NERC-LV-539-1?.
COMPARISON OF FREEZE-OUT AND
ADSORPTION TECHNIQUES FOR COLLECTION OF
ATMOSPHERIC TRITIUM AS KTO
£
Charles W, Forts Vernon. E. Andrews, and Aaron Goldmar
Environmental Surveillance
National Environmental Research Center
U.S. KNfliaOJMSSTAL PROTJtCfjtW AGENCY
Las ¥egas, Nevada
Published November 1972
This study perforated under a Memorandum of
Understanding No0 AT(2.6- .1 )-539
for the
Uc Sc ATOMIC ENERGY COMMISSION
-------
This report was prepared as an account of work sponsored by
the United States Government. Neither the United States nor
the United States Atomic Energy Commission, nor any of their
employees, nor any of their contractors, subcontractors, or
their employees, makes any warranty, express or implied, or
assumes any legal liability or responsibility for the accuracy,
completeness or usefulness of any information, apparatus,
product or process disclosed, or represents that its use would
not infringe privately-owned rights.
Available from the National Technical Information Service,
U. S. Department of Commerce,
Springfield, VA. 22151
Price: paper copy $3.00; microfiche $.95
054
-------
NERC-LV-539-12
COMPARISON OF FREEZE-OUT AND
ADSORPTION TECHNIQUES FOR COLLECTION OF
ATMOSPHERIC TRITIUM AS HTO
by
Charles W. Fort, Vernon E. Andrews, and Aaron Goldman
Environmental Surveillance
National Environmental Research Center
U.S. ENVIRONMENTAL PROTECTION AGENCY
Las Vegas, Nevada
Published November 1972
This study performed under a Memorandum of
Understanding No. AT(26-l)-539
for the
U. S. ATOMIC ENERGY COMMISSION
-------
ABSTRACT
A field study was conducted to compare the atmospheric concentrations
of tritium as HTO determined from a passive freeze-out moisture collector
and an air sampler using an adsorbent column of molecular sieve. Effluent
from production test flaring of the Project Rulison experimental gas well
produced by a nuclear detonation was used as an environmental source of
atmospheric tritium. Also studied was the comparability of absolute
humidity determinations based on two types of psychrometric measurements
and water recovered from a known volume of air by the molecular sieve.
From statistical analysis it was concluded that there was no significant
difference between tritium measurements or humidity determinations as long
as reasonable care was exercised in operating the samplers or making
psychrometric measurements.
-------
TABLE OF CONTENTS
Page
ABSTRACT i
LIST OF FIGURES i±j-
LIST OF TABLES iv
INTRODUCTION 1
OBJECTIVES 2
EQUIPMENT AND PROCEDURES 2
A. Equipment 2
B. Sampler Selection Criteria 3
C. Experimental Design 4
1. Site Description 4
2. Sampler Calibrations 6
3. Sampler Preparation 6
4. Sample Collection 7
5. Sample Analysis 8
D. Calculations 10
RESULTS 11
A. Moisture Collection 11
B. Tritium Results 15
DISCUSSION 17
CONCLUSIONS 20
APPENDICES 26
-------
LIST OF FIGURES
Figure Page
1. Special Study Sampling Locations 5
2. LLL Freeze-Out Sampler and NERC-LV Molecular Sieve Sampler 9
3. LLL Freeze-Out Sampler Collection Rate vs. Absolute 13
Humidity
4. Absolute Humidity Calculated from Psychrometric Data 14
vs. Absolute Humidity Measured by Molecular Sieve Sampler
iii
-------
LIST OF TABLES
Table Page
1. LLL Freeze-Out Samples: Comparison of Rate of 21
Collection with Absolute Humidity
2. Absolute Humidity Calculated from Psychrometric Data and 22
Measured by NERC-LV Molecular Sieve Sampler
3. Tritium Concentrations in Atmospheric Moisture as Collected 23
by NERC-LV and LLL Samplers
4. Tritium Concentrations in Air as Determined from NERC-LV 2 4
and LLL Samplers
5. Analysis of Variance - Calculated and Measured Absolute 25
Humidity
6. Analysis of Variance - 3H Concentration from LLL and NERC-LV 25
Samplers
IV
-------
AN EVALUATION OF FREEZE-OUT AND ADSORPTION
TECHNIQUES FOR COLLECTION OF ATMOSPHERIC TRITIUM AS HTO
INTRODUCTION
Project Rulison was a joint Industry/Government-Sponsored nuclear
experiment conducted as part of the Atomic Energy Commission Plowshare
Program to develop peaceful applications for nuclear explosions. The
underground nuclear detonation was conducted on September 10, 1969 to
investigate the economic and technical feasibility of using an underground
nuclear explosion to stimulate production of natural gas from the low
productivity gas-bearing Mesa Verde formation in the Rulison Field near
Grand Junction, Colorado. Phase III of the experiment involved controlled
drillback into the cavity produced by the nuclear detonation followed by
flow testing to determine the cavity volume and the rate of natural gas
flow. Natural gas released during the various periods of flow testing
was burned, or flared, at the top of a 30-meter stack near surface ground
zero (sgz).
