IR 05000261/1989017
| ML14176A785 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 10/06/1989 |
| From: | Dance H, Garner L, Jury K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML14176A784 | List: |
| References | |
| 50-261-89-17, NUDOCS 8910270075 | |
| Download: ML14176A785 (9) | |
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UNITED STATES S0NUCLEAR REGULATORY COMMISSION o'
REGION II
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101 MARIETTA STREET, ATLANTA, GEOFG IA 30323 Report No.: 50-261/89-17 Licensee: Carolina Power and Light Company P. 0. Box 1551 Raleigh, NC 27602 Docket No.:
50-261 License No.:
DPR-23 Facility Name: H. B. Robinson Inspection Conducted: August 11 - September 10, 1989 Inspector:
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L. W. Garner, Senior Residebt Insoector Ddte'Signed K_. R. ury, 0ident Irt ector/
Dat* Sfgned Approved by:
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. C. Dance, Section Chief Dafe Signed Division of Reactor Projects SUMMARY Scope:
This routine, unannounced inspection was conducted in the area of operational safety verification, physical protection, surveillance observation, maintenance observation, and onsite followup of events at operating power reactor Results:
No violations or deviations were identifie The motor driven auxiliary feedwater (AFW)
pumps exhibited damage due to recirculation cavitation and the steam driven AFW pump exhibited cavitation damage due to both low recirculation flow and inadequate NPS The AFW system inspection/refurbishment and modifications are on-going, paragraphs 2 and The component cooling water system heat exchangers' performance appears to be adequate for plant cooldowns and design accidents, paragraph The Inservice Testing program may not be capable of detecting pump degradatio This issue is identified as an unresolved item, paragraph.Communication and planning between the control room and testing personnel was effective.during performance of operating procedure OP-402, Auxiliary Feedwater System, paragraph PDR ADOCK 05000261
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REPORT DETAILS 1. Persons Contacted R. Barnett, Maintenance Supervisor, Electrical
- D. Crook, Senior Specialist, Regulatory Compliance
- J. Curley, Director, Regulatory Compliance
- R. Dayton, Project Engineer, Technical Support C. Dietz, Manager, Robinson Nuclear Project R. Femal, Shift Foreman, Operations W. Flanagan, Manager, Modification Projects (Outage Manager)
- S. Griggs, Technical Aide, Regulatory Compliance E. Harris, Director, Onsite Nuclear Safety D. Knight, Shift Foreman, Operations D. McCaskill, Shift Foreman, Operations
- A. McCauley, Principal Engineer, Onsite Nuclear Safety
- J. Moon, System Engineer R. Moore, Shift Foreman, Operations
- R. Morgan, Plant General Manager
- D. Nelson, Maintenance Supervisor, Mechanical
- M. Page., Manager, Technical Support D. Quick, Manager, Maintenance D. Seagle, Shift Foreman, Operations
- Sheppard, Manager, Operations
- R. Smith, Manager, Environmental and Radiation Control
- D. Stadler, Onsite Licensing Engineer R. Steele, Operations Coordinator
- H. Young, Director, Quality Assurance/Quality Control Other licensee employees contacted included technicians, operators, mechanics, security force members, and office personne *Attended exit interview on September 15, 198 Acronyms and initialisms used throughout this report are listed in the last paragraph of the inspection repor. Operational Safety Verification (71707)
The inspectors evaluated licensee activities to confirm that the facility was being operated safely and in conformance with regulatory requirement These activities were confirmed by direct observation, facility tours, interviews and discussions with licensee personnel and management, verification of safety system status, and review of facility record To verify equipment operability and cohopliance with TS, the inspectors reviewed shift logs, operations records, data sheets, instrument traces, and records of equipment malfunction Through work observations and discussions with Operations staff members, the inspectors verified the
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staff was knowledgeable of plant conditions, responded properly to alarms, adhered to procedures and applicable administrative controls, cognizant of in-process surveillance and maintenance activities, and aware of inoperable equipment statu The inspectors performed channel verifications and reviewed component status and safety-related parameters to verify conformance with T Shift changes were routinely observed, verifying that system status continuity was maintained and that proper control room staffing existe Access to the control room was controlled and operations personnel carried out their assigned duties in an attentive and professional manne Plant tours and perimeter walkdowns were conducted to verify equipment operability, assess the general condition of plant equipment, and to verify that radiological controls, fire protection controls, physical protection controls, and equipment tagging procedures were properly implemente AFW System Testing/Modification Subsequent to the AFW system's inoperability, delineated in Inspection Report 89-18, the inspectors witnessed various AFW component inspections, system testing and modificatio The unit was placed in hot shutdown on August 22, 1989, at which time the testing/inspections commence All inspections witnessed and performed by the inspectors are detailed in paragraph 4. All testing witnessed and reviewed, as well as the system modifications, are discussed belo On August 22, 1989, the AFW system was tested with various pump configurations, flow paths (i.e., recirculation flow only, feeding the S/Gs, and a combination of both),
and flow rate The testing was performed to verify actual pump/system performance with a CST level of approximately 88 percent ful Each pump was tested individually and in combination with the other respective AFW pump The pumps were aligned in accordance with OP-402, revision 23, Auxiliary Feedwater Syste During the test, communication between the control room and the system engineer coordinating the test was well controlled, with potential problems being addressed prior to test initiatio While testing the SDAFW pump at recirculation flow (approximately 160 gpm) and two MDAFW pumps at 650 gpm combined demanded flow (with an additional recirculation flow of approximately 100 gpm),
reduced flow indications were observed; indicating insufficient NPSH This condition occurred prior to test completion, and the inspectors raised the concern of what effect continuing the testing with higher demanded system flow would have on the pump Additionally, the test was being performed without utilizing a special procedure, which could have addressed observed flow anomalies, effects of these anomalies on equipment, and any resultant required actions. After discussions with the Technical Support manager and other testing personnel, it was determined that further testing was not necessary, since the data taken provided
sufficient information to demonstrate inadequate NPSH Subsequent to the testing, inspections, refurbishing, and repair commenced on the AFW piping, the MDAFW pumps, and the SDAFW pump, respectively (see paragraph 4).
