ML20199M013
| ML20199M013 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 11/26/1997 |
| From: | Hagan J ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GNRO-97-00112, GNRO-97-112, NUDOCS 9712020174 | |
| Download: ML20199M013 (22) | |
Text
- _ _ _ - - - _ - _ _ _ _ _ _ -
Entergy Opecations,Inc.
'i N
bso MS 39150 Tel 601437 6408 Fax 001437 2795 Joseph J. Hagen
-November 26, 1997 gjaga' ocana as nauw stcon U.S. Nuclear Regulatory Commission Mail Station P137 Washington, D.C. 20555 Attention:
Document Control Desk
Subject:
Grand Gulf Nuclear Station Unit i Docket No. 50-416
. License No. NPF-29 Relief Requests for Inservice Testing Program GNRO-97/00112 Gentlemen:
Grand Gulf Nuclear Station will begin the second interval for Inservice Testing (IST) on December 1,1997. The new program complies with the 1989 edition of the ASME Boiler and Pressure Vessel Code,Section XI. This submittal requests relief from certain requirements of this edition of the Code in accordance with 10 CFR 50.55a(f)(5) and (6).
This includes 7 relief requests (5 fo. pumps,2 for valves) which will be included in the IST program.
Should you have any questions or need any additionalinformation, please contact Bill Brice at 601-437-6556.
~ Yours truly,
/
JJH!WBB attachment ec:
(See Next Page) 971 6 174 971126 *
.P ADOCK 0300041g PDRw I!!EElltHI,Mlt vn UlGusa
_ -_ _ __a
GNRO-97/ 00112 Page 2 of 2 cc:
Ms. J. L. Dixon-Herrity, GGNS Senior Resident (w/a)
Mr. L. J. Smith (Wise Carter) (w/a)
Mr. N. S. Reynolds (w/a)
Mr. H. L. Thomas (w/o)
Mr. E. W. Merschoff (wla)
Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 Mr. J. N. Donohew, Project Manager (w/2)
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 13H3 Washington, D.C. 20555
L*.
L' PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO. 1 OF4 VALVE RELIEF REQUESTS VALVE RELIEF REQUEST NO.: VRR GEN-01 System:
Various Component: E38F002A E38F0028 E38F003A E38F003B E51F079 E51F081 Ceteaory:
C Erz Various Function:
Various imoractical Test Reauirements:
Check valves shall be exercised nominally every 3 months (OM Part 10,4.3.2.1) except as provided by OM Part 10,4.3.2.2,4.3.2.3,4.3.2.4, and 4.3.2.5. During operation each check valve shall be exercised or examined in a manner that verifies obturator travel to the full-open, or partially open position required to fulfillits function (OM Part 10,4.3.2.2(a)). As an attemative to the testing in OM Part 10,4.3.2.4(a) or 4.3.2.4 (b), disassembly every refueling outage to ve-ify operability of check valves may be used (OM Part 10,4.3.2.4(c)).
Basis For Relief:
Testing of check valves generally requires knowledge of the position of the disk or verification of the amount of flow passing through the valve. However, for some check valves the disk position or required flow values can not be ascertained, in some cases, establishing required flow for testing purposes may result in damage to plant equipment or is not possible.
Disassembly testing may be used to determine tnat a valve's disk will full-stroke exe,cise open or to verify closure capability, as allowed by OM Part 10,4.3.2.4(c). Due to the scope of disassembly testing, the personnel hazacds involved, planned maintenance activities and system operating restrictions, all valves requiring disassembly and inspection may not be available for such testing during each reactor refueling outage. Generic Letter 89-04 provides approval of Code deviations that are consistent with the NRC positions of the Generic Letter, Attachment 1. This relief request meets the guidelines of Position 2 of the Generic Letter for implementation of a check valve sample disassembly and inspection program.
Alternative Testina:
Where it is determined that it is burdensome to disassemble and inspect all applicab'e valves each refueling outage, the following Sample Disassembly and Inspection Plan for groups of identical valves in similar applications is employed. The requirements for grouping in occordance with this plan are explained below:
The Sample Disassembly and Inspection Plan involves grouping valves of similar design, application and servic.e conditions, and testing one valve in each group during each refueling outage. The giouping technique requires that for each valvc in a group the following, as a minimum, be considered: design, manufacturer, size, model number, service, orientation, and materials of construction. Valve group size is limited to four valves, maximum.
When disassembly testing is performed valves shall be tested as follows:
1
PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO. 2 OF 4 VALVE RELIEF REQUESTS VALVE RELIEF REQUEST NO.: VRR GEN-01 (a) At each disassembly it must be verified that the disassembled valve is capable of full-stroking and that the internals of the valve are structurally sound (no loose, corroded, worn, or failed parts). If the disassembly is to verify the full-stroke capability of the valve, the disk is to be manually full-stroke exercised. Full-stroke motion of the obturator is to be reverified immediately prior to completing reassembly. Check valves (e.g., spring loaded lift check valves, or check valves with the obturator supported from the bonnet) that have their obturator disturbed before full-stroke motion is ve:ified, are to be examined to determine if a condition exists that could prevent full opening or reclosure of the obturator.
(b) A different valve of each group is required to be disassembled, inspected, and manually full-stroke exercised at each successive refueling outage, until the entire group has been tested. At least one valve from each group is to be disassembled and examined at each refueling outage.
Once this is completed, the sequence of disassembly must be repeated. All valves in each group are to be disassembled and examined at least once every six years.
(c) Before return to service, valves that were disassembled for examination or that received maintenance that could affect their performance, are to be exercised full-or part-stroke, with flow, if practicable.
(d) If disassembly is the only means of verifying the valves full stroke, the check valve should be partially stroked quarterly or during cold shutdown, if practicable.
(e) If the disassembled valve is not capable of being full-stroke exercised or there is binding or failure of valve internais, the remaining valves in that group must also be disassembled, inspected, and manually full-stroke exercited during the same outage.
t
PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO.
