ML18153C646
| ML18153C646 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 06/07/1991 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-312A, NUDOCS 9106130263 | |
| Download: ML18153C646 (13) | |
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VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 June 7, 1991 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 ASME SECTION XI INSTRUMENT ACCURACY INTERIM RELIEF REQUESTS Serial No.
91-312A NO/ETSR4 Docket Nos. 50-280 50-281 License Nos. DPR-32 DPR-37 During the development of the calibration procedures for the newly installed instruments to support the ASME Section XI pump testing program, it was noted that the initial calibration of the new and existing flow instrument loops was completed using incorrect instrument accuracy requirements. In order to assess operability of the affected pumps, the results of the latest Performance Test for each pump on both units were evaluated against the acceptance criteria, considering the applicable maximum potential loop inaccuracy. In each case the measured flow rate or differential pressure remained above the "action level" per ASME Section XI and the pumps remained operable. In our June 3, 1991 letter (Serial No.91-312) we informed you of this potential instrument loop accuracy concern and our intent to determine which pump flow instrument loops were actually outside the +/-2% accuracy requirements of ASME Section XI. The letter also indicated that we would submit the appropriate interim relief requests by June 7, 1991.
We have completed our evaluation of the most recently performed instrument calibration procedures for both units. We have determined that the instrument loops for 12 pumps in Unit 1 (Component Cooling, Residual Heat Removal, Auxiliary Feedwater, Emergency Service Water and Inside Recirculation Spray) and 11 pumps in Unit 2 (Component Cooling, Residual Heat Removal, Inside Recirculation Spray, Low Head Safety Injection, and Auxiliary Feedwater) were actually outside the +2% accuracy requirement. Therefore, pursuant to 10 CFR 50.55a (g) (5), we are requesting interim relief from the flow instrument accuracy requirement of ASME Code,Section XI, subparagraph IWP 411 O, Table IWP 4110-1, for the pumps included in the Attachment 1 and 2 for Units 1 and 2, respectively. The interim relief for those pumps tested quarterly will be required until the first scheduled pump test after September 30, 1991. This additional time is necessary to develop the total instrument loop calibration procedures, which will require additional engineering effort to establish the required accuracies associated with the individual components in each loop.
After the calibration procedures are developed, the flow instrument loops will be calibrated and the pumps tested. For those pumps tested every Cold Shutdown, the interim relief is required until
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the next Cold Shutdown of sufficient duration after September 30, 1991. For those pumps tested every Reactor Refueling, the interim relief is required until the next refueling outages, currently scheduled for April, 1992 and February, 1993, for Units 1 and 2, respectively We have been experiencing difficulty during calibration of the recently installed flow instruments for the Charging Pumps and the Boric Acid Transfer Pumps. The pumps have been evaluated for operability and determined to be fully operable. We intend to have these difficulties resolved before the first quarterly test interval is complete for Unit 2 and, therefore, no interim relief for these pumps is required at this time.
In addition, we have been experiencing difficultly in establishing repeatable flow measurements for the Emergency Diesei Generator Fuel Oil Transfer Pumps, the Charging Pump Component Cooling Water Pumps, and the Charging Pump Service Water Pumps. We are currently investigating the cause of the flow inconsistencies and expect to have completed the investigation by July 31, 1991. We will inform you of the results of the investigation and, if necessary, provide a schedule for any additional modifications by August 31, 1991. Based on their Performance Tests, the Emergency Diesel Fuel Oil Transfer Pumps have been shown to be operable in that they produce significantly more than the minimum flow required by design. In addition, based on evaluation of discharge pressure from Performance Tests for the Charging Pump Component Cooling Water Pump and the Charging Pump Service Water Pumps, these pumps have also been shown to be operable. Therefore, we are requesting interim relief from the flow accuracy requirement of +/-2% for these pumps, until the appropriate corrective action can be taken.
These interim relief requests are included in Attachments 1 and 2.
These interim relief requests have been reviewed and approved by the Station Nuclear Safety and Operating Committee. If you have any further questions or require additional information, please contact us.
