ML20244A680
| ML20244A680 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 03/31/1988 |
| From: | Pace N EG&G IDAHO, INC. |
| To: | NRC |
| Shared Package | |
| ML20244A681 | List: |
| References | |
| CON-FIN-D-6023 EGG-NTA-8011, NUDOCS 8904180138 | |
| Download: ML20244A680 (16) | |
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Appendix A s
EGG-NTA-8011 l
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l-TECHNICAL EVALUATION REPORT FOR l~
REVIEW OF BYRON NUCLEAR GENERATING STATION ESSENTIAL SERVICE WATER COOLING TOWER THERMAL PERFORMANCE TEST REPORT Docket N6s. 50-454 and 50-455 N. E. Pace Published March 1988-INEL Idaho National Engineering Laboratory i
EG&G Idaho, Inc.
Prepared for the U. S. Nuclear Regulatory Commission l
Washington DC 20555 Under DOE Contract No.DE-AC07-761001570 FIN No. D6023 89@/fhl3T p
OlSCLAIMER This book was prepared as an account of work sponsored by an agency of the Urvted States Government. Neither the United States Governrmnt nor any agency thoroof.
not any of their employees, makes any warranty. express or impled, or assumes any legal liaonlity or responsibdity for tne accuracy. completeness, or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not ininnge onvatefy owned rights. References herein to any specific commercal product, process, or service by traos name. tracemark, inanufacturer, or otherwise, does not necessardy constitute or imply its endorsement, recommendation or favonng by the United States Govemment or any agency thereof. The views and opinions of autPors expressed herein do not necessanly state or reflect those of the United States Government or any agency thereof.
4 ABSTRACT Byron Nuclear Generating Station had Environmental Systems Corp.
perform thermal performance tests on their essential service water cooling tower to assure themselves and NRC that the cooling tower was adequate to handle the required accident heat load.
Extensive testing was done and the cooling tower characteristic curves developed to allow the tower to be rated at design conditions. This technical evaluation report was written to document the review of the draft and final thermal performance test reports; the main focus of the review was on the test procedures and results.
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SUMMARY
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l The review of the Byron cooling tower thermal performance test draft l
and final reports was completed. The tests done far exceeded the acceptance testing required by either the ASME power test code or the CTI acceptance test code and allowed characterization of this cooling tower so that'it's capability could be accurately predicted for the design conditions. The tests done were conservatively designed and resulted in a l
reasonable estimate of the cooling tower's capability over the expected range of conditions.
Some errors and omissions were discovered in the draft report; these were transmitted to Byron and were corrected in the final report.
The test results are believed to be applicable and the conclusion that the cooling tower is adequate to remove the peak accident heat load of 580 million Btu /hr at the design conditions with four cells is believed to be correct. The cooling tower characteristic curves were developed from the test results so the Byron operators can determine the tower capability at any operating conditions with reasonable accuracy.
This extensive characterization of the cooling tower far exceeds the standard acceptance testing of cooling towers practiced in industry today.
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FORWARD This report is supplied as part of the " Technical Assistance to NRC/NRR for Resolving Plant Specific Licensing Actions for Operating Reactors" that is being conducted for the U.S. Nuclear Regulatory Comission Office of Nuclear Reactor Regulation, Division of Engineering by EG&G Idaho, Inc., NRR Technical Assistance Group.
The U. S. Regulatory Comission funded this work under the authorization B&R 20-19-05-02-2 FIN D6023.
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I Docket Nos. 50-454 and 50-455 TAC Nos. 64944 and 64945 iii
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CONTENTS i+
l ABSTRACT..........................................................
i
SUMMARY
ii F0RW'ARD...........................................................
ii 1.
INTRODUCTION..................................................
I 2.
BACXGR0VND...............................,.....................
2 3.
PURP0SE.......................................................
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4.
SC0PE.........................................................
3 5.
EVALUATION................................................
3 Ea rl y I nvol vement........................................
4 Draft RLport Review Comments.............................
4 Fi nal Report Revi ew Comments.............................
7 6.
CONCLUSION....................................................
