ML071760168
| ML071760168 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 06/28/2007 |
| From: | Siva Lingam NRC/NRR/ADRO/DORL/LPLII-1 |
| To: | Christian D Virginia Electric & Power Co (VEPCO) |
| Lingam, Siva NRR/DORL 415-1564 | |
| References | |
| TAC MD4651, TAC MD4652 | |
| Download: ML071760168 (6) | |
Text
June 28, 2007 Mr. David A. Christian Senior Vice President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
SURRY POWER STATION, UNIT NOS. 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING THE STEAM GENERATOR TUBE INSERVICE INSPECTION REPORTS FOR THE 2006 REFUELING OUTAGE (TAC NOS. MD4651 AND MD4652)
Dear Mr. Christian:
By letters dated June 1, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML061520302), November 30, 2006 (ADAMS Accession Number ML063340555), and March 1, 2007 (ADAMS Accession Number ML070650263), Virginia Electric and Power Company (the licensee) submitted steam generator (SG) tube inspection results from the 2006 inspections at Surry Power Station, Unit Nos. 1 and 2. In addition to these reports, the Nuclear Regulatory Commission (NRC) staff summarized additional information concerning the 2006 SG tube inspections at Surry Power Station, Unit No.1 in a letter dated December 4, 2006 (ADAMS Accession Number ML063380371). The NRC staff is reviewing the submittal and has determined that additional information is required to complete its evaluation.
The NRC staffs RAI is enclosed. The licensee is requested to provide a response to the RAI within 30 days.
Sincerely,
/RA/
Siva P. Lingam, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-280 and 50-281
Enclosure:
RAI cc w/encl: See next page
June 28, 2007 Mr. David A. Christian Senior Vice President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
SURRY POWER STATION, UNIT NOS. 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING THE STEAM GENERATOR TUBE INSERVICE INSPECTION REPORTS FOR THE 2006 REFUELING OUTAGE (TAC NOS. MD4651 AND MD4652)
Dear Mr. Christian:
By letters dated June 1, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML061520302), November 30, 2006 (ADAMS Accession Number ML063340555), and March 1, 2007 (ADAMS Accession Number ML070650263), Virginia Electric and Power Company (the licensee) submitted steam generator (SG) tube inspection results from the 2006 inspections at Surry Power Station, Unit Nos. 1 and 2. In addition to these reports, the Nuclear Regulatory Commission (NRC) staff summarized additional information concerning the 2006 SG tube inspections at Surry Power Station, Unit No.1 in a letter dated December 4, 2006 (ADAMS Accession Number ML063380371). The NRC staff is reviewing the submittal and has determined that additional information is required to complete its evaluation.
The NRC staffs RAI is enclosed. The licensee is requested to provide a response to the RAI within 30 days.
Sincerely,
/RA/
Siva P. Lingam, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-280 and 50-281
Enclosure:
RAI cc w/encl: See next page DISTRIBUTION:
Public RidsAcrsAcnwMailCenter RidsOgcRp LPL2-1 R/F RidsNrrDciCsgb(AJohnson) RidsRgn2MailCenter(EGuthrie)
RidsNrrDorlLpl2-1(EMarinos) RidsNrrDciCsgb(LMiller)
RidsNrrDciCsgb(AHiser)
RidsNrrLAMOBrien(hard copy)
RidsNrrPMSLingam(hard copy)
ADAMS Accession No. ML071760168
- transmitted by memo dated. NRR-088 OFFICE NRR/LPL2-1/PM NRR/LPD2-1/LA NRR/DCI/CSGB/BC NRR/LPL2-1/BC NAME SLingam:nc MOBrien AHiser EMarinos DATE 06 / 28 /07 06 / 28 /07 6/19/07*
06 / 28 /07
Enclosure OFFICIAL RECORD COPY REQUEST FOR ADDITIONAL INFORMATION REGARDING STEAM GENERATOR TUBE INSERVICE INSPECTION REPORTS FOR THE 2006 REFUELING OUTAGE SURRY POWER STATION, UNIT NOS. 1 AND 2 DOCKET NOS. 50-280 AND 50-281 By letters dated June 1, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML061520302), November 30, 2006 (ADAMS Accession Number ML063340555), and March 1, 2007 (ADAMS Accession Number ML070650263), Virginia Electric and Power Company (the licensee) submitted steam generator (SG) tube inspection results from the 2006 inspections at Surry Power Station Unit Nos. 1 and 2 (Surry 1 and 2). In addition to these reports, the Nuclear Regulatory Commission (NRC) staff summarized additional information concerning the 2006 SG tube inspections at Surry Power Station, Unit No. 1 (Surry 1) in a letter dated December 4, 2006 (ADAMS Accession Number ML063380371).
