SWRHL-21r
FINAL REPORT OF OFF-SITE SURVEILLANCE
for the
DRILL EVENT of December 5, 1964
by the
Southwestern Radiological Health Laboratory
U. S. Public Health Service
Department of Health, Education, and Welfare
Las Vegas, Nevada
-U MtE.
October 18, 1965
This surveillance performed under a Memorandum
of Understanding (No. SF 54 373)
for the
U. S. ATOMIC ENERGY COMMISSION
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FINAL REPORT OF OFF-SITE SURVEILLANCE
FOR THE
DRILL EVENT OF DECEMBER 5, 1964
by the
Southwestern Radiological Health Laboratory
U. S. Public Health Service
Department of Health, Education, and Welfare
Las Vegas, Nevada
October 18, 1965
Copy No. 25
Southwestern Radiological Health Laboratory
Las Vegas, Nevada
This surveillance performed under a Memorandum
of Understanding (No. SF 54 373)
for the
U. S. ATOMIC ENERGY COMMISSION
-------
ABSTRACT
The Drill Event was an underground nuclear detonation conducted by the
U. S. Atomic Energy Commission at the Nevada Test Site on December 5,
1964. The detonation released radioactivity to the atmosphere and the
, resulting effluent cloud traveled southwest from the Nevada Test Site,
'.jpa's'sing over Lathrop Wells, Nevada and Shoshone, California. The U. S.
Public Health Service provided radiological surveillance in the off-site
area in accordance with a Memorandum of Understanding with the Atomic
Energy Commission. Analysis of the data collected indicates that the
radiological safety criteria for the general population, as established
by the Atomic Energy Commission, were not exceeded as a result of this
event.
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TABLE OF CONTENTS
ABSTRACT . i
TABLE OF CONTENTS i i
LIST OF TABLES AND FIGURES iii
I. INTRODUCTION 1
II. OPERATIONAL PROCEDURES 2
A. RADIATION MONITORING 2
1. Monitoring Teams 2
2. Dose Rate Recorders 2
3. Aerial Cloud Tracking 2
B. DOSIMETRY 3
C. ENVIRONMENTAL SAMPLING 3
1. Air 3
2. Milk Samples 4
3. Water Samples 5
4. Vegetation Samples 5
I I I.RESULTS 6
A. RADIATION MONITORING 6
1. Ground Monitoring 6
2. Dose Rate Recorders 7
3. Aerial Cloud Tracking 7
B. DOSIMETRY . -7
C. ENVIRONMENTAL SAMPLING 7
1. Air 7
2. Mi Ik 1
3. Water 8
4. Vegetat ion 8
IV. CONCLUSIONS '0
APPENDICES
D ISTRIBUTION
i i
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LIST OF TABLES
Table 1. Summary of dose rates observed by monitoring teams,
December 5, 1964.
Table 2. Positive air sample results.
Table 3. Results of vegetation samples containing fresh
f i ss ion products.
LIST OF FIGURES
Figure 1. Air sampler and dose rate recorder locations. 11
Figure 2. Milk and water sampling locations. 12
i i i
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I. INTRODUCTION
The Drill Event was an underground nuclear test conducted by the
Lawrence Radiation Laboratory at the Nevada Test Site as a part of
Operation Whetstone. The event took place on December 5, 1964 and
resulted in a release of radioactive material into the atmosphere.
In accordance with a Memorandum of Understanding (No SF 54 373) with
the Atomic Energy Commission (AEC), the U. S. Public Health Service
(PHS) provided a program of radiological monitoring and environmental
sampling in the off-site area surrounding the restricted area
enclosed by the Nevada Test Site (NTS) and the Nell is Air Force
Range (NAFR). This complex includes the Nuclear Rocket Development
Station (NRDS) and the Tonopah Test Range (TTR) and for simplicity
will be called the test range complex in this report.
PHS monitors begin tracking an effluent cloud close to Its point of
origin to approximate its trajectory and to initiate positive instru-
ment readings. This report includes descriptions of the methods and
instruments used by the PHS and summaries of the positive data
obtained off-site.
