Gnome shaft was found to have the most
extensive %7Cs contamination (U.S. DOE
1981). The final survey showed a small area at
the same location as survey site 14 that had a
137Cs count rate equivalent to an exposure rate
of 25 to 28 nGy h* (2.8 to 3.3 pR h") ata
height of 1 m. In Table 1, it is evident that the
dose rate from "7Cs measured in this study is
about one third of that value, or approximately
equal to the contribution from the “°Th series.

Survey sites 14, 15, and 17 all show ele-
vated '’Cs abundances. Site 16 is an area that
appeared to be frequently drained, and is not
likely to have the same retention characteris-
tics as the other locations. In all, it would be
difficult to draw conclusions about the extent
of remaining fallout activity without a thor-
ough investigation. Decay and weathering in
the elapsed 31 y would have altered the origi-
nal distribution, and the plume itself which
was released for several hours would certainly

not have left a simple contoured pattern of fis-

' sion products.

Sites 19 through 22 were selected for off-
site control measurements because of their dis-
tance from the Gnome site and because they do
not lie in the recorded path of the plume. The
sites have similar abundances and extended
vertical distributions of "Cs. The activities

-are somewhat low considering the average 30

cm of rainfall the area receives (Gardner and
Sigalove 1970; Miller et al. 1980; Amalds et
al. 1989). The surface of the region around the
Gnome site consists primarily of alluvial mate-
tial.and quartz sand (Mackallor 1965), and in
the immediate vicinity consists of caliche out-
croppings, sand, and sand dunes sparsely cov-
ered with desert vegetation. Poor water reten-
tion characteristics likely account for the low

. "Cs fallout activity and the deep dispersion

relative to other arid regions in North America.


° “ACKNOWLEDGEMENTS :

~ The author would like to thank Brian Moore for the strontium analyses and Don James and Max
Davis for.assistance in collecting field data. :





EXPERIMENTAL PROCEDURE

Field gamma-ray spectra were collected
with a high-purity germanium detector
(HpGe) with a relative efficiency of 30%. The

spectra were collected for periods of 45 min ~

with a portable battery-powered multichannel
analyzer and recorded on diskettes for later
retrieval and analysis with a laboratory mini-
computer. Soil core samples were collected
as described in Beck (1979) and Miller et al.
(1980). Conversion factors to determine dose
rates in air and soil activities were obtained
from Beck (1980), Murith et al. (1986), and
Helfer and Miller (1988). Total gamma-ray
flux was measured at each survey site with a
pressurized ion chamber (PIC) for periods of

15 min. All measurements were taken at a
height of 1 m above ground level.
Calibrations of radiation detection equipment
were performed with radioactive sources
traceable to the National Institute of Standards
and Technology (NIST). In a period of 6 d, a
total of 22 on-site and off-site locations were ~
surveyed, with core samples taken at 11 loca-
tions. Soil samples were packaged and
returned to the laboratory for gamma-ray
analysis as in Faller (1992). Two soil samples

. were analyzed for radiostrontium content by
total dissolution, ion-exchange separation,
and beta-ray analysis.

EXPERIMENTAL RESULTS

Fig. 2 depicts the Gnome Test Site and the
approximate path of the plume from the shaft
vent. On-site and near-site in-situ survey
locations and the positions of facilities that
were removed during clean up operations are
also shown. On-site wells are sampled and
analyzed yearly.

Table 1 lists the gamma-ray dose rates in
air measured at each of the survey locations.
The combined total rates are the summed con-
tributions from the cosmic-ray component,
deduced from the barometric pressure, and the
natural and man-made components, derived
from analysis of the HpGe spectra. Gross
dose rates from PIC measurements, taken at
the same survey locations as the gamma-ray
spectra, are given as a check of the summed
rates. ,

Table 2 lists the °"Cs inventories for each
surveyed site. The depth distribution parame-
ter is expressed as 0/p, where & is the recip-
rocal of the relaxation length of the assumed
exponential profile in the soil, and p is the soil

density (Miller and Helfer 1985). At locations .

\ Je
where soil cores were not taken, parameters of
ee (planar distribution) and 0.05 are given to

" represent a large range in distribution profiles.

Corresponding radiocesium abundances per
unit area deduced from the depth parameters
and the spectral results are listed for each sur-
vey. site. The minimum detectable concentra-
tions per unit area are also given. '’Cs was
the only man-made gamma-emitting nuclide
detected in this study.

