ML040580502
| ML040580502 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 02/25/2004 |
| From: | Wang A NRC/NRR/DLPM |
| To: | Ridenoure R Omaha Public Power District |
| Wang A,/NRR/DLPM/415-1445 | |
| References | |
| TAC MC0266 | |
| Download: ML040580502 (27) | |
Text
February 25, 2004 Mr. R. T. Ridenoure Division Manager - Nuclear Operations Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.
Post Office Box 550 Fort Calhoun, NE 68023-0550
SUBJECT:
FORT CALHOUN STATION, UNIT NO. 1 - 2003 STEAM GENERATOR INSPECTION CONFERENCE CALL
SUMMARY
Dear Mr. Ridenoure:
By letter dated September 17, 2003, the staff requested that a teleconference be scheduled when approximately 75 percent of the 2003 steam generator tube inservice inspection is completed. The enclosure to this letter was a list of 17 questions to be used as discussion points for this call. On August 29, 2003, and October 2, 2003, the NRC staff participated in conference calls with Omaha Public Power District (OPPD) representatives regarding the 2003 steam generator (SG) tube inspection activities at the Fort Calhoun Station, Unit 1 (FCS).
Enclosed are (1) the staffs summary of these two calls, (2) the written material provided by OPPD in support of these calls, and (3) information provided by OPPD in response to the October 2, 2003, telecon.
If you have any questions or comments regarding this summary, please call me at (301) 415-1445.
Sincerely,
/RA/
Alan B. Wang, Project Manager, Section 2 Project Directorate Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-285
Enclosures:
- 1. Summary
- 2. Information Provided by OPPD
- 3. Information Provided by OPPD in Response to 10/2/03 Telecon cc w/encls: See next page
February 25, 2004 Mr. R. T. Ridenoure Division Manager - Nuclear Operations Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.
Post Office Box 550 Fort Calhoun, NE 68023-0550
SUBJECT:
FORT CALHOUN STATION, UNIT NO. 1 - 2003 STEAM GENERATOR INSPECTION CONFERENCE CALL
SUMMARY
Dear Mr. Ridenoure:
By letter dated September 17, 2003, the staff requested that a teleconference be scheduled when approximately 75 percent of the 2003 steam generator tube inservice inspection is completed. The enclosure to this letter was a list of 17 questions to be used as discussion points for this call. On August 29, 2003, and October 2, 2003, the NRC staff participated in conference calls with Omaha Public Power District (OPPD) representatives regarding the 2003 steam generator (SG) tube inspection activities at the Fort Calhoun Station, Unit 1 (FCS).
Enclosed are (1) the staffs summary of these two calls, (2) the written material provided by OPPD in support of these calls, and (3) information provided by OPPD in response to the October 2, 2003, telecon.
If you have any questions or comments regarding this summary, please call me at (301) 415-1445.
Sincerely,
/RA/
Alan B. Wang, Project Manager, Section 2 Project Directorate Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-285 DISTRIBUTION:
PUBLIC
Enclosures:
- 1. Summary PDIV-2 Reading
- 2. Information Provided by OPPD RidsNrrDlpmLpdiv (HBerkow)
- 3. Information Provided by OPPD in RidsNrrPMAWang Response to 10/2/03 Telecon RidsNrrLAEPeyton RidsOgcRp cc w/encls: See next page RidsAcrsAcnwMailCenter RidsRegionIVMailCenter (CMarschall, KKennedy)
MMurphy KKarwoski ACCESSION NO.: ML040580502 OFFICE PDIV-2/PM PDIV-2/LA PDIV-2/SC NAME AWang EPeyton SDembek DATE 2/20/04 2/19/04 2/20/04 OFFICIAL RECORD COPY
Ft. Calhoun Station, Unit 1 cc:
Winston & Strawn Mr. Richard P. Clemens ATTN: James R. Curtiss, Esq. Division Manager - Nuclear Assessments 1400 L Street, N.W. Omaha Public Power District Washington, DC 20005-3502 Fort Calhoun Station P.O. Box 550 Chairman Fort Calhoun, Nebraska 68023-0550 Washington County Board of Supervisors Mr. Daniel K. McGhee P.O. Box 466 Bureau of Radiological Health Blair, NE 68008 Iowa Department of Public Health 401 SW 7th Street Mr. John Kramer, Resident Inspector Suite D U.S. Nuclear Regulatory Commission Des Moines, IA 50309 Post Office Box 310 Fort Calhoun, NE 68023 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 Ms. Sue Semerera, Section Administrator Nebraska Health and Human Services Systems Division of Public Health Assurance Consumer Services Section 301 Cententiall Mall, South P. O. Box 95007 Lincoln, Nebraska 68509-5007 Mr. David J. Bannister Manager - Fort Calhoun Station Omaha Public Power District Fort Calhoun Station FC-1-1 Plant Post Office Box 550 Fort Calhoun, NE 68023-0550 Mr. John B. Herman Manager - Nuclear Licensing Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.
Post Office Box 550 Fort Calhoun, NE 68023-0550
AUGUST 29, 2003 AND OCTOBER 2, 2003 CONFERENCE CALLS
SUMMARY
2003 STEAM GENERATOR TUBE INSPECTIONS OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION, UNIT 1 DOCKET NO. 50-285 As discussed in the NRC staffs review of the Fort Calhoun Station, Unit 1s (FCS) 2002 steam generator tube inspection reports, the NRC staff elected to discuss several questions arising from its review of the 2002 inspection results with the Omaha Public Power District (OPPD/the licensee) in the context of their 2003 inspections. By letter dated September 17, 2003, the staff requested that a teleconference be scheduled when approximately 75 percent of the 2003 steam generator tube inservice inspection is completed. The enclosure to this letter was a list of 17 questions to be used as discussion points for this call. As a result, on August 29, 2003, and October 2, 2003, the NRC staff participated in conference calls with representatives from OPPD to discuss the plans and results of the steam generator tube inspections. The following is a summary of these calls.
In support of the August 29, 2003, conference call, OPPD provided written material in response to the seventeen questions/issues raised by the NRC staff. This material is Enclosure 2. In addition to this written material, the following clarifying information was provided verbally by OPPD.
The manufacturing process employed for bending the tubes at FCS is different than that used in Westinghouse designed steam generators. As a result, the plan for 2003 included a 100 percent inspection of the row 1 and row 2 U-bends with a high frequency
+PointTM coil (since primary water stress corrosion cracking is a concern in the U-bend region in these rows) and a 20 percent inspection of the rows 1 through row 4 U-bends with a mid-frequency +PointTM coil (since outside diameter stress corrosion cracking is a concern in the U-bend region in these rows).
