ML18025B996

Recirculation Sys Testing.

ML18025B996
Person / Time
Site:	Browns Ferry
Issue date:	07/22/1983
From:	TENNESSEE VALLEY AUTHORITY
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Shared Package
ML18025B994	List: ML18025B993 ML18025B996
References
STEAR-8301, NUDOCS 8308230436
Download: ML18025B996 (51)

Text

RECIRCULATION SYSTEM TESTING STEAR 8301 BROWNS FERRY NUCLEAR PLANT CONTENTS Page

1. Introduction . ~ ~ ~ ~ ~ 1 1.1 Ob]ective . ~ 1 1.2 Background ~ 1 1.3 Reactor Recirculation System Description ~ ~

2. Test Methodology . ~ ~ 4 ~ ~ ~ ~ ~ 3 2.1 Sensor Locations ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 3 2.1.1 Accelerometers . ~ ~ ~ 0 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 3 2.1.2 Position Transducers . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 3 2.1.3 Proximity Probes . ~ ~ ~ ~ ~ ~ ~ ~ l ~ ~ ~ ~ ~ 3 2.1.4 Strain Gages . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 3

2. 1.5 Thermocouples ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 4 2.1.6 Moisture Sensors . ~ ~ ~ ~ ~ t ~ ~ ~ ~ ~ ~ ~ 4 2.2 Signal Conditioning .

2.2.1 Charge Amplifiers ~ ~ ~ ~ ~ ~ ~ ~ ~

2.2.2 Strain Gage Amplifiers . ~ ~ ~ ~ ~ ~ ~ ~ ~

2.3 Sensor Calibration/Operability Checks ~ ~ ~ ~ ~ ~ ~ ~ ~ 5 2.3. 1 Acceler ometers . 5 2.3.2 Position Transducers . 5 2.3.3 Proximity Probes 6 2.3.4 Strain Gages . 6 2.3.5 Thermocouples 6 2.3.6 Moisture Sensors . ~ ~ ~ ~ ~ ~ ~ ~ ~ 6 2.4 Data Acquisition System . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 6 2.5 Data Acquisition ~ ~ 4 7

3. Data Processing. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 7 Test Results . ~ ~ ~ ~ ~ ~ ~ ~ 7 4.1 Accelerometers. ~ ~ ~ ~ ~ ~ ~ t ~ ~ ~ ~ ~ ~ ~ ~ 4 7 4.1.1 Noise Condition ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 8 4.1.2 Shutdown Cooling with RHR ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 9 4.2 Strain Analysis . ~ ~ ~ ~ ~ 9 830823043b 8308li .

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CONTENTS (Continued)

Page

5. Conclusions ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 1 1

6. References ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 1 1 Appendixes A. Test Conditions

List of Tables and Fi r es Tables Page Average Blade Pass (5X) Vibration with Both Recirculation Pumps operating near 1,260 rpm . . . . . . . . . . . . . . . . . . 13

