ML18153C506
| ML18153C506 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 01/24/1991 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.147, RTR-REGGD-1.147 90-797, NUDOCS 9101290334 | |
| Download: ML18153C506 (6) | |
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VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 January 24, 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 OUTSIDE RECIRCULATION SPRAY PUMP INSERVICE TESTING RELIEF REQUEST Serial No.
NO/ETS/R2 Docket Nos.
License Nos.90-797 50-280 50-281 DPR-32 DPR-37 The Outside Recirculation Spray Pumps are currently tested on a quarterly basis per the requirements of Section XI, Subsection IWP. These pumps are deep draft pumps and the pump pits are maintained dry. ASME/ANSI OM-1987, Part 6, "lnservice Testing of Pumps and Valves in Light Water Reactor Power Plants" states in Section 5.5 that, "Pumps lacking required fluid inventory, (e.g., pumps in dry sumps) need not be tested in accordance with this Part every three months. These pumps shall be tested at least once every two years except as provided in paragraph 5.4.
The required fluid inventory shall be provided during this test."
It is requested that the frequency of testing be changed for the Outside Recirculation Spray Pumps from quarterly to at least once every two years as allowed by ASME/ANSI OM-1987, Part 6. Regulatory Guide 1.147, Revision 8, November 1990, lists Section ASME Code Case N-465, "Alternative Rules for Pump Testing,Section XI,.
Division 1" as being generally accceptable to the NRC staff for implementation in the inservice inspection of light-water-cooled nuclear power plants. Code Case N-465 states that, "It is the opinion of the Committee that ASME/ANSI OM-1987, Part 6, through the 1987 Addenda, may be used for pump testing in lieu of Subsection IWP."
In addition to the change in test frequency, it is also requested that the test duration be modified so the recirculation spray pumps are only run for two minutes before the Section XI variables are measured. The recirculation spray pump test loop at Surry contains a small volume of water.
This limited volume of water will increase in temperature if the pump is run too long, which can can lead to an excessive pressure in the test loop. Fortunately, due to this small volume of water, hydraulic parameters stabilize quickly and the five minute stabilization period as required by Subsection IWP is not necessary to achieve repeatable test results.
9101?90~~4 910124
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The supporting technical basis is provided in the attached Relief Requests, numbered P-4 for both Units 1 and 2.
If you require additional information regarding these relief requests, please contact us.
Very truly yours, J~,
W. L. Stewart Senior Vice President - Nuclear Attachments cc:
U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. W. E. Holland NRG Senior Resident Inspector Surry Power Station
RELIEF REQUEST P-4 System:
Recirculation Spray Pump(s):
1-RS-P-2A 1-RS-P-2B Class 2
Section XI Code Requirements For Which Relief Is Requested
- 1. An inservice test shall be run on each pump nominally every 3 months during normal plant operation.
- 2. Each pump shall be run at least five minutes under conditions as stable as the system permits prior to measuring the test quantities.
- 3. Measure inlet pressure and differential pressure.
Basis For Request
- 1. The outside recirculation pumps take suction from the containment sump and discharge to the containment spray arrays.
To test these deep draft pumps, the pump pit and the recirculation test loop must be filled with primary grade water and vented.
The filling and venting process takes approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.
After the test is completed, the pump pit and recirculation piping must be slowly drained to avoid flooding the basement.
Testing is the only source of operational based degradation for the pumps.
They are also maintained dry and therefore are not subject to normal corrosion or fouling.
Considering the complexity of testing these pumps described above, the exposure to degradation caused by frequent testing and the dry state in which the pumps are maintained, there is no compensating increase in safety achieved by testing these pumps every three months.
This position is supported by ANSI/ASME OM (Part 6), An American Standard In-Service Testing of Pumps, Paragraph 5.5, which states, "Pumps lacking required fluid inventory, (e.g.,
pumps in dry sumps) need not be tested in accordance with this Part every 3 months.
These pumps shall be tested at least once every 2 years except as provided in para. 5.4.
The
- required fluid inventory shall be provided during this test."
3-15 S1PV-4R4 Rev. 4, Updated January 15, 1991
RELIEF REQUEST P-4 (Cont.)
Paragraph 5.4 discribes the testing frequency of pumps in systems which are declared inoperable or not required for service.
- 2. The test loop for these pumps contains a small volume of water.
A four inch test recirculation line branches off the ten inch pump discharge line a short distance from the pump.
The recirculation line discharges into the pump pit which is a cylinder approximately 50 feet deep and two feet in diameter.
Because of the small volume in the test loop, the hydraulic parameters stabilize quickly.