With respect to NRC question 2.a (see attached material supplied by licensee
[Enclosure 2]), the NRC staff asked what indications were missed during the qualification tests. OPPD indicated that in sample tube 12-4, a 26 percent through-wall flaw was missed. In sample 2-1, a 33 percent through-wall flaw was missed. In addition, a 21.5 percent through-wall flaw and a 35.5 percent through-wall flaw were missed. The dent sizes associated with these flaws was not listed in the paperwork that the licensee had available during the call. The sizes of these flaws were determined using average depths over a 0.1-inch increment.
With respect to NRC question 2.b, OPPD indicated that the changes in the site eddy current guidelines were only for the bent region of the tube since bobbin and +PointTM exams performed in a 400 tube zone do not indicate that a similar issue exists in the straight leg portion of the tubes.
With respect to NRC question 2.c, the following clarifying information was provided. No circumferential cracks have ever been observed at eggcrate supports in Combustion Engineering steam generators (i.e., they have been located at drilled hole tube supports). Of the 23 circumferential indications observed at drilled hole tube supports in the past four outages at FCS, 7 were at "non-dented" intersections based on a review of both bobbin and +PointTM data. No profilometry has been done to verify the presence of a dent at these intersections. When asked about the possible driving force for these 7 circumferential indications (given that no dent has been confirmed at these locations),
OPPD speculated that the tubes may have been bent during installation of the patch plates (i.e., during the fabrication process).
With respect to NRC question 6, OPPD indicated that the dent size was trended in approximately 110 tubes per steam generator from 1985 until 1996. The tubes selected for this sample would not pass a 0.560-inch bobbin probe.
With respect to NRC question 7, OPPD indicated that they are using the best available technology to inspect 3 to 5 volt dents, consistent with the industry guidelines when no specific qualified technique is available. Given the lack of relationship between bobbin voltage and through-wall extent for the various probe sizes (0.540-inch and 0.600-inch),
rotating probe data is used to assess when an in-situ pressure test is needed for outside diameter stress corrosion cracking indications.
In support of the October 2, 2003, conference call, which was in response to an NRC letter dated September 17, 2003 (Accession No. ML032680771), OPPD provided written material in response to the questions provided by the NRC staff (Enclosure 2). In addition to this written material, the following clarifying information was provided verbally by the OPPD representatives.
No tubes were inspected with a 0.540-inch diameter probe. All tubes were inspected using a 0.560-inch diameter probe.
No flaws were detected in the 90-degree bends (as of October 2, 2003).
No flaw-like indications were detected in the U-bend region of the row 1 through row 4 tubes (as of October 2, 2003).
DBH is "dispositioned by history." Data from these tubes were still being evaluated.
Depending on the location of a tube within the steam generator, the tube may be supported by a drilled hole tube support (which is 1-inch thick), an eggcrate tube support (which is 2-inches thick), or both types of support (3-inches thick).
Several non-flaw-like indications were reported at cold leg tube support C8. These indications were attributed to a residual component from the carbon steel tube support plate and were identified at the upper and lower edge of the support. These indications had eddy current phase angles in the outside diameter phase plane and exhibited deposit-like, rather than flaw-like phase rotation, as the eddy current frequency
changed. That is, at high frequencies, they had a phase angle near 160 degrees while at low frequencies they had a phase angle near 60 degrees.
During the call, the NRC staff observed that very few indications were detected with the bobbin coil probe; therefore, the effectiveness of the inspection appears to depend on the rotating probe examinations. OPPD indicated that the majority of the indications are in the critical area or at dented regions, and given the growth rate of the indications, their approach has been effective at maintaining tube integrity.
All crack-like indications are plugged on detection.
No tube wear other than that attributed to loose parts was identified. All tubes with wear indications associated with loose parts are plugged on detection.
Bobbin examination results led the licensee to develop the hot-leg critical area associated with the patch plates in the 1999 timeframe. No bobbin indications were detected below hot leg tube support H5 in the critical area. As a result, any indications below H5 are probably not that large.
In response to a staff question regarding the fact that many indications can be detected with hindsight, it was indicated that the prior outage primary and secondary data analyst calls are not reviewed to see if the resolution process is inadvertently screening defects.
Several of the circumferential indications associated with the tube supports exhibited an axial displacement nearly equal to the support thickness (i.e., the indications were above (or below) the tube supports). The maximum axial displacement observed this outage was approximately 0.7-inch. Historically, the axial displacement of these indications has been 0.3 to 0.4-inches; therefore, the axial displacement of the indications during 2003 is larger than observed in the past at FCS (and also elsewhere in the industry). No tubes with these types of indications have been removed for destructive examination from Combustion Engineering steam generators. The integrity of these tubes is being assessed through the measured arc length of the indication and the amplitude of the signal. Plans (as of October 2, 2003) were to in-situ pressure test one of these indications.
One tube in steam generator B (Row 84 Line 73) had a small circumferential indication located immediately adjacent to a small volumetric indication. Reviewing the prior history for this location, there is a dent at the tube support (4.5 to 5.5 volts) and a small distortion in the bobbin data near the location of the volumetric indication. There was a marginal response in the +PointTM data in 1999, but there has been a change in the data from 1999 to today indicating some slight growth of the indication.
The acronym "LPI" stands for "loose parts indication."
At the time of the call, there were no plans to expand the inspection scope.
Ultrasonic inspections are planned to be performed on 7 tubes (9 locations). The ultrasonic examinations are intended to confirm the degradation mechanism, profile the tube at the location of the defect (to help in determining the nature of the dent, if any),
and size the flaw (for comparison to phase angle measurements from eddy current testing). Ultrasonic inspections are planned for tubes in Row 94 Line 61 where the circumferential flaw is coincident with the top edge of the tube support. No ultrasonic inspection is planned for the circumferential flaw in the tube at Row 95 Line 64.
During the October 2, 2003, conference call, the OPPD representatives agreed to respond to several NRC questions. OPPDs responses to these questions are Enclosure 3.
As a result of the information provided by OPPD, the NRC staff did not identify any issues within the scope or results of the steam generator tube inspections that warranted follow-up during the outage. The NRC staff will review the steam generator tube inspection summary reports that the licensee submits according to their technical specification requirements.
Material Supplied in Support of August 29, 2003 Conference Call Response to NRC Request for Additional Information Regarding the 2003 Ft. Calhoun Station Steam Generator Inspection Program NRC Question 1:
Detailed understanding of the planned scope of inspection of dents during the 2003 outage (with both bobbin and a rotating probe). Broken down into scope of inspection in freespan dents, dents at drilled TSPs, dents at eggcrates, dents at non-horizontal supports, and dents in the cold leg.
