ML021270247
| ML021270247 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/06/2002 |
| From: | John Nakoski NRC/NRR/DLPM/LPD2 |
| To: | Mccollum W Duke Energy Corp |
| Olshan L N, NRR/DLPM, 415-1419 | |
| References | |
| TAC MB4456 | |
| Download: ML021270247 (7) | |
Text
May 6, 2002 Mr. William R. McCollum, Jr.
Vice President, Oconee Site Duke Energy Corporation 7800 Rochester Highway Seneca, SC 29672
SUBJECT:
OCONEE NUCLEAR STATION, UNIT 3 RE: SAFETY EVALUATION OF RELIEF REQUEST ASSOCIATED WITH THE PUMP SPECIFIC RELIEF REQUEST NO. ON-SRP-HPI-02 (TAC NO. MB4456)
Dear Mr. McCollum:
By letter dated March 11, 2002, as supplemented by letter dated March 13, 2002, you requested relief from the vibration monitoring requirements for the standby shutdown facility (SSF) reactor coolant (RC) makeup pump. These requirements are specified in Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code.
We have concluded that compliance with the Code-required test for the SSF RC makeup pump would result in hardship without a compensating increase in the level of quality and safety. On this basis, your proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) until the next power reduction in which a repair or replacement of the sensor can be completed.
On March 12, 2002, we granted verbal approval of this relief request.
Sincerely,
/RA/
John A Nakoski, Chief, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287
Enclosure:
Safety Evaluation cc w/encls: See next page
Mr. William R. McCollum, Jr.
May 6, 2002 Vice President, Oconee Site Duke Energy Corporation 7800 Rochester Highway Seneca, SC 29672
SUBJECT:
OCONEE NUCLEAR STATION, UNIT 3 RE: SAFETY EVALUATION OF RELIEF REQUEST ASSOCIATED WITH THE PUMP SPECIFIC RELIEF REQUEST NO. ON-SRP-HPI-02 (TAC NO. MB4456)
Dear Mr. McCollum:
By letter dated March 11, 2002, as supplemented by letter dated March 13, 2002, you requested relief from the vibration monitoring requirements for the standby shutdown facility (SSF) reactor coolant (RC) makeup pump. These requirements are specified in Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code.
We have concluded that compliance with the Code-required test for the SSF RC makeup pump would result in hardship without a compensating increase in the level of quality and safety. On this basis, your proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) until the next power reduction in which a repair or replacement of the sensor can be completed.
On March 12, 2002, we granted verbal approval of this relief request.
Sincerely,
/RA/
John A Nakoski, Chief, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287
Enclosure:
Safety Evaluation cc w/encls: See next page DISTRIBUTION:
PUBLIC ACRS T-6 E26 OGC PDII-1 R/F GHill(6)
WBeckner RHaag,RII Accession No.: ML021270247
- No major changes to SE OFFICE PDII-1/PM PDII-1/LA EMCB/SC*
OGC PDII-1/SC NAME LOlshan CHawes DTerao SUttal (NLO)
JNakoski DATE 04/25/02 04/24/02 3/21/02 04/30/02 05/01/02 OFFICIAL RECORD COPY
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO PUMP SPECIFIC RELIEF REQUEST NO. ON-SRP-HPI-02 DUKE POWER CORPORATION OCONEE NUCLEAR STATION, UNIT 3 DOCKET NUMBERS 50-270 AND 50-287
1.0 INTRODUCTION
Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a, requires that inservice testing (IST) of certain American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 pumps and valves be performed at 120-month IST program intervals in accordance with a specified ASME Code and applicable addenda, except where alternatives have been authorized or relief has been requested by the licensee and granted by the Nuclear Regulatory Commission (NRC) pursuant to paragraphs (a)(3)(i), (a)(3)(ii), or (f)(6)(i) of 10 CFR 50.55a. In accordance with 10 CFR 50.55a(f)(4)(ii), licensees are required to comply with the requirements of the latest edition and addenda of the ASME Code incorporated by reference in the regulations 12 months prior to the start of subsequent 120-month IST program intervals.
Licensees whose IST program reaches its 120-month interval after September 22, 2000, are required to implement the 1995 Edition with the 1996 Addenda of the ASME Code for Operation and Maintenance of Nuclear Power Plants (ASME OM Code). In proposing alternatives or requesting relief, the licensee must demonstrate that (1) the proposed alternatives provide an acceptable level of quality and safety, (2) compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety, or (3) conformance is impractical for the facility. 10 CFR 50.55a authorizes the NRC to approve alternatives to and grant relief from ASME Code requirements upon making the necessary findings. NRC guidance in Generic Letter (GL) 89-04, Guidance on Developing Acceptable Inservice Testing Program, provides acceptable alternatives to the Code requirements. Further guidance is given in GL 89-04, Supplement 1, and NUREG-1482, Guidelines for Inservice Testing at Nuclear Power Plants.