The one- sigma statistical uncertainties of
the nuclide inventories in Table:2 are general-
ly less than 20% of the calculated values, and
in some cases, as little as 1%. Uncertainties
are as high as 50% for 7Be values, owing to
the small concentrations. Uncertainties intro-
duced by literature conversion factors used to
determine individual nuclide concentrations.
are generally less than 15% (Helfer and Miller
1988). In addition, uncertainties of less than

_ 6% exist in the PIC dose rate in air values, and

some relatively small errors exist in. estima-
tions of vertical distributions where they w were
determined (Faller 1992).



INTRODUCTION

The Gnome Test Site is located in Eddy
County, southeastern New Mexico, approxi-
mately 35 km southeast of the city of Carlsbad.
, and 12 km southwest-of the Department of.
Energy (DOE) Waste Isolation’ Pilot Project
(WIPP) facility (Fig. 1). Project Gnome was a
3.1 kiloton yield nuclear detonation conducted
on 10 December, 1961, as part of the
Plowshare Program of the Atomic Energy
-* Commission. The program was initiated ‘in
1957 to investigate the feasibility of the use of
nuclear explosives for nonmilitary applications
such as large-scale civil engineering projects
and scientific studies. The Gnome experiment
was specifically designed to explore the possi-
bility of converting the energy of a nuclear
explosion to electric power, investigate the
production and recovery of radioactive iso-
~ topes, collect: data on the. characteristics of

nuclear detonations within a salt medium, and ©

to obtain neutron cross-section measurements

over a wide energy range. It was the first of
the Plowshare experiments and the first under-
ground nuclear test conducted outside of the
Nevada Test Site in the United States (U.S.
AEC 1961; Nathans 1965; U.S. DOE 1982).

The nuclear device was detonated 370 m
below the surface of the Gnome site in the
Salado geological formation, ‘which is com-
posed primarily of halite (NaCl) (Gardner. and
Sigalove 1970). Access to the shotpoint was
provided by a horizontal drift tunnel that led to
a vertical shaft 340 m southwest of ground
zero. The explosion created ‘a cavity. about 21
m in height and 46 m in diameter (Gard’ 1968).
By June of 1962, mine-back activities had con-
nected the shaft to the cavity, allowing it to be.
entered. A blanket of collapsed material from’

* the upper hemisphere of the chamber provided

shielding from the highly radioactive melt pro-

- duced in the explosion.

Pm NEW
Ibuquerquel MEXICO ~
El Paso
: Hobbs,
. Monument i
7 &: .
e
N 4 : ad.
269 Heurta tea GE Genter] |
31 Eun ;
: nice
Carisbad . WIPP SITE Fi
tis f ; al
J Bio
: §
Loving? , at Teague als
Malaga 2 Ochoa <a) SI
eS SSC Jal G35
, Bennet}
1. ee A
Texas
7 0 20 cto 30
‘Angeles: Scale in Kilomoters \_Kermit 5

Figure 1. Location of the Gnome Test Site in Eddy County, New Mexico.
a. 4



vi



Co) Survey Location

io Well

4

To Highway 128

Fallout Area

‘ \ Salvage Yard/— Contaminated
“ . pet 8 dn . Waste Dump
. . i . "
Evaporation ’
Rond

XS a
Ground Zero |

=a _(DD-1)
6 7) “Decontamination Pad

4—~ GNOME || Salt Muck Pile Site .

EJ SHAFT
(plugged)

(Nee USGS 4,8
Oo |

COACH SHAFT _
(plugged)
ta :

Scale in Meters

0 : 300 . rt

LRL-7

Stag 0HRD

: Figure 2. Gnome Site survey locations, shaft sites, and operating wells. Locations 16 through 22 are not shown.



