IR 05000413/2014009
| ML14120A262 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 04/30/2014 |
| From: | Gerald Mccoy NRC/RGN-II/DRP/RPB1 |
| To: | Henderson K Duke Energy Corp |
| References | |
| IR-14-009 | |
| Download: ML14120A262 (21) | |
Text
UNITED STATES ril 30, 2014
SUBJECT:
CATAWBA NUCLEAR STATION - NRC SPECIAL INSPECTION REPORT 05000413/2014009
Dear Mr. Henderson:
On March 24, 2014, the U.S. Nuclear Regulatory Commission (NRC) completed its initial assessment of the circumstances surrounding the abnormal rotation of the connecting rod bearings on the Unit 1 diesel generators identified during bearing alignment inspections on March 4 and March 10, 2014. Based on this initial assessment, the NRC sent an inspection team to your site on March 25, 2014. The team completed the onsite portion of a special inspection on March 28, 2014, and discussed the results of this inspection with you and other members of your staff. The inspection team documented the results of this inspection in the enclosed inspection report. No findings were identified during this inspection.
In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of NRCs Agencywide Document Access and Management System (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
/RA/
Gerald J. McCoy, Chief Reactor Projects Branch 1 Division of Reactor Projects Docket Nos.: 50-413 License No.: NPF-35
Enclosure:
Special Inspection Report 05000413/2014009 w/Attachment: Supplemental Information
REGION II==
Docket No.: 50-413 License No.: NPF-35 Report No.: 05000413/2014009 Licensee: Duke Energy Carolinas, LLC Facility: Catawba Nuclear Station, Units 1 and 2 Location: York, SC 29745 Dates: March 25, 2014 through March 28, 2014 Inspectors: Joseph Austin, Senior Resident Inspector, Shearon Harris (Lead)
Alejandro Alen, Project Engineer Approved by: Gerald McCoy, Chief Reactor Projects Branch 1 Division of Reactor Projects Enclosure
SUMMARY OF FINDINGS
IR 05000413/2014009; 03/25/2014 - 03/28/2014; Catawba Nuclear Station, Unit 1; Special
Inspection.
These report documents special inspection activities by one senior resident inspector and one reactor inspector to review the circumstances surrounding the abnormal rotation of the connecting rod bearings on the Unit 1 diesel generators identified during a bearing alignment inspections. The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process, Revision 5. No findings were identified.
REPORT DETAILS
Summary of the Degraded Condition On March 4, 2014, the 1A diesel generator (DG) was declared inoperable for planned maintenance activities involving piston connecting rod bearing alignment measurements. These measurements are taken once every 18 months for each DG. It was discovered that the bearing for connecting rod #7 had rotated approximately 26 degrees from its normal horizontal position. Subsequently, on March 10, 2014, during an extent of condition evaluation on the 1B DG, the licensee identified that the #1 connecting rod bearing had also rotated approximately 11/16 inches. Based on these observations, the licensee decided to replace the bearings to allow for analysis of the cause of the rotation. After inspection of the removed bearings and consultation with the DG vendor, the licensee determined that the amount of movement did not challenge the ability of the DG to perform its safety function.
Special Inspection Charter Based on the deterministic and conditional risk criteria specified in Management Directive 8.3, NRC Incident Investigation Program, a special inspection was initiated in accordance with NRC Inspection Procedure 93812, Special Inspection Team. The inspection focus areas included the following special inspection charter items:
1. Develop a history of bearing issues on the Catawba DGs including a detailed sequence of
events from the 2006 bearing failure of the 1A DG until the 1B DG was returned to service after the replacement of the #1 piston crankshaft bearing.
dimensional tolerances between different bearings and the differences in bearings from different vendors.
3. Review and assess the licensees testing and maintenance practices for the DGs on both
units.
4. Review and evaluate the licensees compliance with vendor recommendations regarding
maintenance and operation of the DGs as it relates to bearing performance.
generators at Catawba, evaluating the cause of these problems, and implementation of corrective actions to resolve identified problems.
and the extent of condition completed for the Unit 2 DGs.
7. Review and evaluate the licensees conclusion that the DG could remain operable but
degraded with the bearing misaligned less than 45 degrees.