Due to AFW system three-pump operation flow rates, it was determined that the existing AFW suction piping (6-inches) was inadequately sized and, with existing head losses due to the rusting/corrosion identified during the piping inspection, adequate NPSHa was not provided to the AFW pump Modification M-1018, was initiated as an "emergency" modification to provide larger diameter AFW suction piping, as well as changing the pipe material from carbon steel to stainless for corrosion protectio This modification is scheduled for completion in October 1989, and consists of the following piping changes:
o Outlet piping from the CST is being increased from 6-inch inner diameter piping to 12-inch up to, and approximately 6-feet past the tee to the MDAFW pump The outlet piping will tap off the CST with two 6-inch nozzles feeding the 12-inch lin o The MDAFW pump piping will remain the same diameter; piping material (as discussed above) was change o The 12-inch piping is to be reduced to 8-inch for approximately 15-feet, then reduced to 6-inch up to the SDAFW pump suctio Additionally, due to the MDAFW pumps'
damage incurred from recirculation cavitation, pump testing methodology and flows are being evaluated to minimize future recirculation cavitation. The above modifications and the effects of this cavitation on the pumps, should adequately address AFW NPSHa deficiencie Resolution of the recirculation flow analysis should prevent future recirculation cavitation concern This is tracked as an IFI:
Review AFW System Hardware Modifications and Testing, 89-17-0 No violations or deviations were identifie. Monthly Surveillance Observation (61726)
The inspectors observed certain safety-related surveillance activities on systems and components to ascertain that these activities were conducted in accordance with license requirement For the surveillance test procedure listed below, the inspectors determined that precautions and LCOs were adhered to, the required administrative approvals and tagouts were obtained prior to test initiation, testing was accomplished by qualified personnel in accordance with an approved test procedure, test instrumentation was properly calibrated, the test was completed at the required frequency, and that the test conformed to TS requirement Upon test completion, the inspectors verified the recorded test data was complete, accurate, and met TS requirements; test discrepancies were
properly documented and rectified; and that the systems were properly returned to servic Specifically, the inspectors witnessed/reviewed portions of the following test activities:
OST-253 (revision 10)
RHR Pump Flow Test On August 27, 1989, during performance of OST-253, the B RHR pump flow rate was measured at 2,592 gpm with a fixed differential pressure of 110 ps This flow rate was determined to be in the IST required action range (i.e., flow less than 2,700 gpm) and the pump was declared inoperable. Calibration of the process instrumentation utilized for the test revealed that all the instrumentation was within their respective calibration tolerances; however, the B pump discharge gauge was found to be reading approximately 5. psi lower than the nominal calibration valu Due to instrument accuracy, indication can vary by plus or minus 12 psi and still be within allowable calibration tolerances. After the instrument was adjusted, the applicable portion of OST-253 was re-performed on August 31, 198 The subsequent indicated pump flow rate of 2,994 gpm fell within the acceptance criteria range of 2,820 to 3,060 gpm and the pump was then declared operabl Apparently, due to the operating characteristics of the RHR pumps, a small change in differential-pressure can result in large changes in flow rate Thus, the installed process instrumentation, as currently utilized, may not be capable of detecting.pump degradation. This situation may also exist for other safety-related pump This item is considered an
- URI:
IST Program May Not be Capable of Detecting Pump Degradation, 89-17-0 During this surveillance test, the flow value is calculated from an average of twelve flow transmitter voltage reading The inspectors observed that this data is routinely recorded on notebook paper and attached to the completed procedur The shift foreman had independently observed the lack of an information data sheet, and had identified the need to generate a procedure change reques No violations or deviations were identifie. Monthly Maintenance Observation (62703)
The inspectors observed safety-related maintenance activities on systems and components to ascertain that these activities were conducted in accordance with TS, approved procedures, and appropriate industry codes and standard The inspectors determined that these activities did not violate LCOs and that required redundant components were operable. The inspectors verified that required administrative, material, testing,
- An Unresolved Item is a matter about which more information is required to determine whether it is acceptable or may involve a violation or deviatio *II5 radiological, and fire prevention controls were adhered t In particular, the inspectors observed/reviewed the following maintenance activities:
o WR/JO 89-AHLX1 Disassembly/Inspection and Repair of A AFW Pump o
WR/JO 89-AHLX2 Disassembly/Inspection and Repair of B AFW Pump o
WR/JO 89-AFGM1 Disassembly/Inspection and Repair of the SDAFW Pump AFW System Inspection Subsequent to August 22, 1989, disassembly and inspection commenced on the AFW system piping, pumps, motors, and valve These inspections were conducted in order to assess the AFW systems components' condition and to implement any necessary corrective actions (refurbishment/replacement).