The National Environmental Research Center-Las Vegas(NERC-LV) provided off-
site stationary, mobile, and aerial radiological surveillance during these
flaring periods. An initial calibration flaring was conducted during which
NERC-LV and the Lawrence Livermore Laboratory2(LLL) collected samples of
atmospheric moisture in the offsite area for measurement of tritium ( H)
concentrations.
At the time this work was performed, the Center was named the Western Envi-
ronmental Research Laboratory.
2Formerly Lawrence Radiation Laboratory.
-------
Techniques of moisture collection used by the NERC-LV and LLL were quite
different because of a basic difference in ultimate use of the resulting
data. Since no information was available from the surveillance effort to
show comparability of data, the NERC-LV initiated a series of field comparison
studies at the Rulison site.
This report describes this study and the results of that effort.
OBJECTIVES
This study was performed with three objectives in mind: (1) to deter-
mine the comparability of data collected by the two systems; (2) to evaluate
the performance of the LLL sampler as an integrating sampler; and (3) to
arrive at some conclusion pertaining to the applicability and use of each
system in a tritium surveillance program.
EQUIPMENT AND PROCEDURES
A. Equipment
The LLL moisture sampling equipment consisted of a 9 1/2-inch pie
tin holding a No. 10 can (equivalent to a three-pound coffee can)
filled with crushed dry ice and placed in the open air. The outer
surface of the can was sandblasted to improve moisture recovery.
The NERC-LV sampling equipment consisted of a battery-operated pump
drawing air through a cannister containing 300 gm of Linde type
13x molecular sieve and discharging through a dry gas meter for
volume determination. Flow rates were approximately 2 to 3 CFM.
-------
B. Sampler Selection Criteria
The different sampling techniques used by the two organizations
resulted from different surveillance requirements and established
procedures. The NERC-LV had the responsibility for measuring environ-
mental concentrations of radioactivity resulting from the Project
Rulison flaring activities. Seven stationary sampling stations had been
established at populated locations around the Rulison site. These
stations incorporated a dehumidifier providing water for rapid field
analysis of 3H, a high volume air sampler for particulate radio-
activity, and a low volume molecular sieve sampler collecting 48-hour
integrated samples of atmospheric moisture for 3H analysis and
CO- for 1I+C analysis. Molecular sieve was chosen for its ability
to co-adsorb H20 and CCL, its utility in collecting long-term
integrated samples, and ease of handling. The molecular sieve
samples were returned to the NERC-LV for more precise analysis than
could be performed on the dehumidifier samples at the field office
in Grand Junction.
The molecular sieve samplers collected water from a known volume of
air, making it possible to determine the airborne 3H concentrations
from sample volume, moisture recovered, and analytical data. Because
it was desirable to use a portable unit providing data comparable to
that available from the fixed stations, a battery-powered sampler was
designed using the same molecular sieve. An additional consideration
was that this type of sampler also provided the capability of collecting
a particulate filter sample. Because the laboratory equipment and
techniques for analyzing molecular sieve samples already existed at
the NERC-LV, laboratory support required no special preparation.
Lawrence Livermore Laboratory had a requirement to collect numerous samples
for the purpose of determining plume trajectories and area covered as a guide
-------
to conducting special environmental studies. The most sensitive
indicator of an increase of 3H above background is to measure the
concentration in atmospheric moisture rather than the airborne con-
centration since the airborne concentration is also a function of
absolute humidity. For this purpose an efficient collector of
atmospheric moisture is perfectly satisfactory. One of the simplest
and most economical collectors to operate for that purpose is
the system employed by LLL.
C. Experimental Design
1. Site Description
Project Rulison was conducted near the upper end of a deep
valley extending to the southeast from Morrisania Mesa. The
valley bottom drops from the 8,154 feet mean sea level (MSL) eleva-
tion of sgz to 6,400 feet MSL at the valley mouth, three miles
northwest of sgz (see Figure 1). Previous surveillance had
shown that nighttime drainage winds carried much of the flaring
stack discharge downhill along the valley to the northwest.
For these studies, four sampling locations were chosen and
marked along the road leading from the Rulison test areas down
the valley to Morrisania Mesa. The station nearest the test
well was located directly across this road from the flare stack,
while the farthest station was located at the old control point pad,
2.5 miles northwest of the flaring stack at 6,800 feet MSL.
The other two stations were placed at approximately even intervals
between the flare stack and the control point pad. All subsequent
sampling of the Rulison flare was conducted at these locations
with two LLL and two NERC-LV samplers used at each location for
each sampling period.