8. Assess the licensees actions resulting from vendor technical bulletins and industry
operating experience concerning bearings on Delaval engines.
9. Collect data necessary to support completion of the significance determination process, if
applicable.
10. Identify any potential generic safety issues and make recommendations for appropriate follow-up action (e.g., Information Notices, Generic Letters, and Bulletins).
OTHER ACTIVITIES
4OA5 Other Activities - Special Inspection (IP 93812)
.1 Develop a history of bearing issues on the Catawba DGs including a detailed sequence
of events from the 2006 bearing failure of the 1A DG until the 1B DG was returned to service after the replacement of the #1 piston crankshaft bearing.
a. Inspection Scope
The inspectors reviewed documents provided by the licensee to develop a detailed sequence of events associated with abnormal connecting rod bearing rotation issues at Catawba since the 1A DG bearing failure in 2006. The inspectors interviewed station personnel in the development of this timeline and reviewed station problem identification program (PIPs) reports to evaluate potential trends and insights related to the DG bearing issues.
b. Findings and Observations
No findings were identified.
Unit 1 Diesel Generators Bearing History Date Event Description 2006 11/11 Unit 1 began refueling outage (RFO).
Outage work on the 1A DG included installation of new #7 connecting rod and bearing shells.
11/22 New lubricating oil (LO) delivered and stored on the 1A DG building roof. The LO was kept on the roof for approximately 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> before it was used to fill the DG LO system. Mean outside temperature was 48 degrees Fahrenheit for 11/22 - 11/23.
11/24 During diesel post maintenance test (PMT) break-in runs, the 1A DG was manually shutdown due to high vibration and abnormal metallic noises.
Internal engine inspection identified that the #4 connecting rod bearing shells had catastrophically failed (PIP C-06-07946). Extent of condition identified the 1B DG #6 connecting rod and bearing shells had rotated but had not failed.
Both bearings had been installed in 1996 and were manufactured from the same manufacturing lot.
12/2 1A DG connecting rod bearing #4 was replaced (WO# 1720696).
12/2 1B DG connecting rod bearing #6 was replaced (WO# 1720907).
12/3 1A DG connecting rod bearing #8, which was from same manufacturing lot as
- 4 and #6 bearings, was preemptively replaced as preliminary root cause evaluation suggested a material defect from same lot.
12/20 Following 1B DG 24-hour run, as-left bearing alignment inspections identified the #2 connecting rod bearing shells for the 1B DG were misaligned by approximately 7/32-inches.
PIP C-06-08628: The licensee concluded the DG was operable and believed the rotation was caused during initial bearing installation, not due to loss of bearing shell crush. Bearing scheduled for replacement during next RFO.
2007 1/16 WO# 1725382: Following 1A DG 24-hour run, as-left bearing alignment inspections identified the #3 connecting rod bearing shells for the 1A DG were misaligned by approximately 3/8 inch.
PIP C-07-00190: The licensee concluded the DG was operable and believed the rotation was caused during initial bearing installation, not due to loss of bearing shell crush. Bearing scheduled for replacement during next RFO.
2/28 PIP C-06-07946: Root cause failure analysis report for the 1A DG #4 connecting rod bearing failure was completed. A definite root cause was not identified; however, the licensee determined the most probable cause for the failure was excessive wearing of the bearing inner diameter Babbit overlay due to material and dimensional deficiencies. The excessively worn surfaces caused the bearing shells to grab onto the crankpin and rotate, on engine fast starts, to a position where the bearing mechanical properties was not designed to handle the combustion load transmitted by the connecting rod.
Licensee established an 18-month preventive maintenance (PM) activity to conduct connecting rod bearing alignment measurements to verify proper alignment. This PM was scheduled to be conducted just before the outage on each Unit 1 and 2 DGs.
2008 2/12 WO# 1789531: 1A DG 18-month connecting rod bearing alignment measurements was satisfactory.
2/26 WO# 1789532: 1B DG 18-month connecting rod bearing alignment measurements was satisfactory.
5/3 Unit 1 began RFO.
Outage work on the 1B DG included a LO change. LO was stored outside on DG building roof before being added to the engine.
5/10 WO# 1724800: 1B DG connecting rod bearing #2, identified with a 7/32 inch misalignment on 12/20/2006, was replaced.
