ML022820328
| ML022820328 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 09/30/2002 |
| From: | Walker R TXU Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10010.1, 10CFR50.55a(g), CPSES # 200203398, GL-95-005, TXX-00055, TXX-01125, TXX-02172 | |
| Download: ML022820328 (4) | |
Text
t TXU TXU Energy Comanche Peak Steam Electric Station P.O Box 1002 (E01)
Glen Rose, TX 76043 Tel 254 897 8920 Fax. 254 897 6652 lance terry@txu.com C. Lance Terry Senior Vice President &
Principal Nuclear Officer Ref. # 10CFR50.55a(g)
GL 95-05 CPSES # 200203398 Log # TXX-02172 File#
10010.1 September 30, 2002 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
UNIT 1, DOCKET NO. 50-445, AMMENDMENT TO THE SUBMITTAL OF UNIT 1 SEVENTH AND EIGHTH REFUELING OUTAGE GL 95-05 REPORTS REF:
- 1)
TXU Energy letter logged TXX-00055 from C. L. Terry to the NRC dated May 2, 2000.
- 2)
TXU Energy letter logged TXX-01 125 from C. L. Terry to the NRC dated July 25, 2001.
Gentlemen; Via references 1 and 2, TXU Generation Company LP (TXU Energy) forwarded the 90-day reports pursuant to the guidance of Attachment 1 to Generic Letter (GL) 95 05; "Voltage-Based Repair Criteria for Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking." These reports provided justification for continued application of the voltage-based repair criteria for outside diameter stress corrosion crack (ODSCC) indications at support plate intersections.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway e Comanche Peak Diablo Canyon a Palo Verde
- South Texas Project Wolf Creek
'0
o TXU TXX-02172 Page 2 of 4 During Comanche Peak Steam Electric Station's sixth refueling outage for Unit 2 (2RF06), TXU Energy's vendor issued a Corrective Actions Process Issue Report which involved eddy current calibration standards. The issue identified only affected the Unit 1 steam generators due to their use of these eddy current calibration standards when implementing GL 95-05 [One Volt Alternate Repair Criteria].
The vendor's Corrective Actions Process Issue Report stated that during the fall of 1997, the vendor supplied ADVB eddy current standards to CPSES for use during its steam generator eddy current inspection. The drawings supplied with the standards have since been used in the conduct of 6 outages at Comanche Peak Steam Electric Station (CPSES) Units 1 and 2. Following the Unit 1 eighth refueling outage (IRF08), the standards were shipped to the vendor for storage. During preparations for the Unit 2 sixth refueling outage (2RF06), the vendor supplied a new set of drawings for all standards. During preparations for this refueling outage, the vendor's lead eddy current analyst discovered that the new drawings supplied did not have the same voltage values as the previous drawings supplied with the standards and used for the previous six refueling outages.
The voltage values at issue are used in the implementation of APC (alternate plugging criteria) examinations as a screening tool to determine tube to tube support plate intersections, which require either examination with other techniques or removal from service. Examinations of this type were conducted during the IRF07 and 1RF08 outages. The voltages on the revised as built drawings were higher than the values used during these two inspections. These drawings were revised after transfer of the standards to the customer, however the revised drawings were not then supplied to the customer.
A TXU Energy deficiency document (SmartForm) was issued for this inconsistency.
Immediate action was taken to evaluate the extent and impact of this inconsistency and to re-examine the highest voltage signals from the potentially affected outages with the latest vendor voltages. The result of this re-examination identified no new tube intersection indications above the voltage screening value. In addition, the vendor was requested to perform a separate detailed evaluation and provide the results to TXU Energy.
eTXU TXX-02172 Page 3 of 4 A summary of the evaluation performed by TXU Energy's vendor is as follows:
During 2RF06 it was determined that the voltage values attributed to the bobbin standards used in the end of cycle (EOC) -7 and EOC-8 NDE inspection of the CPSES Unitl steam generators need to be revised. As a result of the revisions, the EOC-7 and EOC-8 bobbin voltages of some of the top of tube support (TSP)
ODSCC indications increased by up to 7%. None of the indications had its' voltage increase from below to above the lower voltage repair limit (1 volt).
Due to this minor revision of the EOC-7 and EOC-8 bobbin voltages, the peak primary to secondary leak rate during a postulated steam line break (SLB) projected for the Cycle 9 operational assessment increased from 1.1 X 10-3 gpm to 1.5x10-3 gpm, which is well below the acceptance limit of 27.79 gpm. The corresponding peak conditional burst probability estimate changed from 4.7x 10-5 to 4.2x 105. This small decrease in burst probability, in spite of a small increase in the voltages, is an artifact of the different random number sequences used in the two Monte Carlo calculations. The peak SLB leak rate for the EOC-8 condition monitoring increased from 3.1 x 104 gpm to 4.3 x 10-4 gpm, while the conditional burst probability value remained the same (1.9x 10-5).
In summary, after revising the EOC-7 and EOC-8 bobbin voltages the peak leak rate and peak conditional burst probability projected for the EOC-8 condition monitoring and Cycle 9 operational assessment are still 3 or 4 orders of magnitude below their respective allowable limits This communication is for information only, and contains no new licensing basis commitments regarding CPSES Unit 1. If you have any questions, please contact Mr.
Obaid Bhatty at (254) 897-5839.
O TXU TXX-02172 Page 4 of 4 Sincerely, C. L. Terry By:
Rogki D. Walker Regulatory Affairs Manager OAB/oab cc:
E. W. Merschoff, Region IV W. D. Johnson, Region IV D. H. Jaffe, NRR Resident Inspectors, CPSES