3F0705-02, Response to Request for Additional Information (RAI) Regarding the Crystal River Unit 3, 60 - Day Response to Generic Letter 2004-01, Requirements for Steam Generator Tube Inspections
| ML051940269 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 07/08/2005 |
| From: | Roderick D Progress Energy Florida |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 3F0705-02, GL-04-001 | |
| Download: ML051940269 (10) | |
Text
a Progress Energy Crystal River Nuclear Plant Docket No. 50-302 Operating License No. DPR-72 Ref. 10 CFR 50.54(f)
Jul y 8, 2005*
3F0705-02 U.S. Nuclear Regulatory Commission Attn: Document Control Desk 11555 Rockville Pike Rockville, MD 20852
Subject:
Crystal River Unit 3 -
Response to Request for Additional Information (RAI)
Regarding the Crystal River Unit 3, 60-Day Response to Generic Letter 2004-01, "Requirements for Steam Generator Tube Inspections"
References:
- 1. PEF to NRC letter dated October 27, 2004, Crystal River Unit 3, 60-Day Response to Generic Letter 2004-01, "Requirements for Steam Generator Tube Inspections"
- 2. NRC letter dated August 30, 2004, Generic Letter 2004-01, "Requirements for Steam Generator Tube Inspections"
Dear Sir:
Pursuant to 10 CFR 50.54(f), Florida Power Corporation, doing business as Progress Energy Florida, Inc. (PEF), hereby submits the Crystal River Unit 3 (CR3) response to the NRC Request for Additional Information (RAI) regarding the 60-Day response to NRC Generic Letter (GL) 2004-01. The RAI was provided to CR3 via electronic mail and was discussed with the NRC staff on June 3, 2005. The attachment to this letter provides the information requested in the RAI.
CR3 concludes that the inspection techniques applied during the previous Once-Through Steam Generator Tube Inspection, performed in October 2003, met the inspection requirements of the CR3 Improved Technical Specifications, 10 CFR 50, Appendix B requirements and the NRC position provided in the GL.
This letter establishes no new regulatory commitments.
If you have any questions regarding this submittal, please contact Mr. Sid Powell, Supervisor, L'
- ng and Regulatory Programs at (352) 563-4883.
Director Site Operations Crystal River Nuclear Plant DLRIlvc
Attachment:
Response to Request for Additional Information (RAI) Regarding the Crystal River Unit 3, 60-Day Response to Generic Letter 2004-01, "Requirements for Steam Generator Tube Inspections" xc:
NRR Project Manager Regional Administrator, Region II Senior Resident Inspector Progress Energy Florida, Inc.
Crystal River Nuclear Plant 15760 W. Powerline Street Crystal River, FL 34428
U. S. Nuclear Regulatory Commission Page 2 of 2 3F0705-02 STATE OF FLORIDA COUNTY OF CITRUS Daniel L. Roderick states that he is the Director Site Operations, Crystal River Nuclear Plant for Florida Power Corporation, doing business as Progress Energy Florida, Inc.; that he is.
authorized on the part of said company to sign and file with the Nuclear Regulatory Commission the information attached hereto; and that all such statements made and matters set forth therein are true and correct to the best of his knowledge, in n, and belief.
Daniel L. Roderick Director Site Operations Crystal River Nuclear Plant The foregoing document was acknowledged before me this day of 4_
, 2005, by Daniel L. Rooderick Signature of Notary Public State of 'hp3' MY COMMISSION I DO 4085 10 a
EXPIRES: July 8, i (Print, type, or stamp Commissioned Name of Notary Public)
Personally Produced Known
-OR-Identification_
FLORIDA POWER CORPORATION CRYSTAL RIVER UNIT 3 DOCKET NUMBER 50-302/LICENSE NUMBER DPR-72 ATTACHMENT Response to Request for Additional Information (RAI) Regarding the Crystal River Unit 3, 60-Day Response to Generic Letter 2004-01, "Requirements for Steam Generator Tube Inspections"
U. S. Nuclear Regulatory Commission Attachment 3F0705-02 Page I of 7 NRC Ouestion Part 1 By letter dated October. 27, 2004, (ML043060425) Progress Energy, submitted a response for Florida Power Corporation, the licensee of Crystal River Unit 3, regarding Generic Letter (GL) 2004-01, "Requirements For Steam Generator Tube Inspection." The staff has reviewed the letter and has determined that additional information is needed in order for the staff to complete a review.
