled inspection during which VURL and VLRL were Implemented CL
=
cycle length (the time between two scheduled steam generator Inspections)
VS structural limit voltage Gr
=
average growth per cycle NDE
=
95-percent cumulative probability allowance for nondestructive examination uncertainty (i.e., a value of 20-percent has been approved by the NRC)
Implementation of these mid-cycle repair limits should follow the same approach as In TS 5.5.9e.l.m)1 -,
5.5.9e.1 m)2., and 5.5.9e.1l.m)3.
- n. Tube Repair (for Unit 1 only) refers to the process that estabhshFe-stube serviceability. Acceptable tube repairs will be performed In accordance with the process described In Westinghouse WCAP-1 3698, Rev. 3 and Westinghouse Letter WPT-1 6094 dated March 20. 2000, WCAP-1 5090, Rev. 1, and CEN-630-P, Rev. 2 dated June 1997. and WCAP-15918, Rev. 1.1 (continued)
COMANCHE PEAK - UNITS 1 AND 2 5.0-17AmnetNo10 Amendment No. 111L