3 of 4 VALVE RELIEF REQUESTS VALVE RELIEF REQUEST NO.: VRR B21-01 System:
B21 Nuclear Boiler System Component: 821F041A B21F0418 B21F041C B21F041D B21F041E B21F041F B21F041G B21F041K B21F047A B21F047C B21F047D B21F047G B21F047H B21F047L B21F051A B21F0518 B21F051C B21F051D B21F051F B21F051K Cateaory:
C,B Class:
1 Function:
The MSRVs are closed for reactor coolant system boundary. The MSRVs open for overpressure protection and for Automatic Depressurization System (ADS) function (821F041D, F & K; B21F047A & L; B21F051 A, B & C).
Impractical Test Reauirements:
Category B valves are required to be tested to the safety position at least once every 3 months in accordance with ASME OM Part 10,4.2.
Basis For Relief:
Opening these valves during power operation would cause unnecessary transients in the reactor coolant system and require needless operation of the suppression pool cooling system. Cycling of these valves during power operation significantly increases the risk of creating undesired seat leakage and/or escalating deterioration of valve seating surfaces due to such leakage. The initiation and continuation of MSRV seat leakage increases the amount of valve contamination and may necessitate extensive decontamination efforts on the valve prior to testing. The creation of extensive seat leakage would also require unnecessary operation of the suppression pool cooling system. In addition to the potential seat leakage issues, there is the possibility of an MSRV sticking open during testing at power thereby creating a LOCA. Although an inadvertently yi stuck open MSRV is an analyzed event in the UFSAR, it is not the intent for testing to increase the Y
risk of initiating such a casualty.
In NUREG-1482, Guidelines for Inservice Testing at Nuclear Power Plants (April,1995) Section 4.3.4, the NRC Staff recommended reducing the number of challenges to the dual function Automatic Depressurization System (ADS) valves in order to reduce their failure rate. Since both ADS and non-ADS MSRVs perform dual function service, the same recommendation for reduction in the number of challenges to dual function operation is implied by inference for the non-ADS
- MSRVs. The Staff also noted that the ASME OM Committee was reviewing the categorization of safety and relief valves as Category C, rather than Category B,C, and stated that if the OM Committee determines the;e valves are Category C only, meeting the code requirements for Category A or B wi;i be unnecessary.
The ASME OM Committee and Board on Nuclear Codes and Standaros approved a change to the ASME Operation and Maintenance (OM) Code Section ISTC 1.2, which adds the following statement:
" Category A and B safety and relief valves are excluded from the requirements of ISTC 4.1,
" Valve Position Verification" and ISTC 4.2, " Inservice Exercising Test."
PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO.
4 of 4 VALVE RELIEF REQUESTS VALVE RELitEF REQWST NO.: VRR-B2101 Although this approval does not address the categorization of safety and reliaf valves noted in NUREG-1482, it accomplishes the same objective, which is to limit inserdce exercising of the valves when they are installed in the plant. By excluding the safety and relief valves from Sections ISTC 4.1 and ISTC 4.2, the OM Committee has in fact determined that these valves are only subject to Category C testing. Although this approvalis to OM Code-1995, it addresses concoms which have existed since Section XI to the ASME Boiler and Pressure Vessel Code was originally issued. The '95 OM Code requires safety and relief valves to meet the testing requirements of Appendix 1. Similarly OMa-1988 requires safety and relief valves to meet the testing requirements of OM Part 1. Thus, it is reasonable to apply the OM Committee's determination (which was approved in NUREG-1482) to OMa-1988. Therefore, Category B testing and valve position verification is not required.
Per OM-1987 Part 1, para 3.4.1.1(d), the MSRVs are required to be stroked at reduced system pressure to verify open and close capability. As noted above, valve stroking on live steam is not desirable. Additionally, it is GGNS's opinion that the purpose of this Part 1 requirement is to verify correct installation of the air and electrical systems associated with the relief mode operation of the MSRV. Such confirmation can be ac.:omplished without physically lifting the valve disk from the nozzle seat. Thus, GGNS believes that a de-coupled actuator test, as described in the Altemative Testing below, is sufficient to perform this installation verification and will provide an acceptable uvel of quality and safety Alternative Testina:
The MSRVs will be exercised to the open position by manual actuation of the valve control system during setpoint testing and certification activities on the test bench. The response time of MSRV actuation is measured and recorded during certification activities. This response time is well below 1 second, and corrective actions are required should the response time be exceeded.
During installation in the plant following setpoint testing and certification, the va:ve stems will be uncoupled from their actuators. The air actuators will be exercised (without lifting the valve stems) to verify control signal continuity and proper air system configuration, following which the actuatorr will be re-coupled to the valve stems.
6 4
PROGRAM PLAN NO. GGNS-M-189.1 i
REVISION NO. 8 PAGE NO. 1 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PR R-E12-01 System E12 Residual Heat Removal System ComponcDu E12C003A E12C003B E12C003C Tyge.1 Centrifugal Cisss:
2 Function These jockey pumps operate cor;tinuously during normal operation to keep the main Residual Heat Removal (RHR) pump discharge piping full of water.
Impractical Test Reauirements:
OMa-1988 Part 6, para 5.2:
An inservice test shall be conducted with the pump operating at specified test reference conditions. The test parameters shown in Table 2 shall be determined and recorded as directed in this paragraph.
OMa-1988 Part 6, para 5.2(b):
The resistance of the r
.m shall be varied until the flow rate equals the reference value. The pressure shall then be determined and compared to its reference value. Altemately, the flow rate can be varied until the pressure equals the reference value and the flow rate shall be determined and compared to the reference flow rate value.
OMa-1988 Part 6, Table 2:
Differential Pressure is a required test paramemr for centrifugal pumps.
OMa-1988 Part 6 Table 2:
Flow Rate is a required test parameter for pumps.
Basis For Relief:
These jockey pumps are required to operate whenever their respective RHR trains are in the operable condition. As such, the pumps perform continuous duty on a recirculation line and provide makeup as needed.