5/26 WO# 1733528: 1A DG connecting rod bearing #3, identified with a 3/8 inch misalignment on 1/16/2007, was replaced.
6/19 PIP C-08-03898: Inspection of removed bearing shells #2 and #3 for 1B and 1A DG, respectively, revealed that the dowel alignment pin was not in contact with the bearing outer shell and the bearings appeared to have been properly aligned during installation. The inspectors noted this was contrary to licensee conclusion in PIP C-07-00190.
2009 10/6 WO# 1886527: 18-month connecting rod bearing alignment measurements for 1B DG were satisfactory.
10/20 WO# 1886318: 18-month connecting rod bearing alignment measurements for 1A DG were satisfactory.
11/6 Unit 1 began RFO.
Outage work on the 1A DG included a LO change.
11/30 LO stored outside on 1A DG roof. Oil exposed to mean outside temperature of 48 degrees Fahrenheit for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> before being added to the engine.
12/3 First 1A DG run following LO change. Results were satisfactory.
2011 1/25 WO# 1959228: 18-month connecting rod bearing alignment measurements 1B DG were satisfactory.
4/6 WO# 1961434: 18-month connecting rod bearing alignment measurements 1A DG were satisfactory.
4/23 Unit 1 began RFO.
Outage work on the 1B DG included a LO change. LO stored outside on DG roof before being added to the engine.
2012 10/16 WO# 2026831: 18-month connecting rod bearing alignment measurements 1A DG were satisfactory.
10/31 WO# 2026833: 18-month connecting rod bearing alignment measurements 1B DG were satisfactory.
11/24 Unit 1 began RFO.
Outage work on the 1A DG included a LO change.
12/9 LO stored outside on 1A DG roof. Oil exposed to mean outside temperature of 55 degrees Fahrenheit for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> before being added to the engine.
12/12 WO# 2021213: First 1A DG run following LO change. Test results were satisfactory.
2014 3/4 WO# 2109806: 1A DG 18-month connecting rod bearing alignment measurements. Connecting rod bearing #7 found misaligned (rotated) 3.19 inches (approximately 26 degrees). Licensee declared the 1A DG inoperable for repairs and entered a 72-hour technical specification (TS) action statement. The licensee requested, and the NRC granted, a Notice of Enforcement Discretion (NOED) to complete repairs which were expected to extend beyond the TS 72-hour action statement.
3/9 1A DG maintenance and testing completed and engine declared operable.
WO# 2143598: 1A DG #7 connecting rod replacement and functional check.
3/10 WO# 2109916: Extent of condition alignment inspections identified #1 connecting rod bearing for 1B DG rotated approximately 0.69 inches.
Licensee declared the 1B DG inoperable for repairs.
3/12 1B DG maintenance and testing completed and engine declared operable.
WO# 21444023: 1B DG #1 connecting rod replacement and functional check.
3/13 Extent of condition alignment inspections performed on Unit 2 DGs.
WO# 2143787: Results were satisfactory.
WO# 2143788: Results were satisfactory.
3/21 Additional connecting rod bearing alignment inspections performed on 1A and 1B DGs. All eight connecting rod bearings were properly aligned.
dimensional tolerances between different bearings and the differences in bearings from different vendors.
a. Inspection Scope
The inspectors reviewed the condition of the removed #7 and #1 connecting rod bearing shells for the 1A and 1B DG, respectively. The inspectors reviewed the licensees preliminary root cause evaluation fault analysis, metallurgy examination report for connecting rod bolts and bearing alignment pins (for 1A DG #7 bearing), bearing failure assessment report from the DG vendor, root cause report for the 2006 bearing failure, and conducted interviews with licensee personnel to verify that troubleshooting activities adequately identified and considered potential causes for the two bearing rotation instances. The inspectors reviewed station problem identification program reports and trends of engine performance parameters to independently assess other factors that may have been related to this event.