Responses to the following questions are requested:
Your response to GL 2004-01 indicated that the Crystal River Unit 3 steam generator tube inspection approach/methods are in full compliance with the NRC position provided in the GL You stated that the examination of the lower tubesheet (LTS) crevice area, outside of the kidney region (sludge pile) and below LTS-8 inches in the kidney region was performed with a technique that did not meet all Appendix H requirements. You also stated that the bobbin coil probe is acceptable to detect the expected degradation mechanism in the LTS crevice region (e.g., intergranular attack (IGA)). Please provide the basis for this statement considering that other plants with similar design steam generators have stated tubes in the kidney region require the use of rotating coil for better detection of IGA due to sludge build up in the upper portion of the tubesheet crevice.
Response
The inspection techniques, scope, and extent of examination in the lower tubesheet (LTS) area are essentially identical to the other Once-Through Steam Generator (OTSG) plants. Crystal River Unit 3 (CR3) participates in industry forums, such as Electric Power Research Institute (EPRI) Steam Generator Management Project and the Babcock & Wilcox (B&W) Owners Group, to ensure the examinations performed at CR3 are consistent with those performed at other plants and meet the industry guidance.
Although the specific EPRI technique qualification applicability for the bobbin coil examination in the LTS was insufficient to meet EPRI PWR Steam Generator Examination Guidelines, Revision 6,
[EPRI Guidelines], Appendix H, the basis for the CR3 Generic Letter (GL) 2004-01 response is that the bobbin coil technique used at CR3 in the LTS is qualified for use at CR3 in accordance with industry guidelines for site-validation for detection of axial intergranular attack (IGA) in OTSG tubing. Detection of this type of degradation has been demonstrated using actual OTSG tube flaws and the technique was validated in accordance with the EPRI Guidelines, Section 6.2.4 and documented in the CR3 vendor report 51-5005589-02.
The expected degradation mechanism in the lower tubesheet region outside of the sludge pile region is Volumetric Outside-Diameter Intergranular Attack (ODIGA).
ODIGA is three-dimensional intergranular corrosion (IGC) initiating at the grain boundaries on the outside of the tube with no stress corrosion crack-like characteristics.
ODIGA can occur in isolated patches or at multiple initiation sites encompassing a given area. Typically, the width of the corrosion will be equal to or greater than the depth of the corrosion when classified as IGA. In some cases, localized fingers of grain boundary attack may extend below a layer of general IGA.
U. S. Nuclear Regulatory Commission Attachment 3F0705-02 Page 2 of 7 Site-validated technique application evaluation, as documented in the CR3 vendor report 51-5005589-02, has determined that the bobbin coil technique is acceptable to detect the expected degradation mechanism in the lower tubesheet. EPRI Guidelines, Appendix H qualifications for EPRI Specific Technique Sheet (ETSS) 96007.1, 96008.1, aind 96009.1 document bobbin probe technique qualifications for similar degradation which has been used to demonstrate equivalence.
ETSS 96007.1 is qualified for the detection of IGA/Outside Diameter (OD) Stress Corrosion Cracking (SCC) at non-dented drilled tube support plates.
ETSS 96008.1 is qualified for the detection and sizing of axial IGA/ODSCC at non-dented egg-crate supports and/or the sludge pile region. The ETSS 96009.1 technique meets the requirements of Appendix H for detection of IGA in OTSG upper tubesheet crevice regions using a 400/200 kHz differential mix. The site-validated techniques implement the recommendations of the EPRI Steam Generator Examination Guidelines relating to calibration standards, voltage normalization, scanning procedures, sample rates and data analysis methodologies. The EPRI Steam Generator Examination Guidelines define the essential variables for eddy current examination techniques.