The winds aloft at the time of the event were from the north from
the surface to 7000 feet mean sea level (MSL) with speeds ranging
from ten to seventeen knots.
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II. OPERATIONAL PROCEDURES
A. RADIATION MONITORING
1. Monitoring Teams
Five monitoring teams were located off-site and downwind to
observe any radiation dose rates. Each team was equipped
with an Eberline Model E-500B Geiger-Muel1er instrument, a
Victoreen Radector Model AGB-50B-SR integrating ion chamber
and a Precision Model 111 Standard "Scinti1lator".
The Eberline E-500B has a range of 0 to 200 mi 11iroentgens per
hour (mR/hr) gamma and beta-gamma detection in four scales
with an external halogen filled G.M. tube and a supplementary
range to 2000 mR/hr (gamma only) from an internal Anton 302
tube. The Precision Model 111 "Scinti1lator" is used pri-
marily for low level detection and has a range of 0 to 5 mR/hr
gamma in six scales. This instrument employs a l"xl" sodium
iodide crystal as the detector. The Victoreen Model AGB-50B-SR
"Radector" has a range of 0.05 to 50,000.mR/hr gamma or beta :plus
gamma in two scales and employs an internal ionization chamber
detector. These instruments are accurate to approximately
+20%.
2. Dose Rate Recorders
Eberline RM-11 dose rate recorders are routinely operated at
21 locations surrounding the test range complex. These
instruments have a Geiger-Muel1er detector with a dose rate
recorder which logarithmically displays gamma dose rates from
0.01 to 100 mR/hr. The instrument accuracy is +207ğ. Locations
of these recorders are shown in Figure 1.
3. Aerial Cloud Tracking
Two aircraft were used to sample and track the effluent cloud,
a C-45 and a U3-A. The former is primarily for air sampling
2
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and the latter for tracking. The air sample data collected
by the aircraft are not a part of this report.
DOSIMETRY
External gamma dosimetry is accomplished primarily through the
use of film badges. DuPont type 555 film is used with an accuracy
of +50% in the 20 to 100 mR range and +10% in the 100 to 2000 mR
range. The PHS maintains 67 film badge stations in the off-site
area. In addition to these, there are 139 personnel badges issued
to people residing in the areas surrounding the test range
comp1 ex.
ENVIRONMENTAL SAMPLING
1. Air ;
There are 43 air sampling stations in continuous operation
in the vicinity of the test range complex as shown in
Figure 1. Eighteen of the samplers contain MSA charcoal
cartridges with a Whatman No.541 prefilter, the remainder
have the prefilter alone. Each of the ground monitoring
teams is equipped with a generator and air sampler identi-
cal to those used for routine sampling stations. The
sampler used by the PHS is a Gelman "Tempest".
All prefilter papers and charcoal cartridges collected
following the Drill Event were returned to the Southwestern
Radiological Health Laboratory for analysis. The Whatman 541
filters were counted for gross beta activity with a Beckman
Wide Beta system. The detector is a five inch (diameter)
gas proportional chamber. The system has a background of
90
6 cpm and an efficiency of 457., for strontium beta particles,
Based upon the beta activity, the samples are sorted for
further gamma spectrum or radiochemica1 analysis. After the
gross beta counts are used to indicate the effluent trajec-
tory, the samples are stored for five days to allow natural
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radionuclides to decay. The filters are counted again and,
after seven more days are again counted. The results are
extrapolated to the time of sample collection. Several
more active samples are selected for frequent counting to
establish decay curves. The resultant curves have the
general form.of y=ax . In this case the independent vari-
. able is time and b is the slope of the curve plotted
.logarithmically.