There is no practical means of measuring the flow rate of these pumps, nor have attempts with ultrasonic flow measurement been successful. As such, flow rate can not be measured with the current system configuration.
Even though pressure taps exist where pump suction and discharge pressure can be measured, the pump-differential-pressure information provided would be of little use for analyzing the hydraulic condition of the jockey pump without being able to establish a known flow condition.
Additionally, jockey pump pressure is continuously monitored, and an annunciator alarms in the Control Room if the respect;ve discharge header pressure drops below a preset value. Also, GGNS Technical Specification Section SR 3.5.1.1 requires verification every 31 days that the respective header is filled with water by venting the piping at the high point vents. Such continuous monitoring and monthly venting will provide waming if a jockey pump ic failed, or that system leakage has exceeded the capacity of the jockey pump. Since failure of the pump to produce adequate head would be identified by an annunciator in the Control Room, measurement
. of the actual pump differential pressure will not provide any additional benefit to warrant the
I t
PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO. 2 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR-E12-01 system manipulation necessary to measure the pump differential pressure directly. Finally, +.Jch actions are occurring at a periodicity more fra;uent than the quarterly periodicity mandated by OMa-1988 Part 10.
Since these pumps perform continuous duty, any physical degradation of the pumps will be more
- readily identified by the measurement and evaluation of the quarterly vibration data. As such, GGNS believes that t.dequate means exist to assess the hydraulic condition and operational readiness of these pumps without necessitating the measurement of flow rate or differential pressure.
Alternative Testina:
No alternative testing is considered necessary. Vibration will continue to be measured on these pumps as required by ASME OMa 1988, Part 6.
PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO. 3 - OF 16 PUMP RELIEF REQUESTS
. PUMP RELIEF REQUEST NO.: PRR-E21-01 System E21 Low Pressure Core Spray System Component: E21C002 Ty.211 Centrifugal C!ese 2
Fungtion This jockey pump operates continuously during normal operation to keep the main Low Pressure Core Spray (LPCS) pump discharge piping full of water.
ImDractical Test Reauirements:
1 OMa 1988 Part 6, para 5.2:
An inservice test shall be conducted with the pump operating at specified test reference conditions. The test parameters shown in Table 2 shall be determined and recorded as directed in this paragraph.
OMa 1988 Part 6, para 5.2(b):
The resistance of the system shall be varied ur.til the flow rate equals the reference value. The pressure shall then be determined and compared to its reference value. Attemately, the flow rate can be varied until the pressure equals the reference value and the flow rate shall be determined and compared to the reference ficu rate value.
OMa-1988 Part 6, Table 2:
Differential Pressure is a required test parameter for centrifugal pumps.
OMa-1988 Part 6, Table 2:
Flow Rate is a required test parameter for pumps.
Basis For Relief:
This jockey pump is required to operate whenever the LPCS system is in the operable condition.
As such, the pump performs continuous duty on a recirculation line and provides makeup as needed.
There is no practical means of measuring the flow rate of this pump, nor have attempts with ultrasonic flow measurement been successful. As such, flow rate can not be measured with the current system configuration.
Even though pressure taps exist where pump suction and discharge pressure can be measured, the pump-differential-pressure information provided would be of little use for analyzing the hydraulic condition of the jockey pump without being able to establish a known flow condition.
Additionally, jockey pump pressure is continuously monitored, and an annunciator alarms in the Control Room if the discharge header pressure drops below a preset value. Also, GGNS Technical Specification Section SR 3.5.1.1 requires verification every 31 days that the header is filled with water by venting the piping at the high point vents. Such continuous monitoring and monthly venting will provide waming if the jockey pump has failed, or that system leakage has exceeded the capacity of tho jockey pump. Since failure of the pump to produce adequate head would be identified by an annunciator in the Control Room, measurement of the actual pump differentia' pressure will not provide any additional benefit to warrant the system manipulation
PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO. 4 __ OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR E21-01 necessary to measure the pump differential pressure directly. Finally, such a-tions are occurring at a periodicity more frequent than the quarterly periodicity mandated by OMa 1988 Part 10.
Since this pump performs continuous duty, any physical degradation of the pump will be more readily. identified by the measurement and evaluation of the quarterly vibration data. As such, GGNS believes that adequate means exist to assess the hydraulic condition and operational readiness of this pump without necessitating the measurement of flow rate or differential pressure.
Alternative Testina:
No attemative testing is considered necessary. Vibration will continue to be measured on this pump as required by ASME OMa-1988, Part 6.
W
PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO. 5 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PR R-E22 System E22 High Pressure Core Spray System Component: E22C003
.ly.Re_1 Centrifugal Class: -
2 Funct!on This jockey pump operates continuously during normal operation to keep the main High Pressure Core Spray (HPCS) pump discharge piping full of water, impractical Test Reauirements:
OMa 1988 Part 6, para 5.2:
An inservice test shall be conducted with the pump operating at specified test reference conditions. The test parameters shown in Table 2 shall be determined and recorded as directed in this paragraph.
OMa-1988 Part 6, para 5.2(b):
The resistance of the system shall be varied until the flow rate equals the reference value. The pressure shall then be determined and compared to its reference value. Altemately, the flow rate can be varied until the pressure equals the reference va!ue and the flow rate shall be determined and compared to the reference flow rate value.
OMa-1988 Part 6, Table 2:
Differential Pressure is a required test parameter for centrifugal pumps.
OMa-1988 Part 6, Table 2:
Flow Rate is a required test parameter for pumps.
Basis For Relief:
This jockey pump is required to operate whenever the HPCS system is in the operable condition.
As such, the pump performs continuous duty on a recirculation line and provides makeup as needed.
There is no practical means of measuring the flow rate of this pump, nor have attempts with ultrasonic flow measurement been successful. As such, flow rate can not be measured with the current system configuration.