OPPD Response:
The following portion of the total examination scope encompasses the inspection of dents Freespan C 100% of > 5 volt hot leg dents with MRPC C Bobbin screening at < 5 volt dents Drilled TSPs C 100% of hot leg intersections, dented and non-dented with MRPC Eggcrates C 100% of > 3 volt hot leg dents with MRPC C Bobbin screening at < 3 volt dents Non-Horizontal Supports C 100% of > 3 volt dents at DBH, V1, V2, V3, and DBC with MRPC C Bobbin screening at < 3 volt dents Cold Leg C Bobbin screening at all < 5 volt dents C 100% of > 3 volt dents at DBC with MRPC ENCLOSURE 2
NRC Question 2:
Detailed understanding of the planned scope of inspection of all drilled tube-to-tube support intersections (dented and non-dented).
OPPD Response:
The 2003 inspection will include 100% of the hot leg drilled support intersections with the rotating plus point coil irrespective of whether a dent is present. This is the same examination scope as that performed in 2002.
NRC Question 2.a:
Related factors which we would specifically like to address as part of questions 1 & 2 above are; C 2 - 3 volt dents, given the inspection technique for detection of PWSCC is not qualified for dents >2 volts, OPPD Response:
The EPRI technique (ETSS 96012.1) contains the following statement: "The <2 volt criteria was a consensus value determined by the peer review team based on the number of data points in the area of interest." A review of the tubes in this data set show that there are numerous samples in which the flaw is the dominant signal response and it is not possible to obtain that voltage which is attributable to the dent only. Thus the 2 volt criteria represents a qualitative judgement rather than an empirically derived limit. The samples listed below demonstrate detection of axial PWSCC in dents greater than 2 volts.
ID Dent Voltage Met Depth Type 1-3H 2.8 47% Lab Sample 7-1H 4.6 30% Lab Sample 7-3H 3.7 34% Lab Sample 10-22 2.3 38% Diablo Canyon Pulled Tube 42-117* 3.16 71% Maine Yankee Pulled Tube
- Not contained in the EPRI ETSS data set In addition to the industry data, Argonne National Laboratory assessed bobbin coil analyst performance for this mechanism as part of the NRC sponsored steam generator mock-up program. NUREG/CR-6791 "Eddy Current Reliability Results from the Steam Generator Mock-up Analysis Round-Robin" was published in November 2002. Section 2.6.1.4.1 Dented TSP with LIDSCC makes the following observations:
"Figure 2.71 shows the results for the 11 teams using the bobbin coil data only. This graph shows the detection rate increasing with depth. The overall success in detecting LIDSCC in a dented TSP location is somewhat less than for LIDSCC in TSP locations without data (sic).
Nevertheless, success with a bobbin coil in detecting LIDSCC in a dent is generally high for
depths greater than 40% TW. Detection as a function of BC voltage is presented in Fig. 2.72. The dent signal can mask the presence of a SCC, but for the 2.5-4.5 volt range the detection rate was generally good."
In summary, there is no data from industry operating experience, the EPRI ETSS, or the ANL report which would indicate that the bobbin coil may miss significant PWSCC flaws in the 2 to 3 volt range.
NRC Question 2.b:
C Potential impact of noise (e.g., probe wobble) on the reliability of the inspection technique, OPPD Response:
Recent experience from Comanche Peak (CP) Unit 1 has shown that probe wobble in the u-bend area of tubing can influence the phase angle of a defect response such that the indication appears to be outside of the flaw plane. The Fort Calhoun Station (FCS) data analysis procedure has been revised for the upcoming inspection and the reporting requirement for flaw-like signals in the u-bend or 90 degree bend area do not require that the indication measure greater than zero percent.
NRC Question 2.c:
Considering the detection of a circumferential flaw at a non-dented intersection in 2002, OPPD Response:
The presence or absence of a bobbin coil dent response is not a factor in the examination plan for this damage mechanism. All hot leg drilled support locations will be tested with the plus point coil.
NRC Question 2.d:
C and considering the detection of a circumferential flaw at an intersection with a <3 volt dent when dents are not called unless >= 3 volts.)
OPPD Response:
The presence or absence of a bobbin coil dent response is not a factor in the examination plan for this damage mechanism. All hot leg drilled support locations will be tested with the plus point coil.
NRC Question 3:
Provide additional details on the one PWSCC flaw identified during the 2002 inspection.
Specifically, what size dent was the flaw detected in, what size was the flaw estimated to be, was the flaw axial or circumferential in nature, what TSP was the flaw detected in, and was the scope of dents expanded based on the identification of this flaw?
OPPD Response:
The PWSCC flaw is located at the number two hot leg eggcrate support in SG B Row 31 Line 116. The 2002 bobbin coil data from this location shows a 31.48 volt dent response with no flaw-like signal characteristics. This intersection was tested with the plus point coil as part of the initial 20% sample of dented eggcrate locations. The flaw is axially oriented with a 300 KHz amplitude of 2.26 volts, a depth of 36% by phase analysis, and a length of 0.34 inches. This eggcrate location was also tested by plus point coil four years earlier in the 1998 dent sample. A review of this data shows that the indication was present at this time although the dent itself is the dominant signal response. The scope of the 2002 dent inspections was expanded to 100% of the hot leg dented eggcrates at elevations 1 and 2 in both steam generators. Since the detection of this indication occurred in the same timeframe that axial ODSCC was detected at these locations the scope expansion was based on both damage mechanisms.
NRC Question 4:
Various questions (clarifications) on the Tables provided in the July 30, 2003 RAI response.
OPPD Response:
We will address your questions during the conference call.
NRC Question 5:
The July 30, 2003 RAI response states that Comanche Peak experience was being considered in the plans for the Fall 2003 outage. Discuss how this has been factored in.
OPPD Response:
An EPRI SGMP Interim Guidance letter on Comanche Peak was released on April 22, 2003 and listed two problem statements.
A) The requirement to only go back to the previous cycle when reviewing historical data was not sufficient to identify slow-growing ODSCC.
There are significant differences in the practice at FCS compared to the approach initially used at CP. In the case of CP, the sole criterion to determine whether a suspect bobbin signal received a
supplemental plus point examination was whether the signal exhibited change from the previous inspection. The bobbin coil reviews that are conducted at FCS for suspect bobbin signals use inspection data from 1996. This is the first 100% full length bobbin exam at FCS that was recorded on optic disk storage media. All suspect bobbin signals at FCS receive a supplemental plus point examination unless they have been previously tested with this technique.