Report No. EPA 600/R-94/117
Date: July 1994

-RESIDUAL SOIL RADIOACTIVITY AT: THE GNOME TEST SITE
» INEDDY COUNTY, NEW MEXICO -

. . S.H. Faller
. Environmental Protection Agency
P.O. Box.93478
"Las Vegas, Nevada, 89193-3478

ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT _*
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NV 89193-3478 oe

“ t034NRDS3



Table 2. Spectrometry results at Gnome on-site and off-site locations; calculated distribution parameter, "Cs content, and mini-
mum detectable activity (1.0 kBg m2? = 2.7 pCi em?) ;
!Cs Distribution
Activity abundance +
lp (K8q m2) ___MDA
ON SITE
1. Surface ground zero (5 m northeast at monument) 20 142 £ 0.03 0.05
0.05 951 + 017 0.34
2. Coach shaft site (well LRL-7) . os 080 + 002 0.04 ;
0.05 5.38 + 0.14 0.25
3, 70m northeast of Coach shaft site 2 0.096 + 0.009 0.03
0.05 : 0.63 + 0.06 0.16
4, 130m northeast of Coach shaft site . © 0140 £ 0.01 0.02
0.05 0.66 + 0.06 . 0.15
5, Waste tank/evaporation pond site co 014 + 001 ~ 0.02
0.05 0.91 +- 0.07 0.16
6. West side of salt muck pile site , oo 0,033 + 0.008 0.01
0.05 0.22 + 0.06 . 0.16
7. East side of salt muck pile site . °° - 0.32 + 0.02 0.03
+ 0.05 326 + 0.15 > 0.26.
8, Gnome shaft (8 m northeast of plug) eo 145 + 0.03 _ 0.03
0.05. 978 + 0.17 0.19
9. Southeast side of contaminated waste dump cy 0.28 + 0.01 ° 0.02
0.05 185 + 0.08 0.16
10. Central area of contaminated waste dump 0.14 677 + 0:10 0.10
11. Salvage yard © 0.044 + 0.008 0.03
0.05 0.30 +. 0.05 O17: 1
12, Decontamination pad . , 0.04 9.96 + 018 0.22
OFF SITE ,
13, Wells USGS 4 and 8 oo 1.07 + 0.03 . 0.03
0.05 716 + O18 0.19
14, 150 m northeast of Gnome shaft 0.14 1149 + 0.13 012
15, 400 m northwest of Gnome shaft . 0,25 3,71 + 0.08 0.07
16. 2.5 km northwest of Gnome shaft Ont 0.50 + 0.05 O41
17. 10 km northwest of Gnome shalt "054 1.00 £ 0.03 0.04
18, 16km northwest of Gnome shaft 0.26 “069 £ 0.04 "007
19. 2.5 km west of surface ground zero ~ 0.09 0,65 't 0.05 0.10
20. 3 km east of surface ground zero 0.17 053 2 0.04 0.07
21, 4km northeast of surface ground zero 0.13 _. 056 + 0:04 0.09
22. 3 km south of surface ground zero - 0.10 0.42 + 0.04: 0.08
6 .



Table 1. Dose rate Inventorles at Gnome survey locations (1.0 nGy h* = 0.11 pRh).

, ; <5 Dose'tate in air (nGy h)
Cosmic °K TMTh* =U" Be. ~~ Cs——STolal~—~PICTM

ON SITE

1. : Surface ground zero (5 m-northeast of monument) & 78. 84.14 0.6 43° 7° 75

2. Coach shat site (well LRL-7) —_ i AB BT BT t58 - 04 24 7770

3. 70 northeast of Coach that ste a “4 86 83 109038.

4. t90mnotheéstof Coach shal sio’ =| AS. 6B 63 (OM ow eo . 87

“5. Waste tanklevaporation pondsita ABB ; “IP 68. 03 oe Ca)
“6. “West sie of sat muck pl ste : 4 107 «105 97 tO 16 73

7. East side of sat mick pile sie 08 85° 04-02 10 8B

8. ‘Gnome shaft (8 m northeast of plug) re | 84 66-94 04 44. 78

9. . Southeast side of contaminated waste dump 45 43 . 48 : 7.0. os 0° 62 63 7

10. Cental area of contaminated wast duinp 80 59.. 77 08. 88. :
11. Salvage yard , 4s 98 “406. 89° 03)” “Ot oe 70, oo
12 Deconlamintion pad 4 90073753) TB

_ OFF SITE ;
18, Wels USGS 4and ts 88 9005 8B ;

= 14.- 180 mnorthwest of Gnome'shaft 114 102 Ot 03. BB.