These variables were used as the basis for determining equivalence to the site qualification. A comparison of each technique was made using these variables and a matrix developed which records the essentials of both the industry and site qualification.
However, the bobbin coil examination alone is not considered sufficient to provide the defense in depth desired for detecting the onset of tube degradation within the LTS. CR3 performs a 34%
+PointTm probe examination of a defined "kidney region" each refueling inspection which consists of approximately 6040 tubes in OTSG-A, and 4080 tubes in OTSG-B. The "kidney region" bounds the (persistent) sludge/denting region in the CR3 OTSGs.
Volumetric IGA has been confirmed at CR3 in the open tube span between the LTS and the first tube support plate (OlS).
The data comparison was based on indications from CR3 and confirmed degradation from OTSG plants.
Initial detection of degradation in the LTS, surface of origin determination and morphology determination is made with bobbin probe (Techniques 96007.1, 96008.1, 96009.1, Framatome Qualification Reports 77-1258722-00 and 77-5002925-05).
Confirmation and indication characterization is performed with a mid-frequency +PointTm probe (Technique 21409.1) and.115 Pancake rotating coil (Techniques 21401.1 and 21402.1).
The morphology of volumetric ODIGA is essentially the same for all the OTSG plants.
The characteristic "thumbnail" profile, lack of significant corrosion of the base material and minimal pitting in the affected area have been present regardless of location or elevation within the OTSG.
Variations in the chemistry of the deposits and corrosion films at the various plants do not seem to affect the shapes and characteristics of the ODIGA.
IGA has been detected in the upper spans and within the upper tubesheet (UTS) crevice in OTSGs.
This has been attributed to corrosion products transporting up the lane and wedge region into the upper tubesheet crevice. This form of IGA is OD initiated and displays a volumetric morphology with rotating techniques. Pit-like IGA has been confirmed in the first span and lower tubesheet of OTSGs. This form of IGA is OD initiated and displays a volumetric morphology with rotating techniques. IGA/SCC has been confirmed in the sludge pile on the lower tubesheet of the OTSGs.
These indications are characterized as axial with rotating techniques.
U. S. Nuclear Regulatory Commission Attachment 3F0705-02 Page 3 of 7 The 100% bobbin coil examination is the primary detection method for IGA or ODSCC within the CR3 OTSG LTS. The extent of this examination is larger than the 20% sample recommended by the EPRI Guidelines for a non-active damage mechanism. Appenilik A of the EPRI Guidelines supports that the 100% bobbin coil examination, even with a reduced probability of detection, is more likely to detect a degraded tube condition than a 20% sample with a high probability of detection.
U. S. Nuclear Regulatory Commission 3F0705-02 Attachmcnt Page 4 of 7 NRC Ouestion Part 2 In addition, for each indication within the sludge pile and in other areas of the lower tubesheet (excluding tube end cracking), provide a summary that includes the indication's location, the nature of the indication (IGA, stress corrosion cracking, etc.), the indication's severity (length and depth), and whether the indication was detected by bobbin coil inspection, rotating probe inspection, or both.
Discuss whether rotating probe inspections detected indications that were not detected by the bobbin coil probe and if so, the implications of this finding.
Response
Outage (year)
SIG RPC Bobbin Circ Axial Row Tube Volts Degree Indication Inches Inches Location Volts Degree Indication Location 11R(1999)
A 43 63 0.14 78 SCI 0.23 N/A LTS
-0.27 11.15 185 DNT LTS
-0.27 11R (1999)
A 44 64 0.28 105 MCI 0.36 N/A LTS
-0.20 9.18 186 DNT LTS
-0.22.