All charcoal cartridges were scanned for gamma emitting
isotopes as were a few selected Whatman 541-filters. Each
sample was placed directly on a 4"x4" Nal(Tl) crystal, and
given a ten minute count. A 400 channel analyzer was set
to "view" gamma energies from 0 to 2 Mev. Assuming no
break in.the prefilter, the activity on the cartridge should
represent the gaseous fission products only, such as the
.isotopes of iodine. The detection efficiency is 1870 for
1 33
the 0.53 Mev gamma ray from I and 6.47ğ for the 0.364 Mev
gamma ray of I, The detection threshold for I.,
I, I and I is 200 picocuries in the cartridge with
an overall accuracy of +507= for iodines 131, 132 and 133;
and +1007o for iodine 135. An IBM 1620 computer is pro-
grammed for a matrix technique for eight selected isotopes
which allows other isotopic activity to be stripped from
the spectra. The program allows variable input so that many
more than eight isotopes can be gleaned by this method.
Error analysis of the process'does not allow detection of
concentrations of less than one picocurie per cubic rneter.
2. Milk Samples
Routine milk samples are collected monthly from 14 locations
and weekly from five locations in the vicinity of the test
range complex as shown by Figure 2. Other sampling locations
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have been determined from surveys made in cooperation with
the State Health Departments of Nevada, Utah, Arizona, and
California. Milk samples are taken for a minimum of 5 days
from locations suspected of being in the effluent's trajectory,
Each milk sample is placed in a 3.5 liter aluminum Marinelli
beaker, designed to fit over a 4"x4" crystal which is coupled
to a 400 channel analyzer. The lower limit of detection for
the gamma emitters in milk is 20 picocuries per liter. The
error associated with this method is +2Q picocuries per 1iter
(pCi/1) or 107,,, whichever'is greater]
3. Water Samples
Thirty-two water samples are collected on a routine basis
every month from the locations shown in Figure 2. In the
event of a release, additional water samples are collected
from locations within the suspected trajectory. Water
samples are analyzed by the same procedures employed with
milk.
4. Vegetation Samples
Vegetation samples are not collected on a routine basis,
but only in the event of a release of radioactive material.
Vegetation analysis is a good indicator of cloud path. Green
'samples are superior to dormant or dry vegetation; for ob-
vious reasons, greater leaf area is more desirable. These
samples are packed into a beaker and gamma scanned. The
detection limit is on the order of 200 picocuries for the
ent i re samp 1e.
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III. RESULTS
A. RADIATION MONITORING
1. Ground Monitoring
Monitoring teams located off-site first encountered the
effluent cloud as it crossed Highway 95 south of the
test range complex. A maximum dose rate of 0.2 mR/hr
was noted five miles east of Lathrop Wells at 1830 hours
PST-on Highway 95. A reading of 0.01 mR/hr net gamma
was observed on Highway 29 seventeen miles south of
Lathrop Wells from 1900 to 1903 hours PST. A monitoring
team at Pahrump was unable to detect any dose rates
above background. Table 1 summarizes the positive
readings found by the teams. Appendix A lists the com-
plete monitoring results.
Table 1. Summary of dose rates observed by monitoring teams, December 5,
1964.
Location Time
(PST)
Hwy. 95, 5 mi E of Lathrop Wells 1810
1820
1825
1830
1831
1845
1850
1855
1900
1905
1915
1920
Hwy. 29, 17 mi S of Lathrop Wells 1900
1901
1902
1903
Net Gamma Dose Rate
(mR/hr)
0.10
0.14
0.08
0.20
0.15
0.08
0.05
0.05
0.04
0.04
0.04
0.04
0.01
0.01
0.01
0.01
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2. Dose Rate Recorders
The only RM-11 Recorder showing a positive dose rate in
relation to background was at Lathrop Wells. The maxi-
mum dose rate attributable to the effluent cloud was
0.055 mR/hr at 1715 hours PST. Two small peaks (less
than 0.004 mR/hr) were observed at 2130 and at 2225.
3. Aerial Cloud Tracking
Both the C-45 and the U3-A tracked the effluent cloud on
site as the cloud moved slowly to the south. The missions
were terminated after several hours due to the imminent
sunset and lack of fuel. The EG&G NATS plane was able to
trace the effluent south over the Mojave Desert east of
Bars tow toward Yuma, Arizona.
B. DOSIMETRY
Film badges collected since the event have shown no exposure
above the threshold of detection (20 mR) which could be asso-
ciated with the Drill release..
