ML20198M987
| ML20198M987 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 01/09/1998 |
| From: | Jacob Zimmerman NRC (Affiliation Not Assigned) |
| To: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| References | |
| GL-95-05, GL-95-5, TAC-M99840, NUDOCS 9801200200 | |
| Download: ML20198M987 (6) | |
Text
. y.ns:s
.p t.
UNITED STATES i
j NUCLEAR REGULATORY COMMISSION-WASHINGTON, D.C. SeesH001 3anuary 9, 1998 Mr. D. N. Morey Vice Pret,ident-Farley Project Southem Nuclear Operating Company, Inc.
Post Office Box 1295 Birmingham, Alabama 35201-1295
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE USE OF A SMALLER DIAMETER PROBE WHEN IMPLEMENTING GENERIC LETTER 95 JOSEPH M. FARLEY NUCLEAR PLANT, UNITS 1 AND 2 (TAC NO. M99840)
Dear Mr. Morey:
On March 7,1997, you submitted the Joseph M. Farley Nuclear Plant, Unit 2, 90 Day Report" as required by the Technical Specifications to implement Generic Letter (GL) 95-05, " Voltage-
- Based Repair Criteria for Westinghouse Steam Generator Tubes Affected by Outside Diameter a
Stress Corrosion Cracking." As part of the submittal, you requested that the staff review the use of a smaller diameter bobbin coil addy current probe when implementing GL 95-05.
Section 10 of your report summarized the qualification test resulte for the smaller diameter probe.
Currently, GL 95-05 requires the use of a 0.720-inch diameter probe for plants with 7/8-inch diameter steam generator (SG) tubes such as Farley, Unite 1 and 2. However, Section 3.c.7 of of GL 95-05 allows the use of smaller diameter probes to inspect tubes where it is impractical to use a nominal size probe (i.e., the 0.720-inch diameter probe) provided the probe and associated procedure have been demonstrated on a statistically significant basis to give an equiva!ent voltage response and detection capability when compared to the nominal-size probe, subject to NRC staff approval.
On November 10,1997, you provided the details of the testing performed at Farley, Unit 2, to demonstrate the acceptability of the smaller diameter eddy current probe in a report titbd, "Farley Unit 2 Small Bobbin probe (0.640") Qualification Test Report." You also stated in the November 10 letter that the qualification of the smaller diameter probe should be considered generic in natare and applicable to other plants with 7/8-inch diameter SG tubes and that acceptrbility of the 0.640-inch diameter probe automatically qualifies probes with diameters ranging in size from 0.640 inch to 0.720 mch. In addition, you stated your intention to use the
-- smaller diameter bobbin coil eddy current probe on both Farley units.
The staff has reviened your submithi and determined that additional information is required.
The enclosure identifie1 the requested additional information needed.
(
& \\-
NBC RE CENTER COPY
~
2,mes l h.. h.. h..l l.
I 9901200200 980109 PDR ADOCK 03000349 P
pm
=-
a__________
i D. N. Morey e in order to maintain a timely review, it is requested that the information be provided within 30 days of receipt of this letter. If you require 6.ny clarification regarding this request, pleare call me at (301) 415-2426.
Sincerely, cob 1. Zi erman, Project Manager Project Directorate ll-2 Division of Reactor Projects -Ifil Offico of Nuclear Reactor Regulation Decket Nos. 50-348 and 50-364
Enclosure:
Request for Additionelinformation cc w/ encl: See next page t
I D. N. Morey -
January 9,1998 In order to maintain a timely review, it is requested that the information be provided within 30 da/s of receipt of this letter. If you require any clarification regarding this request, please call me at (301) 415-2426.
Sincerely, ORIGINAL SIGNED BY:
Jacob 1. Zimmerman, Project Manager Project Directorate 11-2 Division of Reactor Projects - 1/11 Offica of Nuclear Reactor Regulation Docket Nos. 50-348 and 50-364
Enclosure:
Request for Additionalinfcrmation cc w/ encl: See next page D131Dbutt0IL iDocke*. Hie)
HBerkow ACRS PI)BLIC JZimmerman 1 Johnson, Ril PD 11-2 Rdg.
SCoffin PSkinner, Ril BBoger OGC LBerry DOCUMENT NAME: G: FARLEY\\M99840.RAI To receive a copy of this document, indicate in the box: "C" = Copy without attachment / enclosure "E" = Copy with attachment / enclosure "N" = No copy.
OFFICE PM:PDJ)lff 6 LA:PDil-2 h M fgiPpjb2 NAME JZIMPQ!kMAN:en LBERRY )(D HB$RKOW DATE
/ /1 798
/9 /98
\\
l/3/98
/ /98 OFFICIAL RECORD COPY
' Joseph M. Farley Nuc'e:r Plant S'
eg.
Mr. R. D. Hill, Jr.
