IR 05000483/1998005

Insp Rept 50-483/98-05 on 980413-0501.No Violations Noted. Major Areas Inspected:Maintenance,Engineering & Plant Support

ML20247K268
Person / Time
Site:	Callaway
Issue date:	05/08/1998
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20247K262	List: IR 05000483/1998005 ML20247K256
References
50-483-98-05, 50-483-98-5, NUDOCS 9805220052
Download: ML20247K268 (12)

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ENCLOSURE U.S. NUCLEAR REGULATORY COMMISSION

REGION IV

J Docket No.: 50-483 License No.: NPF-30 Report No.: 50-483/98-05 '

l Licensee: Union Electric Company i

l Facility: Callaway Plant

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Location: Junction Hwy. CC and Hwy. o Fulton, Missouri Dates: April 13 through May 1,1998 Inspector: 1. Bames, Technical Assistant Accompanied by: D. Kupperman, Argonne National Laboratory Approved By: Arthur T. Howell Ill, Director Division of Reactor Safety ATTACHMENT: Supplemental Information

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EXECUTIVE SUMMARY Callaway Plant l NRC Inspection Report 50-483/98-05 l

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Refueling Outage RF9 eddy current examination acquisition and analysis activities appeared effectively controlled, with good overall contractor performance noted

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(Section M1.1).

Engineering l .

The licensee appropriately responded to areas of weakness in the eddy current data analysis guidelines that were identified during a prior NRC inspection (Section E1.1).

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The use of the plus point probe was viewed as an indicator of management support for examination initiatives that would provide for early detection of degradation (Section E1.2).

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An increase in axial and circumferential flaw indications at the top-of-tube sheet location was noted during Refueling Outage RF8 (i.e.,108 tubes pluggad versus 30 tubes in Refueling Outage RF7). The total decreased to 65 tubes in Refueling Outage RF9 for

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top-of-tube sheet axial and circumferential flaw indications (Section E1.2).

Plant Suocort l

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The licensee has successfully maintained iron transport to the steam generators at low levels since adoption in 1993 of ethanolamines for pH control (Section R1.1).

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-3-Reoort Details Summarv of Plant Status l

The unit was in a refueling outage during the onsite portion of the inspectio . Maintenance M1 Conduct of Maintenance M1.1 Review of Tube Examination Activities

! Insoection Scone (50002)

l The inspector and NRC consultant performed limited observations of the acquisition, l analysis, and resolution processes, including review of a sample of eddy current data j from Refueling Outage RF Observations and Findinas The NRC consultant reviewed a sample of plus point eddy current data for tubes, which had been determined by the resolution process, to contain inside diameter and outside diameter axial and circumferential crack-like indications at the top-of-tube sheet location. Included in the review were checks of the reported flaw location, phase angle, volts, and l the three letter defect code. The NRC connultant agreed with the reported results, and noted that the eddy current analysts were, in general, conservative in the calls made. A review was also performed by the NRC consultant of a sample of single circumferential and axial defect calls, that were subsequently changed during review by the lead analyst and independent qualified data analyst (performing oversight of analysis activities for the licensee) to a final call of no detectable degradation' . Appropriate bases for the changes

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were provided by the independent qualified data analyst when questione l t

The current licensee data analysis guidelines, Procedure ETP-BB-01309, Revision 008, ,

indicates that current freespan differential and manufacturing burnish mark indications i should be compared against history prior to making a final call regarding the nature of !