The AFW system suction piping inspection consisted of the following activities: (1) a boroscope was utilized to inspect approximately 60 feet of suction piping (20-feet toward the SDAFW pump from the CST, 20-feet toward the CST from the SDAFW pump, and 20-feet from the MDAFW pumps toward the CST); (2) boroscope inspection of suction piping from the SW header; and (3) inspection of three removed sections of piping (SDAFWP suction line, MDAFWP suction line, and SW supply piping), with the SDAFWP suction line section being sent to the Harris E&E Center for analysi The inspectors witnessed the majority of these evolutions and based on observations and discussions with the responsible engineer, the common piping from the CST to the SDAFW and the MDAFW pumps is in the worst condition (i.e., pitting and corrosion).
The SW header piping was found to be in relatively good conditio The Harris E & E Center's analysis confirmed the boroscope observation The MDAFW pump motors were removed and sent to Westinghouse in Spartanburg, S. C., for inspection and any necessary repair The B pump motor had exhibited arcing and sparking. The results of the inspection revealed minor wear in the B pump motor and vibration induced internal cracking on the pump motor rotor bars. The rotor bars are currently being replaced and were the apparent cause of the observed arcing/sparkin Westinghouse has recommended that the motors be completely overhauled during the 1991 refueling outag The MDAFW pumps were disassembled per WR 89-AHLX1 and AHLX2, respectively, in accordance with procedure CM-007, revision 2, Electric Driven Auxiliary Feedwater Pump Overhau The SDAFW pump was disassembled per WR 89-AFGM1 in accordance with procedure CM-008, revision 2, Turbine Driven Auxiliary Feedwater Pump Overhau The pumps' disassembly and inspection activities were overseen by technical representatives from the respective pump vendors (MDAFW pumps - Dresser, SDAFW pump - Pacific); the inspector observed these activities on a routine basi Results of the MDAFW pumps inspection revealed that there was damage to the pumps which was apparently caused by recirculation cavitatio Recirculation cavitation is caused by inadequate recirculation flow, which could be the result of various factors (i.e., undersized recirculation lines, high DP in recirculation piping, running the pumps with low recirculation flow for an extended period, etc.).
No damage was apparent on the MDAFW pumps from inadequate NPSHa (i.e., suction starvation).
The A pump's cavitation damage was evident on the first three stages of the impeller (high pressure end) and the first five stages of the intermediate cover (diffuser).