20% of these previously MRPC tested indications which show no change by the bobbin coil will be re-tested with MRPC during the 2003 examination to further validate the analysis methodology.
Additional information on this subject is contained in OPPDs response to question number 6 in the NRC RAIs dated July 30, 2003.
B) The leaking tube in the previous outage data was an indication measuring zero percent yet exhibiting flaw characteristics.
The OPPD response to question 2B above addresses this issue.
The Interim Guidance letter also recommends that when history review is being used to determine when additional diagnostic testing shall be performed, then the utility shall define in their site-specific data analysis guidelines what constitutes change.
The FCS data analysis procedure defines quantitative criteria for change. In previous examinations that has been a phase change of 10 degrees or an amplitude change of 0.5 volts.
Based on the CP experience this amplitude criteria for change has been reduced to 0.3 volts for the 2003 examination.
Lessons learned from the CP experience include analyst orientation to process errors. ECT graphics from CP will be presented during the FCS data analyst indoctrination which illustrate the errors made during the CP inspection. In addition, raw ECT data will be available for further review.
NRC Question 6:
The response to Question 8 in the July 30, 2003 RAI response indicates that there is no apparent growth in dent levels for a large population of indications. Does there seem to be a progression (increase) of dent size in some of the dents? Were the dents in the two tubes preventively plugged in 2002 experiencing an increase in dent size?
OPPD Response:
We have not conducted a dent trend analysis on a tube to tube basis due to the ECT voltage variability on large amplitude dents. Based on comparing data from the last five inspections it does not appear that the dents in the two tubes which were preventively plugged are increasing.
Both tubes are located in SG A and Row 80 Line 65 had a 2002 dent response of 143.9 volts at vertical strap V1. In 2001, 1999, 1998, and 1996 the dent magnitudes were 116.3, 130.5, 132.4, and 142.2, respectively. The variance in these measurements is slightly more than + 25 volts.
Row 88 Line 77 had a 2002 dent response of 172.3 volts at the same vertical strap. In 2001, 1999, 1998, and 1996 the dent magnitudes were 157.2, 158.0, 161.0, and 152.7, respectively.
Both of these tubes have been restricted to the passage of a 0.560 inch diameter bobbin probe since 1987 and have been tested with a 0.540 inch diameter probe since that time, including the 2002 examination.
Trending of a specific population of dents was conducted from 1985 until 1996. No dent size progression was observed in the defined population. This validated the chemistry changes instituted to arrest the denting progression. The dent arresting chemistry has been maintained.
If it were practical to trend denting on a tube specific basis and if we were to assume that a pattern was observed, the likely action would be to perform MRPC exams on those dents exhibiting the largest growth rates. Since OPPD is conducting MRPC on 100% of the hot leg dents this probable action is already included in our exam scope.
NRC Question 7:
Further discussion on the RAI response to Questions 9 and 10.
OPPD Response:
We will further discuss our responses during the conference call.
Material Supplied in Support of October 2, 2003 Conference Call STEAM GENERTOR TUBE INSPECTION DISCUSSION POINTS OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION, UNIT 1 DOCKET NO. 50-285
- 1. Discuss whether any primary to secondary leakage existed in this unit prior to shutdown.
Fort Calhoun Station had no measurable primary to secondary leakage prior to shutdown.
- 2. Discuss the results of secondary side pressure tests.
Have not performed any pressure tests.
- 3. For each SG, a general description of areas examined, including the expansion criteria utilized and type of probe used in each area. Also, be prepared to discuss your inspection of the tube within the tubesheet, particularly the portion of the tube below the expansion/transition region.
Bobbin Probe C 100% Full Length
- All with a 0.560" diameter probe
- Restricted supports tested with MRPC Plus Point RPC C 100% HTS from 7 Inches Below the Tubesheet to 3 Inches Above C 100% of All Hot Leg Drilled Supports C 100% of All Tubes in Hot Leg Critical Area from H5 to Hot Leg Batwing C 100% of Square Bends Above Hot Leg Critical Area C 100% of the Dents at Vertical Support Straps & Diagonal Bars C 100% of the Dents at Hot Leg Eggcrates C 100% of the Hot Leg Dings > 5 Volts C 20% of the U-Bends in Rows 1 to 4 (Mid- Range Coil)
C 100% of the U-bends in Rows 1 & 2 (High Frequency Coil)
C 20% Bobbin DBH Codes C MRPC Diagnostics From Bobbin Program as Required (323 in A, 365 in B)
Expansion Criteria C EPRI Guidelines C Engineering Judgement The hot leg critical area and buffer zone was redefined in SG A after finding one tube with freespan axial ODSCC on a tube in the buffer zone. A total of 25 additional exams were conducted with the plus point coil from H5 to the hot leg batwing. No additional flaws were detected in this sample.
Based on the unusual axial displacement of several circumferential indications, the inspection of drilled tube support plates in SG B was expanded to include a 20% sample of the C8 elevation.
No flaws were detected in this population.
- 4. Discuss any exceptions taken to the industry guidelines.
a) Senior analyst does not perform site specific SSPD b) MRPC calibration standards differ from guidelines
- 5. Provide a summary of the number of indications identified to-date of each degradation mode and steam generator tube location (e.g., tube support plate, top of tubesheet, etc.). Also provide information such as voltages, and estimated depths and lengths of the most significant indications.
Tables A & B provide this information.
- 6. Describe repair/plugging plans for the tubes that meet the repair/plugging criteria.
All tubes found to be defective will be plugged with mechanical rolled plugs. In addition, all tubes with circumferential indications will be stabilized.
- 7. Discuss the previous history of SG tube inspection results, including any "look backs" performed. Specifically, for significant indications or indications where look backs are used in support of dispositioning (e.g. manufacturing burnish marks).
Prior cycle ECT data is re-analyzed for all "I" codes identified in the current inspection to determine whether the indication was present in the 2002 examination data. Tables A & B provide a listing of these results. In general, the large majority of flaws were visible in the 2002 data with the benefit of hindsight. Where possible the indications present in the 2002 data will be sized to develop a flaw profile. This growth rate information will be input into the Operational Assessment for the next cycle.
- 8. Discuss, in general, new inspection findings (e.g., degradation mode or location of degradation new to this unit).
a) Circumferential Indications at Hot Leg Drilled Supports Prior to the 2003 inspection a total of 23 circumferential indications had been detected between the two steam generators. This mechanism was initially identified during the 1998 examination. Of the 23 indications, 18 were located at hot leg tube support 7 & 8. Insitu pressure tests of tubes with this indication type were performed on 3 tubes in 2001. The current inspection results show a total of 19 indications at hot leg drilled support intersections. The axial distribution is similar to that observed previously, with 13 of the 19 indications located at H7 & H8. Several of the indications detected in SG B have an axial displacement nearly equal to the support thickness (1 inch).
b) Circumferential Indication in Freespan Tubing The hot leg CA test program in SG B identified a small circumferential indication located below H7. The indication is approximately 25 degrees in circumference with a 300 KHz plus point amplitude of 0.19 volts. The indication is O.D. and is located immediately adjacent to a very small volumetric indication.