8 7.
REFERENCES....................................................
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TECHNICAL EVALUATION REPORT FOR FEVIEW OF BYRON NUCLEAR GENERATING STATION ESSENTIAL SERVICE WATER COOLING TOWER THERMAL PERFORMANCE TEST REPORT
1.0 INTRODUCTION
This report was written to document the review of the Byron essential service water (ESW) cooling tower (CT) test draft (Reference 1) and final (Reference 2) reports written by Environmental Systems Corp. (ESC).
The steady state heat load on this CT is less than 107. of the design heat load so testing was done using the CT basin water as the heat source and running quasi steady state tests on one of the eight tower cells.
By doing this the CT range could be high enough that the errors in the data would be reasonable and the CT could be characterized such that the operators could determine what to expect from the tower under varied operating conditions and the CT performance could be accurately predicted for its design conditions.
The author of this technical evaluation report (TER) was involved in a meeting to review the test plans (Reference 3) and ma'de a plant visit during the testing in addition to reviewing the draft and final test reports for completeness and accuracy (the draft report was discussed with John Yost of ESC by phone).
NRC expressed concern about the applicability of test data obtained at low hot water (HWT) and inlet air wet bulb (WBT) temperatures and CT ranges [HWT - (CWT) cold water temperature] for the higher design operating conditions.
The tower range that could be obtained was less than the design value.
Therefore, extensive CT testing was done over a wide range of operating conditions and CT ranges to enable ESC to develop the tower characteristic curves so the CT design capability could be predicted with reasonable accuracy. Thirty-three CT tests were j
run and additional cell air flow rate tests were done to verify that the I
cell tested was typical or the most restrictive for air flow.
The maximum i
HWT, WBT and tower range obtained during the testing was 96.8'F, 74.9'F, and 20.7'F, respectively compared to the CT design values of 121.4*F, 78'F, and 23.4*F, respectively.
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2.0 BACKGROUND
Normal CT acceptance test practices recommended by the American i
Society of Mechanical Engineers (A5ME) or the Cooling Tower Institute (CTI) are to run one or more acceptance tests at close to the design conditions and use this data and "known" characteristic curves provided by the CT manufacturer to predict the CT capability at the design conditions. However, Byron's ESW CT had been modified since its design (a concrete curb around the basin and a massive missile shield around the CT supply piping were added) so the design curves were not necessarily valid. The CT capability needed to be determined for the design conditions. Testing at near the design heat load proved to be undesirable ft,r Byron because this CT is provided to handle potential accident condition heat loads and the steady state heat load is less than 10% of the design heat load.
To provide the design heat load would mean bringing in a large boiler and disrupting the plant operation while the CT test was conducted.
Byron decided to run a series of tests to actually characterize the CT heat rejection capability. Byron hired ESC to design and perform the CT tests. This work was done and the draft and final reports (References 1 and 2) written; these reports were reviewed and this TER documents the review.
Early tests were performed on the ESW CT but they were unsuccessful because the range was too low (2 to 3*F) to provide acceptable accuracy.
This low range is all that ceuld be obtained during steady state operation without tne use of an auxiliary boiler for the heat source.
3.0 PURPOSE The CT test reports were reviewed to provide NRC with additional assurance that the tests conducted and the resulting CT characterization resulted in an accurate evaluation of the CT's capability to handle the postulated accident condition heat load at the design conditions.
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4.0 SCOPE The scope of the author's work included being involved in discussing the test plan and a visit to the Byron site to witness one of the individual tests and instrument deployment as well as the review of the test draft and final reports. The author recommended during the plant visit that the air flow rate be measured for each of the eight cells as only one was being tested and saae question would remain as to the validity of the assumption that the most air flow restricted cell was used for the test cell.
The review of.the test draft report included scanning all of the data for correctness and possible bad data and reviewing the rest of the report for correctne::s in the development and application of the test results.
