ML20058M406
| ML20058M406 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 12/08/1993 |
| From: | Rehn D DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M86811, NUDOCS 9312200308 | |
| Download: ML20058M406 (5) | |
Text
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l DueIbwer Corramy D L Rats Cataba hcirar Gertemhan Depanment tke fresident 4D0 Osncord Road (bO3fal3205 OWice York SC29745 (803)sT13426 Fax DUKE POWER December 8,1993 U.S. Nuclear Regulatory Commission ATfN: Document Control Desk Washington, D.C. 20555
Subject:
Catawba Nuclear Station, Unit 2 Docket No. 50-414 Request for Relief 93-01 Response to NRC Request for AdditionalInformation (TAC No. M86811)
Reference:
Ixtter from NRC to D.L. Rehn, dated September 8,1993 l
Gentlemen:
Please find attached our response to the NRC request for additional information pertaining to Relief Request 93-01. If you have any questions, please call L.J. Rudy at (803) 831-3084.
Very truly yours, i
D.L. Rehn LIR/s Attachment xc (W/ Attachment):
S.D. Ebneter, Regional Administrator Region II R.J. Freudenberger, Senior Resident Inspector R.E. Manin ONRR
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. REQUEST FOR ADDITIONAL INFORMATION i
1.
Regulation permitting the relief:
A.
Please identify the portion of the regulation under which this relief is requested and pmvide the associated basis for the request.
During ultrasonic examination of the welds shown in Attachment 1 of Relief Request //93-01, the ndnimum 90% coverage requirement of ASME Section XI, 1980 Edition, clarified by Code Case N-460, could not be obtained. Examinanon covemge was limited due to part geometry.
B.
Please identify any conflict with the technical specifications, t
No conflict with any technical specification has been identified in conjunction l
with this relief request.
C.
Is the relief associated with a 10 year ISI program?
1 Yes.
'i D.
Does the request satisfy the time requirements (if any are required)?
j Yes.
2.
Code requirements:
I i
A.
In the Table IWB-2500-7, what figure designation (a, b, c, or d) represents the.
inner radius cladding examination volume (B03.140.001,002,007, and 008)?
ASME Section XI,'IWB-2500-7(d) l 3.
Items:
f A.
What are the wall thickness, outside/inside diameters or radii that are necessary for calculating the area / volume that were not examined in each item?
Ts = Shell or head thickness Ri = Nozzle inside radius.
Examination volume M-N-O-P Ref.' Figure IWB-2500-7(d) r i
4.
Reason for request:
A.
What aspects of the geometry prevents 100% ultmsonic examination (UT)?
i f
i (1)
Nozzle ' wall thickness (Category B-D)
'(2)
Single-sided access (Category B-F & B-J)
(3)
Material type for dissimilar metal welds (Category B-F &. B-J) -
B.
What aspects of the UT methodology prevents 100% UT?
Use of refracted longitudinal waves for examination of Category B-F dissimilar metal welds creates coverage limitations when access is limited to one side of the weld. For Categories B-D and B-J there are no aspects of UT methodology to restrict covemge.
C.
Identifying percent examined.
f (1)
What is meant by " Area of Loss"?
Area of examination not receiving 100% UT coverage.
j (2)
Why aren't the results of the volumetric examinations expressed in volumetric units (i.e., cube units)?
Code Case N-460 specifies that limitations are to be reponed as a
" percentage of reduced examination volume" 4
(3)
How does the axial and circumferential scan contribute to the total actual coverage percentage calculations?
The " Examination Volume" is obtained by multiplying the physical i
volume of material by the number of scans required to achieve 100%
coverage. A combination of axial and circumferential scans are used to cover the examination volume. Ref.Section V, Article 4 and Section XI, Appendix III.
(4)
Why does Item #B09.031.005 show all amas scanned and Attachment I lists the actual coverage at 42.60%? B09.031.005 is similar.
Ci Wrhi rential scan losses are not shown on the sketch but contributed
'c thr ^2. 50% coverage. The item' numbers referenced are the same.
(5) vaat is meant by "Examinanon coverage was not limited"?
i Section HI, Paragraph 2 of Relief Request #93-01 states that co/erage was not limited for surface exam.
t 5.
Alternate:
i A.
Ilow will the most current UT be evaluated with respect to 10CFR50.59 i
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I criterion?
i The acceptability of a particular UT method is verified against ASME Section XI, IWA-2000, Examinations and Inspections, rather than against the provisions of 10CFR50.59. As required by IWA-2000, Duke Power Company employs the services of an " Authorized Nuclear Inservice Inspector". The duties of the inspector include myiew, comment, and approval of inspection procedures. In i
accordance with IWA-2000, alternate inspection procedures to those previously determined to be acceptable may be substituted given inspector approval.
B.
Will a system hydrostatic test be perfonned on these items at the end of the; interval?
The requirements for a IWB-5222 test will be perfonned in the third period of the
{
first interval.
i C.
What difficulties are experienced with mdiography examinations?
Radiography cannot be substituted for ultmsonics when examination of nozzle inner radius areas are required because the geometric conditions are not suitable.
for radiography (i.e., the plane of the Elm must be perpendicular to the plane of the suspe:ted flaw and the center of the mdiation beam must be perpendicular to j
the plane of the film).
i Radiography is not suitable for the steam genemtor nozzle to safe end welds for the following masons:
Double wall exposure would be required making it necessary to radiograph through at least 5.3 inches of steel using a Cobalt 60 source and a fast film speed.
Use of the above exposure tecimique is less sensitive than ultrasonics f
when service induced flaws (inside surface fatigue cracks) are to be detected.
The water level in the system would have to be lowered to a point below the weld. Radiation levels around the bottom of the steam generator are usually higher when the generator is dmined.. The exposure level f
increases the potential' for " fogging" the film, further decreasing the sensitivity of the radiography.
D.
Can the volumetric examination be conducted fmm the ID?
Volumetric examination from the inside cannot be perfonned on these welds because of high radiation levels and restricted access.
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F1gs liVII-25C3-7(d) 1989 SECTION XI - DIVISION 1 l
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NOTES.
(1) Examination regions ere identsfied for the purpos,t of differentaating the acceptance standards in IWB-3512.
(?) Enamination volumes may be determined est'ser by direct measurements on the component or by measurements based on design drawings FIG. IWB-2500-7(d) N0ZZLE IN SHELL OR HEAD (Examination Zone in Nozzles Integrally Cast or Formed in Shell or Head) l 1
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