Even though pressure taps exist where pump suction and discharge pressure can be measured, the pump-differential-pressure information provided would be of !!ttle use for analyzing the hydraulic condition of the jockey pump without being able to establish a known flow condition.
Additionally,' jockey pump pressure is conti. aously monitored, and an annunciator alarms in the Control Room if the discharge header pressure drops below a preset value. Also, GGNS Technical Specification Section SR 3.5.1.1 requires verification every 31 days that the header is filled with water by venting the piping at the high point vents. Such continuous monitoring and monthly venting will provide waming if the jockey pump has failed, or that system leakage has exceeded the capacity of the jockey pump. Since failure of the pump to produce adequate head i
would be identified by an annunciator in the Control Room, measurement of the actual pump differential pressure will not provide any additional benefit to warrant the system manipulation
l t
PROGRAM PLAN NO. GGNS-M-189.1 PEVISION NO. 8 PAGE NO. 6 OF 16 PUMF RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR-E22 01 necessary to measure the pump differential pressure directly. Finally, such actions are occurring at a periodicity more frequent than the quarterly periodicity mandated by OMa 1988 Part 10.
Since this pump performs continuous duty, any physical degradation of the pump will be more readily identified by the measurement and evaluation of the quarterly vibration data. As such, GGNS believes that adequate means exist to assess the hydraulic condition and operational readiness of this pump without necessitating the measurement of flow rate or differential pressure.
Alternative Testina:
No attemative testing is considered necessary. Vibration will continue to be measured on this pump as required by ASME OMa-1988, Part 6.
i
1 PROGRAM PLAN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO. 7 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR-P75-01 System P75 Standby Diesel Generator System Component: P75C002A P75C002B Type:
Centrifugal Class:
3 Function Transfer fuel oil from the storage tank to the day tank to satisfy the seven day fuel oil supply requirement for the standby diesel generators.
Impractical Test Requirements:
OMa-1988 Part 6, para 5.2:
An inservice test shall be conducted with the pump operating at specified test reference conditions. The test parameters shown in Table 2 shall be determined and recorded as directed in this paragraph.
OMa 1988 Part 6, para 5.2(b):
The resistance of the system shall be varied until the flow rate equals the reference valuo. The pressure shall then be determined and compared to its reference value. Alternately, the flow rate can be varied until the pressure equals the reference value and the flow rate shall be determined and compared to the reference flow rate value.
OMa-1988 Part 6, Table 2:
Differential Pressure is a required test parameter for centrifugal pumps.
OMa 1988 Part 6, Table 2:
Vibration is a required test parameter for pumps.
Basis For Relief:
Fuel Oil Transfer System Arrangement The physical locations of the Standby Diesel Generator (SDG) fuel oil transfer pumps are at the bottoms of the respective SDG fuel oil storage tanks, which are buried in the ground outside the diesel generator bays. The pump design specifies each pump to be submerged in the fuel oil with the 3/4 inch discharge piping nsing from the pump, through the fuel oil, and out the top of the tank approximately 13 feet above the pump discharge. Approximately 1 foot above the tank, the 3/4-inch piping widens to 2 inch diameter pipe. A 2-inch check valve near the expansion fitting prevents fuel oil in the transfer piping from draining back into the storage tank. The 2-inch piping rises approximately 15 to 16 inches, elbows twice during the next 29-inch run, and then flanges 20 inches later prior to entering the ground. Since good engineering design requires a minimum of 5 pipe diameters both upstream and downstream for source pressure measurement, the only adequate location for a pressure instrument tap within this exposed piping between the top of the storage tank and the ground entry point is the 29-inch run. However, as the following justification will identify, locating a pressure tap in this exposed pipe run will not provide a significant increase in the usefulness of a discharge pressure measurement.
The 2-inch piping then runs underground to the respective SDG room, and rises above ground level enroute to the day tank. Shortly after the 2-inch piping exits the ground in the respective SDG room, but prior to the SDG fuel oil strainer, is the pressure instrument tap used to measure
PROGRAM PLAN NO. GGNS M 189.1 REVISION NO. 8 PAGE NO. 8 OF 16 PUMP REllEF REQUESTS PUMP RELIEF REQUEST NOc PRR P75-01 the transfer pump discharge pressure. This pressure instrument tap is the current location for measurement of the pump discharge pressure, and is located approximately 12 feet above the 3/4 to 2 inch expansion fitting (24 feet rbove the actual pump dischargo), and approximately 10 feet bebw the highest piping elevation to the day tank.
As noted above, the 3/4 inch diameter discharge piping run and elevation rise are both approximately 13 feet. The 2 inch diameter fuel oil transfer piping run is approxenately 295 feet
('B' DG) and 360 feet ( A' DG), and a total rise of 22 feet before entering the top of the respective SDG day tank.
i For both trains of the SDG fuel oil transfer piping the only isolat!on valve is located,n the highest elevation run of the 2 inch pipe shortly upstream of where the pipe enters the day tank.
Differential Pressure Discussion Between August 1994 and July 1997,15 inservice tests were performed ano documented for trendinc purposts for the 1P75C002A pump. [For brevity, only test data from the 'A' pump is given. ;he 'B' pump exhibits similar results.) For these 15 tests, the pressure readings at the current instrument location ranged from 3.96 to 5.51 psig, which obviously does not reflect the true discharge pressure of the pump. The suction pressure, which is calculated utilizing the level of the storage tank, has ranged from 3.43 to 3.67 psig during these tests. The calculated diffe'ential pressure utilizing only the discharge instrument and suction pressure has rangeo from 0.34 to 2.04 psid. This calculated differential pressure is cic3rly not represer,tative of the actual pump differential pressure.
I Based on a system resistance calculation, these pumps experience approximately 68% to 70% of the total head loss in the 3/4-inch piping. Thus, only approximately 30% of the actual pump dscharge pressure is measurable at the 3/4 to 2-inch reducer, From the reducer to 'he pressure instrument tap location, another 5 psi drop is experienced due to the elevation difference alone.
