ML20198T105
| ML20198T105 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 10/25/1997 |
| From: | External (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20198S910 | List: |
| References | |
| NUDOCS 9711140199 | |
| Download: ML20198T105 (12) | |
Text
{{#Wiki_filter:- . .. ._. - - . _ . - . . . - . . _ t l l 4 i l l ATTACHMENT F 1 Summary Report Tracer Gas Test of CR-3 CCHE Provided by Lagus Technology and NCS Corporation 1 4 (
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* , U, S. Nuclear Regulatory Commi:sion Attachment F 3FJ 197-09 Page 1 of 11
SUMMARY
REPORT TRACER GAS AIR INLEAKAGE MEASUREMENTS WITHIN CRYSTAL RIVER UNIT 3 CONTROL COMPLEX HABITABILITY ENVELOPE OCTOBER 1997 Prepared by: P.L. Lagus, Ph.D., CIH October 25,1997 NCS CORPORATION 4555 Groves Road #41 Columbus, OH 43232 614 864 7613 Phone 614 864 2296 Fax
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* . U, S. Nuclear Regulatory Commission ,
Attachment F
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3FJ 197-09 Page 2 of 11
1.0 INTRODUCTION
AND
SUMMARY
Two tracer gas air inleakage tests were performed on the Control Complex Habitability Envelope (CCHE) at the Crystal River Unit 3 Nuclear Generating Station during the month of October 1997 by a team of test engineers from NCS Corporation (NCS) and Lagus Applied Technology, Inc. (LAT). Air leakage rates were inferred using NCS/LAT Procedure 1204 &v.1 " Tracer Concentration Decay Test" which is based on the methodology described in ASTM Standard E741-93 " Standard Test Method for Determining Air Change Rate in a Single Zone by Means of a Tracer Gas Dilution". For the purposes of air inleakage testing, the Control Complex Habitability Envelope consists of the Ventilation Equipment Room, the Control Room, the Cable Spreading Room, the EFIC Rooms, the Battery Rooms, and the entire Stairwell. Air inleakage into the CCHE was measured with the ventilation system operating in either the Toxic Gas Mode or the High Rad Mode. The electronegative gas, sulfur hexafluoride (SF6), was used as a tracer. This gas is generally recognized as non toxic, non reactive, and inert. Since it is easily deteciable in minute quandties by means of electron capture gas chromatography, SF6 is an ideal tracer gas for vent?ation system performance investigations. Sulfur hexafluoride concentrations were determined using measurement specific analyzers optimized for detection of SF6. i Air samples were obtained using disposable polypropylene syringes. Except for
- the Stairwell, the Cable Spreading Room, and the Main Control Room, air samples were taken directly as grab samples. Air samples at eight levels in the Stairwell, as well as at six locations within the Cable Spreading Room, and at four locations within the Main Control Room were obtained using a pump / manifold sampling system.
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' a . U,. S. clear Regulatory Commission Attachment F l 3FJ W 39 Page 3 of 11 l
l
.n individual air inleakage test was performed by injecting a tracer gas at a l nown rate for period of time into the supp!y air duct and dispersing it uniformly throughout the CCHE. After cessation of tracer injection an additional time period I
was allowed to elapse. At this point tracer samples were obtained at timed l intervals from a number of points throughout the CCHE. By measuring the decay in tracer gas concentration as a function of time one can determine the air exchange rate within the CCHE. Knowledge of the CCHE volume allows calculation of the air inleakage rate in CFM. Tracer gas injection rates were controlled by a Matheson Model 8270 Mass Flow Controller. The tracer gas injection source was a high pressure cylinder containing a mixture of SF6 diluted in nitrogen. The SF6 concentration was analyzed and certified to +/- 1% by an independent laboratory. 2.0 MEASURING BUILDING AIR FLOWS USING TRACER GASES There are three princ.ipal tracer gas techniques for quantifying air flow rates within a structure; namely, the tracer concentration decay method, the constant injection method, and the constant concentration method. All three of these techniques are incorporated in the most recent revision of ASTM Standard E741-93 " Standard Test Method for Determining Air Change in a Single Zone by Means of a Tracer Ges Dilution". The air inleakage testing at Crystal River Unit 3 Nuclear Generating Station used the tracer concentration decay method. This method measures the decay in tracer concentration at a number of spatially distinct locations within the CCHE as a function of time. The logarithmic decay rate in tracer concentration determines the air exchange rate. The essentials of the test method are illustrated schematically in Figure 1.