! - the indications. The NRC consultant reviewed this process and noted that changes in j bobbin coil design since 1992 tend to complicate comparison of older bobbin coil signals j with current data (i.e., the earlier coils had a higher resonance frequency and, as a result, i produced voltages that are approximately twice that produced by a current design coil from the same reflector). In addition, bobbin probe speeds have increased in the last

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3 years, with up to 40 inches per second being used during acquisition of eddy current data. The NRC consultant noted, however, during review of a sample of these types of indications, that Lissajous figures could still be readily compared. Variations in the " fine" ,

structure of the Lissajous figures, related to differences in probe speed, were observe However, even in those cases, the similarity of the Lissajous primary features was clear when an indication was present in both historical and current bobbin coil dat l l

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l -4-l The inspector reviewed acquisition activities with respect to compliance with program requirements for: (1) verification of use of correct probe, (2) bobbin coil noise criteria, and (3) performance of ASME Code required 4-hour calibrations. No problems were noted during this review, with good contpliance to program requirements noted in contractor performanc Conclusions

Refueling Outage RF9 eddy current examination acquisition and analysis activities

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appeared effectively controlled, with good overall contractor performance noted.

11 Enaineerina E1 Conduct of Engineering l

E1.1 Review of Steam Generator Tube Examination Program Requirements l l Insoection Scoce (50002)

The inspector and NRC consdtent reviewed the steam generator tube examination program requirements contained in: (1) Engineering Technical Procedure ETP-BB-01309, " Steam Generator Eddy Current Testing Acquisition and Analysis Guidelines, Revision 008; (2) Document S-1032, " Technical Specification l for Steam Generator Maintenance Services," Revision 6; (3) Westinghouse Procedure MRS 2.4.2 GEN-35, " Eddy Current inspection of Preservice and ,

inservice Heat Exchanger Tubing," Revision 7; and (4) the site-specific performance demonstration requirements developed for Refueling Outage RF i Observations and Findings l

During the initial baseline steam generator tube integrity review inspection, which was documented in inspection Report 50-483/96-10, the inspectors noted areas of weakness in the Procedure ETP-BB-01309 data analysis guidelines. These areas of weakness were indicated to include: (1) absence of criteria for establishing when eddy current noise data was unacceptable, (2) a lack of restrictions on assigning through-wall depths from bobbin coil data, and (3) absence of specific requirements for disposition of potential manufacturer's burnish mark indications. The inspector and NRC consultant .

noted during the current inspection that the licensee had implemented for Refueling l Outage RF9: (1) quantitative noise criteria for determining when bobbin coil probes j should be replaced; (2) a restriction on assignment of bobbin coil through-wall depths to '

I only anti-vibration bar wear; and (3) a process stipulating review of potential i l manufacturer's burnish mark indications against prior eddy current examination history to I verify pre-existence of an indication prior to making a final cal The NRC consultant reviewed the handling of noisy data during Refueling Outage RF9 and noted that, at current noise limits, the main features, which determine the indication call, were not distorted enough to miss a flaw. The inspector concluded that the basic i

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l-5-licensee approach was commendable, in that it removed the onus from the eddy current data analyst in determining when eddy current data was of sufficient quality for analysi As noted in Section M1.1 above, the NRC consultant was able to readily determine when I eddy current indications characteristic of manufacturer's burnish marks were evident in historical eddy current data despite the complications created by changes in bobbin coil probe design and increased acquisition speed During the inspection documented in Inspection Report 50-483/96-10, areas of concern were noted regarding the adequacy of the practices used for training and testing of eddy current data analysts. The specific subjects of concern were: (1) the absence of plus l point probe data in the site-specific performance demonstration test, despite selection of this probe for use in Refueling Outage RF8; and (2) the limited number of stress corrosion cracking eddy current data indications present in the site-specific performance demonstration data base, which resulted in some analysts successfully completing the i site-specific performance demonstration test while analyzing only a small number of stress corrosion cracking indication As a result of the prior observations, an additional review was performed in the current inspection of the Refueling Outage RF9 training and site-specific performance demonstration testing for eddy current data analyst The NRC consultant ascertained that the site-specific performance demonstration test for Refueling Outage RF9 included a time restricted written open book examination on the steam generator design, inservice inspection history, and eddy current data acquisition and analysis requirements. The test was considered to adequately address the most important facets for the eddy current data analysts. The noted absence of lesson plans for the written examination was viewed to be of increasing importance, if degradation modes and locations increased during commercial service. The site specific practical examination required examination of numerous flaw signals from e;1 optical disk containing previous Callaway Plant indications. This test was noted to contain good examples of anti-vibration bar wear, manufacturing burnish marks, and stress corrosion cracking. The inspector considered that the test would be further strengthened by inclusion of data from other plants relative to tube support plate and freespan cracking, and inclusion of data from laser welded sleeve Conclusions The licensee has appropriately responded to areas of weakness in the eddy current data analysis guidelines that were identified during a prior NRC inspection documented in Inspection Report 50-483/96-10.