Additionally, there was a crack in the leading edge of the ninth stage impeller's inlet vane and the eighth stage intermediate cover's diffusing vane's tips were chippe The motor's casings also showed cavitation damage in the first stage diffuser seating face, as well as product wash in a small area leading from the pressurized area of the casing to a stud. Other observed damage/discrepancies observed include, but are not limited to, the following:
o Service water cooling lines were clogged a
Stuffing box cooling jackets were clogged O
Thrust bearing shoes showed excessive wear O
Lube oil was contaminated with sludge and sediment
Drive end and thrust end radial bearings showed excessive wear O
Impeller locking nuts were loose
Heat cracks were visible on the inboard and outboard packing sleeves Additionally, all stages of the impeller are being replaced as the bores were slightly undersize The pump shaft is also being replace The pump casings are currently being machined/repaired by the Pacific Pump Division of Dresser Industries, and are scheduled back on site by October 4, 198 The B MDAFWP showed damage and wear very similar to the A pum Three impeller stages and seven intermediate cover stages were damaged by recirculation cavitatio The B pump's internal element (impeller diffuser and shaft) is being replace The pump casing is also being repaired and machine Commencing the week of September 4, 1989, the SDAFW pump (single stage, centrifugal) and its turbine were disassembled, inspected, and refurbished per WR 89-AFGM This disassembly, inspection, and refurbishment were also conducted under the auspices of the vendor's technical representative. This inspection paralleled that of the MDAFW pumps, in that, worn parts were to be either refurbished or replaced. However, the SDAFW pump's impeller was damaged from cavitation, apparently due to insufficient NPSH The pump's diffuser also exhibited recirculation cavitation damag The turbine appeared to be in relatively good condition with no major repair, nor component replacement necessary. This inspection/refurbishment was still on-going as of September 21, 1989, and is being monitored on a routine basis by the inspector The AFW suction piping valves were removed and inspecte Most of these valves only exhibited normal wear and will be utilized in the replacement piping where possibl No violations or deviations were identifie. Onsite Followup of Events at Operating Power Reactors (93702)
CCW HX Performance Inspection Report 89-11 issued a NOV for failure to perform an adequate 10 CFR 50.59 review associated with the number of plugged tubes in the CCW HX. The report documented that 190 and 36 tubes had been plugged in the A and B HXs, respectively. The licensee has inferred from calculations that under design operating conditions, HX performance has not been degraded (i.e., actual individual HX heat removal capability is greater than the 29.4 million BTU/Hr value specified in the purchase order specification).
During cooldown for the current forced outage, the temperatures of the SW and CCW water entering and exiting the HXs were recorde Based on the measured CCW flow rate, the heat rejected from the CCW via both the A and B HXs was calculated to be 80.2 million BTU/Hr. Using a methodology from ASME paper 84-JPGC-NE-14, the expected heat transfer was calculated for the operating conditions existing during the cooldown. In addition, 200 tubes and 58 tubes were assumed to be plugged in A and B HXs respectivel This calculation yielded an expected heat transfer value of 73.5 million BTU/Hr; thus, the actual HX performance is apparently 9.1 percent better than that predicted by the mode Using the same number of plugged tubes, but assuming design worst case conditions, the model yielded a value of 55.0 million BTU/Hr or 6.5 percent less than the combined specification value for the HX (58.8 million BTU/Hr).
Since the actual system performance is 9.1 percent better than the model predicts under normal operating conditions, it can be expected that the system can also perform approximately 9.1 percent better under worst case design condition Hence, a projected 6.4 percent reduction in performance (under worst case conditions) due to tube plugging is offset by the model under-estimating the actual performance by 9.1 percen Apparently, the better than expected performance is due to less fouling than assumed in the design analysi Subsequent to the report period, three additional tubes were plugged in the A CCW H However, the above conclusion remains valid since A CCW HX has a total of 193 tubes plugged, whereas the above analysis assumed 200 tubes plugge No violations or deviations were identifie. Licensee Quality Assurance Program Implementation (35502)
An internal office evaluation was conducted on July 13, 1989, of the licensee's quality assurance program implementation by reviewing recent inspection reports, SALP reports, open items, licensee corrective actions
for NRC inspection findings, and licensee event report Particular emphasis was placed on all new items or findings since the last SALP report period (October 31, 1988).
It was recognized that an operational safety team inspection was scheduled during this SALP period. Recommenda tions were made to perform additional inspection modules in the Engineering and Technical Support are. Exit Interview (30703)
The inspection scope and findings were summarized on September 15, 1989, with those persons indicated in paragraph 1. The inspectors described the areas inspected and discussed in detail the inspection findings listed below and in the summary. Dissenting comments were not received from the licensee. Proprietary information is not contained in this repor Item Number Description/Reference Paragraph 89-17-01 IFI - Review AFW System Hardware Modifications and Testing (paragraph 2)
89-17-02 URI - IST Program May Not Be Capable of Detecting Pump Degradation (paragraph 3)
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8. List of Acronyms and Initialisms AFW Auxiliary Feedwater ASME American Society of Mechanical Engineers BTU/Hr British Thermal Units Per Hour CCW Component Cooling Water CFR Code of Federal Regulation CM Corrective Maintenance CST Condense Storage Tank ESF Engineered Safety Feature gpm Gallons Per Minute HX Heat Exchanger IFI Inspector Followup Item IR
Inspection Report
Inservice Testing
LCO
Limiting Condition for Operation
Motor Driven Auxiliary Feedwater
Net Positive Suction Head
NPSHa
Net Positive Suction Head available
NRC
Nuclear Regulatory Commission
OP
Operating Procedure
OST
Operations Surveillance Test
Pounds Per Square Inch
System Driven Auxiliary Fedwater
S/G
Sw
TS
Technical Specification
Unresolved Item
WRIJO
Work Request/Job Order