-------
Figure 1. Special Study Sampling Locations
-------
2. Sampler Calibrations
Prior to designing the molecular sieve sampler, the NERC-LV
staff performed a series of tests on molecular sieve to relate
collection efficiency and adsorber capacity for atmospheric
moisture to absolute humidity, temperature, and bed residence
time. The sampler volume and flow rates were selected on the
basis of those tests to give nearly 100 percent collection
efficiency and sufficient collection capacity under the conditions
to be encountered. The dry gas meters used for sample volume
measurement were calibrated against the NERC-LV 500-cubic-foot
spirometer and a calibration factor was assigned to each one.
An experiment was conducted in Las Vegas to provide information
on the collection rate of the LLL sampler over short intervals.
Eight samplers were used, two of which were collected every half
hour and the volume of water collected was measured. The moisture
collection rate was determined to remain constant for the period
of the test under the prevailing conditions of temperature and
humidity. Data from this test are included in Table 1.
3. Sampler Preparation
Molecular sieve used in the NERC-LV samplers was degassed at the
Center in Las Vegas and packed in 300-gm lots in sealed bottles.
Prior to sampling, the sieve was transferred from the bottles
to sieve holders at the field office in Grand Junction. The
filled holder was then sealed in a heavy duty plastic bag which
was then sealed inside a second heavy duty plastic bag. In the
field, the bags were opened, the sieve holder was attached to
the sampler inlet, and the sampler motor was switched on.
-------
Control sieves consisting of molecular sieve prepared and
packaged as described above were handled identically to the
test sieve, including being taken to the field, except that
they were not used for sampling. This provided information
pertaining to extraneous moisture collection prior to and
after the sampling period. Suitable portions of sieve from
each sieve batch were returned to NERC-LV, without the above
handling, for water extraction to ascertain water content prior
to both exposure and handling.
Prior to each sampling period the LLL sampling apparatus was
washed to reduce any cross-contamination potential from one
sampling period to the next. Approximately 8 pounds of dry
ice was crushed and poured into each can at the field sampling
station. Each container was then placed in a pie pan and set
on the ground.
4. Sample Collection
Design of the NERC-LV sampler, using quantitative moisture sampling
from a known volume of air, eliminated the need for making humidity
measurements. Use of the LLL sampler required determination of the
absolute humidity to calculate the airborne concentration of 3H.
Relative humidity measurements by NERC-LV for this project were generally
made using a Princo sling psychrometer. Because of the low tempera-
tures in the Project Rulison area during this study, the sling psy-
chrometer could not always be used. Absolute humidity was then
calculated from measurements of relative humidity, made with a Bacharach
-------
Instrument Co. Model 22-4503 hygrometer, and dry bulb temperature.
Sampling periods were of two-hours duration. At the end of the
sampling period, the frost on the outside of the cold LLL sampler
was carefully scraped into the pie pan. After all loose frost
was removed, the dry ice was removed from the container. A pro-
pane torch flame was then used to slightly heat the inside of
the container to melt the remaining ice allowing it to be collected
in the pie pan. The frost already collected in the pan was melted
and the water carefully poured into a small polyethylene con-
tainer labelled with time, date, and location of collection.
Collection of the molecular sieve consisted of removing the sieve
holder from the air mover, sealing it inside a plastic bag, and
subsequently sealing it in a second bag. At the field office
in Grand Junction, the sieve was transferred from the holder
into a one-quart plastic Cubitainer for shipment to the NERC-LV for
o
water extraction and H analysis. Figure 2 shows the NERC-LV
and LLL equipment set up for collecting atmospheric moisture.
5. Sample Analysis
Water on the molecular sieve was recovered at the NERC-LV. The
extraction technique involves heating the sieve to 350°C and
passing dry helium through the heated sieve column to sweep
water vapor into a condensation trap. A vacuum is pulled on
the enclosure to aid in the removal of water.
-------
Figure 2. LLL Freeze-Out Sampler and NERC-LV Molecular Sieve
Sampler. Open sampler cartridge on top of NERC-LV
sampler box shows molecular sieve used.
-------
Water from both the LLL and NERC-LV samplers was distilled and
a 5-ml aliquot added to a dioxane base liquid scintillation
cocktail. The samples were counted at ambient temperature
for 100 minutes.
D. Calculations
3
Results of the water analysis were expressed as pCi H per ml water
for both type samples. Because the total volume of air pulled
through the sieve is known and all water on the sieve is retrieved, a
"measured" absolute humidity is readily obtained as ml water per cubic
meter of air.
Computer processing of data from the NERC-LV sample gave total water
collected, total volume of air sampled, ml water per cubic meter
3 3
air, pCi H per ml water, and pCi H per cubic meter air.