Attachments cc:
U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station
ATTACHMENT 1 SURRY POWER STATION UNIT 1 ASME SECTION XI INTERIM RELIEF REQUESTS FLOW INSTRUMENT ACCURACY
INTERIM RELIEF REQUEST P-18 System: Component Cooling and Service Water Pump(s):
1-CC-P-2A 1-CC-P-2B Class : 3 Section XI Code Requirements 1-SW-P-1 OA 1-SW-P-1 OB For Which Interim Relief Is Reguested Measure Flow Rate.
Basis For Reguest The installed flow instruments on the discharge lines of these pumps were previously identified in a Section XI instrumentation evaluation as being adequate for Section XI testing. Therefore, flow instruments for these pumps were not included in an extensive Section XI instrumentation upgrade.
Subsequent testing experience has shown that the instruments do not yield repeatable results. Different test methods were explored in an effort to stabilize the flow values. After these efforts proved unsuccessful, the instrument circuit was analyzed and the problem was isolated at the transmitters. Further investigation is necessary to identify the source of the erratic flow values before a modification is made.
Alternate Jesting Proposed Inlet pressure, differential pressure and vibration will be measured every quarter.
When the repeatability problems with the current flow instrumentation have been corrected or new instrumentation installed, flow will be measured every quarter.
The investigation into the source of the erratic flow values will be completed by July 31, 1991. If equipment modifications are required to provide acceptable flow measurements, a schedule for the modifications will be submitted following the investigation.
e INTERIM RELIEF REQUEST P-19 System : Component Cooling Residual Heat Removal Inside Recirculation Spray Auxiliary Feedwater Emergency Service water Pump(s):
1-CC-P-1A 1-CC-P-1 B 1-FW-P-2 1-FW-P-3A 1-RH-P-1 A 1-RH-P-1 B 1-RS-P-1A 1-RS-P-1 B 1-SW-P-1A 1-SW-P-1 B Class:
2 for 1-RH-P-1A, B and 1-RS-P-1A, B 1-FW-P-3B 1-SW-P-1C 3 for 1-CC-P-1 A, B and 1-FW-P-2, 3A, 3B, and 1-SW-P-1 A, B, C Section XI Code Requirements For Which Interim Relief Is Requested Measure Flow Rate Within an Accuracy of+/- 2 Percent.
Basis For Request On May 30, 1991, personnel at Surry Power station determined that flow instrumentation used for testing pumps in the Surry Units 1 and 2 ASME Section XI lnservice Testing Programs may have flow instrument loop accuracies that are not within +/- 2 % as required by the Code because certain calibration requirements may not have been met prior to using the instruments. Further investigation narrowed the number of affected pumps for Unit 1 to the ones given above.
An evaluation was performed to determine if the decreased instrument accuracies affected the operable status of the pumps. The last measured flow rates for the affected pumps were adjusted to compensate for the uncertainty in the decreased instrument accuracies. The adjustment factor FA in gpm was determined as follow:
FA= FS*(CSA - 2) where FS = the full range of the instrument in gpm CSA= the revised loop accuracy in percent For test procedures that compare the measured flow to the ASME acceptance range, the adjustment factor was subtracted from the last measured flow rate. The adjusted flow rate was then compared to the acceptance criteria.
INTERIM RELIEF REQUEST P-19 (Cont.)
For test procedures that set flow to a reference value and then measure differential pressure, the pump curve must be used to determine the adjusted differential pressure. In these cases, FA was added to the recorded reference flow rate which results in an adjusted differential pressure as determined from the pump curve that is lower than the original test value. The adjusted differential pressure was then compared to the acceptance criteria.
The evaluation showed that the Section XI pumps have adequate operational margin after the affects of the decreased instrument accuracies were factored into the comparison of test results to the Section XI acceptance criteria.