C. ENVIRONMENTAL SAMPLING
1 . Ai r
Table 2 lists the results of air samples with positive
activity.. Quantities are extrapolated to the end of the
collection period. Air samples with no detectable concen-
trations are listed in Appendix B.
2. Milk
No fresh fission products were detected in milk samples
taken at Lathrop Wells, Nevada from December 7 to Decem-
ber 10. Based on preliminary information from the EG&G
NATS flight, two milk samples were taken at Summer top,
Arizona on December 11 with no activity detected. The
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effluent did not pass over any other locations having
dairy cows; it is for this reason such distant samples
were taken.
Table 2. Positive air sample results.
Locat ion
Shoshone, Ca 1 i f .
Lathrop Wei 1 s , Nev.
Death Va 1 1 ey Jet. ,
Cal if .
Samp 1 i ng
Per iod
12/5-1000
12/5-1630
12/5-1630
12/6-1218
12/5-1630
12/6-1218
12/5-1910
12/6-1 114
12/5-1910
12/6-1 114
12/5-0630
12/5-1521
12/5-0630
12/5-1521
Total
Vo 1 ume
132 M3
408
408
330
330
177
177
pC i/m
131j 133!
1.1 <1
N.D. N.D.
N.D. N.D.
N.D. <1
N.D. N.D.
<1 <]
N.D. N.D.
Fi Her
135Xe Type
. Whatman
Fi Iter
, Whatman
Fi 1 ter
N-D Charcoal
' Ca rt r i dge
, , Whatman
1 . D .- . ,
Fi Iter
N D Charcoal
'Cartridge
. Whatman
Filter
M D. Charcoal
' Car t r i dge
N.D.=Not detectable
3. Wa t e r
Water samples collected on a routine basis since the event have
not contained fresh fission products.
4. Vegetation
Fourteen vegetation samples were collected and six of these
samples contained fresh fission products. (See Table 3.)
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Table 3. Results of vegetation samples containing fresh fission products.
Loca t ion
5 mi E. of Lathrop Wells
J-2 mi E of Lathrop Wei Is
Amargosa Farm Area
Shoshone, California
Date
Col 1 ected
12/05
12/05
12/06
12/10
12/10
12/10
132T
Te
60
45
N.D.
N.D.
N.D.
N.D.
PC
131,
300
120
150
80
40
N.D.
i/kg
132,
60
45
N.D.
N.D.
N.D.
N.D.
133,
300
150
220
150
70
50
137.
Cs
300
150
390
N.D.
N.D.
N.D.
Appendix C lists the complete vegetation sample results. N.D.=Not detectable.
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IV. CONCLUSIONS
The data indicate that the effluent cloud passed in the vicinity of
Lathrop Wel.ls, Nevada then crossed Highway 95 in a swath extending
at least twelve miles east and five miles west of Lathrop Wells. A
fringe of the cloud passed over Death Valley Junction with the main
path continuing in the direction of Shoshone, California. Shoshone
was the site of the last positive indication of fission product ac-
tivity although the EG&G NATS preliminary flight information indicated
activity further south.
Lathrop Wells received the highest external gamma dose, estimated at
0.025 mR from the RM-11 recorder there. The external dose at
Shoshone, California was on the order of the natural background dose.
Air samples taken from Lathrop Wells, Nevada and Shoshone, California
showed concentrations of fresh fission products. Although positive
results were found in air and vegetation samples taken at Lathrop
Wells, no fresh fission product activity was found in the milk samples
taken there. Atthis time of year, the ca-ttle are fed from stores of
sheltered dry feed which prevented any uptake in the milk chain,
thereby eliminating the primary vector. Also, the water sources for
the cattle were not exposed.
Higher air concentrations might have been expected at Lathrop Veils
based on the dose rates observed. Results indicate, however, that
most of the radionuclides remained airborne in the effluent cloud as
it passed over Lathrop Wells and the dose rates observed were due to
"shine" from the radioactive isotopes above.
It is concluded that the safety criteria established by the Atomic Energy
Commission were not exceeded as a result of this event.