b. Findings and Observations
No findings were identified. The connecting rod bearings provided the interface between the piston connecting rods and the crankshaft. The bearings were made from cast aluminum and were electroplated on the inner diameter surface with a Babbitt overlay that provided a low-friction surface between the crankpin and the bearing. The bearings were installed in the form of half-shells using a dowel pin to hold the bearing and connecting rod in the proper alignment during installation. The bearing shells are held in place via bearing shell crush. Crush is the interference between the bearing and the connecting rod bore, i.e., the bearing is made slightly larger than the connecting rod bore. This interference ranges between 0.000 - 0.001 inches per shell. The bearings were installed at room temperature with 1700 foot-pounds torque applied to the connecting rod bolts. The DGs had bearings from by three different vendors: 1) Vendor A supplied the original bearings that came with the engine; 2) Vendor B supplied replacement bearings after Vendor A stopped producing bearings; and 3) Vendor C currently supplies new bearings. Both rotated bearings (DG 1A #7 and DG 1B #1) were supplied by Vendor B.
The 1A DG #7 bearing shells were removed and visually inspected by the licensee and current bearing supplier (Vendor C). No signs of overheating or burned LO residue were noted indicating there was adequate lubrication. Both upper and lower bearing shells had minimal wear with the Babbitt overlay very much intact. The exterior surface showed two circular markings that appeared to be caused by the alignment dowel hole in the connecting rod bore which indicated the bearing had rotated in two separate movements. The first marking was approximately 22 degrees from the horizontal (correct) position. The second marking was approximately 26 degrees (an additional 4 degrees), which appeared to be the as-found position on March 4, 2014.
Based on information available at the time of the Special Inspection the inspectors reviewed plausible causes that could result in reduction of bearing crush. These included LO temperature, bearing material/manufacturing defects, and installation.
- LO temperature The DG LO system design subjects the bearings to differential temperature conditions during engine startup. The LO system consists of two loops; the keep-warm and the operating loop. The keep-warm loop pre-lubes and maintains internal engine components (i.e. connecting rods, bearings, and crankshaft) at approximately 140 degrees Fahrenheit during standby conditions. On engine startup the keep-warm isolates and the engine driven LO pump provides LO from the operating loop.
The LO in the operating loop was not heated in standby and was at cooler ambient temperature. During engine starts the LO temperature drops from 140 degrees Fahrenheit to 120 degrees Fahrenheit for approximately one minute before recovering to operating temperature (approximately 170 degrees Fahrenheit). Due to the thermal expansion of the aluminum bearing material (three times greater than the connecting rod steel) and lower mass (compared to the connecting rod) the differential temperature had the potential to shrink the bearings, reducing bearing crush and the clearance between the crankpin and bearing internal surface diameter.
The licensee identified that both the 2006 and 2014 bearing rotations were traceable to engine LO changes performed during winter refueling outages in 2006 and 2012.
The new LO was stored on the DG building roof (for approximately 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />) before the DG was ran. Because the LO change was one of the last maintenance activities performed before running the DG and the unheated portion of the system consists of three-fourths of the total LO system volume, it is suspected that the LO on the unheated portion was still close to outside temperatures of 40 - 50 degrees Fahrenheit. Procedures prevent engine start below 120 degrees Fahrenheit; however, operators verify this temperature on the keep-warm portion of the system.
The current bearing vendor calculated a maximum of 72 percent reduction in bearing hoop stress when subjected to a 105 degrees Fahrenheit temperature differential (i.e. cooled from 145 degrees Fahrenheit standby to 40 degrees Fahrenheit). In addition, the vendor stated that the inrush of higher oil viscosity (due to the lower oil temperature) increases the friction between the bearing shell and the crankpin which, that in combination with reduced crush, could cause bearing rotation on engine starts.
- Bearing material/manufacturing defects The rotated bearings were sent to the current bearing vendor and informally measured for crush. Results indicated bearings had lost crush and were outside of specification. Original factory crush measurements records showed the bearings crush was within specification. Crush measurements from a spare set (unused) of shells (Vendor C) from the licensees stock were also measured. Results showed that, in most cases, the crush was marginally lower than the original factory crush measurements. In addition, preliminary metallurgy examination results noted material differences between the original bearings and the replacement bearings from vendors B and C. Mechanical tests showed original bearings had higher yield strength and lower ductility than bearings from vendors B and C. Also, Babbitt overlay material was found on the outside surface (connecting rod bore and bearing interface surface) of vendors B and C bearings; however, not on the original bearings. This could result in vendor B/C bearings being more susceptible to rotate than the original bearings. At the end of the Special Inspection the licensee was working with the bearing supplier to determine the cause for loss of bearing crush and the effects of material differences.