The draft report was reviewed and initial comments were transmitted to Byron and on to ESC personnel; these comments were then discussed and resolved by phone with John Yost of ESC. The final report was then reviewed to assure correctness and completeness. A detailed evaluation of the data handling computer program was beyond the scope of this review; however, the results appear to be consistent and in line with the expected results. Manufacturer provided characteristic curves were not available nor applicable because of the CT modifications so the normal (ASME or CTI recommended) use of the test data to predict the CT capability at the design conditions was not done by the author. An extensive review of the test data and its use was made.
5.0 EVALUATION This section contains the discussion of the author's early involvement with the Byron CT test plans, the review and comment on the test draft report, and the review of the final report.
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Early Involvement Byron and ESC representatives discussed the test plan with NRC in a Washington meeting that the author attended in May 1987 and the Byron plant was visited by the author shortly after that meeting to witness one of the tests and review the test plan in more detail. The test plan including the data handling was sufficient that once completed the data needed to characterize the CT and allow predicting the tower capability at the design conditions would be available. The test plan included using ESC's proprietary computer program to reduce the test data and develop the CT characteristic curves. The hot water temperature effect, &ccounting for the rate of liquid evaporation (not normally done) and verifying that the CT range effect was small, was to be included in the data reduction.
The test witnessed was BYTEST 11. The test conduct was in compliance with the ASME and CTI recommended procedures with some modifications to allow utilization of the CT basin water as the heat source and running a quasi steady state test for 10 to 20 minutes instead of one or more hours during steady state operation. This was acceptable because the CWT leaving the cell was measured directly to eliminate the effect of the CT basin. One of the eight cells was thoroughly tested; this cell (cell OG) was selected because it has the greatest air inlet area reduction from the modifications made to the tower.
It was recommended by the author that all eight cells be tested for fan power and air flow rate to assure that the tested cell was indeed typical or conservatively representative of all eight cells.
This testing was done as recommended.
Draft Reoort Review Comments The test draft report was extensively reviewed for completeness and accuracy of data handling and test results.
Some errors were found and some questions were raised with Byron and later discussed with John Yost.
of ESC.
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The air flow rate test results showed that the test cell (0G) had a lower air flow rate than six of the seven other cells; therefore, it was indeed slightly conservative to test this cell and assume the other seven cells were identical to it. The air flow rate for each of the cells was within -0.7% to +11.4% of the tested cell air flow rate. The air flow rate for each of the eight cells was within 6.5% of the average cell air flow rate which shows that the data scatter was reasonable.
The location where the water flow rate measurement was made was about five diameters downstream of an elbow; a minimum of ten diameters are recommended upstream of flow meters without the use of flow straighteners. However, the use of the pitot tube and making two traverses across the pipe diameter at 90 degrees and using ten equal area I points for each should adequately account for any flow maldistribution that might exist.
The data did not indicate that any significant flow maldistortion existed in the pipe at the measurement location, so it is believed that the use of this flow measurement location as it was used resulted in adequately accurate water flow rate measurements.
e The errors and comments found and the resolutions are contained in the following paragraphs.
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Question:
Some inlet WBT readings were thrown out due to faulty instruments; other WBT readings appear to be in error (too high of temperature reading) but were not thrown out. Why not?
Answer:
The WBT readings thrown out were found to be incorrect due to dry wick or other obvious instrument failure.
The high WBT readings are believed to be correct and a result of air recirculation during the test.
Each WBT instrument that appeared to be giving high readings was checked after each test to see if there was anything wrong with the instrument; this was normally done by reviewing the WBT readings once the test was finished and the CT fans turned off.
If all the WBT readings on each side of 1
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the cell were reading about the same temperature with the CT fans off, the instrument was obviously operating correctly; if not, the instrument was examined.
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Comment: There are inconsistences between the CWT readings indicated to be thrown out in Table 4.!i, in the test log, and in the data usad in compiling the test results.
Answer: This was in error and will be ' corrected in the final report. Reanalysis of the test data from the individual tests affected will be done as required.
3 Guestion: The report states that the water flow rate in each cell was not necessarily the same during the air flow rate. tests.
conducted.