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-6-E Review of Unit Reoair History and Refuelino Outaae RF9 Examination Scoce and Results Insoection Scooe (50002)

The inspector reviewed the tube examination scope and methods that were used in Refueling Outage RF9 with respect to technicM specification requirements, industry guidance, and as a result of emerging degradation modes. A review was also performed of tube plugging history for the unit steam generators in Refueling Outage RF Observations and Findinas

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The licensee planned eddy current examination scope for Refueling Outage RF9 consisted of: (1) a full-length bobbin probe examination of all active tubes in Steam Generators B and C; (2) plus point probe examination at the top-of-tube sheet location cf all active tubes on the hot-leg side of Steam Generators A, B, C, and D; (3) plus point probe examination of all Row 1 low radius U-bend sections in Steam Generator A; (4) plus point probe examination of a sample of 40 laser welded sleeves that were installed in Steam Generators A and C during Refueling Outage RF8; (5) plus point probe examination of a minimum sample of 20 percent of dents with a bobbin coil amplitude of 5 volts or greater; and (6) plus point probe examination of distorted and non-quantifiable bobbin coil indication The inspector considered the overall examination scope to be comprehensive when evaluated against current degradation history. The use of the plus point probe was viewed as an indicator of management support for examination initiatives that would provide for early detection of degradation. The inspector considered the performance of bobbin probe examinations of all active tubes in individual steam generators every two cycles to be an acceptable approach, provided the current absence of flaw indications at tube support locations continue Table 1 lists the cumulative repair history for the individual steam generators. As of the end of Refueling Outage RF9, the respective tube plugging totals in Steam Generators A, B, C, and D during commercial service were 119,38,126, and 75, which corresponded to respective inservice repair pewintages of 1.37,0.68,1.68, and 1.3 The inservice repair percentages were calculated to take into account the presence of tubes in Steam Generators A and C that were repairec by installation of laser welded sleeves in Refueling Outage RF8, with 20 laser-welded sleeves considered thermally equivalent to 1 pit Table 2 shows a cumulative compilation for the unit of inservice tube degradation history by degradation mode. A previous review of tube degradation history through Refueling Outage RF8 was documented in Inspection Report 50-483/96-10. The inspectors noted from the Refueling Outage RF8 eddy current examination results that an increase had occurred from the prior outage in detected axial and circumferential flaw indications at the top-of-tube sheet location (i.e.,108 tubes versus 30 tubes in Refueling Outage RF7). i

l-7-Table 1

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Time of Effective Full SG A SG B SG C SG D Repair Power Years Refueling of Operation Outage (RF) Ot Cu Ot Cu Ot Cu Ot Cu IS% IS% IS% IS%

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l Preservice l N/A 3 N/A l7 N/A 7 N/A l RF1(5/1986) l (a) 0 (b) -

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l0 0.00 l l M*(4/1987) l (b) - 2 0.04 l3 0.05 l(b) -

l RF2(9/1987) .05 (b) -

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l5 0.09 l RF3(4/1989) l (b) - 4 0.11 l9 0.21 l(b) -

l RF4 (10/1990) l .16 (b) -

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l 16 0.37 l RF5 (4/1992) l (b) - 15 0.37 l14 0.46 l 2i' O 41 l l RF6(10/1993) l .50 (b) -