11R (1999)
A 45 54 0.29 121 SCI 0.33 N/A LTS
-0.20 7.55 180 DNT LTS
+0.00 11R (1999)
A 45 55 0.18 90 SCI 0.24 N/A LTS
-0.17 6.34 186 DNT LTS
-0.19 11R (1999)
A 46 62 0.19 82 SCI 0.31 N/A LTS
-0.18 5.43 186 DNT LTS
-0.28:
11R (1999)
A 48 54 0.24 97 SCI 0.71 N/A LTS
-0.29 5.65 190 DNT LTS
+0.00 11R (1999)
A 49 62 0.29 113 SCI 0.35 N/A LTS
-0.25 9.18 184 DNT LTS
-0.14 11R (1999)
A 54 89 0.25 116 SCI 0.60 N/A LTS
-0.42 20.05 181 DNT -,
LTS
-0.15 11R (1999)
A 55 89 0.21 118 SCI 0.18 N/A LTS
-0.58 14.86 184 DNT LTS
-0.15 11R (1999)
A 56 89 0.39 104 SCI 0.24 N/A LTS
- 0.43 13.62 182 DNT LTS
-0.15 11R (1999)
A 58 90 0.26 104 SCI 0.30 N/A LTS
-0.31 12.10 182 DNT LTS
-0.24 11R (1999)
A 58 92 0.46 102 SCI 0.39 N/A LTS
.0.47 16.88 183 DNT LTS
-0.26 11R (1999)
A 59 89 0.17 115 SVI 0.18 0.20 LTS 1.66 Note1
- Note1
- Note1
- Note1 11R (1999)
A 59 89 0.20 71 SVI 0.26 0.12 LTS 5.33 0.31 59 NQI LTS 5.38 11R(1999)
A 103 49 0.24 91 SCI 0.57 N/A LTS
-0.26 13.13 185 DNT LTS
-0.19 11R (1999)
A 104 46 0.53 118 MCI 0.45 N/A LTS
-0.37 17.48 184 DNT LTS
-0.46 11R (1999)
A 104 52 1.37 86 SCI 0.45 N/A LTS
-0.58 6.33 189 DNT LTS
-0.45 11R (1999)
A 105 47 0.10 94 SCI 0.42 N/A LTS
-0.23 11.33 182 DNT LTS
-0.29 11R (1999)
A 105 48 0.33 101 SCI 0.39 N/A LTS
-0.28 13.27 181 DNT LTS
-0.21 11R (1999)
A 105 51 0.26 99 MCI 0.81 N/A LTS
-0.21 10.10 185 DNT LTS
-0.23 11R (1999)
A 106 51 0.60 106 SCI 0.42 N/A LTS
-0.26 13.88 186 DNT LTS
-0.19 1R (1999)
A 106 52 1.07 108 SCI 0.42 N/A LTS
-0.25 8.62 185 DNT LTS
-0.29 11R(1999)
A 107 53 0.50 121 SCI 0.57 N/A LTS
-0.22 4.65 193 DNT LTS
-0.36 11R(1999)
A 107 55 0.13 104 SCI 0.26 N/A LTS
-0.28 12.74 185 DNT LTS
-0.36
U. S. Nuclear Regulatory Commission 3F0705-02 Attachment Page 5 of 7 Outage (year)
SiG RPC Bobbin Circ Axial Row Tube Volts Degree Indication Inches Inches Location Volts Degree Indication Location 11R (1999)
A 107 60 0.12 85 SCI 0.18 N/A LTS
-0.16 7.93 180 DNT LTS
-0.19 11R (1999)
A 108 49 0.81 87 SCI 0.27 N/A LTS
-0.20 23.59 182 DNT LTS
-0.23 11R (1999)
A 108 54 0.23 106 MCI 0.26 N/A LTS
-0.31 6.70 188 DNT LTS
-0.34 11R (1999)
A 108 55 0.27 106 SCI 0.49 N/A LTS
-0.20 6.65 185 DNT LTS
-0.33 11 R (1999)
A 109 48 0.39 92 Sc, 0.59 N/A LTS
-0.25 20.12 183 DNT LTS
-0.25 11R (1999)
A 109 51 0.37 107 SCI 0.34 N/A LTS
-0.25 18.85 185 DNT LTS
-0.17 11R (1999)
A 109 52 0.30 115 SCI 0.47 N/A LTS
-0.23 13.62 185 DNT LTS
-0.32 11R (1999)
A 109 54 0.18 89 MCI 0.34 N/A LTS
-0.29 10.92 182 DNT LTS
-0.26 11R (1999)
A 109 58 0.28 79 SCI 0.26 N/A LTS
-0.25 16.75 184 DNT LTS
-0.32 11R (1999)
A 110 57 0.20 83 SCI 0.24 N/A LTS
-0.39 18.46 183 DNT LTS
-0.26 11R (1999)
A 111 54 0.30 101 SCI 1.86 N/A LTS
