ML043070440
| ML043070440 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 10/27/2004 |
| From: | Oatley D Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML043070440 (7) | |
Text
Pacific Gas and Electrc Company David H. Oatley Diablo Canyon Power Plant Vice President and PO. Box 56 General Manager Avila Beach. CA 93424 805.545.4350 October 27, 2004 Fax: 805.545.4234 PG&E Letter DCL-04-140 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike, Rockville, Maryland 20852 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 60-Day Response to Request for Information on Generic Letter 2004-01, "Requirements for Steam Generator Tube Inspections"
Dear Commissioners and Staff:
This letter is a response to the Nuclear Regulatory Commission's request for information pursuant to Generic Letter (GL) 2004-01, 'Requirements for Steam Generator Tube Inspections," dated August 30, 2004. GL 2004-01 requested licensees to submit a description of the steam generator tube inspections performed and an assessment of whether the inspections ensure compliance with the Technical Specifications requirements in conjunction with 10 CFR Part 50, Appendix B. contains the 60-day response by Pacific Gas and Electric Company to the requested information of GL 2004-01.
If you have any questions, or require additional information, please contact Stan Ketelsen at (805) 545-4720.
Sincerely, David H. Oatley A
member of the STARS (Strategic Teaming and Resource Sharing)
Alliance Callaway
- Comanche Peak.
Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
Document Control Desk PG&E Letter DCL-04-140 October 27, 2004 Page 2 kjse/4328 Enclosure cc:
Edgar Bailey, DHS David L. Proulx Diablo Distribution cc/enc: Bruce S. Mallett A member of the STARS (Strategic Teaming and Resource Sharing)
Atliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project.
Wolf Creek
PG&E Letter DCL-04-140 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of
)
PACIFIC GAS AND ELECTRIC COMPANY)
Diablo Canyon Power Plant
)
Units 1 and2
)
Docket No. 50-275 Facility Operating License No. DPR-80 Docket No. 50-323 Facility Operating License No. DPR-82 AFFIDAVIT David H. Oatley, of lawful age, first being duly sworn upon oath says that he is Vice President and General Manager - Diablo Canyon of Pacific Gas and Electric Company; that he has executed this response to the NRC Generic Letter 2004-01 on behalf of said company with full power and authority to do so; that he is familiar with the content thereof; and that the facts stated therein are true and correct to the best of his knowledge, information, and belief.
@~/g David H. Oatley Vice President and General Manager Subscribed and sworn to before me this 27th day of October 2004.
Notary Public County of San Luis Obispo State of California Commission d 1425m Notary Pubic-California X1 x Son Lub Obispo County M
MyComm. Expires Ai.2007 W
RO PG&E Letter DCL-04-140 Response to the Requested Information of NRC Generic Letter 2004-01 Below is Pacific Gas and Electric Company's (PG&E) 60-day response to NRC Generic Letter (GL) 2004-01, "Requirements for Steam Generator Tube Inspections," dated August 30, 2004.
NRC Request 1:
Addressees should provide a description of the SG tube inspections performed at their plant during the last inspection. In addition, if they are not using SG tube inspection methods whose capabilities are consistent with the NRC's position, addressees should provide an assessment of how the tube inspections performed at their plant meet the inspection requirements of the TS in conjunction with Criteria IX and Xl of 10 CFR Part 50, Appendix B, and corrective action taken in accordance with Appendix B, Criterion XVI. This assessment should also address whether the tube inspection practices are capable of detecting flaws of any type that may potentially be present along the length of the tube required to be inspected and that may exceed the applicable tube repair criteria.
PG&E Response:
Diablo Canyon Power Plant (DCPP) Units I and 2 each have four Westinghouse Model 51 steam generators (SGs). The tubing material in each of the SGs is Inconel Alloy 600 mill annealed. The tubes are explosively expanded into the tube sheet using the Westinghouse explosive expansion process (WEXTEX).
Table 1 provides a description of the SG tube inspections performed at DCPP Units 1 and 2 during the last refueling outages, Unit 1 refueling outage twelve (1R12) in April 2004, and Unit 2 refueling outage eleven (2R1 1) in March 2003. Prior to each inspection, a degradation assessment, which includes operating experience, is performed to identify degradation mechanisms that may be present, and a technique validation assessment is performed to verify that the eddy current techniques are capable of detecting the degradation. For each tube location where degradation may be present, Table 1 includes the type of probe used for the inspection and the inspection scope.