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-?,. U,. S. Nuclear Regulatory Commission Attachment F 3FJ 197-09. Page 5 of 11 To interpret data resulting from a tracer gas test, one employs a mass balance of a tracer gas released within the volume under test.- Assuming that the tracer gas mixes thoroughly within the structure, the mass balance equation is, V dC(t)/dt = S(t)- L(t)C(t) (1) where V is the test volume, C(t) is the tracer gas concentration (dimensionless), .
dC(t)/dt is the time derivative of concentration, L(t) is the volumetric airflow rate into the test volume, S(t) is the volumetric tracer gas injection rate, and t is time. r . The simplest tracer gas technique is the tracer concentration decay method. After an initial tracer injection into the test volume, there is no source of tracer gas, hence S(t) = 0 and assuming A is constant, a solution to equation (1) is; C = Co exp (-A t) (2) where Co is the concentration at time t=0c This method requires only the ineasurement of relative tracer gas concentrations, as opposed to absolute concentrations, and the analysis required to determine A is straightforward, in use, equation (2) is often recast to the following form; In C = in Co - A t (3) In practice one obtains a series of concentration versus time points and then performs regression analysis on the logarithm of concentration versus time to
-find the best straight line fit to the form of the equation given by equation (3).
The slope of this straight line is A, the air exchange rato. The air exchange or infiltration rate, A, is given by A(t) = L(t)N. The units of A l- a e air changes per hour (h-1 or ACH). The value of A represents the volume normalized flowrate of " dilution air" entering the volume during the test interval. l l
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' % U,. S. Nuclear Regulatory Commission Attachment F 3FJ 197 Page 6 of 11 Note that this " dilution air" can be actual outside fresh air or, more generally, it
.. can be air whose origin is not within the test volume.
As depicted in Figure 1, the natural logarithm of the tracer concentration , decreases linearly with time. The slope of this line is A, the air exchange rate. To calculate the air inleakage rate, one must have independent knowledge of . the CCHE volume from which, L=AV (4) The results obtained with this technique are exact only for a well mixed volume, (i.e. concentration at a given time is the same throughout the test volume). Otherwise, the results will be subject to errors, with the magnitude of these errors depending on the extent of the departure from homogeneity. The tracer concentration obtained within the Crystal River Unit 3 CCHE and used in the calculation of the air exchange rates demonstrate that the tracer gas was well mixed, hence equation (2) could be applied. ( The uncertainty for each inteakage measurement was calculated using the prescription provided in ANSI /ASME Standard PT 19.1-1985 " Measurement Uncertainty" and represent 95% confidence limits. This analysis is based upon equation (4) and uncertainties for all derived and measured quantities were incorporated into the analysis.
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* % U, S. Nuclear Regulatory Commission Attachment F 1F4197-09 Page 7 of 11 i t
f 3.0 EXPERIMENTAL TECHNIQUES AND MEASURED DATA in order to investigate air inleakage into the Crystal R'ver Unit 3 Nuclear Generating Station Control Complex Habitability Envelope (CCHE), two tests - . were performed during October,1997.1These tests consisted of:
. Test A: CCHE Inteakago with ventilation system in Toxic Gas Mode. *
- Test B: CCHE Inteakage with ventilation system in High Rad Mode.
. The experiments! details and relevant data for each test will be described in the
- following section of this summary report.