2. Piping Displacements e ~ ~ ~ e ~ s ~ ~ ~ 1 F~lr as Recirculation System Xsometric 15

2. Loop A Accelerometer Locations 16

3. Loop B Accelerometer Locations 17 RHR Accelerometer Locations . 18

5. Strain Gage and Position Transducer Locations . ~ 19

6. ARET Spectral Plot/0 to 200 Hz 20 tt7. ARET Spectral Plot/0 to 800 Hz ~ 21

8. ARET Spectral Plot/0 to 3,200 Hz 22

9. ARET Spectral Plot of Blade Pass Vibration Amplitudes . 23

10. AECBV Spectral Plot of Blade Pass Vibration Amplitudes 24

11. ARAR Spectral Plot of Blade Pass Vibration Amplitudes . 25

12. ARLBV Spectral Plot During RHR Operation 26

13. ARLBV Spectral Plot During Resonance 27

14. AECBV Spectral Plot During RHR Operation 28

15. AECBV Spectral Plot During Resonance 29

16. Loop B Out-of-Plane Spectral Plot of Displacement and Strain 30

17. Loop B Out-of-Plane Spectral Plot of Acceleration and Strain 31

18. Loop B Out-of-Plane Spectral Plot of Coherence and Phase 32

I List of Abbreviations rpm - Revolutions per minute Hz - Hertz ac - Alternating current dc - Direct current dB - decibel V Volt RCS - Reactor coolant system micro in/in - micro inch/inch IRIG - Inter-range instrumentation group ips - inch per second kHz - kilohertz MWe - Megawatts RHR - Residual heat removal g - Gravitational aoceleration at sea level 5X - 5 times ksi ,kilopounds per square inoh psi - pounds per square inch micro in/in/mil - micro inch per inch per mil

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'1

1

,I 1 ' INTRODUCTION 1.1 ~Ob eotXve The objective of this test was to determine whether indications found on reactor recirculation system risers A2E and A2F at the KR-2-36 (loop B) and KR-2-10 (loop A) sweepolet-to-manifold welds could have been initiated by system piping vibration during startup and operation of the unit 2 reactor.

1.2 ~Bank round Recirculation system testing conducted in December 1979 (BF STEAR 7903) and site observations during star tup of the unit 2 reactor revealed that, during operation of the recit cu-lation pumps in the balanced flow mode at approximately 1260 rpm, a loud, audible noise could be heard in the unit 2 reactor and control areas. Test results indicated that the noise was possi-bly caused by flow-induced vibration which excited a resonance in the recirculation system piping. Additional testing was sched-uled in March 1980 to further define the source of the excitation and to determine whether corrective action was necessary, but it was subsequently postponed.

During the cycle 0 refueling outage, TVA examined the sweepolet-to-manifold welds nearest the manifold end caps in response to an NRC region II request. This examination detected a total of four unacceptable indications in the KR-2-36 and KR-2-14 welds. TVA's metallurgical analysis (reference 1) of the outside surface of the pipe in the vicinity of the indications did not reveal any sign of sensitization; therefore, the indications were believed to be fatigue-induced.. This assumption was supported by the following facts:

1. The subject sweepolet-to-manifold joints would most likely experience fatigue problems because of the expected higher vibration near the free ends of the recirculation manifold.

2. The indication locations in the sweepolet joints are in a higher stress area and would be susceptible to fatigue cracking if (reference 2).

subjected to vibration-induced cyclic stresses

3. Previous experience would indicate the possibility of recirculation system piping vibration during balanced operation of the recirculation pumps.

1.3 Reactor Recirculation S stem Descri tion The reactor recirculation system is designed to provide forced cooling of the core and a variable moderator (coolant) flow to the reactor core for adjusting reactor power level.

The system consists of the two recirculation pump loops external to the reactor vessel which provide the driving flow of wate'r to the reactor vessel )et pumps. Each external loop contains one high-capacity, motor-driven recirculation pump and two motor-operated gate valves for pump maintenance. Each pump discharge line contains a venturi-type flowmeter nozzle. The recirculation loops are a part of the nuclear system process barrier and are located inside the drywell containment structure.

Each recirculation pump is a single-stage, variable-speed, ver-tical, centrifugal pump equipped with mechanical shaft seal assemblies. The pump is capable of stable and satisfactory performance while operating continuously at any speed corre-sponding to a power supply frequency range of 11.5 to 57.5 Hz.

For loop startup, each pump operates at a speed corresponding to a power supply frequency of 11.5 Hz with the main discharge gate valve closed.

Each recirculation pump motor is a variable-speed, ac electric motor which can drive the pump over a controlled range of 20 to 102 percent of rated pump speed. The motor is designed to operate continuously at any speed within the power supply frequency range of 11.5 Hz to 57.5 Hz. Electrical equipment is designed, constructed, and tested in accordance with the applicable sections of the NEMA Standards. A variable-frequency, ac motor -generator set located outside the dr ywell supplies power to each recirculation pump motor. The pump motor is electrically connected to the generator and is started by engaging the variable-speed coupling between the generator and the motor.