10
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NEVA DA
UTAH
Kolidf I eld
&
Dd Knarr^vi ] ]
A I amo
PA HRA NA CA T
Wartr3\ HesquiteD
0 10 ;p 30 Ğ0 50
5C4LE IN HILE5
KEY
O - Ai r Sampler
)/*)'! I 11 - Air Sampler w/charcoal
]Springs
I
nd i an Springs
ARIZONA
Furnace
- NAT. HON. \
cartridge
- Dose Rate Recorder
Figure 1. Air sampler and dose rate recorder locations.
11
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NEVA DA
UTAH
Duckwater1 A
AMehhattan yB|ue Jay
Warm A
Spri
Warm ASprings Rn.
ARIZONA
A - Milk sampling locations
A - Water sampling location
v i rs ;
rmerjionl RrK?
Figure 2. Milk and water sampling locations.
12
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APPENDIX A
GROUND MONITORING RESULTS
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GROUND MONITORING RESULTS
LOCATION
Lathrop Wei Is
Lathrop Wells to the Junction of Ash Meadows
Road and Hwy . 95
Junction of Ash Meadows Road and Hwy 95 to
Lathrop Wei 1 s
Lathrop Wells to 5 mi NW on Hwy 95
From 5 mi NW of Lathrop Wells to Jet. of
Ash Meadows Road and Hwy 95 and return
to Lathrop Wei I s
Junction of Ash Meadows Road and Hwy 95
(5 readings).
1 .5 mi E of Lathrop Wei Is
3 mi E of Lathrop Wells (10 readings)
1 mi E of Lathrop Wells
1/2 mi E of Lathrop Wells
Lathrop Wei 1 s
5 mi E of Lathrop Wells
TIME
1415
1430
1445
1500
1500-
1525
1525-
1545
1545-
1550
1550-
1633
1610-
1745
1637
1700-
1745
1750
1751
1755
1810
1810
- 1820
1825
1830
NET GAMMA
DOSE RATE
(mR/hr)
BKG
BKG
BKG
BKG
BKG
BKG
BKG
BKG
BKG
BKG
BKG*
BKG
BKG
BKG*
BKG*
0.1 0
0.14
0.08
0.20 '
*0ccasional excursions of the scintillator indicated the possible presence
of airborne contamination.
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GROUND MONITORING RESULTS (cont1)
LOCATION TIME
* 5 mi -E of Lathrop Wells (cont1) 1830
-.- " 1845
1850
1850
1855
1900
1905
1915
1920
Lathrop Wells 1930
17 mi S of Lathrop Wells on Hwy 29 1730-
(29 readings) 1850
17 mi S of Lathrop Wells on Hwy 29 1900
1901
1902
1903
NET GAMMA
DOSE RATE
(mR/hr)
0.15
0.08
0.05
0.05
0.05
0.04
0.04
0.04
0.04
BKG
BKG
0.01
0.01
0.01
0.01
A monitor located at Pahrump, Nevada during the time following this event
was unable to detect any dose rate above background.
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APPENDIX B
AIR SAMPLING RESULTS
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AIR SAMPLING RESULTS
1. LOCATION DATA
STATION NAME
(Ailmulli and Olilono)
Death Valley Jet . , Cal i f
Shoshone, California
Indian Springs, Nevada
Las Vegas, Nevada
Lathrop Wells, Nevada
Pahrump, Nevada
F=f i 1 ter
Ocar tr i dge
ND=not detectable
II. COLLECTION DATA
UJ
ĞiĞ~
*?*
177
85
227
132
408
477
510
99
330
441
SAMPLING PERIOD
BEGIN
Mo.
12
12
12
12
12
12
12
12
12
12
Doy
05
05
05
05
05
05
05
05
05
05
Time
0630
1521
1930
1000
1630
0832
14)0
1410
1910
1535
END
Mo.