3
Output from the LLL sample results gave only pCi H/ml water. To
3 3
convert to airborne concentrations of tritium (pCi H/m air)
psychrometric information was obtained providing "calculated"
3
absolute humidity information in ml water/m air.
To calculate absolute humidities, wet and dry bulb temperature
measurements were made. If wet bulb temperatures were less than
20 F, as was the case during some of these runs, direct reading
hygrometer and dry bulb temperature measurements were made to
provide the appropriate psychrometric information. When wet and
dry bulb data were available, they were used directly in calculating
the humidity using a standard psychrometric chart and psychrometric
formulas. When the hygrometer and dry bulb were used, the equations
10
-------
of Appendix A (derived at the NERC-LV from the Carrier
Corporation's psychrometric chart and formulas) were em-
ployed to calculate the absolute humidity. Wet-bulb read-
ings for use in this equation were extracted from the U.S.
Weather Bureau Bulletin No. 1071 (Relative Humidity from
Wet and Dry Bulb Thermometer).1
Atmospheric 3H concentrations as pCi 3H/m3 air were determined
by multiplying the 3H concentration in water from both LLL and
NERC-LV samplers by the appropriate humidity values; i.e.
"measured" humidity for NERC-LV results and "calculated" humidity
for LLL results.
RESULTS
A. Moisture Collection
The first comparison made was the approximate collection
rate of the LLL sampler to absolute humidity and to de-
termine whether or not the collection rate varies during
the collection period. Table 1 summarizes the collection
rates and humidities observed during the field experiment
at Project Rulison and the collection rate experiment at
the NERC-LV. As shown by the May 10 results at the
NERC-LV, the collection rate remained constant over a two-
hour period with an absolute humidity of 8.4 ml H»0/m3 air.
Since that humidity was higher than any encountered
during surveillance of Project Rulison flaring or
Handbook of Chemistry and Physics, 44th Edition, Chemical Rubber Company.
11
-------
during this field experiment, it is reasonable to believe that
a uniform collection rate would be the case under normal circum-
stances. This should prevent a short-term condition of either a
high or low activity exposure from being over-weighted in deter-
mining the average concentration, as could be the case with a
varying collection rate.
Figure 3, a plot of collection rate versus absolute humidity, shows
that over the range of humidities encountered, the relationship is
linear. Ambient temperature apparently had little or no effect
on the collection rate. This is most likely due to the large
difference between ambient temperatures and the temperature of dry
ice. With knowledge of the relation between collection rate and
absolute humidity, field humidity measurements can be used to deter-
mine the length of sampling period required to collect sufficient
water for analysis.
The NERC-LV sampler had been designed to be nearly 100 percent efficient
as a water vapor sampler. Even so, it was desirable to compare
absolute humidites "calculated" from field measurements of relative
humidity and temperature to absolute humidities "measured" from the
air volume sampled and moisture recovered from the NERC-LV sampler.
The comparison is tabulated in Table 2 and is shown graphically in
Figure 4. A statistical analysis of all data showed no difference
between the two methods of measuring absolute humidity at the
99 percent significance level. Investigation of the data in
the "absolute humidity" columns of Tables 1 and 2
12
-------
Figure 3.
LLL FREEZE - OUT SAMPLER
COLLECTION RATE
VS.
ABSOLUTE HUMIDITY
El
©
© CALCULATED FROM
PSYCHROMETRIC DATA
H MEASURED WITH
MOLECULAR SIEVE SAMPLER
EJ
©
m
©
Q
©
I
0
0.05
0.1
0.15
0.2
0.25
0.3
0.3E
COLLECTION RATE , ml H2O/ MIN
13
-------
8
oo
CM
X
e
i
8 4
O
<
O
Figure 4.
ABSOLUTE HUMIDITY CALCULATED FROM PSYCHROMETRIC DATA
VS.
ABSOLUTE HUMIDITY MEASURED BY MOLECULAR SIEVE SAMPLER
(NUMBERS BESIDE DATA POINTS INDICATE MULTIPLE IDENTICAL RESULTS)
0
0
MEASURED HUMIDITY, ml H O/m3AIR
14
-------
shows that the "calculated" absolute humidity is usually higher
than the "measured" absolute humidity. A biasing of the
results for "calculated" absolute humidity on the high side
is to be expected, since the commonest error in making psychro-
metric measurements is to obtain a high wet bulb temperature.
This would result in overestimating the humidity.
The "calculated" and "measured" absolute humidity data were subjected
to a statistical analysis of variance (See Table 5) assuming a two-way
non-additive model. There appear to be no differences among locations,
no differences between calculated and measured humidity, and no inter-
actions present at the .90 significance level.