After review of the documents listed above, the NRC staff has determined that the following additional information is required to complete the review.
1.
Please discuss any insights that have been gained regarding the denting phenomena at the 6th and 7th tube support plates for Surry 1 and 2. Please discuss whether the size of the dents is increasing with time.
2.
On Page 16 of Enclosure 1, the Figure 1 title references Examination Technique Specification Sheet (ETSS) 96810.1; however, the text on Page 14 references ETSS 96910.1. Please clarify which reference is correct.
3.
During the Surry 1 outage, there was extensive discussion concerning the in-situ pressure test of Tube Row 35 Column 68 in SG A. Please provide a copy of the leak rate and pressure versus time plot for this in-situ pressure test (for historical reference).
4.
On Pages 7 and 8 of Enclosure 1, Table 2 lists several tubes that had indications in 2001 that were not detected during the 2006 outage. Please provide any insight into this phenomenon and discuss any actions taken to confirm that the indications were not present in 2006. For Unit 2, there was one indication that was detected in 2002 but not reported in 2006. Please discuss whether the indication was still present (and not reportable per your guidelines) or whether there was no longer an indication at this location. If the latter is true, discuss any insights into why the indication is no longer present.
5.
Please discuss the extent to which the non-anti-vibration bar (AVB) volumetric indications in Surry 1 and 2 were detected with the bobbin coil. If all the indications werent detected by bobbin, discuss the basis for not performing 100% rotating probe examinations on both the hot-leg and cold-leg. If a turbo mix was used (e.g., near the top of the tubesheet), please discuss the extent to which the turbo mix identified the area with loose parts or loose parts damage.
6.
Figures 1 and 2 of Enclosure 1 and Figures 3 and 4 of Enclosure 2 to your March 1, 2007, letter provide condition monitoring curves for volumetric degradation (other than wear at the anti-vibration bars). It is the NRC staffs understanding that the curves in these figures include eddy current uncertainty. However, the differences in these curves are not significant despite the discussion in the text of the report that sizing of flaws using ETSS 21998.1 is very conservative for flaws greater than approximately 0.25-inch.
Although two data points supporting the over-estimation of flaw sizes using ETSS 21998.1 were provided in Enclosure 2 to your March 1, 2007, letter, please provide any additional data that supports your conclusion that ETSS 21998.1 is very conservative for flaws greater than approximately 0.25-inch in length. In addition, please provide your basis for concluding that ETSS 96910.1 is appropriate for sizing flaws greater than 0.25-inch (including a discussion of the uncertainties associated with sizing with this technique). Please discuss how the uncertainties vary with flaw size (axial length, circumferential extent, and depth).
The NRC staff notes that Figures 1 and 2 list the structurally significant length and depth. Although the use of the structurally significant length and depth is probably appropriate for assessing the structural integrity of the flaw, please confirm that the non-destructive examination uncertainties are also based on the structurally significant dimensions rather than the actual dimensions of the flaw (i.e., was the qualification data assessed using actual dimensions or structurally significant dimensions of the flaw). It may be useful to provide the actual flaw depth, the measured flaw depth, the actual structurally significant depth and length, and the measured structurally significant depth and length for the qualification samples. If any data exists that provides destructive examination results associated with flaws sized by both ETSS 21998.1 and ETSS 96910.1, such data may be useful in assessing the uncertainty associated with these techniques.
