ML20197K083
| ML20197K083 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 12/18/1997 |
| From: | Thomas K NRC (Affiliation Not Assigned) |
| To: | Randolph G UNION ELECTRIC CO. |
| References | |
| TAC-M95204, NUDOCS 9801050201 | |
| Download: ML20197K083 (6) | |
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i Decembqr: 18,1997 jg Mr. Garry L. Randolph l
Vice President andLChief Nuclear Officer---
Union Electric Companyt Post Office Box.620.
Fulton,; Missouri: 65251
- SUBJECT! -REQUEST FOR ADDITIONAL INFORMATION (PAI) REGARDING UNION ELECTRIC COMPANY'S REQUEST FOR AMENDMENT T0-THE TECHNICAL SPECIFICATIONS FOR CALLAWAY PLANT. UNIT:1_(TAC N0. M95204) i
Dear Mr.'Randolph':
The' NRC staff has. reviewed Uniori Electric Company's ' April 12. 1996-application.'and supplements, to change the Technical Specifications and Bases to allow the installation of Framatome Electrosleeves in-the Callaway Plant.
-: Unit:1 steam generators. As a result of the review, the staff has determined that additional:information is needed to complete the review.
The-information needed is detailed in-the enclosure.
- To assistithe
- NRC staff in meeting its review schedule, we request that you respond-to the RAI in writing astsoon as possible, with priority placed on Ouestions 1 through 6.
If you'have ar. Lquestions please contact me at (301) 415:1362.
' Sincerely.
Original Signed By Kristine Mc Thomas. Project Manager Project. Directorate IV-2 Division-of Reactor Projects - III/IV
, Office of Nuclear Reactor Regulation
- [g.
I Docket No. 50-483 DISTRIBUTION:
Docket File-ACRS. TWFN
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Enclosure:
Request for Additional. PUBLIC PDIV-2 Reading-Information EAdensam (EGA1) 0GC. 015B18' 1
WBateman WJohnson. RIV cc w/ encl:.See next page KThomas PGwynn RIV BWestreich EPeyton CBeardslee TSullivan s
DOCUMENT'NAME: CALFRAMA.RAI OFC-PDIV-2/LA!
'P91V-2/PM NAME-XT$omas' EE$tG?
'DATE 12/18/97
'12/17/97 0FFICIAL RECORD-COPY:
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9001050201 971218 PM ADOCK 05000483 P
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Mr. Garry L. Randolph December 18, 1997 CC w/ encl:
Professional Huclear Mr. Otto L. Maynard Consulting. Inc.
President anci Chief Executive Officer 19041 Raines Drive Wolf Creek Nuclear Operating Corporation Derwood Maryland 20B55 P.O. Box all Burlington Kansas 66B39 Gerald Charnoff. Esq.
Thomas A. Baxter. Esq& Trowbridge Mr. Dan 1. Bolef. President Shaw. Pittman. Potts Kay Drey. Representative 2300 h. Street. N.W.
Board of Directors Coalition Washington. D.C.
20037 for the Environtrent 6267 Delmar Boulevard Mr. H. D. Bono University City. Missouri 63130 Supervising Engineer Quality Assurance Regulatory Support Mr. Lee Fritz Union Electric Company Presiding Commissioner Post Office Box 620 Callaway County Court House Fulton, Missouri 65251 10 East Fifth Street Fulton. Missouri 65151 U.S. Nuclear Regulatory Commission Resident inspector Office Mr. Alan C. Passwater. Manager B201 NRC Road Licensing and fuels Steedman. Missouri 65077-1302 Union Electric Company Post Office Box 66149 Mr. J. V. Laux. Manager St. Louis, Missouri 63166-6149 Ouality Assurance Union Electric Company Post Office Box 620 Fulton. Missouri 65251 Manager - Electric Department Missouri Public Service Commission 301 W. High Post Office Box 360 Jefferson City. Missouri 65102 Regional Administrator. Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavilion 611 Ryan Plaza Drive. Suite 400 Arlington Texas 76011-8054 Mr. Ronald A. Kucera. Deputy Director Department of Natural Resources P.O. Box 176 Jefferson City. Missouri 65102
b, RE00EST FOR ADDITIONAL INFORMATION REGARDING REVIEW OF LICENSE AMENDMENT REQUEST TO All0W FRAMATOME ELECTROSLEEVING OF STEAM GENERATOR TUBES CAtlAWAY PLANT. UNIT 1 DOCKET NO. 50-483 The staff has reviewed Union Electric Company's license amendment request to allow installation of Framatome Electrosleeves in the Callaway Plant. Unit I steam generators and has determined that the following additional information is needed to proceed with the review, 1.