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l 18 0.73 l l RF7(4/1995) l .69 5 0.46 l20 0.82 l4 0.80 l l RF8(10/1996) l 9.97 48* 0.80"" 8 0.60 l44m j 04m> l25 1.24 32 1.37*) 4 0.68 36 1.68*) 5 Tntal Renmirt 177 41 1 133 I R7 (a) - Not provided; (b) - Steam generator tubes not examined during outage; (c) - Maintenance outage; (d)- Steam generator tubes not examined. Two tubes preventively plugged based on Refueling Outage RF4 examination results; (e) - 44 tubes repaired with laser welded sleeves; (f) - 33 tubes repaired with laser welded sleeves; (g) - Cumulative inservice plug equivalent percentage; (h) - Based on 20 laser welded sleeves being considered thermally equivalent to 1 plu l l

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.g-The inspector considered the inferred (or probable) degradation mechanism for the axial and circumferential eddy current indications to be stress corrosion cracking. The tube l plugging total for top-of-tube sheet axial and circumferential indications decreased in

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Refueling Outage RF9 to 65 tubes. The inspector noted during the onsite portion of the i inspection that the flaws appeared in general to be small, with none viewed as potentially l not meeting Regulatory Guide 1.121 structuralintegrity criteria. No degradation was detected in the thermally treated Rows 1 through 10 tubes. Examination of the sample of laser welded sleeves found no evidence of defects after one cycle of operatio Conclusions The use of the plus point probe was viewed as an indicator of management support for examination initiatives that would provide for early detection of degradation. An increase in axial and circumferential indications at the top-of-tube sheet location was noted during i Refueling Outage RF8 (i.e.,108 tubes plugged versus 30 tubes in Refueling Outage l RF7). The corresponding plugging total for this type of degradation decreased in Refueling Outage RF9 to 65 tube E8 Miscellaneous Engineering issues E LClosed) Violation 50-483/9610-01: Failure to assure use during analysis of plus point probe data cf settings for span and phase rotation that were qualified in accordance with Appendix H of the Electric Power Research Institute, "PWR Steam Generator Examination Guidelines," Revision The inspector verified that span and phase rotation settings had been established in the Refueling Outage RF9 analysis technique specification sheets for the plus point probe method, which were technically appropriate and consistent with the Appendix H (of the Electnc Power Research Institute "PWR Steam Generator Examination Guidelines")

qualifications. Additionally, the licensee had a contractor perform an independent review of all analysis technique specification sheets to assure their consistency with Appendix H requirement E (Closed) Unresolved item 50-483/9610-02: Monitoring of power used in laser welding of sleeves in steam generator tube The inspector reviewed the correspondence (included as Attachment 4 in inspection  ;

Report 50-483/96-10) on this item and infrared feedback data that was collected by i Westinghouse during the testing and qualification of weld heads. The inspector noted during the review of the infrared feedback data that the data did provide an indication of l

when degradation was occurring in laser energy reaching the weld. Accordingly, the inspector concluded that the infrared feedback system could be considered to perform a I power monitoring function, which together with the nondestructive examinations of the

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l completed welds, provided assurance of maintenance of required weld qualit i

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-10-IV. Plant Suonort R1 Radiological Protection and Chemistry Controls R fron Transoort to Steam Generators (50002) Insoection Scooe The inspector performed a review of trend data from November 1995 through March 1998 for iron transport to the steam generators, Observations and Findings The results of initial review of iron transport to the steam generators through Cycle 8 were documented in Inspection Report 50-483/96-10. It was noted (at the time of the initial review) that the licensee had successfully maintained iron transport below the Electric Power Research Institute secondary water chemistry guideline limit of 5 ppb, since the replacement of ammonium hydroxide with ethanolamines for pH control in l September 1993. The inspector noted during the current review that feedwater iron

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values ranged from approximately 2.5 ppb to 3.5 ppb in the first 3 months of 1996 and from approximately 2.5 to 3 ppb in the first quarter of 1998. A 2.75 ppb average value was documented for Cycle 9, indicating the licensee is continuing to maintain iron transport at low levels; thereby, minimizing fouling and deposit buildup in the steam l generators. The inspector considered the iron transport history to be an indicator of both l excellent chemistry staff performance and management support for steam generator tube integrity initiatives.