Minimum speed corresponds to a frequency of 11.5 Hz.

The recirculated coolant consists of saturated water from the steam separators and dryers which has been subcooled by incoming feedwater. This water passes down the annulus between the reactor vessel wall and the core shroud (see figure 1). A portion of the coolant exits from the vessel and passes through the two external recirculation loops to become the driving flow for the Jet pumps. The two external recirculation loops each discharge high pressure flow into an external manifold from which individual recirculation inlet lines are routed to the jet pump risers within the reactor vessel. The remaining portion of the coolant mixture in the annulus becomes the driven flow for the get pumps. This flow enters the get pumps at the suction inlet and is accelerated by the driving flow. The driving and driven flows are mixed in the get pump throat section resulting in par tial pressure recovery. The balance of recovery is obtained in the get pump diffusing section (reference 3).

2.0 TEST METHODOLOGY 2.1 Sensor Locations 2.1.1 Accelerometers Endevco model 2273 AM20 high-temperature; radiation-hardened acceler ometer s were used to detect recirculation system piping vibration. The accelerometers were attached at selected locations using special clamps fabricated for this purpose. The mirror insulation was also modified as required to accommodate each accelerometer and its associated instrumentation cables. The accelerometer locations are shown schematically in figures 2, 3, and 4.

2.1.2 Position Transducers Houston Scientific International, Inc., series 1850 position transducers were used to measure the thermal growth of the recirculation loop header during heatup and low frequency piping vibration. Three transducers were mounted triaxially near each of the end cap locations.

Special mounting clamps, similar to those fabricated for the accelerometers, were used in the installation of the transducers. Also, each position transducer was shielded with lead foil to decrease its radiation exposure.

2.1.3 Proximit Probes A Bently Nevada 7200 series proximity transducer system was used to monitor the recirculation pump speeds. Two transducers, an active and a redundant, were mounted on each pump for this purpose. Small "L" brackets were fabricated and attached to a water seal bolt so that the proximity probe was aligned with the keyway in the motor shaft.

Ailtech model SG 125 high-temperature, weldable strain gages were used to measure the static and dynamic strains in the recirculation loop piping during the unit heatup and operation. Each gage was individually welded in place using a low-energy, capacitive discharge welding technique. After installation, the gages were protected from damage by covering them with a fiberglass mat and by

indenting the mirror insulation to prevent surface contact strains. Figure 5 illustrates the locations where the gages were installed.

Type T, copper-constantan thermocouples were secured to the recirculation loop risers A2E and A2F to measure the surface temperature of the pipe during testing. The thermocouples were installed to aid in the evaluation of thermal-induced pipe growth.

2.1.6 Moisture Sensors A Techmark model TUM 100 leak detection system was installed on the recirculation system header with the moisture sensors located near each of the four unaccept-able indications. The system was installed as a precau-tionary measure only to detect leaks resulting from throughwall crack propagation.

2.2 Si nal Conditionin 2.2.1 Char e Am lifiers The accelerometers used in this test were the piezoelectric type. This type of sensor consists of a piezoelectric crystal which develops an electric charge when deformed; deformation is a result of vibration sensed by the accelerometers. Preamplifiers or charge converters (Unholtz-Dickie model RCA-2TR) convert the electrical charge to a voltage signal and allow the signal to be transmitted through long cable runs with little signal degradation or noise induction. Charge amplifiers (Unholtz-Dickie model D22PMHS) amplify the sensor outputs to usable levels for recording.

2.2.2 Strain Ga e Am lifiers Bell and Howell type 1-183 strain gage amplifiers were used to condition the signals generated by the strain gage transducers. The amplifiers provide a wide range of

signal conditioning for transducers in a Wheatstone bridge configuration; the features include adjustable bridge excitation, signal amplification from 0.1 to 10,000, variable offset adjustment from -10 to +10 volts, and an internal, switch selectable, 12 dB per octave, low pass filter. These features afford a wide signal dynamic range by reducing dc offset and extraneous noise contamination.