DCPP Units 1 and 2 apply three different alternate repair criteria (ARC) that have been reviewed and approved by the NRC: voltage-based ARC for axial outside diameter stress corrosion cracking at tube support plates (TSPs), per GL 95-05; primary water stress corrosion cracking (PWSCC) ARC for axial PWSCC at dented TSPs, per WCAP-1 5573, Revision 1; and W* ARC for axial PWSCC in the WEXTEX tubesheet region, per WCAP-14797, Revision 1. Many of the SG tube inspection requirements applied at DCPP Units 1 and 2 are the result of NRC commitments and Technical Specification requirements that implement the ARC.
PG&E Letter DCL-04-140 A complete description of the 2R1 1 and 1 R1 2 inspections, including the inspection results, are provided in PG&E Letters DCL-03-076, dated June 23, 2003 (2R1 1 90-day report), and DCL-04-112, dated September 7, 2004 (1 R12 90-day report). These 90-day reports provide the detailed condition monitoring and operational assessment for all ARC and non-ARC degradation mechanisms.
The DCPP Units 1 and 2 SG tube inspection methods are consistent with the NRC's position regarding SG tube inspections. Therefore, the remainder of the requested information in NRC Request 1 is not applicable.
NRC Request 2:
If addressees conclude that full compliance with the TS in conjunction with Criteria IX, Xl and XVI of 10 CFR Part 50, Appendix B, requires corrective actions, they should discuss their proposed corrective actions (e.g., changing inspection practices consistent with the NRC's position or submitting a TS amendment request with the associated safety basis for limiting the inspections) to achieve full compliance. If addressees choose to change their TS, the staff has included in the attachment suggested changes to the TS definitions for a tube inspection and for plugging limits to show what may be acceptable to the staff in cases where the tubes are expanded for the full depth of the tubesheet and where the extent of the inspection in the tubesheet region is limited.
PG&E Response:
The SG tube inspections performed at DCPP Units 1 and 2 are consistent with the NRC's position regarding SG tube inspections. Therefore, NRC Request 2 is not applicable and a response is not required.
NRC Question 3:
For plants where SG tube inspections have not been or are not being performed consistent with the NRC's position on the requirements in the TS in conjunction with Criteria IX, Xl, and XVI of 10 CFR Part 50, Appendix B, the licensee should submit a safety assessment (i.e., a justification for continued operation based on maintaining tube structural and leakage integrity) that addresses any differences between the licensee's inspection practices and those called for by the NRC's position. Safety assessments should be submitted for all areas of the tube required to be inspected by the TS where flaws have the potential to exist and inspection techniques capable of detecting these flaws are not being used, and should include the basis for not employing such inspection techniques. The assessment should include an evaluation of (1) whether the inspection practices rely on an acceptance standard (e.g., cracks located at least a minimum distance of x below the top of the tube sheet, even if these cracks cause complete severance of the tube) which is different from the TS acceptance standards (i.e., the tube plugging limits or repair criteria), and (2) whether the safety assessment constitutes a change to the "method of evaluation" (as defined in 10 CFR 50.59) for establishing the structural and leakage integrity of the joint. If the PG&E Letter DCL-04-140 safety assessment constitutes a change to the method of evaluation under 10 CFR 50.59, the licensee should determine whether a license amendment is necessary pursuant to that regulation.
PG&E Response:
The SG tube inspections performed at DCPP Units I and 2 are consistent with the NRC's position regarding SG tube inspections. Therefore, NRC Request 3 is not applicable and a response is not required.
PG&E Letter DCL-04-140 Table 1 Summary of DCPP Unit I and Unit 2 SG Inspections Performed in 1R12 and 2R11 Item Area of SG Bundle Probe IR12 Inspection Scope 2R11 Inspection Scope
- 1.