-0.20 18.23 185 DNT LTS
-0.19 11R (1999)
A 112 66 0.35 89 SCI 0.37 N/A LTS
-0.39 5.83 189 DNT LTS
-0.15 11R (1999)
A 113 66 0.46 100 SCI 0.56 N/A LTS
-0.55 4.33 187 DNT LTS
-0.13 12R (2001)
A 79 84 0.14 125 SVI 0.25 0.19 LTS
+1.16 0.15 87 NQI LTS
+1.12 13R (2003)
B 46 2
0.47 59 SVI 0.38 0.23 LTS
+0.00 0.54 93 NQI LTS
+0.00 13R (2003)
B 78 67 0.59 7
SVI 0.24 0.17 LTE
+0.95
'Lower Roll Transition Area 13R (2003)
B 81 74 1.05 10 SVI 0.30 0.25 LTE
+1.03
- Lower Roll Transition Area 13R (2003)
B 85 62 0.98 22 SVI 0.29 0.38 LTE
+1.11
- Lower Roll Transition Area SCI = Single Circumferential Indication (typically SCC)
MCI = Multiple Circumferential Indication (typically SCC)
SVI = Single Volumetric Indication (typically IGA)
DNT = Dent Indication NQI = Non-Quantifiable Indication with the Bobbin Coil LTS = Lower Tubesheet Secondary Face LTE = Lower Tube End
- Note 1: This indication was first recorded with the rotating coil, and as such, was not re-recorded for the bobbin coil examination. The indication can be seen on the raw bobbin coil data and would meet the recording guidelines if the indication was not previously identified.
- The bobbin coil is not qualified to detect indications in roll transition areas, such as the three indications in the OTSG-B lower roll transition area. Typically degradation in the roll transition areas is detected using rotating coil techniques.
The indications were initially identified with the bobbin coil and confirmed with the rotating coil. The techniques are not qualified to measure depth of IGA or SCC. Therefore, no depth measurements are provided.
U. S. Nuclear Regulatory Commission Attachment 3F0705-02 Page 6 of 7 NRC Ouestion Part 3 Discuss your future plans for qualifying the inspection technique for the area outside the kidney region and below LTS-8 inches in the kidney region to industry standards (e.g.,
Appendix H).
Response
CR3 has no plans to further qualify the bobbin coil technique since it already meets the industry guidelines for qualification and site-validation. The probability of detection (POD) for bobbin coil is acceptable to detect expected degradation mechanisms in the LTS crevice region. The equivalency evaluation performed for a similarly designed plant documented the ability of the bobbin coil to identify flaws outside the sludge pile region. During the development of ETSS 96009 and ETSS 96011, signals from the lower crevice were compared with those from the upper crevice, which showed little difference in noise levels. There was little difference in the indication responses from the EPRI qualification IGA eddy current indications compared to IGA indications at CR3.