- 9. Discuss your use or reliance on inspection probes (eddy current or ultrasonic) other than bobbin and typical rotating probes, if applicable.
The delta coil MRPC test has been used to assist in the confirmation and characterization of the circumferential indication discussed above. The delta probe head has a conventional pancake coil and two directional coils. A comparison of the directional coil terrain maps can be used to determine the orientation of the flaw. The results from these tests have confirmed the circumferential orientation of the flaws in the drilled support plate and also indicates that there are multiple peaks present in the data which would indicate axially spaced layers of circumferential ODSCC. The low frequency data shows an area where the carbon steel support is missing and the flaw indication is on the opposite side of the tube.
The UTEC ultrasonic test will be used to obtain additional information on the nature of these indications. The UTEC has three transducers; a straight beam used for wall thickness measurements, profilometry measurements, and detection of volumetric flaws; and two shear wave oriented for axial and circumferential flaw detection.
- 10. Describe in-situ pressure test plans and results, if applicable and available; include tube selection criteria.
All indications which exceed the screening criteria will be pressure tested. At the present time we have one test candidate in SG B. Row 94 Line 65 has a circumferential indication which will be tested for leakage integrity based on its amplitude of 1.07 volts.
- 11. Describe tube pull plans and preliminary results, if applicable and available; include tube selection criteria.
There are no plans to remove tubes during this outage.
- 12. Discuss the assessment of tube integrity for previous operating cycle (i.e., condition monitoring).
C Eighty-nine (89)*** OD Axial indications have been detected.
C No ID Axial or Circ indications have been detected.
C Twenty- two (22) OD Circ Indications have been detected. There is uncertainty about the nature of some of the OD Circ indications and UT is being used to investigate further.
C One (1) small Volumetric Indication has been detected.
C Two (2) loose parts indications show wear less than 40% TW. These have been confirmed as previously existing by history.
- Co-linear axial ECT indications are combined to make one enveloping indication.
All axial indications have been sized with a quantified sizing technique and are below the condition monitoring limit.
All circumferential indications are sized at less than 20% PDA which is well below the condition monitoring limit. The circumferential extent of all circ indications is less than 140 degrees.
The predictions for this outage were 117 OD axial indications and 14 OD circ indications. The number of freespan axial indications is somewhat higher than predicted, but that is offset by a lower number at HTS. The freespan indications are generally smaller than the indications at the supports. The number of circ indications is eight (8) indications higher than predicted, but the indications are small in circumferential extent.
- 13. Provide the schedule for steam generator related activities during remainder of current outage.
10/03 - Complete ECT in SG A 10/04 - Perform ISPT in SG B 10/04 - Complete ECT in SG B 10/06 - Complete Repairs
- 14. Discuss the following regarding loose parts:
C what inspections are performed to detect loose parts All ECT data is screened for the presence of possible loose parts (PLPs). The ECT responds to a magnetic permeability change which can occur if a loose part is in contact with the tube.
A similar response can occur from the presence of a sludge rock which is why the ECT results are categorized as possible loose parts.
In addition to the ECT, a visual inspection is conducted in the annulus area at the top of the tubesheet. The results are these two examinations are subsequently compared and differences are evaluated.
C a description of any loose parts detected and their location within the SG A total of 28 PLPs have been reported by ECT. All of the PLP indications were present in the 2002 examination.
C if the loose parts were removed from the SG Flexitallic gasket material has been removed from SG A. The gasket material came from the secondary manway closure and judging by its appearance (shiny) it came from opening the manway for the current inspection of the upper internals. Additional smaller amounts of gasket material were removed from the annulus area of SG B.
C indications of tube damage associated with the loose parts Two tubes near the periphery in SG A have shallow wear indications at approximately 2.7 and 3.8 inches above the hot leg tubesheet. The depth of the indications are estimated at 19% and 26% respectively.
C the source or nature of the loose parts if known A FOSAR examination has been completed and flexitallic gasket material has been observed at the location of the wear indications (Row 94 Line 41 and Row 95 Line 42). The material is firmly lodged between the tubes and cannot be removed. These two tubes will be removed from service.
- 15. Once Through Steam Generators - if you have Babcock and Wilcox (B&W) welded plugs installed in the steam generators, be prepared to discuss the actions taken in response to Framatomes notification of the effect of tubesheet hole dilation on the service like of B&W welded plugs.
Not applicable
- 16. Once Through Steam Generators - describe your inspection/plugging plans with respect to the industry identified severed tube issue (NRC Information Notice (IN) 2002-02 and IN 2002-02, Supplement 1).
Not applicable
- 17. If steam generators contain thermally treated tubing (Alloy 600 or 690), discuss actions taken (if any) based on Seabrooks recent findings (Reference Information Notice (IN) 2002-21)?