Full Length of tubing Bobbin 100% (Except Rows 1 and 2 U-bends) 100% (Except Rows 1 and 2 U-bends) 100% of hot leg TTS, all SGs 100% of hot leg TTS, all SGs WEXTEX top of 100% of repeat W ARC tubes 100% of repeat W ARC tubes
- 2.
tubesheet (TTS)
+PoinP Minimum inspection extent: TTS +2 inch to TTS SG 2-4: 100% of cold leg TTS region
-8.5 Inch SG 2-1, 2-2, 2-3: 20% of cold leg TTS Minimum inspection extent: TTS +2 inch to TTS
-8.5 Inch Hot leg deplugged
+PointTM 100%
Not applicable tube ends Inspection extent: tube end hot +4 Inch Low Row U-bends
+PoinTM 100%
100%
4._____
(Rows 1 and 2)
High Row U-bends
.oTM 100% of Rows 3 to 10 100% of Rows 3 to 46
- 5.
(Rows 3 and higher) 20% of Rows 13 to 17 Repeat PWSCC ARC 100%
100%
- 6.
indications at dented
+Point' TSP SG 1-1: 100% 1H to 4H; 20% 5H to 7H 100%
2:5 olt V)
DntedSG 1-2: 1 00% 18H to 7G. 20% 6C
- 7.
5 Volt (
Dented
+PointTM SG 1-3: 20% 1 H to 7H SG 1-4: 100% 1H to 6H; 20% 7H (Note 1)
SG 1-1: 100% 1H to 4H; 20% 5H SG 2-1: 20% 1H SG 1-2: 100% IH to 7C; 20% 6C SG 2-2: 100% IH to 5H; 20% 6H
- 8.
>2Vand <5V
+PointTh SG 1-3: 20% 1 H SG 2-3: 100% 1 H to 3H, 20% 4H Dented TSP SG 1-4: 100% 1H to 6H; 20% 7H SG 2-4: 100% 1H to 38; 20% 4H (Note 1)
(Note 1) 100% of DIS 100% of DIS
- 9.
<2 V Dented TSP
+PointTr SG 1-1: 100% of dents >0.21 V at 18. 20% of dents >0.21V at 2H (Note 1) 100% of DOS at dented TSP 100% of DOS at dented TSP
- 10.
+PointTm 100% of >1.7 V DOS 100% of >1 V DOS
.SG 1-1. 1-2: 100% of DOS >1.4 V and <1.7 V SG 2-1: 100% of DOS 100% of DOS in ARC exclusions zones 100% of DOS in ARC exclusions zones
- 11.
SPR
+Poini*
100% of hot leg TSP with >2.3 V SPR 100% of hot leg TSP with >2.3 V SPR
- 11.
_Minimum of 5 largest hot leg SPR per SG Minimum of 5 largest hot leg SPR per SG TSP l et 100% of baseline indications (LIC and LIG) 100% of baseline indications (LIC and LIG)
- 12.
T dicgament
+Pointm 100% of new SLC 100% of new SLC indicatons100%
of SLC with DIS or DOS 100% of SLC with DIS or DOS 100% of Z5 V free span dings 100% of Z5 V free span dings
- 13.
Free span dings
+Pointm 100% of 22 V free span dings in U-bend that are 100% of free span dings In U-bend coincident with AVB location
- 14.
Free span bobbin
+Pointm 100% that are new or exhibit growth or change 100% that are new or exhibit growth or change
- 1.
indications_____
- 15.
New % calls at cold
+Pointfm 100%
100%
leg T S P Bobbin 100% bobbin 100% bobbin
- 16.
Loose parts
+Pointf*m 100% +Pointfm of PLP location plus surrounding 100% +Pointm of PLP location plus surrounding I
I tube locations tube locations Notes:
- 1. For any 20 precent dent samples, a minimum of 50 dents were Inspected. If the population of dents at that TSP elevation is less than 50, then 100 percent of dents at that TSP were Inspected.
Indication codes:
DOS - distorted outside diameter support plate bobbin signal DIS - distorted inside diameter support plate bobbin signal at a dented TSP intersection SLC - suspected TSP ligament cracking bobbin signal LIC - TSP ligament crack +PointThl signal LIG - TSP ligament gap +Pointm signal SPR - support plate mixed residual bobbin signal PLP - possible loose part signal