Additionally, the eddy current signal response in the LTS outside the sludge pile is comparable to the eddy current signal in the UTS. Due to the high cross flow at the top of the tubesheet, very little sludge accumulates. Sludge deposits will become trapped in the LTS crevice region, just as there are deposits in the UTS crevice region carried over by the steam flow. Based on the similarity of the upper and lower crevice geometry and signal quality, the technique is site-validated for both the upper and lower crevices outside the dented/sludge pile region. Per ETSS X96009.1 and #96011.1, this was acceptable since the damage mechanism morphology and extraneous test variables were essentially the same at both locations.
The bobbin coil has been proven to detect ODIGA in the LTS, however, the bobbin technique is not a qualified technique for detecting Primary Water Stress Corrosion Cracking (PWSCC) in the crevice region because the bobbin coil sensitivity is influenced by the defect orientation, sludge, or deformation in the dented region of the tube. Therefore, a Motorized Rotating Pancake Coil (MRPC) examination is performed at the lower tubesheet secondary-side face (LTSF) region which is the higher stress region within the CR3 OTSG. The lack of interference of sludge and dents in the lower tubesheet area outside of the dented/sludge pile region at CR3 allows the detection capabilities of the bobbin probe to be sufficient for IGA.
NRC Ouestion Part 4 If you have no plans to qualify the technique to the industry standard, provide the acceptance standard, specification or criteria you are using and the technical basis for this standard, specification, or criteria to ensure the adequacy of this technique.
Response
The bobbin coil technique in the lower tubesheet is acceptable for use at CR3 in the LTS because it was site-validated in accordance with industry recommendations, EPRI Guidelines, Section 6.2.4, for detection of axial intergranular attack (IGA) in OTSG tubing. The criterion used to qualify the bobbin coil examination technique at CR3 meets the industry guidelines for a site-validation of a technique.
U. S. Nuclear Regulatory Commission Attachment 3F0705-02 Page 7 of 7 An industry qualification is considered one which meets the requirements of industry accepted practice for qualifying non-destructive examination (NDE) techniques. The site-validated technique implements the recommendations of the EPRI Guidelines relating to calibration standards, voltage normalization, scanning procedures, sample rates and data analysis methodologies.
The EPRI Guidelines define the essential variables for eddy current examination techniques. These variables were used as the basis for determining equivalence to the site qualification.
The qualified technique used for the CR3 steam generators was reviewed to determine the applicability to the site conditions. A review of the pulled tube samples and laboratory samples used to support these qualifications were performed. An analysis of a sample of eddy current examination data from CR3 ensure that the characteristics of the in-generator tubing (i.e., denting, deposits, geometrical changes) are consistent with those used to develop the qualified techniques. The industry qualification data was also reviewed for similarity and applicability to CR3 tubing conditions, noise levels and essential variables to be used during the examination.
Although the POD for bobbin coil technique is less than 80% in this area, CR3 credited the bobbin coil exam in the LTS crevice region and those areas not inspected with MRPC with a reduced POD in the tube integrity evaluation. The relative POD values are used to project the undetected population of flaws in the LTS region. The bobbin coil sensitivity is affected by the interference of sludge or deformation in the dented/sludge pile region; therefore, an MRPC examination will be accomplished in a sampling of the kidney region. The lack of interference of sludge and dents in the lower tubesheet area outside of the dented/sludge pile region at CR3 allows the detection capabilities of the bobbin probe to be sufficient.
NRC Ouestion Part 5 If as a result of your response to the questions above, you concluded that full compliance with the Technical Specifications (TS) in conjunction with Criteria IX, XI and XVI of 10 CFR Part 50, Appendix B, requires corrective actions, please discuss your proposed corrective actions as requested by GL 2004-01, Requested Information #2. In addition, if the inspections are not being performed consistent with the NRC position on the requirements, please submit a safety assessment as requested in GL 2004-01, Requested Information #3.
Response
CR3 concludes that inspection techniques applied during the previous OTSG Inspection performed in October 2003 meet the inspection requirements of the CR3 Improved Technical Specifications, 10 CFR 50, Appendix B requirements and the NRC position provided in the GL.