12
12
12
12
12
12
12
12
12
12
Day
05
05
06
05
06
06
06
05
06
06
Time
1521
1930
0630
1630
1218
0742
1500
1905
1 1 14
1200
COLLECTOR
F
C
F
C
F
C
F
F
C
F
C
F
C
F
C
F
C
F
C
III. RADIOASSAY DATA
GROSS BETA COUNT
DATE-TIME
COUNTED
10 09 1 9
10 0828
11 0835
10 09 1 7
11 0830
1 1 0842
11 0837
10 0826
11 0832
1 1 0840
ACTIVITY
(pCi/m3)
0.32
0.62
0.27
0.30
0.30
0.29
0.24
0.38
0.40
0.27
GAMMA PULSE HEIGHT ANALYSIS
DATE-TIME
COUNTED
06 1739
06 1756
06 1759
06 1744
06 1746
06 1751
06 1736
06 1754
06 1749
ACTIVITYCoCi/mJ)
131. 133. 135. 135V
I 1 I Xe
<1 <1 ND <1
ND ND ND ND
ND ND ND ND
ND ND ND ND
I.I
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APPENDIX C
VEGETATION SAMPLING RESULTS
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VEGETATION SAMPLING RESULTS
LOCATION
Summerton, Arizona
0.4 mi W of
0.6 mi W of
Shoshone, Ca
Ogi Iby , Cal i forn ia
Ogilby, Cal i forn i a
1 i forn ia
Selbach Ranch, Lathrop Wells, Nev.
Dansby Ranch
12 mi SE of
, Lathrop Wei 1 s , Nev .
Lathrop Wells, Nev..
5 mi SE of Lathrop Wells, Nev.
DATE
COLLECTED
12/1 1/64
12/1 1/64
12/07/64
12/07/64
12/07/64
12/07/64
12/10/64
12/10/64
,2/10/64
12/07/64
12/06/64
12/06/64
12/05/64
12/05/64
DATE
COUNTED
12/12/64
,2/12/64
12/08/64
12/08/64
12/08/64
12/08/64
12/10/64
12/10/64
12/10/64
12/08/64
12/08/64
12/08/64
12/06/64
12/06/64
132T
Te
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
45
60
131,
ND
ND
ND
ND
ND
ND
ND
40
80
ND
ND
150
120
300
132,
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
45
60
,33,
' ND
ND
ND
ND
ND
ND
50
70
,50
ND
ND
220
,50
300
,35,
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
137Cs
250
155
400
280
580
320
ND
ND
ND
70
800
390
150
300
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DISTRIBUTION
James E. Reeves, Manager, NVOO/AEC, Las Vegas, Nevada
Henry G. Vermillion, NVOO/AEC, Las Vegas, Nevada
Otto H. Roehlk, OSD, NVOO/AEC, Las Vegas, Nevada
Col. E. G. Halligan, DASA, NVOO/AEC, Las Vegas, Nevada (2)
Test Manager, AEC Operations Coordination, Mercury, Nevada
Dr. R. H. Goeckermann, LRL, Livermore, California
Dr. Gilbert Potter, LRL, Livermore, California
Dr. E. H. Fleming, LRL, Livermore, California
Wayne R. Woodruff, LRL, CP-1, Mercury, Nevada
Bryce L. Rich, LRL, Bldg. 101, Mercury, Nevada
Harry Jordan, LASL, Los Alamos, New Mexico
Dr. William E. Ogle, LASL, Los Alamos, New Mexico
Dr. Gordon M. Dunning, DOS, USAEC, Washington, D. C.
Philip W. Allen, USWB, NVOO/AEC, Las Vegas, Nevada
Gilbert J. Ferber, USWB, MRPB (R-3.3), Washington, D. C.
James G. Terrill, Jr., DRH, PHS, Washington, D. C.
E. C. Anderson, DRH, PHS, Washington, D. C.
D. J. Nelson, TOB, DRH, PHS, Washington, D. C.
A. H. Dahl, DRH, PHS, Rockville, Maryland
D. L. Snow, DRH, PHS, Washington, D. C.
Victor M. Milligan, REECo, Rad-Safe, Mercury, Nevada
Mail & Records, NVOO/AEC, Las Vegas, Nevada
SWRHL, Las Vegas, Nevada (2)
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