The current stack design calls for the sampling probe to be located about 10 diameters downstream of the junction of the duct from Fan A with the stack. In accordance with the statement of work and the test plan, the test measurements were made at that location and also at one point upstream and another downstream. An adjustment was made for the distance between a typical sampling probe inlet and the centerline of its mounting flange. Thus, the test measurements were made at three positions designated as Test Port 1, 2, and 3, respectively.The designed HV-C2 exhaust system includes dampers on the fan discharges. Custom-scale model dampers were fabricated to simulate the same number and configuration of damper blades shown in the design documents received from BNI. A subset of the test runs was run without the dampers to determine whether the dampers should be included in future tests on scale models.The testing addressed the following criteria from ANSI/HPS N13.1-1999:1. Angular Flow-The purpose is to determine whether the velocity vector is aligned with the sampling nozzle. The average yaw angle relative to the nozzle axis should not be more than 20°. The measured average values ranged from 3.73 to 6.15 degrees, regardless of the test port and presence of the dampers. These same types of flow angle measurements will have to be made on the constructed stack during cold startup to show that the mean flow angle is <20°. There is no criterion for agreement with the scale-model flow-angle results.2. Uniform Air Velocity-The gas momentum across the stack cross section where the sample is extracted should be well mixed or uniform. The uniformity is expressed as the variability of the measurements about the mean, the coefficient of variance (COV). It is calculated as the standard deviation divided by the mean and expressed as a percentage-the lower the COV value, the more uniform the velocity. The acceptance criterion is that the COV of the air velocity must be ≤20% across the center two-thirds of the area of the stack. The maximum result was 12.8% COV, indicating that this criterion is met regardless of test port, fan configuration, and damper presence. The values declined with increasing distance from the duct junction. To confirm the validity of these scale-model tests, air-velocity uniformity measurements will have to be made on the constructed stack during cold startup to check for agreement with the velocity-uniformity results presented here for the same relative probe location. The agreement must be within 5% COV.x 3. Uniform Concentration of Tracer Gases-A uniform contaminant concentration in the sampling plane enables the extraction of samples that represent the true concentration. This was first tested using a tracer gas to represent gaseous effluents. The fan is a good mixer, so injecting the tracer downstream of the fans provides worst-case results. The two acceptance criteria are that 1) the COV of the measured tracer-gas concentration is ≤20% across the center two-thirds of the sampling plane and 2) at no...

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The 222 Rn concentration in exhaust air is being measured at underground uranium mines in the Grants, New Mexico area. The objective of the work is to determine relationships between U 3 0 8 production and the mine characteristics and practices relative to 222 Rn emission. Concentrations in the vent air from two mines ranged from 90 nCi/m 3 to 3800 nCi/m 3 during a month of observations. Diurnal radon emission patterns were seen from each mine which were inversely related to barometric pressure. The average diurnal emission patterns on weekends when no mining occurred were very similar to those on weekdays during active mining, indicating that the mining activities had little short-term effect on those radon emissions. The radon emission rate from each mine vent showed a correlation with the associated ventilated surface area and the cumulative tons of U 3 0 8 extracted there and a higher correlation with cumulative tons of ore extracted. Grab samples of vent air collected at 14 additional mines in the Grants area showed radon concentrations from 7 nCi/m 3 to 21,000 nCi/m 3 •

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Estimated Radon Emission From Waste Following Closure of the Mines. Piles at Four Mines Estimated Radon Storage Piles Release from Six Mine 10. Estimated Radon Release in Mine Water From Six Mines 11. Relationship Between Radon Emission and Mine Production C.l Distribution of Grab Sampling Times and Associated Biases C.2 lntercomparison of Vent Flow Measurements Using Different Instruments