Although the actual pressure readings documented durir g the test period haalyzed have been in the range expected, the information has provided very little value as a pump-degradation tool.
The average measured discharge pressure over the analyzed tests is approximately 5.30 psig, with the average suction pressure being approximately 3.57 psig, thus the average differential pressure has been around 1,73 psid. As an attempt to make the differential pressure measursment a more practical pump performance indicator, a correction factor was calculated based on the respective SDG fuel oil system resistances. However, testing experience has indicated that ever the use of a correction factor has not increased the usefulness of the differential-pressure determinations for these pumps, as the following discussion will establid.
Tho system resistance is based on the flow rate, and therefore the correction factor utilized would need to be based on the system flow rate during the test. This would necessitate setting the flow rate at a fixed value (32.75 gpm being the current reference value), and detennining the pump different'ai pressure, OR setting the differential pressure and determining the flow rate. Both of these test methods are considered to be impractical for the following reasons:
(1) Flow rate is determined by measuring the day tank level change from the low-level alarm to the pump shutoff level, and dividing the change by the pump run time. As such, instantaneous
PROGRAM PLAN NO. GGNS-M 189.1 REVISION NO. 8 PAGE NO. 9 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR P75-01 flow measurement is not available to allow simple adjustment to establish a fixeo flow. There are no installed flowmeters or taps for measuring flow rate directly. Ultrasonic flow measurement attempts have proven to be inco'isistent when compared to the level change method. The current method for determination of flow rate meets the loop accuracy requirements mandated per Table 1 of OMa 1988 Part 6. Modification to install a flow meter solely for the purpose of providing instantaneous flow indication to allow establishment of a fixed flow rate is cicarly not the inient of OMa 1988 Part 6.
(2) Differential pressure is determined by a calculation of the measured discharge pressure plus the correction factor minue the suction pressure. The suction pressure is from a real time calculation based on the storage tank level measurement during pump run. To ensure fullloop accuracy, a Barton tube gauge (0-200 inches of water) is utilized to measure the discharge pressure, and thus requires a real time calculation to convert inches of water to psi. Thus, three calculations are required for each valve adjustment to establish a differential pressure. To utilize differential pressure as the fixed parameter, each sy. item adjustment to set the differential pressure to the reference value would necessitate the performance of these three calculations.
Each performance of these calculations adds time to the pump run duration and unnecessarily increases the potential for calculational error.
(3) The pump run is typically 810 minutes which, as noted above, will not allow for a fixed parameter adjustment during the pump run. Thus, the day tank would need to be drained to the low level for another pump run once the differential pressure is correctly adjusted. The breaker for the pump must be opened in order to drain the day tank to the low level alarm. Unnecessary cycling of component breakers solely for the purpose of performance testing is not desirable.
(4) The globe valve is the only available means of adjusting the system resistance to set either flow rate or differential pressure equal to its refe,ence value; however, adjusting the globe valve w,ll change the system resistance upon which the differential pressure correction factor is based.
The corresponding resistance factor for the position of the globe valve would need to be determine 1 to re-pe form the system resistance calculation, and could necessitate the performance of the system resistance calculation during each pump test depending upon the sensitivity of the valve's resistance factor versus valve position in either case, valve adjustment would add 6dditional uncertainty to the correction factor applied to the differential pressure measurements, which would further reduce the usefulness of the differential pressure as a pump perfonnance parameter.
(5) Evaluation of the inservice testing results for these pumps hcs shown that differential pressure mea urement is not providing any substantial benofit as a diagnostic tool for pump hydraulic perfo. mance.
The current differential pressure reference values for these pumps are 28.11 ('A') and 28.29 ('B')
psid. These refe,'ence values are based on a correction factors ! rom the system resistance at an average flow rate of approximately 33.0 gpm. f.vun though a different reference flow rate (32.75 gpm) has been established since the original differential pressure reference value was determined, there has been absolutely no change in the average differential pressure results fu the tests at the new flow reference value. If a new reference value is established based on a correction factor at 32.75 gom, the same test results would be averaged around the new correction facior beccuse of the very little variation between the measured suction and discharge
PROGRAM PLAN NO. GGNS-M-189.1 REVIS'ON NO. 8 PAGE NO.10 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR P75-01 pressures. However, establishing new correction factors or reference values would provide no additional benefit as noted below.
Per Table 3b of OMa-1988 Part 6, tho acceptance criteria can deviate from the reference value by as much as 10% (2.8 psi) before corrective action is necessary, in order to achieve a 2.8 psi drop in differential pressure, the measured discharge pressure would have to drop to approximately 1.2 to 2.4 psig since suction pressure remains fairly constant. The pressure drop due solely to the elevation difference between the pressure instrument location and the maximum elevation i
i experienced enroute to the day tank is approximately 4 psl. As such, flow would have to drop dramatically, and even cease, before the differential pressure ever came close to the lower required action value. Therefore, it has become clear that the only parameter which is currently i
providing any true representation of the pump hydraulic condition is the flow rate.
To make the measurement of the pump differential pressare a useful parameter for pump performance evaluation, it would be necessary to perform a modification to install the pump discharge pressure gage closer to the pump discharge. Such a modification is considered to r
represent an unusual hardship without a compensating increase in the level of quality and safety i
for the following reasons:
(a) Any modificr tion would rquire removal of the fuel oil transfer pump from the associated fuel oil storage tank to make the necessary modification.
(b) A direct sensing instrument at the discharge penetration elevation would be submerged in the fuel oil with the pump. For this application, a pressure transducer would be required in lieu of a pressure gage. Such an arrangement would necessitate the removal of the pump assembly from the storage tank every time the pressure transducer required calibration.
(c) If a pressure gage option were used with the tap location at the discharge of the pump, the least impact would be caused by routing the gage line along with the fuel cisenarge piping.