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The licensee has successfully maintained iron transport to the steam generators at low l levels since adoption in 1993 of ethanolamines for pH contro V. Management Meetinas X1 Exit Meeting Summary The inspector presented the results of the onsite inspection to members of licensee management on April 17,1998, at the conclusion of the onsite inspection. The licensee acknowledged the findings presented. No information was identified during this meeting as being considered proprietary. During the exit meeting, the inspector informed licensee management that the inspection would remain in an open status until the final eddy current examination results became available and had been reviewed. A final telephone conversation regarding the eddy current examination results was held with licensee staff on May 1,199 _ _ - _ _ _ _ _ - _ - _ - _ _ _ _ _ _ _ _ _

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ATTACHMENT

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SUPPLEMENTAL INFORMATION l 1 PARTIAL LIST OF PERSONS CONTACTED Licensee R. Affolter, Plant Manager T. Hermann, Supervising Engineer, NSSS and HVAC Design G. Hughes, Acting Quality Assurance Manager E. Olson, Supervisor, Chemistry T. Pettus, Steam Generator Engineer G. Randolph, Vice President and Chief Nuclear Officer 1

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M. Reidmeyer, Engineer, Quality Assurance E. Thornton, Quality Assurance Engineering Evaluator i I

NflR F. Brush, Resident inspector J. Hanna, Reactor Engineer D. Passehl, Senior Resident inspector i INSPECTION PROCEDURES USED 50002 Steam Generators t

92903 Followup-Engineering ITEMS CLOSED Closed 50-483/9610-01 VIO Failure to assure use during analysis of plus point probe data of settings for span and phase rotation that were qualified in accordance with Appendix H of the Electric Power Research Institute "PWR Steam Generator Examination Guidelines,"

Revision 4 50-483/9610-02 URI Monitoring of power used in laser welding of steam generator tube sleeves LIST OF DOCUMENTS REVIEWED Procedures / Documents

I ETP-BB-01309, " Steam Generator Eddy Current Testing Acquisition and Analysis Guidelines,"

Revision 008 l

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-2-S-1032, " Technical Specification for Steam Generator Maintenance Services," Revision 6 MRS 2.4.2 GEN-35 (Westinghouse), " Eddy Current inspection of Preservice and inservice Heat Exchariger Tubing," Revision 7 Callaway Plant Refuel IX Site Specific Written Exam, Test 1 and 2, dated April 1998

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Acquisition Technique Specification Sheet SCP-01-198, Revision 1 Acquisition Technique Specification Sheet SCP-02-198, Revision 1 l Acquisition Technique Specification Sheet SCP-03-198, Revision 0 Acquisition Technique Specification Sheet SCP-04-198, Revision 1 Acquisition Technique Specification Sheet SCP-05-198, Revision 1 Acquisition Technique Specification Sheet SCP-06-198, Revision 1 Acquisition Technique Specification Sheet SCP-07-198, Revision 3 Acquisition Technique Specification Sheet SCP-08-198, Revision 1 Acquisition Technique Specification Sheet SCP-09-198, Revision 1 Analysis Technique Specification Sheet SCP-A-198 (Bobbin), Revision 2 Analysis Technique Specification Sheet SCP-B-198 (Plus Point MRPC), Revision 1 Analysis Technique Specification Sheet SCP-C-198 (U Bend Plus Point MRPC), Revision 1 Analysis Technique Specification Sheet SCP-D-198 (520-Plus Point MRPC), Revision 2 Analysis Technique Specification Sheet SCP-E-198 (Sleeve Plus Point MRPC), Revision 1 Analysis Technique Specification Sheet SCP-F-198 (Cecco), Revision 1 l

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