To be compatible with Ailtech model SG 125 strain gages in a 1/4 arm, self temperature compensated configuration, bridge completion and shunt calibration resistors were installed on the local calibration boards in the 1-183 amplifiers. The gain of each amplifier was adjusted for 100.

2.3 Sensor Calibration/0 erabilit Checks 2.3.1 Accelerometers Each accelerometer/charge converter/hardline cable combi-nation was calibrated with a shaker table in the Vibration and Diagnostic Section's lab; the accelerometers were then removed and replaced by an Endevco model 4815A simulator. The simulator sensitivity was adjusted acceler-'meter until a calibration signal equivalent to that of the shaker-driven accelerometer was obtained. This value was recorded for each acceler ometer/hardline cable/charge converter combination. As the accelerometers were installed on the recirculation system piping, the simula-tor sensitivity was matched to the previously tabulated value and the charge amplifier sensitivity adjusted,to obtain the proper calibration signal. This procedure ensured, with a minimum of personnel exposure, that the hardline cable, charge converter, field-routed cable, and charge amplifier were operable and calibrated. The simu-lator was then removed and the hardline cable attached to the installed accelerometer. Each accelerometer was verified operational by tapping its mounting block lightly with a small metal object and listening to its response.

The calibration data were recorded for future reference.

2.3.2 Position Transducers Each position transducer was supplied 1-V dc excitation and verified operational by monitoring the transducer output while extending and retracting the transducer cable.

2.3.3 Proximit Probes Each proximity probe was supplied minus 24-V dc power.

The probe-to-target surface gap was ad)usted during recirculation pump operation until stable, twice per revolution pulses could be obtained; the pulses were generated each time the two motor shaft keyways passed the proximity probe. External instrumentation was used to measure the time between pulses and display the pump speed in rpm.

'ach strain gage channel was calibrated after gage installation using shunt calibration resistors in the amplifiers to simulate approximately 1,300 micro in/in and 2,600 micro in/in compressive loads. The calibration was referenced from zero strain at a RCS temperature of 200oF (dictated by unit conditions during the calibration).

Thermocouple temperatures and position transducer voltages were also recorded at this reference point.

Before installation, each thermocouple was verified operational by comparing the indicated drywell air temperature with the temperature measured by permanent plant instrumentation.

2.3.6 Moisture Sensors The Techmark TUM 100 system was ad)usted and verified to be operational by a vendor representative. Daily checks are made by site personnel to ensure leak detection system operation and pipe integrity. No leak detection information will be submitted in this report.

2.4 Data Ac uisition S stem All test data were recorded on two Honeywell model 101 frequency modulated (FM), 14-channel, 1-inch magnetic tape recorders configured to IRIG wide band group 1. The data tapes were recorded at 3-3/4 ips providing an effective signal bandwidth from dc to 2.5 kHz.

Channel 8 of each tape recorder was dedicated for servo control and time code signals. The servo control signal provides a reference to the servo control system to minimize speed variations during recording or playback. The time code signal provides time references for data correlation.

Test signals were recorded on the remaining 13 channels.

Selected signals were recor ded on both tape recorders so that they could be used for cross correlation during data analysis.

2.5 Data Ac uisition Test data were recorded on the Browns Ferry unit 2 recirculation system starting with the vessel hydro and concluding at a unit generator load of 1050 We. During each data set, all relevant parameters were recorded on tape data sheets for future reference.

3.0 Data Processi Test signals were reproduced on a Honeywell model 101 instrumentation tape recorder and principally analyzed with a Hewlett-Packi d 5423A structural dynamics analyzer. The analyzer is a two-channel, fast-Fourier-transform based signal analyzer capable of several time domain and frequency domain measurements. As a part of its broad measurement capability, the 5423A provides complete facilities for analyzing the vibration characteristics of mechanical devices and displaying animated mode shapes. Test signals were also examined with a Nicolet Explorer XX digital oscillosoope and audibly using filters, amplifiers, and speakers.