However, this option would require an additional modification to the existing discharge flange airangement at the top of the storage tank to allow the sensing line to penetrate the tank (any other penetration location would necessitate an entry nto the tank to disconnect the sensing line i
t whenever the pump is required to be pulled for planned or corrective maintenance.) Once this modification was performed, a correction factor will still need to be calculated to account for the elevation difference between the gage and the pump.
(d) The current test configuration allows the fuel oil transfer s'/r*em to be treated as a fixed-resistance system due to the negligible head loss between the current discharge measurerNnt location and the day tank, if a modification were performed to allow for more practical discharge pressure measurement, the system may no longer qualify as a fixed-reshtance system depending upon the modification performed. If such were the case, resistance adjustment would necessitate at least two pump runs per quarter as discussed above. The option does exist to keep the drain open on the day tank while the adjustment is made, and then the drain would be shut for the level measurement. This option, however, could significantly reduce the accuracy of the flow rate measurement due to the shorter pump run time and due to the need to measure the initial tank level while the pump is actually filling the tank instead of during a stable, no-flow condition.
(e) Safety related maintenance activities, such as the rernoval of this pump for any reason, are
PROGRAM PLAN NO. GGNS-M 189.1 REVISION NO. 8 PAGE NO.11 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR P75-01 expensive undertakings and involve risks associated with the disassembly of any piping system.
)
Performance of a modification requiring wch activities will significantly increase the cost burden.
(f) Working with fuel oil systems involves additional personnel and equipment safety hazards, which should be minimized whenever possible.
l (g) If the transducer option were installed, removal and reinstallation of the pump assembly would i
be necessary for calibration purposes. This would require additional testing to be performed on the system to ensure that the maintenance activity did not impact the hydraulic performance capability of the fuel oil transfer system. Such testing would require verification that the reference i
values of the pump hydraulic parameters were not affected. If a transducer arrangement were i
used, then revalidation of the referer.ce values would be required at the same periodicity as the instrument calibration. This is clearly not the intent of Part 6.
i (h) Finally, diesel-generator operability and availability could be adversely affected by an installation of any modification that would require multiple test runs of the fuel oil transfer pump or frequent storage tank entries for calibration purposes st. auld such instrumentation be installed.
l Vibration Discussion The physicallocation of each pump is at the bottom of the respective SDG fuel oil storage tank, which is buried in the ground outside the diesel generator bay. Due to the pumps being submerged, vibration measurements cannot be performed. Additionally, installation of permanently mounted transducers are considered impractical for the same reasons as discussed for pressure transducer installation impracticality. It should be noted that OMa 1988 Part 6, paragraph 4.6.4(a), requires vibration measurements to be performed on centnfugal pumps only if they have " accessible" pump bearing housings.
Alternative Testina:
As noted 8n the preceding discussion, the existing means of measuring pump differential pressure does not 1. ' ovide any useful information regarding the pump hydraulic condition that would not be readily apparent by a corresponding decrease in pump flow. For the fuel oil transfer system t
pump.s. the measurement or flow alone, with the following additional requirements, will provide an acceptable level of quality and safety while having minimal negative impact on diesel-generator operability and availability.
Before starting the pumps, adequate storage tank level will be ensured for pump NPSH reqdrements. The systems will be left in their normal alignment with no valves throttled. The day tanks wi!I be drained to a low level and then refilled using the associaud fuel oil transfer pump.
An average flow rate will be calculated and compared to its reference value in order to determine if any pump degradation is occurring. A lower" alert value"(not presently required per Table 3b of Part 6 for centrifugal pumps) of 93% of the reference flow value will be established for each of the pumps. If the measured flow rate f alls below this " alert value", then the analyses and evaluation actions required by Section 6 of OMa 1988 Part 6 will be performed.
Vibration measurements will not be performed due to the inaccessibility of these pumps.
l
PROGRAM Pl.AN NO. GGNS-M-189.1 REVISION NO. 8 PAGE NO.12 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR P81-01 Eyfitru P81 HPCS Diesel Generator System Comk'*t011 P81C001
.Txeni Centrifugal Class:
3 Function Transfer fuel oil from the storage tank to the day tank t' satisfy the seven day fuel oil supply requirement for the HPCS diesel generator, imoractical Test Reauirements:
OMa 1988 Part 6, para 5.2:
An inservice test shall be conducted with the pump operating at specified test reference conditions. The test parameters shown in Table 2 shall be determined and recorded as directed in this paragraph.
OMa 1988 Part 8, para 5.2(b):
The resistance of the system shall be varied until the flow rate equals the reference value. The pressure shall then be determined and compared to its reference value. Alternately, the flow rate can be varied until the pressure equals the reference value and the flow rate shall be determined and compared to the reference flow rate value.
OMa-1988 Part 6, Table 2:
D;fferential Pressure is a required test parameter for centrifugal pumps.
OMa 1988 Part 6, Table 2: Vibration is a required test parameter for pumps.
Basis For Relief:
Fuel Oil Transfer System Arra",gement i
The physical ;ocation of the High Pressura Core Spray Diesel Generator (HPCS DG) fuel oil transfer pump is at the bottom of the HPCS DG fuel oil storage tank, which is buried in the ground outside the diesel generator bay. The pump design specifies the pump to be submerged in the fuel oil with the 3/4 inch discharge piping rising from the pump, through the fuel oil, and out the top of the tank approximately 11 feet above the pump discharge. Less than 1 foot above the tank, the 3/4-inch piping widens to 2-inch diameter pipe. A 2 inch check valve near the expansion fitting prevents fuel oil in the transfer pioing from draining back into the storage tank. The 2-inch piping rises approximately 4 inches, elbows twice during the next 14-inch run, and then flanges 9 inches later prior to entering the ground. Since good engineering design requires a minimum of 5 pipe diameters both upstream and downsteam for source pressure measurement, there is no adequate location for a pressure instrument tap within this exposed piping between the top of the storage tank and the ground entry point.