3.1 AIRINLEAKAGE TESTS On October 14-15,1997 an air inteakage test was performed with the CCHE ventilation in the Toxic Gas Mode (Test A). For this test Supply Fan 17B and Return Fan 19B were operating. At 20:15, an SF6 in nitrogen mixture possessing a concentration of 706 ppm was injected at a flowrate of 6.8 SLPM into the suction side of Air Handling Unit 17B. Injection continued for 90 minutes. Tracer gas samples were collected from 43 different locations throughout the CCHE at 60 minuta intervals beginning at 00:00 (midnight) and ending at 06:00. On October 16-17,1997 an air inleakage test was performed with the CCHE ventilation in the High Rad Mode (Test B). For this test Supply Fan 18A and Return Fan 19A were operating. At 21:30, an SF6 in nitrogen mixture possessing a concentration of 706 ppm was injected at a flowrate of 5.5 SLPM into the suction side of Air Handling Unit 18A Injection continued for 90 minutes. Tracer gas samples were collected from 43 different locations throughout the CCHE at 60 minute intervals beginning at 23:30 and ending at 05:30. During the actual testing, portable fans were used to assist tracer gas mixing and distribution within the Ventilation Equipment Room, the Cable Spreading LRoom, the Control Room level bathrooms, and the Stairwell. Eight portable
. . . s 4 U,. S. Nucle:r Regulatory Commission Attachment F 3FJ 197-09 Page 8 of 11 J
t mixing fans were arranged within the Ventilation Equipment Room, twelve portable fa,1s were emplaced at successive levels within the Stairwell, and two portable fans were positioned to circulate room air to the two bathrooms on the ' Control Room level. Three portable fans were positioned on the south half of the Cable Spreading Room. in addition, during the actual testing, two large - capacity halon system circulating fans located on the north side of the Cable
- Spreading Room were activated.
All internal doors on the 108,124,134 levels as well as the two bathroom doors on the 145' level were propped open during the testing to assist in the mixing of the tracer gas. In addition, the stairwell door to the elevator mechanical equipment room was propped open during the test and a single portable fan was positioned to circulate air into this room from the adjacent stairwell landing. No additional mixing fans were used in the CCHE as previous experience in other nuclear power plant Control Room Envelopes has shown that ventilation flows into well ventilated rooms (such as the Battery and EFIC rooms) are sufficient to mix tracer over tha time interval that elapsed prior to initiation of sampling. The measured concentration data during this testing demonstrated that all levels of the CCHE were, in fact, well mixed. 4 A summary of mean tracer concentration values for the entire CCHE (43 sample points per time interval) at each sampling interval are provided in Tables 1 and
- 2. The standard deviation of all tracer measurements at a given measurement interval is also shown.
The standard deviation is a statistical measure of how much a collection of
. measurements differs from the mean of the collection. The smaller the standard deviation, the closer individual values in the collection are to the mean.
Inspection of Table 1 discloses that for Test A the standard deviation of the
- mean concentration ranges from +/- 2.5 % to
+/- 4.2 %, thereby confirming that tracer was well mixed throughout the CCHE for this test, inspection of Table 2 discloses that for Test B, the standard deviation of the mean concentration ranges from +/- 2.85 % to +/- 3.32 %,
. - thereby confirming that tracer was well mixed throughout the CCHE for this test
. also.
g. U,. S; Nuclear Regulitory Commission Attachment F 3 %1197-09 .,j Page 9 of 11-l f
<_ Table 1 -
, Mean CCHE Concentrations, Test A
,- . ELAPS 8ED TIME MEAN CONC. STD. DEVIATION (hr) (ppb) (%)
0 42,64 2.5 1 39.87 3.0 2 3 37.29 3.3 i 3 34,71 3.0 4 31.90 4.2 ^ 5 29.61 4.2 6 27.94 ' 3.6 1
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So, U,. S. Nuc! car Regulatory Commission Attachment F 3%I197-09 Page 10 of 11 1. Table 2 . Mean CCHE Concentrations, Test B ELAPSED TIME MEAN CONC. STD. DEVIATION (hr) (ppb) (%) 0 34.05 3.13 1 31.53 2.92 2 29.3 3.01 3 27.46 2.85 4 25.50 2.87 5 23.57 3.32
-6 21.97 3.05 l
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% t,I S. Nuclear Regulatory Commission Attachment F 3N 197 09 Page11of1I 4.0 CONCLUSIOreS The air exchange rate into the Control Complex Habitability Envelope with the CCHE ventilation system in the Toxic Gas Mode was measured as 0.07211 air changes per hour Assuming a volume for the CCHE of 364,922 Cu. Pt. this implies that the air inleakage rate is 439 +/- 17 CFM.
The air exchange rate into the Control Complex Habitability Envelope with the CCHL ventilation s,ystem in the High Rad Mode was measurod as 0.0727 air changes per hour. Assuming a volume for the CCHE of 364,922 Cu, Ft. this implies that the air inteakage rate is 442 +/ 20 CFM. These data are summarized in the following table. Table 3 Summary of Measured Air Inleakage rates VENTILATION TEST MEASURED MODE INLEAKAGE (CFM) TOXIC GAS 439 +/ 17 HIGH RAD 442 +/- 20
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