Not applicable
Ft. Calhoun 2003 RFO Steam Generator Eddy Current Inspection Summary Steam Generator A Test Type Tests Planned Latest Total Tested Retests Final % Complete Tested HL .560 Bobbin 234 0 197 0 197 84.19%
HL .560/.540 RST Bobbin 94 0 91 0 91 96.81%
HL TTS +PT 4743 0 4742 1 4742 99.98%
HL Drilled TSP +PT 2998 1 2996 2 2996 99.93%
HL Vertical Dent +PT 2539 2 2528 11 2528 99.57%
HL Vertical Ding +PT 18 6 15 0 9 50.00%
HL Square Bend +PT 434 9 424 9 424 97.70%
HL DBH/V1 Dents +PT 243 1 235 7 235 96.71%
HL H5-DBH/V1 +PT 434 9 424 9 424 97.70%
CL .560 Bobbin 4652 0 4652 0 4652 100.00%
CL .560/.540 RST Bobbin 86 0 86 0 86 100.00%
CL U-Bend MR +PT 59 0 58 1 58 98.31%
CL U-Bend HF +PT 113 0 108 5 108 95.58%
CL Horizontal Ding +PT 22 0 22 0 22 100.00%
CL V2/V3/DBC Dent +PT 686 0 686 0 686 100.00%
.560/.540 +PT For Bobbin RRT 47 0 47 0 47 100.00%
20% History Review +PT 37 0 9 0 9 24.32%
HL SI & PID +PT 198 49 136 5 94 47.47%
CL SI & PID +PT 67 0 67 0 67 100.00%
Total HL Tests 11935 77 11788 44 11740 98.4%
Total CL Tests 5769 0 5735 6 5735 99.4%
TOTAL 17704 77 17523 50 17475 98.7%
A - Pluggable Tubes 39 Steam Generator B Test Type Tests Planned Latest Total Tested Retests Final % Complete Tested HL .560 Bobbin 237 0 237 0 237 100.00%
HL .560/.540 RST Bobbin 104 0 104 0 104 100.00%
HL TTS +PT 4734 0 4277 5 4277 90.35%
HL Drilled TSP +PT 2915 0 2912 3 2912 99.90%
HL Vertical Dent +PT 4673 0 4658 15 4658 99.68%
HL Vertical Ding +PT 19 4 5 1 5 26.32%
HL Square Bend +PT 388 0 343 42 343 88.40%
HL DBH/V1 Dents +PT 247 0 238 29 210 85.02%
HL H5-DBH/V1 +PT 388 0 343 33 343 88.40%
CL .560 Bobbin 4630 0 4630 0 4630 100.00%
CL .560/.540 RST Bobbin 75 0 75 0 75 100.00%
CL U-Bend MR +PT 66 0 65 6 60 90.91%
CL U-Bend HF +PT 113 0 109 4 109 96.46%
CL Horizontal Ding +PT 62 0 62 0 62 100.00%
CL V2/V3/DBC Dent +PT 676 0 676 0 676 100.00%
.560/.540 +PT For Bobbin RRT 53 1 49 1 49 92.45%
CL 20% C8 +PT 164 0 164 0 164 100.00%
20% History Review +PT 38 12 22 0 22 57.89%
HL SI & PID +PT 283 113 158 15 131 46.29%
CL SI & PID +PT 77 0 77 0 77 100.00%
Total HL Tests 13988 4 13117 128 13089 93.6%
Total CL Tests 5954 13 5852 11 5847 98.2%
TOTAL 19942 17 18969 139 18936 95.0%
B - Pluggable Tubes 62 Steam Generators A & B Grand Totals Tests Planned Latest Total Tested Retests Final % Complete Tested Total HL Tests 25923 81 24905 172 24829 95.8%
Total CL Tests 11723 13 11587 17 11582 98.8%
Grand Total Tests 37646 94 36492 189 36411 96.7%
As of 0400 On 10/02/2003 Page 1 of 1
TABLE A FORT CALHOUN SG A PRELIMINARY INDICATION
SUMMARY
OPPD Ft Calhoun Station 10/02/2003 Fall 2003 Outage S/G A Preliminary Repair List Row Line 2003 Bobbin 2003 MRPC Volts Deg % CircDeg Axial Location Bobbin Dent 2002 Review 1 9 94 NDD SCI HTS + 0.18 0.16 87 63 20 HTS TS Exp Present 2 11 30 NDD SCI HTS + 0.09 0.14 90 77 76 HTS TS Exp Present 3 16 63 NDD SAI HTS + 0.28 0.17 83 25 0.14 HTS TS Exp Present 4 23 58 NDD SAI HTS + 0.49 0.2 101 30 0.32 HTS None Present 5 25 56 NDD SAI HTS + 0.81 0.16 111 24 0.2 HTS None Present 6 30 73 NDD SAI HTS + 1.70 0.22 102 28 0.26 HTS None Present 7 33 74 NDD SAI HTS + 1.55 0.23 132 31 0.26 HTS None Present 8 35 74 NDD SAI HTS + 1.73 0.15 127 26 0.19 HTS None Present 9 56 81 NDD SAI H6 + 0.32 0.42 119 39 0.42 EC 3.95 Volt No Data 10 61 50 NDD SAI H7 + 0.10 0.39 87 40 0.2 EC 8.49 Volt No Data 11 81 62 NDD SAI H1 - 0.59 0.23 109 31 0.61 EC 53.59 Volt Present 12 85 68 NDD SAI H5 + 37.97 0.17 85 21 0.17 FS None Present 13 86 47 NDD SAI H7 + 10.18 0.19 121 28 0.29 FS None Present NDD SAI H7 + 11.05 0.16 114 26 2.25 FS None Present 14 87 56 NDD SAI H5 + 36.24 0.11 106 24 0.26 FS None Present 15 87 60 NDD SAI H5 + 37.22 0.14 92 25 0.22 FS None Present 16 90 55 NDD SAI H7 + 1.61 0.13 124 16 0.51 FS None Present DBH SAI H7 + 3.52 0.15 127 17 0.4 FS None Present NDD SAI H7 + 9.91 0.55 113 42 0.46 FS None Present NDD SAI H7 + 10.81 0.26 106 26 1.27 FS None Present NDD SAI H7 + 11.54 0.16 125 29 0.58 FS None Present NDD SAI H7 + 14.57 0.27 94 36 0.88 FS None Present 17 90 59 NDD SAI H6 - 0.92 0.28 121 34 0.35 FS 37.01 Volt NDD NDD SAI H6 - 0.23 0.68 119 52 0.41 TSP 37.01 Volt Present 18 90 63 NDD SAI H7 + 12.76 0.15 90 28 0.9 FS 26.22 Volt Present 19 90 71 NDD SAI H7 + 9.18 0.21 138 30 0.21 FS 56.86 Volt Present 20 90 77 NDD SCI H1 - 0.15 0.32 100 49 66 TSP 36.47 Volt Present 21 91 58 NDD SAI H6 + 0.1 0.76 116 54 0.72 TSP 56.86 Volt Present 22 91 64 NDD SAI H5 +35.59 0.28 112 34 0.74 FS None Present 23 93 58 DSI SCI H8 - 0.24 0.24 105 53 33 TSP 6.12 Present 24 93 76 NDD SAI H7 - 0.22 0.21 89 28 0.22 TSP None Present 25 93 82 NDD SAI H1 +1.42 0.16 79 24 0.43 TSP Present Present 26 94 41 NDD LPI HTS + 3.12 0.32 108 26 34 0.56 FS None Present 27 94 61 NDD SAI H6 + 18.74 0.15 93 25 0.33 FS None Present NDD SAI H6 + 21.43 0.12 111 23 0.79 FS None Present NDD SAI H7 + 2.65 0.34 123 43 4.06 FS None Present 28 94 83 NDD SAI H1 + 1.42 0.26 117 27 0.51 TSP None Present 29 95 42 DFI LPI HTS + 2.51 0.19 132 19 32 0.39 FS None Present 30 96 41 NDD SVI H5 + 32.07 0.25 121 22 33 0.59 FS None Present NDD SVI H5 + 32.01 0.12 132 16 29 0.19 FS None Present 31 96 55 NDD SAI H7 + 9.99 0.07 97 26 0.18 FS None Present