It is important to have nearly the same water flow rate in each cell when making the air flow rate measurements; this is understood as the water flow rate does affect the air side pressure drop and the air flow rate. How do you know the water flow rate in each of the cells is nearly the same during the air flow rate tests?
Answer:
ESC will review the test data and notes.and will respond to how they know the water flow rate in each cell is about the same for all tests.
If the water flow rate was greatly different it would be obvious from the air flow rate obtained. The air flow rate tests were done with water flow through four cells which is typical for normal operation and the design conditions.
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Comment: A number of typing and set-up errors were found and were discussed with John Yost of ESC by phone.
Answer: These will be corrected in the final report.
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Comment: The report should contain a statement of the overall accuracy of the resulting. correlation with respect to the expected CT performance at the design conditions.
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Answer:
ESC wi11' incorporate this into the final report.
Final Reoort Review Comments The final report was reviewed to be sure that all the stated comments
- were addressed as indicated. They were all included and the results found to be acceptable.
The final CT characterization curves have been developed for the Byron CT and are specific to that CT and have taken into consideration the
~ HWT effect that one encounters when going from the colder test HWT to the design HWT. The error normally introduced by neglecting _ the evaporation of liquid was also eliminated in the test data correlation by including the affect of the liquid flow rate at the tower top being different than it is at the bottom.
The lower inlet WBT affect on the data was found to be an insignificant factor with respect to its affect on the test results. Also some of the inlet WBTs encountered during the testing (up to 74.9'F) were not that much lower than the 78'F design WBT.
The CT range obtained during the testing was between 8.7'F and 20.7'F (neglecting BYTEST 02 which was one of the three tests thrown out due to air recirculation from adjoining cells) and is not that much smaller than the 23.2*F design range. The test data is applicable to the CT at the design conditions.
It is also true that the range is not as great a factor in the CT behavior as is the HWT and the liquid to air flow rate ratio. The cell water flow rate during the fan tests of all eight cells was as uniform as could be obtained; water was flowing over four cells with fully open supply valves for each of the cell fan tests.
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The conclusion reached that the Byron CT is adequate to remove the 580 million Btu /hr peak heat load at the design conditions with four of the eight cells in operation is believed to be correct.
From the extensive testing done, Byron now has specific CT characteristic curves with which they can estimate quite accurately how the CT will perform at any normal conditions. The tests done are valid for using to predict the CT performance at the design conditions. The accuracy of this type of testing is believed to be at least as accurate as the ASME or CTI I
l recommended CT acceptance testing which is to use one or a few tests and manufacturer furnished CT characteristic curves based on the tower design to predict the CT performance at the design conditions.
6.0 CONCLUSION
S The conclusion is that the Byron ESW CT tests and associated data reduction have resulted in CT characteristic curves that allow accurate prediction of the CT performance at the design conditions. The ESW CT is believed to be capable of removing the peak accident heat load of 580 million Stu/hr at the design conditions with four of the eight cells. The accuracy of the CWT prediction i.s believed to be within 0.6*F.
The hot water effect has been taken into account in the formulation of the CT characteristic curves and some of the more common but accepted formulation errors have been eliminated by the data reduction methods used.
7.0 REFERENCES
1.
Byron Nuclear Generatina Station Essential Service Water Coolina Tower Thermal Performance Test Reoort, Environmental Systems Corp.,
TIN 87-1137, Rev. O, September 16, 1987 2.
Byron Nuclear Generatina Station Essential Service Water Coolina 4
Tower Thermal Performance Test Reoort, Environmental Systems Corp.,
TIN 87-1137, Rev. 1,,lanuary 19, 1988.
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3.
C. F. Obenchain letter to Mayo Carrington, NRC, " Transmittal. of Byron ESW Cooling Tower Test Plan Evaluation Letter Report", Oben-73-87, May 22, 1987.
4.
Atmospheric Water Coolino Eouioment Performance Test Codes, The American Society of Mechanical Engineers, ANSI /ASME PTC 23-1986.
5.
CTI Code Tower' Standard Specifications. Accentance Test Code for Water-Coolino Towers, Cooling Tower Institute, CTI Code ATC-105, June 1982.
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