4.0 Test Results 4.1 Accelerometers Vibration information obtained on the unit 2 recirculation system during heatup through full power operation revealed the following .

information:

A. The most significant vibration amplitudes occurred during power operation at approximately 950 We with both recirculation pumps operating at approximately 'l,260 rpm. Near these pump speeds, audible noise characteristic of beating could be heard throughout the reactor building and in the control areas.

B. During RHR system operation for shutdown cooling with RHR pumps A and C running, the recirculation system experienced no significant vibration amplitudes at any of our instrumentation

locations. However, the general overall or background vibration was higher during RHR operation. This condition is indicative of flow noise caused by turbulent flow, cavitation, or by both mechanisms.

4.1.1 Noise Condition Recirculation system vibrations peaked during power ascension at approximately 950 MNe with both recirculation pumps operating near 1,260 rpm. The predominate vibration frequency was 5X the recirculation pump speed. This is known as the blade-pass frequency of the pump. Figures 6, 7, and 8 show the difference between the blade-pass frequency amplitude (5X) and other spectral information for bandwidths of 0 to 200 Hz, 0 to 800 Hz, and 0 to 3,200 Hz full scale respectively, for aocelerometer ARET. Similar information was obtained at each accelerometer location.

Data analysis was then concentrated on the blade-pass frequency by altering the 5423A analyzer's center frequency and bandwidth adjustments to allow for greater data resolu-tion. Plots were generated to illustrate the blade-pass frequency amplitude at seleoted recirculation pump speeds.

Samples of these plots are presented in figures 9, 10, and 11 for accelerometers ARET, AECBV, and ARAR respectively.

Notice that the approximate pump speeds are indicated above the blade-pass frequency peaks in each figure. The analysis clearly showed that pump operation near 1,260 rpm excited a system resonance. During this condition, audible nois'es characteristic of beating could be heard in the unit 2 reactor and control areas. The noises varied in amplitude as the driving forces (blade-pass) moved in and out of phase; at one point reinforcing each other and at another canceling each other. The beat frequency was verified to increase as the pump speeds were separated; the beat and noise disappeared altogether as the pump speeds were moved out of the resonant range. There was no measureable vibration at the beat frequency.

The above observations, and the fact that large piping system fundamental resonances normally occur at frequencies signifioantly less than 40 Hz, would indicate that the increased vibration during pump operation at 1,260 rpm is caused by a hydraulio resonance in the recirculation system piping. The resonance ocours when pressure waves traverse.

the recirculation system piping at the speed of sound and reflect off its boundaries (reference 4).

Average vibration levels for each accelerometer are presented in table 1. The vibration varied according to the phase relationship between the driving forces. The maximum vibration levels occur red on riser E, in the tangential direction (ARET), with both pumps at

approximately 1,260 rpm. The levels occasionally reached

1. 1g at 105 Hz (5X) which corresponds to a 0.002 inch displacement. All other accelerometer locations experienced less vibration than acoelerometer ARET.

4.1.2 Shutdown Coolin with RHR Before the unit 2 heatup, test data were obtained at the instrumented locations on the recirculation system and selected locations on the RHR system. The RHR was config-ured for shutdown cooling with RHR pumps A and C in opera-tion. In this mode, the RHR pumps draw suction from recirculation loop A (shutdown supply line, see figure 2) and discharge through two heat exchangers. They subsequently supply cooling water to the reactor through the RHR return line which is attached to the recirculation system loop B piping (see figure 3). While in this mode of operation, no significant vibration levels were noted at any accelerometer locations. A comparison of spectral plots during the beat condition (figures 13 and 15) and during RHR operation (figures 12 and 14), clearly show the higher broad band background noise levels during RHR-oper ation. The higher broad band vibration levels are indicative of flow noise. Figures 12 and 13 illustrate this point for accelerometer ARLBV. In this case, the difference is more noticeable because no flow exists in the RHR system during power operation; however, similar information was obtained at other accelerometer locations as shown in figures 14 and 15.