32 96 67 NDD SAI H5 + 0.26 0.25 114 33 0.22 TSP 13.58 Volt Present 33 96 71 NDD SAI H7 + 13.92 0.1 119 23 0.15 FS None Present NDD SAI H7 +13.94 0.17 111 28 0.33 FS None Present NDD SAI H7 + 15.37 0.18 104 29 0.36 FS None Present NDD SAI H7 + 16.34 0.18 107 29 0.27 FS None Present 34 97 46 NDD SAI H7 + 0.01 0.28 113 33 0.17 TSP 4.25 Volt Present 35 97 50 NDD SAI H7 + 0.01 0.53 130 46 0.43 TSP 7.18 Volt Present 36 97 68 NDD SAI H6 + 13.51 0.19 113 31 0.34 FS None Present 37 98 59 NDD SCI H1 + 0.27 0.36 110 47 59 TSP 12.37 Volt Present 38 100 69 NDD SAI H1 + 0.03 0.23 112 36 0.52 TSP None Present 39 101 70 DSI SAI H1 +0.00 0.16 103 26 0.52 TSP None Present 40 102 55 NDD SCI H7 + 0.12 0.3 115 28 32 TSP 5.78 Volt Present NDD SAI H8 + 11.18 0.13 116 18 0.23 FS None Present DFI SAI H8 + 15.61 0.15 81 25 0.19 FS None Present 41 103 64 NDD SCI H1 + 0.00 0.21 102 50 68 TSP 14.83 Volt Present
TABLE B FORT CALHOUN SG B PRELIMINARY INDICATION
SUMMARY
OPPD Ft Calhoun Station 10/02/2003 Fall 2003 Outage S/G B Preliminary Repair List Row Line 2003 Bobbin 2003 MRPC Volts Deg % CircDeg Axial Location Bobbin Dent? 2002 Review 1 16 73 NDD SAI H5 + 1.68 0.18 103 23 0.24 FS None No Data 2 20 55 NDD SAI H5 - 0.45 0.27 107 34 0.25 EC 3.96 V No Data 3 23 22 NDD SAI H1 + 0.40 0.57 114 46 0.47 EC 13.53 V Present 4 23 44 NDD SAI H6 + 0.43 0.63 109 45 0.31 EC 19.35 V Present 5 23 62 NDD SAI H5 + 2.69 0.32 123 34 0.48 FS 4.91 V NDD 6 23 112 NDD SAI H5 - 0.34 0.28 125 36 0.21 EC 5.98 V No Data 7 25 70 NDD SAI H6 + 0.58 0.59 112 49 0.23 EC 19.04 V No Data 8 27 114 NDD SAI H5 +1.24 0.27 111 30 0.54 FS None No Data 9 28 33 NDD SAI H4 - 0.08 0.4 112 39 0.4 EC 3.34 V No Data 10 31 46 NDD SAI H5 + 0.25 0.49 105 44 0.2 EC 9.10 V Present 11 36 33 NDD SAI H2 + 0.64 0.55 112 41 0.12 EC 13.14 V Present 12 47 116 NDD SAI V2 + 4.75 0.39 119 39 0.28 FS None No Data 13 48 39 NDD SAI H4 + 5.22 0.29 125 33 0.44 FS None No Data 14 54 51 NDD SAI H6 + 1.15 0.69 86 51 0.17 FS 5.73 V No Data 15 55 70 NDD SAI V2 + 3.92 0.25 121 29 0.32 FS None No Data 16 55 74 NDD SAI V2 - 3.62 0.27 127 30 1.24 FS None No Data 17 56 79 NDD SAI H6 - 0.34 0.45 128 36 0.64 EC 5.55 V No Data 18 63 60 DFI SAI V2 +10.90 0.53 143 44 0.68 FS None No Data DFI SAI V2 + 12.74 0.39 145 42 0.85 FS None No Data 19 68 69 NDD SCI H2 + 0.28 0.46 112 38 112 TSP 123.6 Present 20 70 59 NDD SAI H6 - 0.40 0.3 97 31 0.48 EC 6.78 V No Data 21 71 26 NDD SAI H5 - 1.40 0.38 79 30 0.19 EC 9.54 V No Data 22 71 76 NDD SAI H5 + 0.81 0.7 132 55 0.7 EC 4.29 V No Data 23 76 43 NDD SAI H8 - 0.02 0.28 92 32 0.35 TSP None Present 24 76 39 NDD SAI H8 + 0.16 0.23 108 29 0.27 TSP None Present 25 76 81 NDD SAI H2 + 0.22 0.57 117 41 0.57 EC 12.21 V No Data 26 78 61 NDD SAI H1 -0.57 0.31 116 35 0.63 FS None Present 27 79 68 NDD SAI H2 + 0.00 0.22 100 29 0.51 TSP None Present 28 80 59 NDD SAI H6 + 20.60 0.22 76 30 0.44 FS None Present NDD SAI H6 + 21.57 0.21 117 29 0.22 FS None Present 29 81 84 NDD SAI HTS + 2.89 0.11 113 21 0.41 FS None Present 30 83 58 NDD SAI H4 + 2.89 0.23 121 33 0.25 FS None Present 31 84 37 NDD SCI H8 + 0.17 0.17 99 56 90 TSP 32.65 V Present 32 84 57 NDD SAI H5 + 34.69 0.43 92 41 0.78 FS None Present 33 84 73 NDD SCI H7 - 4.61 0.19 105 33 48 FS None Present NDD SCI H7 -1.61 0.37 92 39 75 EC 4.46 V Present 34 84 75 NDD SAI H4 - 1.40 0.78 110 51 0.56 EC 7.78 V Present 35 86 67 NDD SAI H8 +0.00 0.39 73 40 0.34 TSP 15.48 V Present 36 87 52 NDD SCI H4 - 1.10 0.27 109 33 21 EC 8.13 V Present 37 87 62 NDD SAI H7 + 2.85 0.22 97 28 0.4 FS 18.45 V No Data 38 89 70 NDD SAI H8 + 1.26 0.35 128 38 0.81 FS None Present NDD SAI H8 + 3.46 0.2 128 32 0.51 FS None Present
39 90 61 NDD SCI H8 + 0.36 0.51 101 71 82 TSP 51.54 V Present 40 90 77 NDD SCI H1 - 0.03 0.24 116 24 116 TSP None Present 41 91 52 NDD SAI H7 + 0.73 0.42 100 36 0.84 FS None Present 42 91 54 NDD SAI H3 + 0.15 0.31 122 35 0.25 TSP None Present 43 91 56 NDD SAI H1 - 0.18 0.17 102 26 0.41 TSP None Present 44 91 74 NDD SAI H8 - 0.92 0.53 121 46 0.6 FS None Present 45 92 59 NDD SAI H6 + 1.57 0.2 108 27 0.26 FS None Present NDD SAI H6 + 2.05 0.26 104 30 0.23 FS None Present NDD SAI H6 + 2.25 0.29 71 27 0.2 FS None Present NDD SAI H6 + 2.74 0.3 73 30 0.6 FS None Present 46 92 65 NDD SAI H7 + 13.04 0.16 80 26 0.16 FS None Present NDD SAI H7 + 15.90 0.23 93 31 0.25 FS None Present 47 92 69 NDD SAI H7 + 16.03 0.17 71 26 0.78 FS None Present 48 92 73 NDD SAI H7 + 12.01 0.25 111 32 0.57 FS None Present NDD MAI H7 + 13.92 0.13 55 25 0.21 FS None Present NDD SAI H7 + 14.11 0.23 99 31 0.2 FS None Present NDD SAI H7 + 14.22 0.22 90 31 0.2 FS None Present NDD MAI H7 + 14.99 0.2 122 28 0.47 FS None Present 49 93 64 NDD SAI H7 + 3.15 0.2 98 26 0.39 FS None Present NDD SAI H7 + 4.25 0.16 107 22 0.33 FS None Present 50 93 66 NDD SAI H7 + 0.88 0.28 116 25 0.32 FS None Present NDD SCI H8 + 0.18 0.45 129 8 69 TSP 8.12 Present 51 94 61 NDD SCI H7 + 0.67 0.19 105 42 31 FS 2.21 Present NDD SAI H8 - 