. 15. 490:m northwést of Gnome shaft “114 104 97 08 AA 8, 76
46. - 25 km northwest of Gnome shatt 130. 184 106 «= 03, 0d 7B
| "417. 40 kr noithwest of Gnome shatt “92 412 © 108. 04 14 7B BT

“18. 16 km northwest of Gnome shaft 213.8 12.9 89 05 ‘0.8 82, 7

19. - 2.5 km west of surface ground zero 10.3 90 04 04 ~ 2 70

20. 3 km east of surface ground zero 84 68: 75. 03 (05. BBB

21. 4 km northeast of surface ground zero

EB RoR @ & & & #8

22, 3.km south of surface ground zero” 8.4 65 6.3 03 03 59 65

 * > Contribution from series.
» Assuming a/p = 0.05 (no core taken). .



SURFACE CONTAMINATION AND
REMEDIATION

Immediately following the firing of the
device, a low pressure vent from the Gnome
shaft occurred owing to the failure of a rupture
disk in a blast door in the access tunnel. For
more than a day, steam and short-lived
radioactive gases vented from the shaft and
were carried in a northwest direction from the
site (Fig. 2). After the event, a considerable
amount of contamination was present on the
surface of the site (Gardner and Sigalove
1970). Later reentry mining and core sam-
pling operations also brought contaminated
material to the surface, mostly in the form of
salt muck.

From 1968 to 1969, a cleanup program
was conducted at the site, with guidelines
specifying the removal of all radioactive mate-
rial with a reading of 2.6 x 10% C kg’ h! (0.1
mR h", beta plus gamma) as measured with a
30 mg cm? window Geiger Muller survey
probe. Contaminated soil and debris were dis-
posed into the Gnome shaft and drift tunnels or
were interred beneath uncontaminated soil. In
addition, all surface facilities were removed
and all bore holes were plugged except for
those retained for hydrological monitoring
(U.S. AEC 1973). In 1977, a second more
extensive cleanup program was initiated with
guidelines for removal of soil with beta-
gamma activity above 0.74 Bq g! (20 pCi g")
or a moisture 7H activity above 1.1 kBq ml
(30 nCi mI"). This operation included the
removal of debris from the contaminated waste
dump and salvage yard (Fig. 2) that had been
exposed by weathering, and the disposal of

contaminated soils and approximately 3 x 10*7
kg of salt muck into the Gnome cavity. The
Coach shaft denoted on the figure was con-
structed for a. second Plowshare detonation
that was later abandoned. It was also used for
disposal of contaminated materials, and
because the Gnome and Coach shafts were
connected by a horizontal drift tunnel, the
associated well LRL-7 was used for water
monitoring and recovery during the operation.
Once the cavity had been filled to near capaci-
ty, remaining radioactive materials’ were

_ Temoved to the Nevada Test Site for burial in a

low-level waste site. The operation concluded
in 1979, and the site has since been decom-
missioned (U.S. DOE 1981, 1982).

In 1991, a study was undertaken to deter-
mine in-situ gamma-ray exposure rates and
radionuclide concentrations in surface soils at
nuclear test locations outside of the Nevada
Test Site (Faller 1992). In June of 1992, the
Gnome site was selected for a surface charac--
terization that would coincide with the annual
hydrological testing of the area (U.S. EPA
1992). This study was conducted to assess the
extent of remaining activity at the site and pro-
vide data on the distribution of the contamina-
tion in the desert environment.

, Survey sites were selected from locations
of previous operational facilities such as waste
disposal sites, building foundations, and shaft
sites. In addition, radiological survey maps
from previous surveillance reports were used
to determine contaminated locations and areas
with background levels of radiation (U.S. DOE
1981).



ABSTRACT

A surface soil characterization was conducted at the Gnome Test Site surrounding areas near
Carlsbad, New Mexico to determine the abundances of gamma-emitting radionuclides and total expo- _
sure rates. Cs was the only man-made nuclide detected in measurements taken at 22 on-site and
off-site locations, with a maximum concentration of 11.49 + 0.13 kBq m?(31.02 + 0.35 pCi cm?).
Extended '°’Cs verticle distributions and lower than expected inventories at undisturbed sites can be
attributed to the unconsolidated sandy surface of the area. Results of the in-situ spectrometry indicate
that at all locations the dose rate due to /°’Cs is small compared to that of the naturally occurring back-
ground. :



SUMMARY

The dose rates deduced from in-situ spec-
trometry and. soil core analysis are in close
agreement with the measured PIC rates at all
surveyed locations. As in-previous surveys,
137Cs dbundances were found to be highly vari-
able in the Gnome area, with the highest con-
centration lying 150 m northwest of the

Gnome shaft site. Presumably this activity
-was deposited from the low-pressure ‘venting .

that occurred immediately after the detonation,
and it currently accounts for a dose rate about
equal to: the contribution from. the naturally
occurring Th series, or about one-eighth of
the total dose rate measured at that.location.