Therefore, a five minute stabilization period is not necessary to achieve repeatable test results.
In addition, if the pump is run for too long of a period, the water will heatup due to the limited water volume.
This heatup can lead to excessive pressures in the test loop.
- 3. Inlet pressure instrumentation is not installed.
However, the outside recirculation spray pumps obtain flow through a suction bell immersed in the pump casing.
During testing, a casing level is established by filling the casing with PG water to provide NPSH to the pump.
Flow is recirculated through the pump, recirculation line, and back to the casing.
By establishing a casing level and maintaining it constant for the tests, any variation in pump differential pressure would be directly indicated by monitoring pump discharge pressure.
The static inlet pressure will be calculated and subtracted from the discharge pressure to yield a differential pressure.
Alternate Testing Proposed These pumps will be flow tested on their recirculation paths at least once every two years.
Maintaining a constant pump casing water level from test to test by filling the casing with PG water will yield the same suctirin pressure for each test.
The static inlet pressure will be calculated and subtracted from the discharge pressure to.yield a differential pressure.
After a two minute stabilization period, static inlet pressure, differential pressure as determined from the calculated static inlet pressure and measured discharge pressure, flow rate and vibration measurements will be taken.
3-15a S1PV-4R4 Rev. 4, Updated January 15, 1991
). ~*
RELIEF REQUEST P-4 System:
Recirculation Spray Pump(s):
2-RS-P-2A 2-RS-P-2B Class..
2 Section XI Code Requirements For Which Relief Is Requested
- 1. An inservice test shall be run on each pump nominally every 3 months during normal plant operation.
- 2. Each pump shall be run at least five minutes under conditions as stable as the system permits prior to measuring the test quantities~
- 3. Measure inlet pressure and differential pressure.
Basis For Request
- 1. The outside recirculation pumps take suction from the containment sump and discharge to the containment spray arrays.
To test these deep draft pumps, the pump pit and the recirculation test loop must be filled with primary grade water and vented.
The filling and venting process takes approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.
After the test is completed, the pump pit and recirculation piping must be siowly drained to avoid flooding the basement.
Testing is the only source of operational based degradation for the.pumps.
They are* also maintained dry and therefore are not subject to normal corrosion or fouling.
Considering the complexity of testing these pumps described above, the exposure to degradation caused by frequent testing and the dry state in which the pumps are maintained, there is no compensating increase in safety achieved by testing these pumps every three months.
This position is supported by ANSI/ASME OM (Part 6), An American Standard In-Service Testing of Pumps, Paragraph 5.5, which states, "Pumps lacking required fluid inventory, (e.g.,
pumps in dry sumps) need not be tested in accordance with this Part every 3 months.
These pumps shall be tested at least once every 2 years except as provided in para. 5.4.
The required fluid inventory shall be provided during this test."
3-15 S2PV-4R2 Rev. 2, Updated January 15, 1991
RELIEF REQUEST P-4 (Cont.)
Paragraph 5.4 discribes the testing frequency of pumps in systems which are declared inoperable or not required for service.
- 2. The test loop for these pumps contains a small volume of water.
A four inch test recirculation line branches off the ten inch pump discharge line a short distance from the pump.
The recirculation line discharges into the pump pit which is a cylinder approximately 50 feet deep and two feet in diameter.
Because of the small volume in the test loop, the hydraulic parameters stabilize quickly.
Therefore, a five minute stabilization period is not necessary to achieve repeatable test results.
In addition, if the pump is run for too long of a period, the water will heatup due to the limited water volume.
This heatup can lead to excessive pressures in the test loop.
- 3. Inlet pressure instrumentation is not installed.
However, the outside recirculation spray pumps obtain flow through a suction bell immersed in the pump casing.
During testing, a casing level is established by filling the casing with PG water to provide NPSH to the pump.
Flow is recirculated through the pump, recirculation line, and back to the casing.
By establishing a casing level and maintaining it constant for the tests, any variation in pump differential pressure would be directly indicated by monitoring pump discharge pressure.
The static inlet pressure will be calculated and subtracted from the discharge pressure to yield a differential pressure.
Alternate Testing Proposed These pumps will be flow tested on their recirculation paths at least once every two years.
Maintaining a constant pump casing water level from test to test by filling the casing with PG water will yield the same suction pressure for each test.
The static inlet pressure will be calculated and subtracted from the discharge pressure to yield a differential pressure.
After a two minute stabilization period, static inlet pressure, differential pressure as determined from the calculated static inlet pressure and measured discharge pressure, flow rate and vibration measurements will be taken.
3-lSa S2PV-4R2 Rev. 2, Updated January 15, 1991