Attachmert 3 of the September 10. 1997 submittal contains a discussion of the lab grown ODSCC data sub-set.
Fourteen of the samples contained flaws that were essentially 100 percent through the parent tube.
Half of these samples were u..dersized more than the proposed 12 mil NDE uncertainty value.
The other half were not.
During the December 9.
1997 meeting, a technical basis was provided to the NRC staff for the UT sizing differences between the two subsets.
Document the technical basis along with all supporting data.
Be sure to include destructive examinaticn data for all fourteen samples such as flaw extents (e.g..
axial or circumferential) and descriptive photographs of etched samples that support the technical basis.
2.
Two examples of incorrect da'6a being supplied to the NRC staff were recently identified. The NRC staff identified errors in Table 1.2 of the September 10. 1997 submittal.
In addition, the licensee nctified NRC staff in the September 10. 1997, submittal that some data previously submitted to NRC staff was incorrect.
Discuss the quality assurance process (for both the licensee and the vendor), and how it meets 10 CFR
- 50. Appendix B criterion.
Discuss whether you have identified the cause of these errors.
Submit a copy of your corrective action program rela +ive to these issues. What are the 1mplications this las for other electrosleeve submittals or other parts of the program?
3.
Section 4.3.2. " Structural Margin for Circumferential Part-TW Flaw." of Document 32-1264476-00 submitted on September 5. 1997. discusses the approach utilized to determine the structural limits for circumferentially-oriented flaws in electrosleeve repairs. The text cites two references as the source of an equation and associated empirical constants listed in the section. The staff has reviewed Reference 2.6 (Ranganath and Mehta. " Engineering Methods for the Assessment of Ductile Fracture Margin in Nuclear Power Plant Piping")
and Reference 2.9 (Kurihara et ai, " Estimation of the Ductile Unstable Fracture of Pipe with a Circumferential Surface Crack Subjected to Bending") and concluded that the equation and associated empirical constants referenced in Section 4.3.2 do not come from the noted references. Clarify the source of the equation and constants listed in this section, or provide the associated technical basis for the part through-wall circumferential flaw limit.
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FTl procedure 54 151-168. Rev. I states that angle beam scanning for reflectors shall be performed from two opposing beam directions, where 3ractical, or from one direction, as a minimum.
FTl stated at the
)ecember 8.1997, meeting that they did collect data from tube s)ecimens used in their September 10. 1997 submittal from two directions.
- iowever, the submittal contained the examination results from only one direction examinations. The data from seven tubes with lab generated flaws exhibited a large. number of flaw under calls.
Experience in UT indicates that examinations conducted from two directions provide more accurate results than one sided examinations.
Provide a table that conta1ns comparisons between destructive examination depths and UT examination depths derived from analyzing the data from two directions for the seven tubes.
5.
In the September 10, 1997 submittal. FTl discusses the use of corner trap signals for depth sizing flaws. The submittal also mentions using tip diffraction signals for d1scerning flaws. Tip diffraction is considered an effective depth sizing technique.
In the meeting on December 8. 1997. FTI stated that they have been unsuccessful with tip diffraction for depth sizing.
Instead, for depttt sizing. FTI relies on corner trap signals that walk up the flaw face.
Provide an explanation with supporting physical data if available, to explain the ineffectiveness rJ tip diffraction in sizing flaws in SG tubes. The explanations should include what techniques are available or being developed for discerning multiple tip signals (SCC) and low sound-to-noise ratios (tip vs corner trap).
6.
NRC has concluded that an electrosleeve tube pull program will be needed to provide confirmatory data to address potential degradation and NDE uncertainties. The tube pull progra should be based both on length of
" time-in-service" g.n.d condition-baser (i.e.
based on NDE indication of n
Electrosleeve degradation).
Union Electric should propose a program for NRC staff review and commit to it through a TS change or license condition.
7.
Union Electric Company's proposed technical specifications currently reference Revision 1 of the electrosleeving topical report.
A substantial amount of additional work has been completed in sup) ort of the electrosleeving process since Revision 1 was issued in Marc 11996.
Update the topical report to raflect new data and any necessary changes to Revision 1.