In addition to the above, please provide the size estimates for all volumetric flaws (other than wear at the anti-vibration bars) using ETSS 96910.1 and ETSS 21998.1.
7.
Cracking has been observed in units with thermally treated Alloy 600 tubes at the tube-ends near the tube-to-tubesheet welds. This includes cracking of the welds that penetrated into the parent tube. Please discuss the extent to which the tube end area (including the tack expansion and the parent tube near the tube-to-tubesheet weld) was examined during your inspections of Surry 1 and 2. If no inspections were performed, please discuss the basis for not examining this area.
8.
On Page 8 of Enclosure 2, the text states 60 bulges were identified in SG A of Surry 2.
Please discuss the cause of these bulges and the three bulges identified on Page 10 of for Surry 1.
9.
Please discuss the differences between an over-expansion (OXP) and a bulge (OXP within the tubesheet, over-expansion (OVR) above tubesheet). In addition, discuss the total population of OXPs and bulges (if bulges reported in the tubesheet region) in the hot leg of SGs A and C in Surry 1.
10.
What is the reporting threshold for an overexpansion, either OXP or OVR, at Surry 1 and 2?
11.
Please discuss whether the cracking that occurred in OXPs and bulges at other units were preferentially located in larger OXPs or bulges. If the cracking at these other units was not biased to the larger OXPs or bulges, and a significant number of OXPs or bulges were not inspected throughout the reported voltage range for these locations at Surry, discuss the potential that cracking could be occurring and summarize your tube integrity assessment for these uninspected locations.
12.
Please confirm no degradation was identified during your examination of the over-expansions (OVRs) in Surry 1.
13.
You indicated that you would continue to perform visual examinations of the plugs in the tube in Row 41 Column 27 of SG A and that these examinations would reveal whether significant tubesheet corrosion was occurring. Please discuss whether you plan to continue to monitor the channel head damage to confirm that the extent of corrosion is consistent with your expectations.
14.
Several pit-like indications were detected and not plugged during the 2006 outage at Surry 1. Please discuss your basis for leaving these indications in service. Include in your response the results from tube pulls that confirm the indications are pits and provide the eddy current sizing qualification data for pits. Please refer to the letter that the NRC sent to Mr. J. P. OHanlon on August 23, 1999.
15.
Please discuss whether the inspection data acquired for the permeability variation indications that were plugged was adequate to determine whether the area may have had a significant flaw. If not, please discuss how tube integrity was assessed at these locations (e.g., in-situ testing).
Surry Power Station, Units 1 & 2 cc:
Mr. David A. Christian Senior Vice President and Chief Nuclear Officer Virginia Electrical and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711 Ms. Lillian M. Cuoco, Esq.
Senior Counsel Dominion Resources Services, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, Connecticut 06385 Mr. Donald E. Jernigan Site Vice President Surry Power Station Virginia Electric and Power Company 5570 Hog Island Road Surry, Virginia 23883-0315 Senior Resident Inspector Surry Power Station U. S. Nuclear Regulatory Commission 5850 Hog Island Road Surry, Virginia 23883 Chairman Board of Supervisors of Surry County Surry County Courthouse Surry, Virginia 23683 Dr. W. T. Lough Virginia State Corporation Commission Division of Energy Regulation Post Office Box 1197 Richmond, Virginia 23218 Dr. Robert B. Stroube, MD, MPH State Health Commissioner Office of the Commissioner Virginia Department of Health Post Office Box 2448 Richmond, Virginia 23218 Office of the Attorney General Commonwealth of Virginia 900 East Main Street Richmond, Virginia 23219 Mr. Chris L. Funderburk, Director Nuclear Licensing & Operations Support Dominion Resources Services, Inc.
Innsbrook Technical Center 5000 Dominion Blvd.
Glen Allen, Virginia 23060-6711