4.2 Strain Anal sis Strain gages and position transducers were located, as shown in figure 5, on the A2F (loop A) and A2E (loop B) recirculation system risers to measure the thermal and ser vice-induced loading during unit operation. In-plane (movement in the two-dimensional plane of the riser and the header) and out-of-plane (movement orthogonal to in-plane) were selected as the principal orienta-tions of the gages because of the risers'usceptability to fatigue-induced cracking in those directions. Also, the indica-tions found in the manifold were in a region where fatigue cracking could be expected. Position transducers were mounted triaxially at approximate header azimuths of 140o and 220o.

Data recorded during the testing were analyzed assuming the following.

1. The modulus of elastioity for the header and riser piping was 28.5 ksi.

2. The measured strains were in the linear-elastic range and could be evaluated using Hooke's law.

3. The strain gages were temperature compensated for 304SS.

In-plane and tangential measurements were collinear.

5. Out-of-plane and radial measurements were collinear .

6. The referenoe point for all calculations, zero strain and zero pipe displacement, was at a RCS temperature of 200oF.

Based upon the above assumptions, the maximum strain levels recorded near the subject indications immediately above the sweepolet-to-riser welds were in the out-of-plane direction on both risers (see figure 5) during heatup but before loading the unit. Loop A static strains peaked at approximately 570 micro in/in (16.2 ksi) while loop B strains in the same condition were 450 micro in/in (12.8 ksi). Dynamic strains were negligible throughout heatup. Piping displacements, as indicated in table 2, were also at a maximum during heatup with a resultant defleotion on the A and B loops of 0.90 and 0.78 inch respectively.

During power ascension, strains deoreased and stabilized at approximately 530 mioro in/in (15.1 ksi) on the A2F riser and 430 micro in/in (12.3 ksi) on the A2E riser. Assuming strain linearity from ambient to 200oF, these measurements would have peaked at approximately 750 micro in/in (21.4 ksi) and 610 micro in/in (17.4 ksi). Data analysis proved this assumption to be conservative beoause of a decreasing slope (hmicro in/in/ARCS temperature) as the RCS temperature approached 200oF.

Alternating strains imposed on the static strains during the resonant condition peaked at 1.2 micro in/in (34.2 psi) and 2.4 mioro in/in (68.4 psi) on the A2F and A2E risers. The cyclic strains were measurable only with both pumps operating at approximately 1,260 rpm; the frequenoy of the cyclic strains was.

105 Hz (the blade-pass frequenoy).

Dynamio strains in the in-plane direction were also at a maximum during the resonant condition; the highest .level recorded on the A2E riser was 0.86 micro in/in (24.5 psi). Static measurements were not available at this looation. Position transducer data, however, would indicate that in-plane static strains were less than strains in the out-of-plane direction.

As with the strain gages, the deflections measured by the position transducers decreased when the unit was loaded and remained stable throughout power ascension. The resultant A and B loop header displacements during operation were 0.82 and 0.70 inch respectively. Vibration amplitudes during all modes of operation were lower than the resolution of the position transduoers.

Averaged spectra, examples of which are displayed in figures 16, 17, and 18, illustrate the similiarities between typical accelerometer and strain gage measurements in the same direction.

Neglecting 60 oycle noise and its harmonics, figures 16 and 17 identify 105 Hz as the predominant mode of vibration while figure 18 verifies the coherence of the measurement. Based upon the collinearity of the transducers and the coherence of the spectral plots generated from each strain gage/accelerometer, an average sensitivity of 4.1 micro in/in/mil displacement was calculated.

This sensitivity was applicable when evaluating dynamic strains during all modes of operation. Using this sensitivity along with strain measurements near the ARER accelerometer, vibration amplitudes at the ARER location during the noise condition were found to be less than the ARET accelerometer.

The remaining strain gages, located on the sweepolet-to-manifold welds, were only installed to measure the response of the gages on a weld. Since these measurement locations were not considered appropriate for general testing purposes, data obtained from these transducers were not included in the data analysis.