0.11 0.44 132 41 0.46 TSP 14.46 V Present NDD SCI H8 + 0.27 0.57 111 45 98 TSP 14.46 V Present 52 94 63 NDD SCI H8 + 0.11 0.63 104 39 96 TSP 17.25 V Present 53 94 65 NDD SCI H8 + 0.06 1.07 108 28 69 TSP 6.03 V Present 54 95 58 NDD SAI H6 + 18.57 0.14 81 24 0.19 FS None Present NDD SAI H6 + 19.76 0.14 84 22 0.49 FS None Present NDD SAI H6 + 20.82 0.22 115 30 0.49 FS None Present 55 95 64 NDD SCI H8 - 0.60 0.29 90 67 31 FS 8.59 V Present 56 95 66 NDD SCI H8 + 0.14 0.75 112 15 85 TSP 7.32 V Present 57 95 70 NDD SAI H6 + 20.67 0.24 118 28 0.43 FS None Present 58 96 65 NDD SCI H8 - 0.32 0.25 131 8 44 TSP 3.46 V Present 59 98 83 NDD SAI H6 + 20.00 0.52 135 46 0.26 FS 17.91 V Present 60 99 62 NDD SAI H8 + 2.33 0.15 120 27 0.31 FS None Present 61 100 69 NDD SAI H3 + 0.17 0.51 138 45 0.71 TSP None Present 62 101 72 NDD SAI H7 + 0.3 0.26 113 34 0.29 TSP 16.63 V Present 63 102 63 NDD SAI H1 - 0.13 0.23 102 35 0.32 TSP None Present
Material Supplied on October 3, 2003 in response to NRC Questions from October 2, 2003
- 1. Were any flaws detected as a result of the 20% sample of bobbin DBH dispositioned by history) Codes? If so, please describe the indications and expansion plans.
The 20% sample in SGA (37) has been completed with no flaws reported. In SG B the 20%
sample is 38 of which 27 had been completed as of 0600 hours25 days <br />3.571 weeks <br />0.822 months <br />. No flaws have been detected in this sample.
- 2. A circumferential flaw was identified in SG B, Row 87, Column 52 in an eggcrate. Did this location contain a combination of an eggcrate and tube support plate or just an eggcrate?
The ECT data for this intersection was reviewed after yesterdays phone call. The support structure at this elevation consists of an partial eggcrate with a drilled support on top. The indication resides in the eggcrate portion of the support assembly.
- 3. NRC staff questioned whether OPPD had reviewed historical eddy current data analyst calls if an effort to obtain additional information regarding possible indications. We are interested in knowing whether OPPD decided to review additional information related to the staffs questions. If so, what were they finding and did they modify inspection activities as a result (i.e., calling more indications, additional training of analysts, re-reviewing certain 2003 inspection data, etc.).
Background:
The question above came up in two instances. 2003 inspection results indicate that the majority of flaws called this outage were present in the 2002 inspection data (in hindsight). The staff questioned whether OPPD had reviewed the primary, secondary and resolution analyst calls from the 2002 inspection to determine if any of these indications were initially called indications in 2002 (and "thrown out" by more senior analysts). If so, this data may provide OPPD with insights in identifying indications earlier. The same information could further assist OPPD in determining if the signals identified at the C8 TSP (initially called circumferential indications by analysts) are in fact small flaws.
OPPD has continuously updated and improved the analysis process at Fort Calhoun Station. Our analyzed results have consistently met condition monitoring criteria as verified by insitu pressure test results from each outage since 1996. In addition, the operational assessments have provided reasonable predictions in the number and distribution of flaw indications. It has been and remains OPPDs objective to improve the probability of detection; however we view the review of ENCLOSURE 3
historical ECT data, as a post-outage activity. Since 1996, the data analysis indoctrination, data analysis procedure, and training materials have been updated to include lessons learned from review of prior history as well as missed indications. Since 2001 the data analysis indoctrination also includes relevant industry experience. After the fall outage season OPPD will perform a review of the 2002 ECT results including primary, secondary, and resolution analysis performance. Indications which are judged to have met acceptance criteria will be included in the training and testing materials to be used for the next inspection. Data analysis procedures will be modified as appropriate based on the results of this review.
With regard to the preliminary results which showed indications at the C8 support plate, we are confident that these signals are deposits. The phase angles are similar to those observed in tubes removed from FCS in 1998. There were deposits present on these tubes which were initially reported as flaws however the destructive exam found no degradation present. The indications in the tubes removed in 1998 were axial and the preliminary indications reported at C8 are circumferential. Since the coil windings in the plus point coil are identical, one would expect similar false positive responses on the circumferentially sensitive coil. Similar indications have been observed in the hot leg where historical data from 1999 (first available) show no change.