- Bearing Installation The break-away torque on connecting rod bolt #4 of the 1B #1 bearing was measured at approximately 1200 foot-pound, which was below the specified 1700 -
1785 foot-pound. All other bolts (for the 1A #7 and 1B #1 connecting rod bearings)where within specification. The 1B #1 connecting rod bolts were sent to a laboratory for metallurgical examination and were still under evaluation at the end of the NRC Special Inspection.
Overall, the inspectors determined the licensees preliminary causal evaluation related to the 1A #7 and 1B #1 connecting rod bearing rotation appeared adequate and sufficiently broad. However, the licensee was still developing the root cause and was working with the DG vendor and bearing supplier to determine the root and contributing causes for the loss of bearing crush. At the end of the Special Inspection, the most contributing factor to the loss of bearing crush appeared to the LO differential temperature.
.3 Review and assess the licensees testing and maintenance practices for the DGs on
both units.
a. Inspection Scope
The inspectors reviewed maintenance procedures related to the connecting rod bearings to determine whether the licensees preventative maintenance was consistent with original equipment manufacturer (OEM) and the Enterprise Owners Group maintenance recommendations, and were reasonably effective in preventing bearing failures. The inspectors reviewed inspection, removal, and installation procedures for the connecting rod bearings to verify the licensee was properly controlling these activities and did not introduce conditions that could cause bearing rotation. The inspectors also reviewed DG testing procedures to verify that testing practices did not introduce conditions that could challenge performance of the connecting rod bearings. The inspectors conducted interviews with licensee personnel pertaining to preventative maintenance and testing activities.
b. Findings and Observations
No findings were identified. DG engines were model DSRV-16-4, manufactured by Transamerica Delaval, Inc. (TDI), which are four-stroke-cycle, turbocharged, after-cooled, V-type engines. The licensee was committed to maintain the DGs in accordance with the Enterprise Owners Group (EOG) preventive maintenance program methodology and recommendations to ensure adequate DG reliability. Recommended preventive maintenance activities related to the connecting rod bearings included visual inspection of LO passages and edges of bearings every three years, and bearing shell thickness measurement and visual inspection every fifteen years and whenever pistons are removed. The inspectors reviewed connecting rod bearing maintenance procedures and determined that maintenance practices were in accordance with the OEM and EOG recommendations. The inspectors noted that the licensee did not perform as-found bearing shell thickness measurements. The licensee indicated that as-found measurements were required if bearings were to be reused; however, the licensee installs new bearing shells every time they are removed. The inspectors verified that the licensee measured the thickness of the new replacement bearings on the DG 1A #7 and 1B #1 bearings and verified to be within specification. The inspectors reviewed DG operability and periodic test procedures and determined test practices were consistent with the OEM recommendations.
.4 Review and evaluate the licensees compliance with vendor recommendations regarding
maintenance and operation of the DGs as it relates to bearing performance
a. Inspection Scope
The inspectors reviewed maintenance and operating procedures, as they related to connecting rod bearing performance (e.g. LO system operating/standby temperature and pressure, LO type and sampling, connecting rod bolt torque, bolt thread lubrication, bolt installation sequence, bearing installation alignment, bearing inspection and thickness measurements, bearing and crank pin clearance, etc) against specifications and recommendations contained in the OEM vendor manual to verify that the licensee was appropriately implementing vendor recommendations. The inspectors conducted interviews with licensee personnel to verify that deviations from vendor recommendations were controlled.
b. Findings and Observations
No findings were identified. The inspectors concluded that, overall, the licensee followed and properly incorporated OEM recommendations into their maintenance procedures and operating procedures with deviations being properly controlled.