5.0 Conclusions Vibration and strain levels were measured on the unit 2 reactor reoirculation system piping during startup and operation of the unit following the oycle 4 refueling outage; the measured levels were not considered to be of sufficient amplitude to initiate fatigue-induced cracking in the sweepolet-to-manifold welds. The maximum vibratiori levels ocourred during power operation with both recirculation pump speeds near 1,260 rpm. Vibration amplitudes peaked to 1.1g at 105 Hz on aocelerometer ARET. Similiarly, the statio/dynamic strains for loops A and B were 530 micro in/in (15.1 ksi)/1.2 micro in/in (34.2 psi) and 430 micro in/in (12.3 ksi)/2.4 micro in/in (68.4 psi) respectively.

. Thus, under the present operating conditions, the sub)ect indications in the sweepolet-to-manifold welds could not solely be attributed to fatigue.

6.0 References

1. Metallurgical Report, TVA Document No. L29830113934 Analysis Report, Browns Ferry Nuolear Plant unit 2 Field Metallography on Reactor Recirculation System Headers November 10, 1983

2. Battelle Memorial institute Columbus Laboratories 506 King Avenue Columbus, Ohio 43201

Fatigue Evaluation of Sweepolet Branch Connections in Carbon Steel Pipe to Bonney Forge and Foundry, Inc.

May 15, 1970

3. Browns Ferry FSAR Volume 2, section 4.3

4. Formulas for Natural Frequency and Mode Shape, Robert D. Blevins, Ph.D. Van Nostrand Reinhold Company, copyright 1979.

JJS:VD 7/22/83 B4174A.KH

Table 1 Average Blade Pass (5X) Vibration with Both Recirculation Pumps Operating near 1,260 rpm A Pump2 8 Pump2 Sensor Designation1 (g peak) (g peak)

ARAR o.45 0.24 ARAT 0.07 0. 13 ARCV o.o6 0 ~ 20 ARCR 0.18 0.12 ARCT o.o4 0.05 AECBV 0.10 o.44 AECBR 0.18 0.31 AECBT 0.05 o.14 ARER Inoperable ARET o.14 o.74 ARFR 0.26 0.08 AECAR 0.14 o.16 AECAT Inoper able ARHR 0.10 o.14 ARHT 0 ~ 05 o.o4 APAV 0.07 0 ~ 11 APBV o.o4 0.06 ARLAV 0.15 0.02 ARLBV 0.03 0.26 ASLAR o.o6 0.02 The location and orientation of each accelerometer are shown in figures 2, 3, and 4.

During the beat condition, the recirculation pump speeds are slightly unbalanoed causing slight differences in each pumps'lade pass vibration amplitude component. The 5423A analyzer, by virtue of its enhanced data

'esolution capabilities, accurately identifies both frequency and average amplitude of both pumps 5X vibration. This is averaged information; the aotual peak vibration levels were higher.

Table 2 Piping Displacements RCS LOOP Fl LOOP B PRESS TEHP LORD PECAR PECRT PECRV R PECBR PECBT PECBV 8 288 8 8 ~ 88 8. 88 8 88~ 8. 88 8. 66 8.88 8. 88 8. 88 45 273 8 85 - 85 .86 .89 .20 -. 81 ~ 89 ~ 22 129 334

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1. 2888 ABET, 3G. f191. 897. 88. 37. HH 5X NAG Figure 8 ARET Spectral Plot/0 to 3200 Hz

A'SPEC 1 //Ac 28 EXPAND

1. HHHH ABET SX HI-RES HAG

/320

+<5

/2Z2

//82

8. 8

98. 888 HZ Figure 9 ARET Spectral Plot of Blade Pass Vibration Amplitudes

/262 A SPEC 1 Pha 28 EXPAND 588. 88 AECBV

/288 5X HI-RES

/2<3 MAC

/320

/345

//82

98. 888 HZ Figure 10 AECBV Spectral Plot of Blade Pass Vibration Amplitudes

h SPEC 1 Pha 28 EXPAHO 588. 88 hRAR SX HI-RES

/262

/288 HhG

/345

/222

/320 082

98. 888 Figure 11 ARAR Spectral Plot of, Blade Pass Vibration hmplitude

-2G-A SPEC 2 PA) 188 EXPAND 588. 88 ARLBV. 188G. 813. 873. 11. 24. 88 MAG Figure 12 ARLBV Spectral Plot During RHR Operation