B. Tritium Results
Tritium results for atmospheric moisture are expressed both in
terms of concentration in the water and in air (pCi 3H/ml H-O
and pCi 3H/m3 air). The former is most useful in detecting small
additions of HTO to the atmosphere while the latter is required to
make dose calculations or to compare airborne concentrations to
radioactivity concentration guides. Table 3 lists the results of
3H analysis on the NERC-LV and LLL samplers as pCi 3H/ml H20. Tritium
concentrations in air are given in Table 4. Concentrations for
the LLL sampler are the product of absolute humidities in Table 2
and concentrations in water given in Table 3. Concentrations for
the NERC-LV sampler are derived from the total 3H activity collected
from the measured volume of air sampled.
15
-------
An analysis of variance was performed on the reported concentrations
of 3H in air as determined from the two sampler types (Table 6). A two-
way classification non-additive model was assumed. The F ratio was less
than one in all cases, indicating no interactions, no differences between
samplers, and no differences among locations at the .90 significance level,
Some data were excluded from the analysis. Reasons for this omission
will be given in the Discussion Section.
As can be seen in Tables 3 and 4, the average LLL sampler results at
location 1 for the February 10 and 12 sampling periods are almost
three times those of the average NERC-LV sampler results. Two expla-
nations were advanced regarding the anomaly. During both collection
periods a rather brisk drainage wind was flowing, causing some
drifting snow to be collected in the LLL sampler. Snow samples
were not collected in conjunction with these atmospheric moisture
samples. However, snow samples collected around the stack during
this same period as a part of the NERC-LV surveillance program were
found to have elevated levels of 3H. These are documented in the
NERC-LV Rulison surveillance report.*
A second possible explanation was that the LLL sampler was collecting
3H "rainout" in the immediate vicinity of the stack, whereas the
NERC-LV system was positioned with the molecular sieve holder inlet pointed
downward so that falling particles or droplets would not fall on,
and be collected by, the molecular sieve. "Rainout" occurred in the stack
vicinity as a result of water injection into the flare to dispose of
water separated at the well-head.
* Off-site Radiological Safety Program for Project Rulison Flaring, Phase III;
National Environmental Research Center-Las Vegas. NERC-LV-539-15.
16
-------
An attempt to verify the "rainout" theory was made on March 6 and 7
(results in Tables 3 and 4 as location 1A). Four NERC-LV
molecular sieve and four LLL collectors were used on these two days
at location 1. On both days two molecular sieve holders were turned
up so that falling water droplets or ice particles would be easily
collected, and two sieve holders were turned down as usual. The
corresponding LLL set-up consisted of two collectors placed on the
ground (packed snow) and two collectors placed off the ground on top
of the wooden case of the NERC-LV sampler. The data show excellent
agreement between the NERC-LV and LLL collectors and appear no different
from the results of the standard set-up. However, since they were
collected in addition to the regular samples and were treated
differently, it was felt that they, also, should be disqualified
from the subsequent statistical analysis. It should be noted from the
data that the original discrepancy did not appear during subsequent
sampling periods. It was concluded that snow contamination had
accounted for the difference in data.
DISCUSSION
The following discussion of operational characteristics is primarily
subjective, based on the operating experience gained during this test. The
basic conclusion was that although the LLL sampler is somewhat simpler to
operate, overall, the NERC-LV sampler is easier to operate in the field.
Varying degrees and types of attendance to the LLL sampler are required,
depending on weather conditions, in order to assure uniform sampling rate and
to effect satisfactory recovery of the collected moisture. Contamination of
an open sampler such as this from precipitation or drifting snow can be
17
-------
serious, but proper design can eliminate this. Problems such as
frost blowing away while scraping the can in a high wind were found to make
the operation difficult and, at times, frustrating. Daytime operation in
warm sunlight can cause the dry ice to sublime away from the container wall,
reducing the collection rate and allowing melting and possible evaporation
of frost. Use of a shade would probably correct this. The necessity of
using a torch to melt the frost when ambient temperatures are low is another
field operation that may be required at times. The LLL sampler used required
a minimum of two hours to collect the required sample under the lowest humidity
conditions. If a shorter sampling period is desired, use of additional samplers
or redesign of the current model would be required.
One distinct advantage of the LLL sampler is the direct recovery of water
which can be used as is or distilled for liquid scintillation counting. This
reduces analytical complexity and cost and shortens the time required to obtain
a measure of the airborne concentrations.
Field operation of the NERC-LV molecular sieve sampler is very simple,
requiring only that the sieve holder be connected to the sampler inlet.
Psychrometric measurements are made and a sampling time is selected to obtain
sufficient sample without exceeding the capacity of the molecular sieve. No
variation in operating procedures is necessary because of weather conditions
other than selecting the proper sampling time. Because of the large difference
between the minimum required amount of water and the bed capacity, this time
is quite flexible.
Although the NERC-LV sampler was operated at each location during the same
two-hour period as the LLL unit, it would not normally need to operate this
long to collect the minimum 5 ml of water required for 3H analysis, even
18
-------
under the very low humidity conditions encountered. These samplers were
operated at about one-half their normal flow rate and collected 10-15 ml
under the lowest humidity conditions of about 1 ml/m3. The LLL unit collected
about 5 ml total volume for the lowest humidity.