The 2 inch piping then runs underground to the HPCS DG room, and rises above ground level enroute to the day tank. Shortly after the 2-inch piping exits the ground in the HPCS DG room, but prior to the DG fuel oil strainer, is the pressure instrument tap used to measure the transfer pump discharge pressure. This pressure instrument tap is the closest practical point for measurement of tne pump discharge pressure, and is located approximately 11.5 feet above the
PROGRAM PLAN NO. GGNS-M 189.1 REVISION NO. 8 HAGE NO.13 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: EBR-P8101 3/4 to-2 inch expansion fitting (23.5 feet above the actual pump discharge), and 6.5 feet below the highest piping elevation to the day tank.
As noted above, the 3/4 inch diameter discharge piping run and elevation rise are approximately 11 feet. The 2 inch diameter fuel oil transfer piping run and total rise is approximately 177.5 feet and 19 feet respectively before entering the top of the HPCS DG day tank.
The only isolation valve in the HPCS DG fuel oil transfer piping is located in the highest elevation run of the 2 inch pipe shortly upstream of where the pipe enters the day tank.
Difforential Pressure Discussion Between August 1994 and July 1997,20 inservice tests were performed and documented for trending purposes. For these 20 tests, the pressure readings at this instrument location ranged from 2.95 to 3.80 psig, which obviousl/ does not reflect the true discharge pressure of the pump.
The suction pressure, which is calculated utilizing the level of the storage tank, has ranged from 3.51 to 3.80 psig during these tests. The calculated differential pressure utilizing only the discharge instrument and suction pressure has ranged from 0.71 to 0.17 psid. This calculated differential pressure is clearly not representative of the actual pump differential pressure.
Based on a system resistance calculation for the HPCS DG fuel oil transfer system, the expected pump discharge pressure for the current reference flow rate (36.7 gpm) is 35.4 psig. Also, based on the same resistance calculation, the pump experiences approximately 75% of the total head loss in the 3/4-inch piping. This would yield an approximate pressure measurement of 8.8 psig at the 3/4 to-2 inch reducer. From the reducer to the pressure instrument tap location, another 6 psi drop is experienced due to the elevation difference alone.
Although the actual pressure readings documented during the test period analyzed have been in the range expected, the information has provided very little value as a pump-degradation tool.
The average measured discharge pressure over the analyzed tests is approximately 3.65 psig, with the average suction pressure being approximately 3.68 psig, thus the average differential pressure has been around -0.03 psid As an attempt to make the differential pressure measurement a more practical pump performance indicator, a correction factor was calculated based on the HPCS DG fuel oil system resistance. However, testing experience has indicated that even the use of a correction factor has not increased the usefulness 9f the differential-pressure determinations for this pump, as the following discussion will es:ablish.
The system resistance is based on the flow rate, and therefore the correction factor utilized would need to be tased on the system flow rate during the test. This would necessitate setting the flow rate at a fixed value (36.7 gpm being the current reference value), and determining the pump differentirst pressure, OR setting the differential pressure and determining the flow rate Both of these test methods are considered u be impractical for the following reasons:
(1) Flow rate is determined by measuring the day tank level change from the low-level alarm to the pump shute'f level, and dividing the change by the pump run time. As such, instantaneous flow measurement is not available to allow simple adjustment to establish a fixed flow. There are no installed flowmeters or taps for meauring flow rate directly. Ultrasonic flow measurement
PROGRAM PLAN NO. GGNS-M 189.1 REVISION NO. 8 i
PAGE NO.14 OF 16 PUMP RELIEF REQUESTS t
PUMP RELIEF REQUEST NO.: PRR-P8101 attempts have proven to be inconsistent when compared to the level change method. The current method for determination of flow rate meets the loop accuracy requirements mandated per Table 1 of OMa 1988 Part 6. Modification to install a flow meter solely for the purpose of providing instanteneous flow indication to allow establishment of a fixed flow rate is clearly not the intent of OMa 1988 Part 6.
(2) Differential pressure is determined by a calculation of the measured discharge pressure plus i
the correction factor minus the suction pressure. The suction pressure is from a real time t
calculation based on the storage tank level measurement during pump run. To ensure fullloop accuracy, a Barton tube gauge (0-200 inches of water) is utilized to measure the discharge pressure, and thus requires a real time calculation to convert inches of water to psi. Thus, three t
calculations are required for each valve adjustment to establish a differential pressure. To utilize
- differential pressure as the fixed parameter, each system adjustment to set the differential pressure to the reference value would necessitate the performance of these three calculations.
Each performance of these calculations adds time to the pump run duration and unnecessarily increases the potential for calculational error.
(3) The pump run is typically 9-10 minutes which, as noted above, will not allow for a fixed 4
parameter adjustment during the pump run. Thus, the day tank would need to be drained to the low level for another pump run once the differential pressure is correctly adjusted. The breaker for the pump must be opened in order to drain the day tank to the low level alarm. Unnecessary cycling component breakers solely for the purpose of perfe nancu testing is not desirable.
(4) The globe valve is the only available means of at ng the system resistance to set either flow rate or differential pressure equal to its reference Wue; however, adjusting the globe valve will change the system resistance upon wnich the differential pressure correction factor is based, i
The corresponding resistance factor for the position of the globe valve would need to be determined to re-perform the system resistance calculation, and could necessitate the performance of the system resistance calculation during each pump test depending upon the sensitivity of the valve's resistance factor versus valve position, in either case, valve adjustment would add additional uncertainty to the correction factor applied to the differential pressure measurements, which would further reduce the usefulness of the differential pressure as a pump performance parameter.
t (5) Evaluation of the inservice testing results for this pump has shown that differential pressure measurement is not providing any substantial benefit as a diagnostic tool for pump hydraulic performance.
The current differential pressure reference value for this pump is 33.7 psid which was based on a system resistance at the old reference flow rate of approximately 35 gpm. Even though a different reference flow rate (36.7 gpm) has been established since the original differential pressure reference value was determined, there has been absolutely no change in the average differential pressure results for the tests at the new flow reference value. If a new reference value is established based on a correction factor at 36.7 gpm, the same test results would be averaged around the new correction factor because of the very little variation between the measured suction and discharge pressures. However, establishing a new correction factor or reference value would provide no additional benefit as noted below.