Alternate Testing Proposed For pumps that are tested quarterly, the necessary instrument calibrations will be performed by September 30, 1991 to ensure that the flow instrument loop accuracies are within +/- 2%. For pumps that are tested at cold shutdown, the necessary instrument calibrations will be performed at the next cold shutdown of sufficient duration after September 30, 1991. For pumps that are tested every refueling, the necessary instrument calibrations will be performed during the next scheduled refueling outage. Pumps 1-CC-P-1A and B, 1-FW-P-2, 3A and 38, and 1-SW-P-1A, B and Care tested every quarter, pumps 1-RH-P-1A and Bare tested every cold shutdown, and pumps 1-RS-P-1A and Bare tested every reactor refueling.
ALTERNATIVE TESTING FOR NON-:CODE PUMPS According to the minutes of public meeting on Generic Letter 89-04, "Paragraph (g) of 1 OCFR 50.55a requires the use of Section XI of the ASME Code for inservice testing of components covered by the Code. For other components important to safety, the licensee also has the burden of demonstrating their continued operability." The minutes go on to state that, "The Code-required 1ST program is a reasonable vehicle to provide a periodic demonstration of the operability of pumps and valves not covered by the Code. If non-Code components are included in the ASME Code 1ST program (or some other licensee-developed inservice testing program) and certain Code provisions cannot be met, the Commission regulations (1 O CFR 50.55a) do not require a 'request for relief' to be submitted to the staff. Nevertheless, documentation that provides assurance of the continued operability of the non-Code components through the performed tests should be available at the plant site." Non-Code components are components that are important to safety but are not in systems or portions of systems that are classified ASME Class 1, 2 or 3.
Surry Power Station has elected to include certain non-Code components in the ASME 1ST program. Where the Code provisions cannot be met for non-Code components, alternative testing is performed that is adequate to ensure continued operability. The alternate testing is given in the attached Non-Code Alternative Testing description PNC-1.
I NON-CODE ALTERNATIVE TESTING PNC-1 System : Fuel Oil Pump(s): 1-EE-P-1 A 1-EE-P-1 D 1-EE-P-1 F Class : NC Section XI Code Requirements Which Cannot Be Met Measure flow rate Basis For Alternate Jesting Surry Power Station committed to installing flow instrumentation for the diesel fuel oil transfer pumps as described in the Safety Evaluation Report issued by the NRC in August 1990. The flow instrumentation was installed, however, the indicators show 12 gpm, which is the upper limit of the gauge. Further investigation is needed to determine the cause of the problem. The investigation will be completed by July 31, 1991. If equipment modifications are required to provide acceptable flow measurements, a schedule for the modifications will be submitted following the investigation.
Alternate Testing Inlet pressure, differential pressure and vibration will be measured every quarter.
The investigation to identify the source of flow problem will be completed by July 31, 1991. If equipment modifications are required to provide acceptable flow measurements, a schedule for the modifications will be submitted following the investigation.
ATTACHMENT 2 SURRY POWER STATION UNIT 2 ASME SECTION XI INTERIM RELIEF REQUESTS FLOW INSTRUMENT ACCURACY j
INTERIM RELIEF REQUEST P-15 System: Component Cooling and Service Water Pump(s):
2-CC-P-2A 2-CC-P-28 Class : 3 Section XI Code Requirements 2-SW-P-10A 2-SW-P-108 For Which Interim Relief Is Requested Measure Flow Rate.
Basis For Reguest The installed flow instruments on the discharge lines of these pumps were previously identified in a Section XI instrumentation evaluation as being adequate for Section XI testing. Therefore, flow instruments for these pumps were not included in an extensive Section XI instrumentation upgrade.
Subsequent testing experience has shown that the instruments do not yield repeatable results. Different test methods were explored in an effort to stabilize the flow values. After these efforts proved unsuccessful, the instrument circuit was analyzed and the problem was isolated at the transmitters. Further investigation is necessary to identify the source of the erratic flow values before a modification is made.
Alternate Testing Proposed Inlet pressure, differential pressure and vibration will be measured every quarter.
When the repeatability problems with the current flow instrumentation have been corrected or new instrumentation installed, flow will be measured every quarter.
The investigation into the source of the erratic flow values will be completed by July 31, 1991. If equipment modifications are required to provide acceptable flow measurements, a schedule for the modifications will be submitted following the investigation.
