ML050980146
| ML050980146 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 04/04/2005 |
| From: | Bird E, Trench R MPR Associates |
| To: | Office of Nuclear Reactor Regulation, Public Service Enterprise Group |
| References | |
| Task No. 1108-0502-0002-00 1108-0002-RCT-01 | |
| Download: ML050980146 (6) | |
Text
MPR Associates, Inc.
I*M PR 320 King Street Alexandria, VA 22314 CALCULATION TITLE PAGE Client:
PSEG Nuclear LLC Page 1 of 6 Project: Task No.
Hope Creek Decontamination Port 1108-0502-0002-00
Title:
Calculation No.
Reactor Recirc Vibration Acceleration Estimate 1108-0002-RCT-01 Preparer/ Date Checker / Date Reviewer &Approver Date Rev. No.
Randolph C. Trench Edward Bird Edward Bird 0 QUALITY ASSURANCE DOCUMENT This document has been prepared, checked, and reviewed/approved in accordance with the Quality Assurance requirements of IOCFR5O Appendix B, as specified in the MPR Quality Assurance Manual.
MPR-OA Fomi k3A-3.1-, Rev. 1
MPR Associates, Inc.
E*MPR 320 King Street Alexandria, VA 22314 RECORD OF REVISIONS Calculation No. Prepared By Checked By Page: 2 1108-0002-RCT-01 /$ -7 4 4 p </// Zj.
Revision Affected Pages Description 0 All Initial Issue Note: The revision number found on each individual page of the calculation carries the revision level of the calculation in effect at the time that page was last revised.
MPR OA Form OA-3.1-2, Rev. 0
MPR Associates, Inc.
- M PR 320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By Page: 3 1108-0002-RCT-01 Revision: 0 Table of Contents 1.0 Purpose 4 2.0 Summary of Results 4 3.0 EstimatingPeak Accelerationsfrom Average Accelerations Reportedby SIA 4 4.0 Accelerations to Use for Analysis at Vane PassingFrequencies 6 5.0 References 6 MPR OA Form: OA-3.1-3, Rev. 0 SiMI'R Farm: QA.3.I.2.
PR QA Form: Rev. 0O QA-3.1-2. Rev. MPR QA Form: OA-3.1-3, Rev. 0
MPR Associates, Inc.
- AMPR 320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By Page: 4 1108-0002-RCT-01 6 X Revision: 0 1.0 PURPOSE The purpose of this calculation is to provide an estimate for the vibration accelerations that occurred in 2004 and 2005 in the Hope Creek Loop A and Loop B Recirculation System piping, on the suction side of the reactor recirculation pumps, at the recirculation pump vane passing frequency (5X) range.
2.0
SUMMARY
OF RESULTS The results are shown in the following table.
Table 2-1.
Estimated Peak Accelerations Occurring at 5X Vane Passing Frequencies For Recirc Suction Piping Elbows Maximum Average Acceleration Reported Estimated Peak Direction by SIA (2004-2005) at Acceleration the 5X Vane Passing Frequency Axial 0.2 g's ims 0.6 g's Vertical 0.18 g's rms 0.54 g's Perpendicular 0.13 g's rms 0.39 g's 3.0 ESTIMATING PEAK ACCELERATIONS FROM AVERAGE ACCELERATIONS REPORTED BY SIA Reference I summarizes accelerations measured in the recirculation piping near the elbows on the pump suction piping. The SIA results summarized in Reference 1 are average accelerations, expressed in root-mean-square g's, for each accelerometer. This information is obtained by the following method (excerpted from Reference 2, Section 2.2):
The FFTtime-averaged the signal over the 120 seconds in groups of 4096 samples (transfornm size); that is, the 120 seconds was broken into (120 seconds/1024 sps) samples and then grouped into successive 4096 sample groups. An F1FTwas generatedfor each group and then all FFTgroups were summed together, and divided by the number of MPR DA Form: OA-3.1-3, Rev. 0 MPR QA Farm:
NMPR Rev. 00 QA-3.1-2, Rev.