By letter dated March 11, 2002, as supplemented by letter dated March 13, 2002, Duke Energy Corporation (the licensee) submitted a relief request for vibration testing of the standby shutdown facility (SSF) reactor coolant (RC) makeup pump at Oconee Nuclear Station, Unit 3.
Oconee Nuclear Station, Unit 3 is currently in its third interval. The ISI program for this interval was developed in accordance with the requirements of the ASME Code,Section XI, 1986 Edition.
2.0 RELIEF REQUEST FOR SSF RC MAKEUP PUMP The licensee requested relief for the SSF RC makeup pump vibration monitoring requirements of paragraph IWP-4510 of the 1986 Edition of the ASME Code,Section XI. Concerning placement of the vibration sensor (probe) on pumps, paragraph IWP-4510 states On reciprocating pumps, the location [of the probe] shall be on the bearing housing of the main pump drive shaft, approximately perpendicular to both the shaft and the line of plunger travel.
2.1 Licensees Basis for Requesting Relief (as stated)
During an accident, the SSF RC Makeup pump takes suction from the spent fuel pool and injects into the reactor coolant pump (RCP) seals. During accident conditions, the SSF RC Makeup pump would be required to inject flow into the RCP seals at 2350 psig. The SSF RC Makeup pump is tested during power operation through a recirculation test flow path that takes suction from the spent fuel pool and returns to the spent fuel pool.
The SSF RC Makeup pump is a positive displacement pump located within the containment building. Quarterly vibration parameters are monitored via permanently installed vibration sensors that are routed through a containment penetration. Two vibration sensors (accelerometers) are mounted on the pump bearing housings. The pump outboard bearing probe is in the vertical direction (perpendicular to the crankshaft and perpendicular to the line of plunger travel) and the pump inboard probe is in the horizontal direction (perpendicular to the crankshaft and parallel to the line of plunger travel).
Currently, the pump outboard vibration probe is not functioning properly such that valid data is unobtainable from this instrument. During an extended pump run on 3/8/02, the pump outboard bearing vertical vibration was observed to be responding erratically. After a detailed engineering analysis of the vibration data, it was concluded that there is no known machinery defect that would cause the erratic vibration signature. In addition, other pump parameters (the inboard bearing horizontal vibration value, discharge pressure, flow) remained steady and consistent with past pump performance. Furthermore, such significant changes in the pump outboard bearing vertical vibration instrument readings would also be observed to some degree in the pump inboard bearing horizontal vibration instrument readings if the pump were degrading.
Due to the location of the malfunctioning vibration sensor (inside the containment building biological shield wall), a unit power reduction from 100% to approximately 20% would be required to enter containment and correct the problem. The power reduction is necessary to reduce the radiation field that makes the equipment inaccessible at full power.
Monitoring of the pump vibration with only one probe functioning will ensure the health of the pump is sufficiently examined. For this component, degradation of the pump would be characterized by specific frequencies of vibration corresponding to the shaft speed and plunger cycling. In addition to reviewing acceptability of the overall vibration level at the horizontal sensor, Engineering will evaluate the frequency spectrum for each test. Review of pump failure modes with the manufacturer has determined that increases in vibration amplitude at shaft speed and plunger cycling frequency will give early indication of a degrading condition. Furthermore, the manufacturer has concluded that there is no credible failure mechanism for the pump that would manifest itself in such a way that this level of monitoring would not detect failure.
Compliance with IWP vibration measurement requirements would be a hardship without a compensating increase in the level of quality and safety pursuant to 10 CFR 50.55a(a)3(ii), with the hardship being the unit power reduction that would be required in order to correct the malfunctioning vibration sensor.
2.2 Licensees Proposed Alternative Testing (as stated)
The SSF RC Makeup Pump will be tested in accordance with IWP requirements except for the stated location of the vibration measurement point. Rather, vibration will be monitored on the pump inboard bearing in the horizontal direction that is perpendicular to the crankshaft and parallel to the line of plunger travel. This alternative will only be utilized until the next power reduction that would accommodate repair to the pump outboard bearing probe in the vertical direction.
3.0 EVALUATION The ASME Code,Section XI (1986 Edition) requires an inservice test be run on the SSF RC makeup pump every 3 months during normal plant operation. Specifically, paragraph IWP-4510 requires that at least one displacement vibration amplitude (peak-to-peak) be read during each test. Paragraph IWP-4510 further specifies for reciprocating pumps that the location of the probe shall be on the bearing housing of the main pump drive shaft, approximately perpendicular to both the shaft and the line of plunger travel.
