ML20215L990
| ML20215L990 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 05/22/1987 |
| From: | Pace N EG&G IDAHO, INC., IDAHO NATIONAL ENGINEERING & ENVIRONMENTAL LABORATORY |
| To: | NRC |
| Shared Package | |
| ML20215L983 | List: |
| References | |
| CON-FIN-D-6023 OBEN-73-87, NUDOCS 8706260237 | |
| Download: ML20215L990 (6) | |
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Enclosure May 22, 1987 Oben-73-87 i Page 1 of 6 j l
i BYRON NUCLEAR PLANT ESW COOLING TOWER TEST PLAN PRELIMINARY EVALUATION
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by N. E. Pace j
EG&G Idaho, Inc. 1 l
IDAHO NATIONAL ENGINEERING LABORATORY P. O. Box 1625 Idaho Falls, ID 83415 l v-so2 2 i
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BYRON NUCLEAR PLANT ESW COOLING TOWER TEST PLAN PRELIMINARY EVALUATION INTRODUCTION I This report contains the preliminary evaluation of the Byron Nuclear Plant Essential Service Water (ESW) cooling tower (CT) tests planned by Commonwealth Edison Co. (CECO) and their consultants, Environmental Systems Corp (ESC), that was presented to the NRC in a meeting in Bethesda, Wednesday, May 13, 1987. A discussion of the planned test details is first presented followed by a conclusion of the evaluation.
Some comments on the wet bulb temperature restrictions Byron is currently operating under is also included.
DISCUSSION The preliminary evaluation is based on the following test plan information (obtained from the May 13, 1987 meeting) as compared to a normal Cooling Tower Institute (CTI) specified test. Only one of the eight CT bays will be tested because the heat load available is small compared to the whole CT design heat load.
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- 1. Hot water temperature (HWT) will be measured in 2 locations every 15 sec for /10 min once " steady state" conditions are reached (80 or more data points). The CTI Code ATC-105, Acceptance Test Code for Water-Cooling Towers, requires that the CT be operating at steady state and that data be taken for a minimum of 1 hr with at least 12 data points taken. The 1 hr test time is normally required to average out the test conditions, especially the inlet air wet bulb temperature (WBT) and the water basin average temperature; neither of these should be a problem for the planned Byron CT test because the basin water is eliminated from the test.
- 2. The cold water temperature (CWT) will be the average of 20 i temperature measurement locations where the water from the CT 1
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bay will be collected'and data.taken every 15 sec over the
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>10 min test period (40 or more average. CWT data points). The
'CTI specifications require 12 or more data points per hour be taken;-these are normally taken at the pump discharge' header in an attempt to get a well-mixed average CWT. The 20 collection q
= location's temperature measurements should provide an adequate' )
l average CWT for the Byron CT test.
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- 3. The inlet air wet bulb temperature (WBT) will be'the. average of !
8 locations where data will be taken every 15 sec-(320 data' points) using powered psychrometers. The CTI- specification probably requires 8 locations (depends on inlet flow area) for !
this' tower design, but only requires 12 or more data points per
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location per hour (96 data points). 1 4 . The test plan calls for heat balance calculations to be made j between the CT water side and air side flows. -The CTI:
l specification does not require this check calculation to be made. It is an additional check that'will be provided by the l test engineers on the quality of the data obtained.
I S. Aireflow rate will be measured by taking velocity measurements from 8 anemometers and comparing their readings with .
" calibrated" readings developed from two perpendicular traverses of the tower test bay stack with 20 equal area measurements each. Fan motor input power and fan rotational speed will also be taken and correlated to the flow. rate datac The CTI specification requires that the fan flow rate / fan motor horse power relationships be developed,.but even allows vendor i l supplied fan curves to be used; the CTI specification says very little about measuring the air flow rate. . (Byron's plan exceeds ,,
what EG&G Idaho, Inc. did for the Advanced Test Reactor [ATR].in Idaho last summer, with the exception that four of;the six fans '
were tested.