Appendix B is a set of calculations used by NERC-LV field teams in estimating
absolute humidity for the purpose of adjusting sampling periods. The
calculations are simple and are more than adequate for field use. These same
calculations could be used to advantage with the graph of Figure 3, to estimate
sampling times required for the LLL unit to collect desired water volumes.
The figures of Appendix B are graphical representations of psychrometric
equations. A psychrometric chart must be consulted in addition to the figures
to arrive at the absolute humidity.
Initial expense of the NERC-LV sampler would normally be greater than that
of the LLL sampler because of the need for an air mover, dry gas meter,
batteries, and sample holder. Since NERC-LV already had the necessary air samplers
and laboratory facilities to handle the molecular sieve samples, very little
additional cost was actually required to conduct this type of surveillance.
Two significant facts were established regarding moisture collection.
First, over a reasonable sampling period under the conditions of May 10
(Table 1) the sampling rate of the LLL sampler was uniform. Second, with
reasonable care in obtaining field measurements absolute humidities calculated
from two types of psychrometric data agreed with those measured by the NERC-LV
molecular sieve sampler. These facts assure comparability of data between
the samplers when they are operated properly.
19
-------
CONCLUSIONS
Analyses of variance performed on data from this study on the LLL
collector and NERC-LV molecular sieve sampler showed that at the .90 sig-
nificance level there is no difference between atmospheric tritium con-
centrations measured by two sampling techniques nor between the calculated
and measured absolute humidities.
It was concluded that with proper precautions, both samplers
provided reliable measurements of the airborne concentration of % in the form
of water vapor. One sampler or the other might be chosen for a particular
application, or both might be used, with assurance that the results are comparable.
On the basis of initial and operating costs, some form of the LLL freeze-out
sampler would normally be the portable sampler of choice for collection of atmos-
pheric moisture. When dry ice is not available or operators must remain in the
field too long to maintain a reserve supply of dry ice, the NERC-LV sampler is
especially useful.
20
-------
TABLE 1
LLL Freeze-Out Sampler:
Comparison of Rate of Collection with Absolute Humidity
Location
1
1
1
2
2
4
4
WERL
WERL
Date
Collected
3/4
3/6
3/7
3/6
3/7
3/6
3/7
5/7
5/10
Sampling
Period
(Hours)
2
2
2
2
2
2
2
2
0.5
1
1.5
2
Collection Rate
(ml H_0/min) ' •"•)
0.18
0.04
0.08
0.06
0.06
0.08
0.08
0.22
0.30
0.31
0.31
0.35
f^LJJ V/ J_U L.
(ml H2
Measured (2)
2.7
1.0
1.7
1.1
1.6
1.2
1.5
7.0
NA<4>
NA
NA
NA
c. Liu.uiJLVJ.Jw ujr
0/m3 air)
Calculated^3)
2.9
1.0
1.6
1.3
1.7
1.1
1.8
8.0
8.4
8.4
8.4
8.4
(2)
(3)
(4)
Average of duplicate LLL samples.
Average of multiple NERC-LV sampler results.
Single psychrometric measurement at start of sampling period.
NA = Np Analysis
21
-------
TABLE 2
Absolute Humidity Calculated from Psychrometric Data
and Measured by NERC-LV Molecular Sieve Sampler
Absolute Humidity
Location
(altitude )
(feet, MSL)
1
(8200)
2
(7600)
3
(7200)
4
(6800)
Grand Valley
(5100)
Las Vegas
(2000)
Temp.
(°F)
7
10
16
18
34
34
12
12
19
27
36
12
27
38
12
14
23
29
38
28
45
63
Relative
Humidity
(Percent)
56
59
62
56
46
53
37
57
52
48
53
40
52
51
36
56
52
48
51
57
41
48
(ml H2
Measured ^ '
1.2
1.2
1.7
1.4
2.7
2.6
1.0
1.1
1.6
1.5
2.7
1.0
1.8
2.6
1.0
1.2
1.5
1.9
2.6
3.1
2.7
7.0
T
0/nT air)
Calculated (2)
0.9
1.0
1.6
1.5
2.9
3.2
1.0
1.3
1.7
2.4
3.6
1.0
2.0
3.6
1.0
1.1
1.8
2.8
3.6
2.7
2.4
8.0
Collection
Date
3/3
3/6
3/7
2/12
3/4
2/10
3/3
3/6
3/7
2/12
2/10
3/3
2/12
2/10
3/3
3/6
3/7
2/12
2/10
2/12
2/11
5/7
(1)
(2)
Average of multiple samples.
Single psychrometric measurement at start of sampling period.