Form: QA.3.I.2. MPR OA Form: CIA-3.1-3, Rev. 0
MPR Associates, Inc.
XM PR 320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By Page: 5 1108-0002-RCT-01 4 4 Revision: 0 groups to provide time-averagefrequency spectra. Plotsfor each averagedfrequency spectra were generated,for each channel, in a graph of amplitude (grns), versus frequency (hz).
As documented in Reference 3, MPR's review of SIA data showed that the averaging technique used has the effect of "blunting" the accelerations in the case when the recirc pump speed varies slightly over the time interval. This occurs because slight fluctuations in the pump running speed, on the order of a quarter of a Hertz or more over the two minute data collection period, cause the peak accelerations to vary from one discrete frequency bin to another. Thus, over the 120 seconds, for a given discrete frequency bin, the average acceleration value is calculated for some time periods when the peak acceleration occurred in that frequency bin, and some time periods when the peak acceleration was in a different bin. Therefore, the average acceleration over the total time period for any single discrete frequency bin can underestimate the peak acceleration, if the frequency shifts over the time period.
In Reference 3, MPR showed that FT1results taken over 4-second intervals yield acceleration magnitudes (measured in g's rms) that are about double the average reported by SIA over the 120-second interval. Accordingly, the SIA average accelerations can be doubled to represent the peak acceleration (again, measured in g's rms). This doubling accounts for slight frequency shifts that may occur during the 120-second data collection interval.
Estimated g's rms = 2 * (SIA Average g's rms)
Reference 3 also shows that the zero-to-peak acceleration can be estimated from the rms acceleration by multiplying by the square root of two (1.414):
Estimated Peak Acceleration (g's) =
(1.414) * (Estimated g's rms) = (1.414) * (2) * (SIA Average G's rms)
Combining these factors, and noting that (1.414) * (2) can be conservatively approximated as 3, yields:
Estimated Peak Acceleration (g's) = (3) * (SIA Average G's rms)
In summary, peak accelerations in the recirculation system can be estimated by tripling the average rms accelerations presented by SIA in their PET plots.
MPR QA Form: OA-3.1 -3. Rev. 0 QA Form:
NIPR QA MPR Rev. 00 QA.3.I.2. Rev.
Form: QA-3.1-2. MPR QA Form: QA-3.1-3, Rev. 0
MPR Associates, Inc.
- FMPR 320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By Page: 6 1108-0002-RCT-01 Revision: 0 4.0 ACCELERATIONS TO USE FOR ANALYSIS AT VANE PASSING FREQUENCIES Tables and figures in Reference I show the average accelerations (in g's rms) calculated by SIA for the accelerometers installed on the Loop A and B recirculation loop suction piping elbows, resulting from the 5X vane passing frequency. Table 4-1 below lists the maximum average accelerations for either Loop A or Loop B for each accelerometer direction reported by SIA over the 2004-2005 period.
These accelerations are averages expressed in g's rms. As described above, to convert these values to estimated peak accelerations, the SIA values should be tripled. Tripled accelerations are also shown in Table 4-1.
Table 4-1.
Estimated Peak Accelerations Occurring at 5X Vane Passing Frequencies For Recirc Suction Piping Elbows Maximum Average Acceleration Reported Direction by SIA (2004-2005) at Estimated Peak the 5X Vane Passing Acceleration Frequency (From Ref. 1)
Axial 0.2 g'srms 0.6 g's Vertical 0.18 g's rms 0.54 g's Perpendicular 0.13 g's rms0.39 g's
5.0 REFERENCES
- 1. MPR Calculation H-1-BB-CDC-2065, Reactor Recirc Vibration Data Analysis, Revision 0.
- 2. Hope Creek Recirculation System Vibration Data Reduction. San Jose, CA.: Structural Integrity Associates, Inc., May 2004. HC-06-301, Revision 0.
- 3. MPR Calculation 0108-0316-RVO1, Hope CreekIRHR Pipe Vibration Analysis, Revision 0.
MPR QA Form: OA-3.1-3. Rev. 0 QA Form:
Form: QA-3.I-2. MPR OA Formn: OA-3.1-3, Rev. 0