The inspectors identified, however, that during an EOG meeting on January 8 - 9, 2007, (shortly after the licensees 2006 bearing rotation event) the OEM recommended that LO temperatures should stay as close to actual (standby) temperatures and to minimize significant temperature difference during engine starts. This was based on operating experience from a commercial application that experienced a spun bearing due to cold LO temperatures. The OEM took an action item to develop a position to, in part, recommend minimum LO temperatures as it related to the potential spinning of bearing shells. The OEMs final recommendation was that bearings should be pre-heated between 140 degrees Fahrenheit and 160 degrees Fahrenheit for best performance and recommended that the oil in the piping system from the LO pump suction to the engine inlet header, including the main filter and LO heat exchanger, be heated to greater than 120 degrees Fahrenheit. The inspectors determined these recommendations had been provided to the licensee during and shortly after their completion of the root cause analysis (RCA) for the 2006 bearing rotation event; however, the licensee had not implemented these recommendations. Potential licensee performance issues associated with licensee compliance with LO temperature recommendations will be evaluated during inspector follow-up of the URI opened in Section 4OA5.5.
generators at Catawba, evaluating the cause of these problems, and implementation of corrective actions to resolve identified problems.
a. Inspection Scope
The inspectors reviewed licensee corrective action documents to assess the effectiveness of the licensees corrective actions in addressing previous issues and abnormal indications relative to bearing-related issues. The inspectors evaluated potential trends and the inclusion of industry operating experience into corrective actions. The inspectors interviewed station personnel to assess the licensees methodology for determining the cause of the bearing issues. The inspectors also reviewed applicable station procedures and vendor correspondence to evaluate the completeness of corrective actions and ensure that long term corrective action was in place.
b. Findings and Observations
Introduction:
The inspectors identified an unresolved item (URI) to review the completed RCE and the implementation and effectiveness of corrective actions.
Description:
The inspectors reviewed the RCA from the 2006 bearing failure of the 1A DG and the resultant corrective actions. The inspectors also reviewed the interim actions as they related to the most recent #7 bearing rotation on the 1A DG. The licensee was still conducting the RCA for the #7 bearing rotation and was also reviewing their previous corrective actions to prevent recurrence for the 2006 bearing failure. The completed RCA and corrective actions will need to be reviewed to determine if the 2006 CAPRs were ineffective and if the new CAPRs are adequate. This is identified as URI 05000413/2014009-01: Review the Root Cause Analysis for the #7 Bearing Rotation and Effectiveness of Previous Corrective Actions.
issue and the extent of condition completed for the Unit 2 DGs.
a. Inspection Scope
The inspectors interviewed station personnel in the development of the timeline. The inspectors evaluated the licensees immediate actions to return the 1A and 1B DG to service, reviewed corrective action reports and interviewed station personnel to access the licensees corrective actions. The inspectors also reviewed station work orders and procedures to determine the effectiveness of these corrective actions in restoring the system to operable, including interim actions.
b. Findings and Observations
Introduction:
The inspectors identified a URI to review the completed prompt determination of operability and any associated compensatory actions.
Description:
The inspectors reviewed the licensees corrective actions and noted that while an immediate determination of operability (IDO) had been performed, a prompt determination of operability (PDO) had not been initiated. The licensee had established interim actions, but the inspectors questioned the completeness of those actions relative to the LO temperature difference and effects it may have on the bearing positions. The inspectors also questioned the current bearing crush on the DGs (Unit 1 and Unit 2).
The licensee initiated a PDO with a scheduled completion date of April 17, 2014. This is identified as URI 05000413/2014009-02: Review of Completed PDO and Compensatory Actions.
.7 Review and evaluate the licensees conclusion that the DG could remain operable but
degraded with the bearing misaligned less than 45 degrees.
a. Inspection Scope
The inspectors reviewed the RCA from the 2006 1A DG bearing failure and interviewed station personnel associated with the previous bearing issues (2006 and 2014). The inspectors reviewed vendor reports on the failures and recent bearing rotation. The inspectors examined metallurgical reports and the bearings that were recently removed.
The inspectors also reviewed the licensees corrective actions from 2006 and 2014.
b. Findings and Observations
No findings were identified. The inspectors review the licensees assessment and vendor report with respect to functionality and operability of a DG with a bearing that has rotated. The inspectors concluded that if a bearing had rotated then there had been conditions established that could allow additional rotation and possibly damage to the bearing or DG. Hence, any bearing rotation would require, at a minimum, an operability and engineering evaluation, regardless of the vendors limit of 45 degrees, to determine the cause of bearing rotation and ability of the DG to perform its design function.