For example:
Types of parent tube degradation electrosleeves are or are not qualified to repair (e.g.. IGA. stress corrosion cracking, pitting, etc.) and sumary of respective UT qualification data.
Limitations on locations electrosleeves can be applied (e.g.. no application to UBends, dented intersections greater than a predetermined size [see Question 9 below). etc.).
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Additional ' discussion on flaw s9ecific structural limits-(i.e..: the discussion of Issue 2 in the Se;)tember 10. 1997.: submittal describes flaw specific structural limits which differ from the structural
? limits described,in Table 8.5.1-of Revision 1 of the topical report).
.Any changes to the' topical report regarding material-properties required to support the flaw specific structural limits.
Summaries of UT qualification work (e.g., de)th sizing' qualification) updated since Retision 1 of tle topical report was written.
In addition, modify the technical specifications accordingly to -
. reference the updated version of the topical report.
18.
The initial inspection scope, as described in Table 4.4-3 of the Technical Specifications, for future ISI inspections of SG sleeves should consist of a minimum of 20 percent of garfl.ty.pg of installed-sleeve.
Revise the proposed technical _ specifications to reflect-this, 9.
The February 5. 1997, submittal discusses the ability to inspect dented intersections-containing electrosleeves. -It implies that there may be limits on-the size of dents-that can be reliably inspected.
Please
. clarify if there are limits, what those limits are, and the size of dents which will be electrosleeved. Summarize the technical' basis for these limits and how these limits were verified in the NDE qualification.
Portions of previous submittals may be referenced if applicable. These limits and a summary of the technical basis should be documented in the next revision of the-topical report (as discussed in Question #7 above),
10.
The response.to Issue-#1 in the September 10, 1997. submittal indicates that six-tubes from the Salem Unit 1 SG contained dents.
Please describe the size of these dents and whether they are within the dent
. size limits as discussed in response to Question #9 above.
11.
It is> not clear whether the licensee intends to repair tubes containing IGA with-electrosleeves. Please clarify.
If electrosleeves will be applied to tubes with IGA, provide a summary of the inspection qualification data that. supports this application.
In addition, the-revised topical-report (discussed in Question #7)-should-state whether
- electrosleeving will be' applied to SG tubes with IGA.
If electrosleeving is to be applied to SG tubes with. IGA.:the summary;of the inspection qualification data requested above should also be i
included'in the revised topical report.
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'12.
Table 1.0 of the submittal dated February 5.1997, states that the ssleeve: structural? limit for locked; tubes in the peripheral TSP wedge regions is lower than that for unlocked tubes. : Clarify whether 4
electrosleeving will be permitted in the. peripheral-TSP wedge regions where locking.may be present.
If electrosleeve repairs will be applied 4-
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in these areas, discuss the basis :for the structural limits for the
-Callaway plant. Otherwise,= discuss how the currently proposed technical
' specifications-exclude repairs for potentially-locked tubes.
Per-
' discussions held in the meeting on November.20. 1997, the licensee indicated that-the locking phenomenon did not apply to Westinghouse Model F steam generators.
If this is the basis for not. utilizing locked tube structural limits, provide the basis in writing for this Lassumption.
Include in the response a discussion on the potential for secondary side corrosive degradation that could lead to tube support plate. locking. Also discuss the results of secondary side steam ~
. generator inspections completed in these areas to verify these assumptions.
13.
At the meeting on December 9,1997, it was stated that additional work was being performed as a result of feedback from the peer review of the UT )cocess and qualification.
Provide the results of the additional worc (e.g., additional pit and unbond samples. etc.).
14.
In recent years UT techniques have made large imarovements in detecting and sizing. flaws.
FTI selected a basic 45 shear JT technique with computer assisted flaw analysis. This UT technique, however, exhibited limited effectiveness in sizing dee) lab grown flaws.
Explain FTI's evaluation / review (in more detail tlan FTI's February 5, 1997 submittal) of other UT techniques (divergent transducers, convergent transducers with narrow band frequencies, computer focusing, surface waves with the detail on surface roughness discussed at the-December 9, 1997 meeting).
higher frequencies, and different transducer angles.
Where test ~results supporting the above discussion are known, they should be summarized and referenced in the submittal. Note: the staff has no questions on the technique used for depth sizing with the 0 degree transducer.
15.
The procedure 54-151-168 Rev 1. dated January 28, 1997, was in the
)rocess of being upoated with the findings from the peer review.
3rovide the NRC staff with a copy of the updated procedure and the report containing the peer review findings and/or recommendations.
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