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- 6. Meteorological conditions (wind velocity, dry bulo temperature, and barometric pressure) will be recorded and comments mado during the meeting indicate they will be within the CTI specification recommendations (velocity fl0 mph with gusts 115 mph). The CTI recommended location for these perimeters to be measured is upwind and within 100 ft of CT and about 5 ft j above the basin curb elevation. j
- 7. The Byron CT test will provide a number of test data points (I think they said 24 or 27 test points) for one CT bay from which they will develop the Byron CT's performance curves. The CTI specified test gives one data point as near to the design conditions as possible and relies on the manufacturer provided performance curve for their fill and type of CT. I believe the Byron test approach will give a more reliable performance curve for use by Byron, assuming that each bay will perform as well as the one tested.
ESC indicated that the data will be processed by a proprietary computer program and the results provided for Byron and NRC review. This is really the only reasonable way to handle this much data and the results (input and output) can easily be made available for review. I recommend a few check calculations be made to spot check the results, but otherwise the validity of the data eau M be good. 'i My impression of Environmental Systems Corp. from the meeting was positive and since these type of tests are their business, I assume the ;
instrumentation being used will be high quality and accurate. (This is not easily done unless one spends the money and effort to do it; this is more than is normally done for one time tests done by the CT owners, but normal for third party companies such at ESC in the CT testing business.) ;
f While reviewing the information from Byron supplied earlier by the NRC, it -I was obvious that Byron had not taken into account the heat capacity of the water in the CT basin in their analysis. In the meeting Byron indicated they would like to do that in an attempt to relax or eliminate the WBT restrictions they are currently operating under. The heat capacity of the 3 .I 1
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o, f basin water is probably the most secure short term heat sink they have and it is reasonable to consider it in the overall safety evaluation. This is even more reasonable considering the transient nature of the CT required heat load (S10 min above the current predicted CT capability for three q bays).
The restrictions requiring Byron to shut one unit down if the WBT gets above 75 F seems unnecessary for two reasons: (1) the CT basin water supplies a more than adequate heat sink to accommodate the accident conditions heat load above the estimated 425 x 106 Btu /hr (three bay) CT capability at design (accident and environment) conditions for the time required; (2) the behavior of cts is such that they will reject the heat load supplied to them, but the CWT may increase (the CWT will increase about 1 F for every 2 F increase in the WBT at the same heat loading). The time required for the increase in CWT to.be detected in equipment being cooled by the CT basin water would be long because the basin contains a large volume of water. The hotter water coming into the basin will either mix resulting in a small increase in the average basin temperature or stratify resulting in an.even longer delay of this hotter water getting to the equipment being cooled.
Therefore, it is recommended that NRC consider action completely lifting the WBT restrictions from the Byron plant. This action could be >
re-evaluated if needed once the CT testing was complete, depending on the l test results.
CONCLUSIONS The preliminary evaluation of the Byron Essential Service Water CT test planned by Commonwealth Edison Co. and their consultants, Environmental Systems Corp., is that these tests will result in sufficient data from which the cooling tower's capability to remove the design (accident) heat load at design conditions can be determined. The test planned is significantly more extensive than and as accurate as the test required by j the CTI Design' Specification for acceptance testing new cooling towers.
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1 L 'The Byron CT test plan includes obtaining enough data points (>20) to l allow-the CT design ~ curve to be' developed for this specific CT. The CT manufacturer normally provides these curves and 'het slope of them is ba' sed on:their knowledge of their CT design but has only one data point-(the acceptance t'est) to verify.it is. valid for this CT. Therefore, the slope .i of the-CT performance curve is normally never verified for specific-cts. !
Byron's proposed CT testing and. expected data reporting goes significantly beyond this " normal" CT capability verification.
The. current Byron plant operating restrictions based on WBT seem'to be unnecessary. The CT (three bays) will' dump the accident heat load at the 1
78 F. design wet bulb temperature and design air and water flow rates, I but the cold water temperature might increase slightly above its design value for a short time (%10 min)(based on their current test results).
The CT basin'large water volume will prevent that higher temperature water from reaching the equipment being cooled by-the ESW system-by its large heat capacity.
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