.8 Assess the licensees actions resulting from vendor technical bulletins and industry
operating experience concerning bearings on Delaval engines.
a. Inspection Scope
The inspectors reviewed the licensees evaluation of vendor technical bulletins, NRC generic communications, industry and site-specific operating experience (associated with DG bearing failures, rotated bearings, connecting rod bearing, etc) to assessed licensees actions in response to operating experience applicable DGs bearing rotation events.
b. Findings and Observations
No findings were identified. The licensee performed an extensive review of different operating experience databases and sources, including INPO, NRC Adams website, EOG meeting minutes, internal OE (corrective action program), and industry OE (nuclear and commercial) for TDI and similar type of DGs.
Although the root cause for the recent 1A and 1B bearing rotation was in progress, the 2006 RCA (PIP-C-06-7946) was the only OE identified which could have potentially impacted or prevented the bearing rotation experienced in March 2014. The 2006 RCA discussed a failure mode relative to the effects of cold LO temperature on aluminum bearings. However, the licensee refuted this failure mode, which was of concern to the OEM, based on fact that the connecting rod bearing movement had not been previously experienced. Potential licensee performance issues associated with the 2006 RCA will be evaluated during inspector follow-up of the URI opened in Section 4OA5.5.
.9 Collect data necessary to support completion of the significance determination process,
if applicable.
a. Inspection Scope
The inspectors reviewed the failure mechanism(s) understood at the time of the inspection and provided their findings to the Regional Risk Analysts. They provided additional information relative to past and present licensee functionality assessment, interim corrective actions, and the risk profile associated with the most recent bearing rotation.
b. Findings and Observations
No findings were identified. The inspectors provided their observations to a Regional Risk Analyst.
.10 Identify any potential generic safety issues and make recommendations for appropriate
follow-up action (e.g., Information Notices, Generic Letters, and Bulletins).
a. Inspection Scope
The inspectors assessed information provided by the licensee in documents and interviews for potential generic safety issues. The inspectors reviewed plant history related to previous DG bearing issues. The inspectors also evaluated licensees preliminary fault tree analysis in an effort to discover potential causes and likely potential generic safety issues.
b. Findings and Observations
No findings were identified. The inspectors determined this condition was unique to the licensee because of the arrangement of the LO system. Therefore, there was no potential for a generic safety issue.
4OA6 Meetings, Including Exit
On March 28, 2014, the inspection team presented the inspection results to Mr. Kelvin Henderson and other members of the licensee staff. The inspection team confirmed that proprietary information was provided and examined during the inspection period. The inspection team left all proprietary information at the site.
ATTACHMENTS:
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee personnel
- D. Barker, Operations Manager
- J. Brady, Regulatory Affairs - General Office
- D. Cantrell, Chemistry Manager
- M. Carwile, Nuclear Procedures Manager
- B. Carroll, PRA Manager
- B. Foster, NOS Manager
- S. Gibby, Reactor and Electrical Services Engineering Manager
- T. Hamilton, Interim Training Manager
- R. Hart, Regulatory Affairs Manager
- W. Jarman, Assistant Operations Manager - Shifts
- C. Kamilaris, Organizational Effectiveness Director
- K. Henderson, Catawba Site Vice President
- L. Keller, Engineering Manager
- T. Poetzsch, BOP Engineering Manager
- K. Phillips, Work Control Manager
- R. Rischel, Director Nuclear Engineering, PRA
- T. Simril, Plant Manager
- B. Suslick, Director Design Engineering
NRC personnel
- B. Wolfgang, Senior Mechanical Engineer
- A. Hutto, Senior Resident Inspector, Catawba
- R. Cureton, Resident Inspector, Catawba
- G. McCoy, Chief, Region II Reactor Projects Branch 1
LIST OF REPORT ITEMS
OPENED
- 05000413/2014009-01 URI Review the Root Cause Analysis for the #7 Bearing Rotation and Effectiveness of Previous Corrective Actions (Section 4OA5.5)
- 05000413/2014009-02 URI Review of Completed PDO and Compensatory Actions (Section 4OA5.6)