,.-.,----va,---,-
.. - - -,. - ~. -,,
.. - -_-_ - - - ~_-.- - - - -
PROGRAM Pt AN NO. GGNS M 189.1 REVISION NO. 8 PAGE NO.15 OF 16 PUMP RELIEF REQUESTS PUMP RELIEF REQUEST NO.: PRR P81-01 i
Per Table 3b of OMa 1988 Part 6, the acceptance criteria can deviate from the reference value by as much as 10% (3.3 psi) before corrective raction is necessary. In order to achieve a 3.3 psi drop in differential pressure, the measured discharge pressure would have to drop to approximately 0.4
[
to 0.5 psig since suction pressure remains fairly constant. The pressure drop due solely to the elevation difference between the pressure instrument location and the maximum elevation experienced enroute to the day tang is approximately 2.5 psi. As such, flow would have to diop
{
dramatically, and even cease, before the differential pressure ever came close to the lower t
required action value. Therefore, it has become clear that the only parameter which is currently I
providing any true representation of the pump hydraulic condition is the flow rate.
To make the measurement of the pump differential pressure a useful parameter for pump performance evaluation, it would be necessary to perform a modification to install the pump discharge pressure gage closer to the pump discharge. Such a modification is considered to represent an unusual hardship without a compensating increase in the level of quality and safety for the following reasons:
(a) Any modification would require removal of the fuel oil transfer pump from the associated fuel oil storage tank to make the necessary modification.
(b) A direct sensing instrument at the discharge penetration elevation would be submerged in the fuel oil with the pump. For this application, a pressure transducer would be required in lieu of a pressure gage. Such an arrangement would necessitate the removal of the pump assembly from the storage tank every time the pressure transducer required calibration.
(c) If a pressure gage option were used with the tap location at the discharge of the pump, the least impact would be caused by routing the gage line along with the fuel discharge piping.
However, this option would require an additional modificatior to the existing discharge flanga arrangement at the top of the storage tank to allow the sensirig line to penetrate the tank (any other penetration location would necescitate an entry into the tank to disconnect the sensing line whenuver the pump is required to be pulled for planned or corrective maintenance.) Once this modification was performed, a correction factor will still need to be calculated to account for the elevation difference between the gage and the pump.
(d) The current test configuration allows the fuel oil transfer system to be treated as a fixed.
resistance system due to the negligible head loss between the current discharge measurement location and the day tank. If a modification were performed to allow for more practical discharge pressure measurement, the system may no longer qualify as a fixed-resistance system depending upon the modification performed, if such were the case, resistance adjustment would necessitate at least two pump runs per quarter as discussed above. The option does exist to keep the drain open on the day tank while the adjustment !s made, and then the drain would be shut for the level measuremont. This option, however, could sigt:ificantly reduce the accuracy of the flow rate measurement due to the shorter pump run time and due to the need to measure the initial tank level while the pump is actually filling the tank instead of during a stable, no-flow condition.
. (e) Safety-related maintenance activities, such as the removal of this pump for any reason, are expensive undertakings and involve risks associated with the disassembly of any piping system.
Performance of a modification requiring such activities will tignificantly increase the cost burden.
p.-m
.e
..c.e---.
+-~y
..-d y
+-...m-v--
Y t.
e PROGRAM PLAN NO. GGNS-M 189.1 REVISION NO. 8 PAGE NO.16 OF 16 PUMP RELIEF REQUECTS PUMP RELIEF REQUEST NO.: PRR P8101 (f) Working with fuel oil systems involves additional personnel and equipment safety hazards, which should be minimized wnenever possible.
(g) If the transducer option were installed, removal and reinstallation of the pump assembly would be necessary for calibration purposes. This would require additional testing to be performed on the system to ensure that the maintenance activity did not impact the hydraulic performance capabil:ty of the fuel oil transfer system. Such testing would require verification that the reference values of the pump hydraulic parameters were not affected. If a transducer arrrngement were used, then revalidation of the reference values would be required at the same periodicity as the instrument calibration. This is clearly not the intent of Part 6.
(h) Finally, diesel-generator operability and availability could be adversely affected by instal'ation of any modification that would require multiple test runs of the fuel oil transfer pump or frequent storage tank entries for calibration purposes should such instrumentation be installed.
Vibration Discussion The physicallocation of the pump is at the bottom of the HPCS DG fuel oil storago tank, which is buried in the ground outside the diesel generator bay. Due to the pump being submerged, vibration measurements cannat be performed. Additionally, installation of permanently mounted transducers are considered impractical for the same reasons as discussed for pressure transducer installation ;mpracticality, it should be noted that OMa 1988 Part 6, paragraph 4.6.4(3), requires vibration measurements to be performed on centrifugal pumps only if they have "accussible" pump bearing housings.
Bernative Testina:
As noted in the preceding discussion, the existing means of measuring pump differential pressure does not prodde any useful information regarding the pump hydraulic condition that would not be readily apparent by a corresponding decrease in pump flow. For the fuel oil transfer system pump, the measurement of flow alone, with the following additional requirements, will provide an acceptable level of quality and safety while having minimal negative impact on diesel-generator operability and availability.
Before starting the pump, adequate storage tank level will be ensured for pump NPSH requirements. The system will be left in its normal alignment with no valves throttled. The day tank will be drained to a low level and then refilled using the fuel oil transfer pump. An average flow rate will be calculated and compared to its reference value in order to determine if any pump degradation is occurring. A lower " alert value"(not presently required per Table 3b of Part 6 for centrifupl pumps) of 93% of the reference flow value will be established for the pump. If the
. measured fimv rate falls below this " alert value", then the analyses and evaluation actions required b Nction 6 of OMa 1988 Part 6 will be performed.
i Vibration measurements will not be oerformed due to the h accessibility of the pump.
L~
--