. Considering the time elapsed since the ear-
lier surveys, radiocesium concentrations at
contaminated locations. detected in: this study
were lower than expected. Also, surveys con-:
ducted at surrounding control areas. away from
the path of the vent plume-show low '°’Cs

_ abundances relative to other regions that .

receive less or equal rainfall. Both discrepan-

cies are probably due to the predominance of

an ‘unconsolidated sandy surface with poor .
water retention characteristics.



Nathans, M.W. U.S. Atomic Energy Commission, Plowshare Program, Project Gnome
-Carlsbad, New Mexico, isotope.program - final report. Las Vegas NV: U. S: Atomic Energy
~ Commission; Report No. PNE 102F; 1965: »

_ U.S. Atomic Energy Commission, Project ‘Gnome Organization. Project Gnome; Part of the
U.S. Atomic Energy Commission’s Plowshare Program for peaceful uses. ‘Albuquerque,
NM: Albuquerque Operations Office; AL Pamphlet 3100-1; 1961.

U.S. Atomic Energy ( Commission, Nevada Operations Office. Gnome/Coach site disposal
options. Las Vegas, NV: Us S. Atomic Energy Commission; NVO-131; 1973.

US. Department of Energy, Gnome Site decontamination and decommissioning project; phase I
_Tadiological survey and operations report; Carlsbad, New Mexico. Las Vegas, NV: U S.
Department of Energy, Nevada Operations Office; NVO/0410-48; 1978.

U. ‘S. Department of Energy, Gnome Site decontamination and decommissioning project : radia:
tion contamination clearance Teport. Las Vegas, NV: U.S. - Department of Energy, Nevada
_ Operations. Office; Report No. DOE/NV/00410-59; 1981. :

’ U.S. Department of Energy, Nevada Operations Office, Health Physics:Division, Environmental
3 Branch. Long-term hydrologic monitoring program; Gnome Site, Eddy County, New.”
Mexico. Las Vegas, NV: U.S. Department!of Energy, Nevada Operations Office; Report
No. NVO-241;.1982. :

U.S. Environmental Protection Agency, ‘Radiochémical analytical procedures for analysis of.
environmental samples. Las Vegas, Nevada: U.S. Environmental Protection Agency; EMSL-
LV-0539-17; 1979.

U.S. Environmental Protection Agency, Nuclear Radiation Assessment Division ‘Annual Report
1992. Las Vegas, NV; Environmental Monitoring Systems Laboratory - Las Vegas: | in Prepa-
: ration., : . .

Wo



Contents

Notice .
° Abstract - :
Acknowledgements .

Introduction a1
, - | Surface Contamination and Remediation v2
. Experimental Procedure. .... . “wp aeee Dawe eee Lecce Preble eee cee cab gen ed ees 4.
‘ Experimental Results : ee , rented
Discussion F
Summary . . : : riiPe penne s es
“References ....... 005... e bev eee ee Vee Wha det ee enes Fe egee 210
. : Figures a
. : . Page
-Figure 1. Location of the Gnome Test Site in Eddy County, New Mexico wo veeeceeee 1
Figure.2; Gnome Site survey locations, shaft sites, and operating. wells. ; :
: Locations 16 through 22 are not shown. ..i....66.. 05008 Leeda ee nee 3
Tables

Table.1. -Dose rate inventories at Gnome survey locations.

Table 2. Spectrometry results at Gnome on-site and off- Site locations; calculated .
: distribution parameter, '°’Cs content, and minimum detectable activity. .... 16



NOTICE

The information in this document has been funded wholly or in part by the United States Environ- .
mental Protection Agency through Interagency Agreement DE-A108-91NV10963 from the United States
Department of Energy. It has been subject to the Agency’s peer and administrative review, and it has been
approved for publication as an EPA document. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.



The summied totals of the dose-rates from
cosmic radiation and radionuclides at all sur-
veyed locations are in. close agreement with
the measured PIC rates at the same sites. The
average PIC value in this study is 2.0% lower
than the average summied value, and differ-
“ences in the two values at each location are
within the estimated uncertainties.