To measure the pump vibration during the Code tests, the licensee has permanently mounted two vibration sensors on the SSF RC makeup pump bearing housings. The pump outboard bearing probe is in the vertical direction (perpendicular to the crankshaft and perpendicular to the line of plunger travel) and the pump inboard probe is in the horizontal direction (perpendicular to the crankshaft and parallel to the line of plunger travel). Since the SSF RC makeup pump is located inside containment and is inaccessible during plant operations, the leads attached to the vibration sensors are routed through a containment penetration.
The pump outboard bearing vertical vibration probe is used by the licensee to meet the requirements in paragraph IWP-4510 for reciprocating pumps. During an extended pump run on March 8, 2002, the pump outboard bearing vertical vibration was found to be erratic. After a detailed engineering analysis of the vibration data and consultation with the pump manufacturer (APV Gaulin), the licensee concluded that there is no known machinery defect that would cause the erratic vibration signature. In addition, other pump parameters (the inboard bearing horizontal vibration value, discharge pressure, flow) remained steady and consistent with past pump performance. Vibration signals recorded during the same test period showed erratic readings by the vertical sensor while the horizontal sensor supplied a steady vibration signal.
Such significant changes in the pump vertical vibration instrument readings would likely be observed to some degree in the pump inboard bearing horizontal vibration instrument readings if the pump were degrading.
As an alternative to the ASME Code requirement, the licensee proposed to test the SSF RC makeup pump in accordance with IWP requirements except for the stated location of the vibration measurement point. Vibration will be monitored on the pump inboard bearing in the horizontal direction that is perpendicular to the crankshaft and parallel to the line of plunger travel. In addition to reviewing acceptability of the overall vibration level at the horizontal sensor, the licensees engineering staff will also evaluate the frequency spectrum for each test.
In the licensees review of the pump failure modes with the manufacturer, it was determined that increases in vibration amplitude at shaft speed and plunger cycling frequency will give early indication of a degrading condition. Furthermore, the manufacturer has concluded that there is no credible failure mechanism for the pump that would manifest itself in such a way that this level of monitoring would not detect failure. This alternative will only be utilized until the next power reduction that would accommodate repair to the pump outboard bearing probe in the vertical direction.
Compliance with ASME Code vibration measurement requirements would result in a hardship due to the location of the malfunctioning vibration sensor (inside the containment building biological shield wall). A unit power reduction from 100 percent to approximately 20 percent would be required to enter containment and correct the problem. The power reduction is necessary to reduce the radiation field that makes the equipment inaccessible at full power.
Based on the above information, the staff finds that compliance with the Code test for vibration with the probe approximately perpendicular to both the shaft and the line of plunger travel would necessitate reducing unit power to permit replacing the defective sensor and would, thus, cause hardship without compensating increase in level of quality and safety. The licensees proposed alternative will provide reasonable assurance of operational readiness of the pump until the next power reduction in which the repair or replacement of the sensor can be completed.
4.0 CONCLUSION
Based on the review of information provided by the licensee, the staff concludes that compliance with Code-required test for the SSF RC makeup pump would result in hardship without a compensating increase in the level of quality and safety. On this basis, the licensees proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) until the next power reduction in which a repair or replacement of the sensor can be completed.
Principal Contributor: J. Strnisha Date: May 6, 2002
Oconee Nuclear Station cc:
Ms. Lisa F. Vaughn Legal Department (PBO5E)
Duke Energy Corporation 422 South Church Street Charlotte, North Carolina 28201-1006 Anne W. Cottingham, Esquire Winston and Strawn 1400 L Street, NW Washington, DC 20005 Manager, LIS NUS Corporation 2650 McCormick Drive, 3rd Floor Clearwater, Florida 34619-1035 Senior Resident Inspector U. S. Nuclear Regulatory Commission 7812B Rochester Highway Seneca, South Carolina 29672 Mr. Henry Porter, Director Division of Radioactive Waste Management Bureau of Land and Waste Management Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201-1708 Mr. Michael A. Schoppman Framatome ANP 1911 North Ft. Myer Drive Suite 705 Rosslyn, VA 22209 Mr. L. E. Nicholson Compliance Manager Duke Energy Corporation Oconee Nuclear Site 7800 Rochester Highway Seneca, South Carolina 29672 Ms. Karen E. Long Assistant Attorney General North Carolina Department of Justice P. O. Box 629 Raleigh, North Carolina 27602 Mr. C. Jeffrey Thomas Manager - Nuclear Regulatory Licensing Duke Energy Corporation 526 South Church Street Charlotte, North Carolina 28201-1006 Mr. Richard M. Fry, Director Division of Radiation Protection North Carolina Department of Environment, Health, and Natural Resources 3825 Barrett Drive Raleigh, North Carolina 27609-7721 Mr. Peter R. Harden, IV VP-Customer Relations and Sales Westinghouse Electric Company 6000 Fairview Road 12th Floor Charlotte, North Carolina 28210