C

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C n h SPEC 2 Phs 188 EXPhNO 588. 88 hRLBV. 3G, )$ 89. 896. 23. 57. 88 MAG Figure 13 ARLBV Spectral Plot During Resonance

t > y L

h SPEC 2 PA> 188 EXPAND 288. 88 AECBV. 38G. 812. 873. 18. 47. 88 Figure 14 AI,"CBV Spectral Plot During IUIR Operation

h SPEC Z Pha 188 EXPAHO ZHH. 88 AECBV. 3G, 091, 897. 88. 37. 8 HAG HZ Figure 15 hECBV Spectrnl Plot During lhesonance

A SPEC Phs 258 EXPAND A SPEC 2 Phs 258 EXPAND

28. 888

/20 iii98, 97. 88. 11. 8 ~i-'R /80 AELBR. 18H1L. GREEN GO SBRDP6. 18UE. RED

/05 LGHAG LGHAG DB DB t

........ -28. 888 288. 88 Figure 16 Loop 8 Out-of-Plane Spectral Plot of Displacement and Strain

A SPEC 1 Phs 158 EXPAND A SPEC 2 PAa 158 EXPAND

95. 888 115. QQ 2liL HM L L 898. 97. QQ. 11. P4"I AECBH. 1QG, HEO SBROPG. 1QUE, BLUE

/05 LGHAG LGt<AG OS OB j

J

-BH. QHQ "ZH. HHH

)

95. 888 115. QQ Figure 17 Loop B Out-of-Plane Spectral Plot of Acceleration and Strain

~g t ) '

COHER O'As 158 EXPAHD TRbl'jS PA) 159 EXPAt j[3

95. BQB 115. M

2. BHHH

..258. 88 898, 97. 88. 11. )J4-4 AECHR-SBROi'6 l '1

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al l)~ ) PHAGE.

l

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-258. HB r--

95. 888 115. 88 Figure 18 Loop 8 Out-of-Plane Spectral Plot of Coherence and Phase

0 l )

0

APPENDIX A TEST CONDITIONS Data Set Number Test Conditions

~Ta e No. 1 1 through 6 Vessel hydro/various pressures and recirculation pump speeds.

7 through 16 Shutdown cooling/various RHR pumps in service.

17 through 19 Recirculation pump A in operation only, RCS temperature <200oFe

~Ta e No. 2 20 through 25 Both recirculation pumps in service at speeds <500 rpm.

26 through 38 Unit heatup.

39 through 44 Power operation/recirculation speeds C500 rpm.

~Ta e llo.

45 through 49 Power operation/r ecirculat ion speeds approximately 580 rpm.

50 through 51 Power operation/recirculation speeds approximately 680 rpm.

52 through 54 Power operation/recirculation speeds approximately 725 rpm.

55 through 78 Power operation/preconditioning to full power, reoirculation speeds from approximately 740 to 1,025 rpm.

Note: Unit 2 removed from service for repairs.

~ .

l'

~Ta s No. 4 79 through 81 Power operation, 990 MWe/recirculation speeds approximately 1,430 rpm.

Note: Unit 2 generator load reduced to aocommodate system conditions.

82 through 87 Power operation, 900 to 960 MWe/preconditioning, recirculation speeds from approximately 1,160 to 1,265 rpm.

88 Power operation, 960 MWe/recirculation speeds .

are unbalanced, A = 1,238 rpm; B = 1,265 rpm.

89 through 94 Power operation, 970 MWe to 1,000 MWe/preconditioning, recirculation speeds from approximately 1,260 to 1,345 rpm.

~Ta s No. 5 95 through 103 Power operation, 1,000 MWe to 1,055 MWe/preconditioning, recirculation speeds from approximately 1,345 to 1,470 rpm.

~ lfL t

j t "a r

e I