22
-------
Location
,(1)
i<«
l(l)
1
1
1
1
1
1
1
1A(2)
1
1A(2)
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
TABLE 3
Tritium Concentrations in Atmospheric
Moisture as Collected by. TiERC-T,V and LLL Samplers
Date
Collected
2/10
2/10
2/12
2/12
3/3
3/3
3/4
3/4
3/4
3/4
3/6
3/6
3/6
3/6
3/7
3/7
3/7
3/7
2/10
2/10
2/12
2/12
3/3
3/3
3/6
3/6
3/7
3/7
2/10
2/10
2/12
2/12
3/3
3/3
2/10
2/10
2/12
2/12
3/3
3/3
3/6
3/6
3/7
3/7
3
H Concentration
ILL Sampler
17
21
75
86
85
82
3.7
4.3
3.8
4.0
23
22
24
24
23
24
27
26
1.6
1.2
5.4
5
44
45
64
64
4.4
4.2
0.59
0.92
17
17
64
61
0.99
0.70
15
14
55
56
8.3
8.3
7.1
7.2
(pCi 3H/ml H20)
NERC Sampler
8.9
8.4
25
29
76
77
4.2
4.7
3.7
4.0
22
20
23
22
24
24
25
24
1.3
1.1
6.3
7.1
52
52
59
54
3.9
3.7
0.69
<0.4
16
16
54
52
0.94
0.90
15
14
41
32
7.2
7.4
5.8
6.1
Data not used in statistical analysis
(2)
See discussion section; data not used in statistical analysis.
23
-------
TABLE 4
Tritium Concentrations in Air as
Determined from NERC-LV and LLL Samplers
Date
Location Collected
1 2/10
2/12
3/3
3/4
3/6
(3)
(3)
3/7
(3)
(3)
2 2/11
2/12
3/3
3/6
3/7
3 2/11
2/12
3/3
ii vjvxu
LLL Sam
67
54
117
133
75
72
10
12
10
11
23
22
24
24
37
39
44
42
5.8
4.3
13
13
42
44
44
44
7.4
7
2.1
3.3
34
34
62
59
Using pCi/ml and calculated ml/m .
Using pCi/ml and measured ml/m .
3 33
H Concentration (pCi H/m air)
NERC Sampler
24
22
41
37
90
86
12
13
10
10
21
23
33
24
41
35
43
46
3.3
3
10
9.9
51
51
77
53
6
6.1
1.9
24
32
52
55
(2)
(3)
Location 1A.
24
-------
Date
Location Collected
4 2/11
2/12
3/3
3/6
3/7
LLL Samp]
3.6
2.5
41
39
52
53
9.4
9.4
12
12
Table 4 (Continued)
3H Concentration (pCi 3H/m3 air)
NERC Sampler^
2.4
2.4
28
25
37
32
9
9.7
9.2
8.2
Using pCi/ml and calculated ml/m3.
/ Q\
Using pCi/ml and measured ml/m3.
Table 5
Analysis of Variance
Calculated and Measured Absolute Humidity
Source
Location
Types
Interaction
Error
DF
4
1
4
32
SS
2.94933
.315571
.656762
24.6920
MS
.737333
.315571
.164190
.771625
F
< 1
< 1
< 1
Table 6
Analysis of Variance
3H Concentration from LLL and NERC-LV Samplers
Source
Location
Sampler
Interaction
Error
DF
3
1
3
64
SS
1625.93
62.0773
50.4385
41432.5
MS
541.978
62.0773
16.8128
647.384
F
< 1
< 1
< 1
25
-------
APPENDICES
APPENDIX Page
A. ABSOLUTE HUMIDITY CALCULATIONS FROM WET BULB -
DRY BULB MEASUREMENTS 27
B-l. ABSOLUTE HUMIDITY FIELD CALCULATIONS 28
B-2. FIGURE A, AW^ VS. ALTITUDE 29
B-3. FIGURE B, AIR DENSITY VS. ALTITUDE 30
26
-------
APPENDIX A
Absolute Humidity Calculations from
Wet Bulb - Dry Bulb Measurements
Using Wet Bulb and Dry Bulb - Calculate for Sea Level
Conditions as follows:
WB S 26°
0 nsAA TJR
H20 = 4.9 e0'03^ W - 1.375 (DB - WB) grains/lb air
26° < WB g 32°
H20 = 7.1 e°-04025 WB - 1.375 (DB - WB) grains/lb air
32° < WB g 50°
TT _ .. 1 0.04025 WB 1 c, /T._ rTT>N . ... .
