ML050800381

Request for Additional Information, Steam Generator Tube Inspection Summary for the Fall 2003 Outage

ML050800381
Person / Time
Site:	Seabrook
Issue date:	03/21/2005
From:	Nerses V, Peschel J NRC/NRR/DLPM/LPD1
To:	Warner M Florida Power & Light Energy Seabrook
Nerses V, NRR//DLPM, 415-1484
References
TAC MC4907
Download: ML050800381 (4)

Text

March 21, 2005 Mr. Mark E. Warner, Site Vice President c/o James M. Peschel Seabrook Station FPL Energy Seabrook, LLC PO Box 300 Seabrook, NH 03874

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION, REGARDING SEABROOK STATION, UNIT NO. 1, STEAM GENERATOR TUBE INSPECTION

SUMMARY

FOR THE FALL 2003 OUTAGE (TAC NO. MC4907)

Dear Mr. Warner:

By letters dated November 3, 2003, and October 12, 2004, you submitted the fall 2003 refueling outage steam generator tube plugging and inspection summary reports for Seabrook Station, Unit No. 1, in accordance with the plants Technical Specifications. Additional information concerning this outage was summarized by the Nuclear Regulatory Commission staff in a letter dated December 29, 2003.

The staff reviewed the information you submitted and determined that additional information is required in order to complete the evaluation. The additional information requested is attached.

If you have any questions, please contact me at (301) 415-1484.

Sincerely,

/RA/

Victor Nerses, Senior Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-443

Enclosure:

As stated cc w/encl: See next page

ML050800381 OFFICE PDI-2/PM PDI-2/LA EMCB/SC PDI-2/SC NAME VNerses CRaynor ALund DRoberts DATE 3/15/05 3/15/05 02/10/2005 3/16/05 REQUEST FOR ADDITIONAL INFORMATION SEABROOK STATION, UNIT NO. 1, FALL 2003 REFUELING OUTAGE STEAM GENERATOR TUBE INSPECTION REPORT DOCKET NO. 50-443

1. The Technical Specifications for Seabrook Station, Unit No. 1 require that you provide the location and percentage of wall thickness for each indication of an imperfection.

Your October 12, 2004 submittal does not appear to provide this information for all indications of imperfections (e.g., wear at antivibration bars (AVBs)). If you have not supplied the location and through-wall percent of all imperfections, please provide this information.

2. On page 4 of your inservice inspection report, submitted October 12, 2004, you stated that based on inspection data from refueling outage 8 (RFO8), AVB wear was an active degradation mechanism in steam generators (SGs) A, B and D. Subsequently, on page 8 of the report you stated that prior to RFO9, AVB wear was classified as an active degradation mechanism in SG D and as an ongoing degradation mechanism in SGs A, B and C. Please clarify which SGs currently have active wear.

3. On page 7 of your inservice inspection report, you indicated that among the tubes in the critical area (tubes with absolute drift signals), seven indications were detected in three tubes. Subsequently, on page 8 of the same report, you indicated that nine indications were confirmed at seven tube support plate intersections in three of the six tubes in the defined critical area. Please clarify how many indications of outside diameter stress corrosion cracking at tube support plates were identified during your last inspection.

4. In Table 2 of your inservice inspection report, you indicated the number of possible loose parts (PLP) identified in the SGs. Subsequently, in Table 7 of the same report, you provided a more detailed analysis of the PLP indications. There seems to be a difference between the number of PLPs listed in Table 2 and the number of PLPs listed in Table 7. Please clarify the difference.

5. In Table 2 of your inservice inspection report, you provided the number of volumetric (VOL) indications identified in the SGs. Subsequently, on Table 6 of the same report, you provided a more detailed listing of the VOL indications. Not all the VOL indications reported in Table 2 appear to be listed in Table 6. For example, for SG A, you reported five VOL indications while on Table 6 you only listed four. Please clarify the discrepancy between the two tables. If there are more VOL indications than identified and discussed in Section 6.4 of your report, please discuss the nature and cause of the additional indications.

Enclosure

6. In Table 6 of your inservice inspection report, you indicated that for SG C, three new VOL indications were attributed to non-resident foreign objects. Please discuss how these new VOL indications were attributed to foreign objects.

7. On page 14 of the report, you indicate that the performance criterion for tube burst is 3774 pounds per square inch (psi). You then indicate that the predicted 90/50 burst pressure at 1022 effective full power days (EFPD) is 3778 psi. Presumably, the calculation was performed for 1022 EFPD since no tube inspections are planned for your next RFO. If no tube inspections are planned for your next RFO, please discuss the following. Given that your predicted burst pressure is close to the performance criterion, please provide a discussion of how this calculation was performed (e.g.,

growth rates, thresholds of detection, material property distributions, etc.) and the basis for your assumptions in the analysis. Given that all tubes are required to meet the performance criterion, please discuss your basis for selecting the 90/50 burst pressure versus a more conservative projection such as 95/95. If a 95/95 burst pressure was used, would the most limiting tube still meet the performance criterion?

8. On page 14 of the report, you indicated that wear is expected to continue in SG A due to the presence of a foreign object (presumably identified before RFO9). In addition, you indicate that a boundary zone was established by plugging all of the tubes adjacent to the tube experiencing wear. This boundary zone is intended to provide an adequate margin against potential damage propagation from the foreign object for continued operation for the life of the SG. Please discuss whether the tubes were stabilized and provide a summary of the analysis performed to reach the conclusion that this condition is acceptable for the life of the SG. For example, if continued tube wear is expected on the one tube next to the foreign object, it appears this tube could sever and then whip around unconstrained (if this tube is not stabilized). This whipping action could impact the adjacent tubes, which are plugged. If these latter tubes are not stabilized, it is not apparent why these tubes could not eventually sever and whip around and cause degradation to their neighboring tubes, which may not be plugged.

9. With respect to the bulge and overexpansion indications identified in SG D, please discuss whether these indications have changed and the reasons for any change.