INTERIM RELIEF REQUEST P-16 Systems: Component Cooling Auxiliary Feedwater Residual Heat Removal Inside Recirculation Spray Low Head Safety Injection Pumps :
1-CC-P-1 C 2-FW-P-2 2-RH-P-1A 2-RS-P-1A 2-SI-P-1A 1-CC-P-1 D 2-FW-P-3A 2-RH-P-1 B 2-RS-P-1 B 2-SI-P-1 B 2-FW-P-38 Class :
2 for 2-RH-P-1A, Band 2-RS-P-1A, B, and 2-SI-P-1A and B, 3 for 1-CC-P-1C, D and 2-FW-P-2, 3A, 38 Section XI Code Requirements For Which Interim Relief Is Reguested Measure Flow Rate Within an Accuracy of + 2 Percent.
Basis For Reguest On May 30, 1991, personnel at Surry Power station determined that flow instrumentation used for testing pumps in the Surry Units 1 and 2 ASME Section XI lnservice Testing Programs may have flow instrument loop accuracies that are not within + 2 % as required by the Code because certain calibration requirements may not have been met prior to using the instruments. Further investigation narrowed the number of affected pumps for Unit 2 to the ones given above.
An evaluation was performed to determine if the decreased instrument accuracies affected the operable status of the pumps. The last measured flow rates for the affected pumps were adjusted to compensate for the uncertainty in the decreased instrument accuracies. The adjustment factor FA in gpm was determined as follow:
FA= FS*(CSA - 2) where FS = the full range of the instrument in gpm CSA= the revised loop accuracy in percent For test procedures that compare the measured flow to the ASME acceptance range, the adjustment factor was subtracted from the last measured flow rate. The adjusted flow rate was then compared to the acceptance criteria.
INTERIM RELIEF REQUEST P-16 (Cont.)
For test procedures that set flow to a reference value and then measure differential pressure, the pump curve must be used to determine the adjusted differential pressure. In these cases, FA was added to the recorded reference flow rate which results in an adjusted differential pressure as determined from the pump curve that is lower than the original test value. The adjusted differential pressure was then compared to the acceptance criteria.
The evaluation showed that the Section XI pumps have adequate operational margin after the affects of the decreased instrument accuracies were factored into the comparison of test results to the Section XI acceptance criteria.
Alternate Testing Proposed For pumps that are tested quarterly, the necessary instrument calibrations will be performed by September 30, 1991 to ensure that the flow instrument loop accuracies are within +/- 2%. For pumps that are tested at cold shutdown, the necessary instrument calibrations will be performed at the next cold shutdown of sufficient duration after September 30, 1991. For pumps that are tested every refueling, the necessary instrument calibrations will be performed during the next scheduled refueling outage.
Pumps 1-CC-P-1C and D, 2-FW-P-2, 3A and 38, and 2-SI-P-1A and Bare tested every quarter, pumps 2-RH-P-1A and Bare tested every cold shutdown, and pumps 2-RS-P-1 A and B are tested every reactor refueling.
NON-CODE ALTERNATIVE TESTING PNC-1 System : Fuel Oil Pump(s): 1-EE-P-1 B 1-EE-P-1C 1-EE-P-1 E Class : NC Section XI Code Requirements Which cannot Be Met Measure flow rate Basis For Alternate Testing Surry Power Station committed to installing flow instrumentation for the diesel fuel oil transfer pumps as described in the Safety Evaluation Report issued by the NRC in August 1990. The flow instrumentation was installed, however, the indicators show 12 gpm, which is the upper limit of the gauge. Further investigation is needed to determine the cause of the problem. The investigation will be completed by July 31, 1991. If equipment modifications are required to provide acceptable flow measurements, a schedule for the modifications will be submitted following the investigation.
Alternate Testing Inlet pressure, differential pressure and vibration will be measured every quarter.
The investigation to identify the source of flow problem will be completed by July 31, 1991. If equipment modifications are required to provide acceptable flow measurements, a schedule for the modifications will be submitted following the investigation.