~A large variability in °’Cs activity is evi-
dent across the Gnome site (locations 1
through 12). However, at all of the on-site
locations and other survey sites close to the
Gnome shaft, the range of 19’Cs values should
be considered only an estimate ‘because the
ground has been disturbed several times since
the original contamination, and it is. unlikely
that the radiocesium has an exponentially
“decreasing vertical distribution, as assumed in
the calculation’ of the ‘inventories and dose
rates. .Also, at locations 9 and 10, it is quite
possible that the observed '°’Cs activity is due
to contaminated materials buried: within. the
waste dump.

It was suspected that the relatively high
.cesium activity at the surface ground zero, sur-

vey location 1, may have been caused by over-

flow or spillage from well DD-1 which is used
to monitor the water within the Gnome cavity.
A surface soil sample was taken next to the
wellhead and returned to the laboratory for
tadiochemical analysis, The ratio of *Sr to
137Cs in soil was found to be 0.029 + 0.010,
while the ratio. in water obtained from well
DD-1 was 0.24 + 0.05 (U.S. EPA 1979). The
large difference implies that the. source of the
soil contamination was not the well water, and

was probably the post detonation venting and

DISCUSSION

drilling operations. Ratios of *Sr to “Cs
determined for many soil samples at the site
prior to the cleanup program of 1977 were also
generally very small (U.S DOE 1978). ~

Survey location 13 is located between two
US. Geological Survey wells used for a tracer’
experiment in 1963 (Beetem 1964). The
experiment was designed to determine physi-
cal characteristics of dispersion’ and chemical
absorption reactions of radionuclides in the-
Culebra Dolomite. Aquifer, which ‘is .consid--

- ered to be the only. significant aquifer at.the
Gnome site (Gardner.and Sigalove 1970). The

nuclides were injected into well: USGS 8 and
recovered from USGS ‘4 for analysis and rein-
jection. Nuclides “I, 3H, gr, and 137Cs in a
range of 0.4 to. 1.8 TBq (10-50 Ci) were intro- -
duced during the course of the experiment
(U.S. DOE 1982), and the latter three nuclides
are presently detected in the waters of both
wells. A laboratory analysis of a surface soil
sample taken near. USGS 8 showed a Sr to
837Cs activity ratio of 0:11 + 0.03 while the
water of USGS 8 had a ratio of 0.74 +'0.11,
again indicating that the activity is probably
not due to well water spillage.

Survey sites 14 through 18 were selected
for a cursory investigation of remaining fallout
from the Gnome vent. ‘The sites lie within the
general path of the fallout plume (Fig. 2) at:

varying distances from the Gnome shaft. Of

all locations surveyed in this study, site 14
which lies 150 mr from the shaft, showed the
highest °’Cs inventory. This is not unexpect-,
ed because in aerial surveys flown before and
after the 1977 to 1979 decontamination opera-
tion, the region immediately northwest of the



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Beck, H.L. The natural radiation background of Utah-Preliminary report on radionuclides in’
soils in populated areas. New York: U.S. Department of Energy, Environmental
Measurements Laboratory; Report No. EML-362; 1979.

Beck, H.L. Exposure rate conversion factors for radionuclides deposited on the ground. New
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Beetem, W.A.; Angelo, C.G. Carlsbad hydrology-2, tracer study at Project Gnome site, near
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Faller, S.H. In-situ gamma Tay site characterization of the Tatum Salt Dome Test Site i in-Lamar
County, Mississippi. Health Phys. 62:571-575; 1992.

Gard, L.M., Jr. Geologic studies, Project Gnome area, Eddy County, New Mexico. Denver,
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Gardner, M.C.; Sigalove, J.J. Evaluation of the Project Gnome/Coach Site, Carlsbad, New
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Helfer, L.K.; Miller, K.M. Calibration factors for Ge detectors used for field spectroscopy.
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Mackallor, J.A. Aeroradioactivity survey and geology of the Gnome (Carlsbad) area, New ©
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Miller, K.M.; Gogalak, C.V.; Tanabe, H. Natural background radiation and '*"Cs inventories in
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Miller, K.M.; Helfer, .K. In situ measurements of BCs i inventory in natural terrain. In:
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10