General Manager -
Southem Nuclear Operating Company Post Office Box 470 Ashfard, Alabama 36312 Mr. Mark Ajiuni, Licensing Manager Southerr, Nuclear Operating Company Post Office Box 1295 Birmingham, Alabama 35201-1295 Mr. M. Stanford Blanton Balch and Bingham Law Firm Post Office Box 306 1710 Sixth Avenue North Birmingham, Alabama 35201 Mr. J. D. Woodard Executive Vice President '
Southem Nuclear Operating Company Post Office Box 0.95 Birmingham,/labama 35201 State Health Officer Alabama Department of Public Health
(
434 Monroe Street Montgomey, Alabama 36130-1701 Chairman Houston County Commission
- Post Office Box 6406 Dothan, Alabama 36302 Regional ',dministrator, Region 11 U.S. Nuclear Regulatory Commission Atlanta Federal Center 61 Forsyth Street, S.W., Suite 23T85 Atlanta, Georgia 30303 Resident inspector lj S. Nuclear Psegulatory Commission 7388 N. State Highway 95 Columbia, Alabama 36319
... - - _ - - - ~ ~ ~
.----._----..-_-_-_____.__.__---_.-_-____--_-_-___-_--._---__--.-__.-.--__-._----_----.2
REQUEST FOR ADDITIONAL INFORMATION USE OF A SMALLER DIAMETER PROBE WHEN IMPLEMENTING GENERIC LETTER 95-05 JOSEPH M. FARLEY NUCLEAR PLANT. UNITS 1 AND 2 Nondestructive Examination (NDE) UNCERTAINTY Relative to a nominal-size probe, the 0.640-inch probe may introduce more NDE uncertainty due to its srnaller size; this is due primarily to an increase in probe wobble that results in a degraded signal-to-r$oise ratio.
1.
As discussed in GL 95-05, eddy current voltagc measurement uncertainty stems primarily from two sou,ces: (1) voltsge response variability due primarily to probe wear, and (2) voltage measurement variability among data analysts. These uncertainties have been quantified based on testing performed with nominal-size probes and are currently used by licensees in the prediction of the end-of-cycle (EOC) voltage distribution in the implementation of GL 95-05. Discuss how the smaller diameter bobbin coil eddy current probe differs from the nominal-sito probe with respect to the vol+ age response variability and the voltage measurement variability. Provide the quantitative basis for concludhg the current values of the mean and standard deviation for probe wear and analyst uncertainty are acceptable to use when predicting the EOC voltage distribution if some of the beginning of-cycle (BOC) voltage values were obtained using a smaller diameter bobbin coil eddy current probe.
2.
Oiscuss how other aspeca related to contrclling NDE uncertainty, such as the probe variability criteria and the noise criteria in the data analysis procedures, should be 3
modified from current practice to minimize these sources of NDE uncertainty.
PROBABILITY OF DETECTION (POD)
As a point of clarification, the staff notes the POD results are based on a comparisun with the nominal-size probe, not with metallurgical results. Thus, the statement that the smaller diameter probe POD meets or exceeds the Electric Power Research Institute's Appendix H requiremenM is not e.: curate because the accuracy of the nominal ' te probe is itself subject to uncensinty.
3.
To demonstrate a POD of at least 80% at a 90% confidence level, Southem Nuclear evaluated only indications confirmed with a rotating pancake coil (RPC). Provide the technical justification for not including indications that were either not RPC inspected or not RPC confirmed. Include a reevaluation of the POD performance of the smaller diameter probe using all indications, regardless of RPC results, voltage or classification (e.g., potential indications (Pis), unusual OD phase angle indications (UOAs), and indications not reportable (INRs)).
g 4.
- The staff noted that supporting data from the spring 1994 Cook, Unit 1, and Farley, Unit 1, inspection results were not discussed in the submittal. Reevaluate the POD performance of the smaller diameter probe using the data from all three plants.
REPORTING REQUIREMENTS Additional reporting requirements in the 90-Day Reports may be appropriate to provide confidence that if the use of a smaller diameter probe results in miscing or under sizing a number of indications and/or resu'ts in a nonconservative estimation of the NDE uncertainty models, that these conditions will be identified.
5.
Discuss the appropriateness of additional reporting requirements in the GL 95-50 90-day report such as the following: If any significant differences exist between the actual and the predicted EOC voltage distributions (e.g., number of indications, size of largest indications, distribution of indications, etc.), the root cause should be evaluated and reported to the NRC. The effects of using a smaller diameter probe should be explicitly considered in this evaluation. If use of a sma"Sr diameter probe is determined to be one of the factors for the difference, actions should be taken to prevent recurrence.
MISCELLANEOUS 6.
Referring to pays 6 of the report cubmitted November 10,1997, tne number of indications discussed in Section 4.0 that refer to Table 4 do not correspond with the number of indications listed in Table 4. Provide corrected text and/or a corrected Table 4.
7.
Provide the specific circumstances under which the smaller diameter probe would be employed 'or dispositioning tubes in accordance with GL 95-05. How many tubes and associated tube support plate intersections currently match those circumstances et Farley, Units 1 and 2?
8.
Provide Reference 1 of SG-97-01-002 for staff review.
1