ML16342E141
| ML16342E141 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 06/23/1998 |
| From: | Steven Bloom NRC (Affiliation Not Assigned) |
| To: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| References | |
| TAC-M98283, TAC-M98284, NUDOCS 9806240149 | |
| Download: ML16342E141 (6) | |
Text
June 23, 1998 It
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Mr. Gregory M. Rueger,'Senior Vice President and General Manager'acific Gas and Electric Company NPG - Mail Code A10D P. O. Box770000 San Francisco, California 94177
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SUBJECT:
REQUEST FOR ADDITIONALINFORMATION-PROPOSED W* STEAM GENERATOR TUBE REPAIR CRITERIA (TAC NOS. M98283 AND M98284)
Dear Mr. Rueger:
The NRC staff has reviewed your response to its recent request for additional information (RAI) dated March 13, 1998, relating to the proposed W*steam generator tube repair criteria. Based on this review we have developed an additional set of questions as enclosed.
Please provide a response to this RAI within 60 days of receipt of this letter.
Sincerely, Original Signed By Steven D. Bloom, Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos. 50-275 and 50-323
Enclosure:
Request for Additional Information cc w/encl: See next page DOCUMENT NAME:DC98283. RAI Docket Files 1
PUBLIC PDIV-2 Reading EGA1 WBateman SBloom EPeyton ACRS OGC KPerkins, RIV WCFO PGwynn, RIV RWessman
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'D To receive a copy of this document, indicate in the box: "C" = Copy without enctosures "E" = Copy with enctosures "N"= No copy OFFICE NAME DATE PM/PDIV-SBloom r 06iQ98'AIP DIV-2 EPeyton 06&a]98 OFFICIALRECORD COPY 980b240'f49
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Mr. Gregory M.Rueger'2-June 23, 1998 cc w/encl:
NRC Resident Inspector Diablo Canyon Nuclear Power Plant cjo U.S. Nuclear Regulatory Commission P. O. Box 369 Avita Beach, California 93424 Dr. Richard Ferguson, Energy Chair Sierra Club California 1100 11th Street, Suite 311 Sacramento, California 95814 Ms. Nancy Culver San Luis Obispo Mothers for Peace P. O. Box 164 Pismo Beach, California 93448 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, California 93408 Mr. Truman Burns Mr. Robert Kinosian California Public Utilities Commission 505 Van Ness, Room 4102 San Francisco, California 94102 Mr. Steve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94232 Diablo Canyon Independent Safety Committee
'ATTN: Robert R. Wellington, Esq.
Legal Counsel 857 Cass Street, Suite D Monterey, California 93940 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Christopher J. Warner, Esq.
Pacific Gas & Electric Company
. Post Office Box 7442;
'an Francisco, California 94120 Mr. Robert P. Powers Vice President and Plant Manager Diablo Canyon Nuclear Power Plant P. O. Box 56 Avila Beach, California 93424 Telegram-Tribune ATTN: Managing Editor 1321 Johnson Avenue P.O. Box 112 San Luis Obispo, California 93406
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The response to the staffs request for additional Information dated January 6, 1998, does not appear to respond to the question which the NRC staff had intended on having resolved.
It was noted in that letter that equation 4.4-7 in WCAP-14797 does not account for a contraction of the tube by the poisson effect due to tube end loading. This phenomenon will reduce the radial contact pressure between the tube and the,,
tubesheet.
Since the expression for radial contact pressure is used extensively throughout WCAP-14797, discuss the net result of tube radial contraction on the W*
leak rate analysis.
Discuss whether steam generator tube denting has been observed (based on eddy current and tube pulls) in the top of tubesheet area.
Ifdenting has been identified, describe the extent (i.e., severity and number of tubes affected) of the denting.
Alternate repair criteria permitting steam generator tube flaws to remain in service increases the potential for leakage through degraded tubes. The possibility exists that, in a loss of coolant accident (LOCA), secondary coolant could enter into the primary system.
Discuss the impact of secondary-to-primary leakage from in service W*tubes during postulated LOCAevents.
The data plotted in Figure 6.4-2 of WCAP-14797 suggests a nonnormal distribution as indicated by the plot of residuals in Figure 6.5-3. Provide the correlation coefficient for the data plotted in Figure 6.&4. Also, the calculated loss coefficients for each specimen listed in Table 6.2-3.
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