HO = 7.1 e - 1.57 (DB - WB) grains/lb air
50° < WB
H20 =9.3 e°'0352 WB - 1.57 (DB - WB) grains/lb air
To above value of H?0 add correction, A HO, as follows:
WB g 32°
A H20 = 0.000245 x (Altitude) x e°'0472 WB grains/lb air
WB > 32°
A H20 = 0.000328 x (Altitude) x e0'0381 WB grains/lb air
W = H20 + A H20
Calculate local pressure from Altitude: Calculate volume of moist air:
p 29.92 „ _ 0.754 (DB + 459.7) f W
F" 288 5.256 V P L
(288 - 0.00198 x Altitude)
r\ O Q CTJ
Calculate moisture content: M = —'— : ml/m^
27
-------
APPENDIX B
Absolute Humidity Field Calculations
1. Find T , TL^ and altitude* of sampling location.
2. Consult psychrometric chart for sea-level humidity conditions,
grains water per pound air.
3. Consult Figure A for water correction factor at your altitude
using T from Step 1.
4. Add the values of Step 2 and 3.
5. Consult Figure B to find volume of moist air at your altitude,
3
FT air per pound a:
6. From Steps 4 and 5.
3
FT air per pound air using TD from Step 1.
Total Weight H0/# Air m Grains H
FT3 Air/# Air FT3 Air
7. 2.3 X Step 4 _ ml H 0/m Air
Step 5
*Request from Control by radio after arriving on station.
28
-------
2 3
Figure A:
567
ALTITUDE , MSL X 1000'
8
10
29
-------
VOLUME OF MOIST AIR
TDB=100°F
•) TDB=50°F
•> TDB=°°F
I
11
0 2
Figure B:
6 8
MSL ALTITUDE, FT X 1000
10
12
14
30
-------
DISTRIBUTION
1 - 13 National Environmental Research Center, Las Vegas, Nevada
14 Man!on E. Gates, Manager, NVOO/AEC, Las Vegas, Nevada
15 Robert H. Thalgott, NVOO/AEC, Las Vegas, Nevada
16 Henry G. Vermillion, NVOO/AEC, Las Vegas, Nevada
17 Chief, NOB/DNA, NVOO/AEC, Las Vegas, Nevada
18 Robert R. Loux, NVOO/AEC, Las Vegas, Nevada
19 Donald W. Hendricks, NVOO/AEC, Las Vegas, Nevada
20 Technical Library, NVOO/AEC, Las Vegas, Nevada
21 Mail & Records, NVOO/AEC, Las Vegas, Nevada
22 Martin B. Biles, DOS, USAEC, Washington, D.C.
23 Director, DMA, USAEC, Washington, D.C.
24 Harold F. Mueller, ARL/NOAA, NVOO/AEC, Las Vegas, Nevada
25 Gilbert J. Ferber, ARL/NOAA, Silver Spring, Maryland
26 Stanley M. Greenfield, Assistant Administrator for Research & Monitoring,
EPA, Washington, D.C.
27 William D. Rowe, Deputy Assistant Administrator for Radiation Programs,
EPA, Rockville, Maryland
28 Dr. William A. Mills, Dir., Diy. of Criteria & Standards, Office of
Radiation Programs, EPA, Rockville, Maryland
29 Ernest D. Harward, Acting Director, Division of Technology Assessment,
Office of Radiation Programs, EPA, Rockville, Maryland
30 Bernd Kahn, Chief, Radiochemistry & Nuclear Engineering, NERC, EPA,
Cincinnati, Ohio
31 - 32 Charles L. Weaver, Director, Field Operations Division, Office of
Radiation Programs, EPA, Rockville, Maryland
33 Gordon Everett, Director, Office of Technical Analysis, EPA,
Washington, D.C.
34 Kurt L. Feldmann, Managing Editor, Radiation Data & Reports, ORP, EPA,
Rockville, Maryland
35 Regional Administrator, EPA, Region IX, San Francisco, California
36 Regional Radiation Representative, EPA, Region IX, San Francisco, California
37 Eastern Environmental Radiation Laboratory, EPA, Montgomery, Alabama
38 Library, EPA, Washington, D.C.
39 William C. King, LLL, Mercury, Nevada
40 James E. Carothers, LLL, Livermore, California
-------
DISTRIBUTION (continued)
41 Charles I. Browne, LASL, Los Alamos, New Mexico
42 Harry S. Jordan, LASL, Los Alamos, New Mexico
43 Arden E. Bicker, REECo, Mercury, Nevada
44 Savino W. Cavender, REECo, Mercury, Nevada
45 Carter D. Broyles, Sandia Laboratories, Albuquerque, New Mexico
46 Robert H. Wilson, University of Rochester, Rochester, New York
47 Richard S. Davidson, Battelle Memorial Institute, Columbus, Ohio
48 J. P. Corley, Battelle Memorial Institute, Rich!and, Washington
49 Frank E. Abbott, USAEC, Golden, Colorado
50 John M. Ward, President, Desert Research Institute, University of
Nevada, Reno
51 - 52 Technical Information Center, Oak Ridge, Tennessee (for public
availability).
------- |