ITR-8
SOUTHWESTERN RADIOLOGICAL HEALTH LABORATORY
INTR A LABORATORY TECHNICAL REPORT
December 14, 1965
A summary of exposures to the Off-Site Population
as a result of nuclear tests conducted at the Nuclear
Rocket Development Station during 1965,,
Donald T. Oakley
SUMMARY
A summary of whole body and thyroid exposures resulting from
five nuclear reactor experiments conducted at NRDS during 1965
is presented. The exposures are compared with protection
standards and it is shown that the exposures are small compared
to the standards.
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During 1965 five releases of radioactivity from NRDS were detected
in the off-site area. The releases resulted from the Kiwi TNT
experiment, Experimental Plans 4S 5S and 6 of the NRX-A3, and
Experimental Plan 4 of Phoebus 1=A0 A summary of exposures
from th@ tests is presented in the following tables; additional
information may be found in the surveillance reports
1. 2, 3
on
each test. For convenience a summary of data pertinent to the
surveillance is presented in Table 1.
Table 1 Reactor Test Data
TEST
KIWI TNT
DATE
TIME
1/12/65
1058 PST
Nominal operating
power megawatts
Transient
NRX-A3, EP4
4/23/65
1254-1Z58 PST
1100
NRX-A3, EP5
NRX-A3, EP6
PHOEBUS 1-A, EP4
5/20/65
1032-1046 PDT
5/28/65
1030=1100 PDT
6/25/65
1315-1326 PDT
1100
<500
1100
Whole Body Exposure
Monitors equipped with survey instruments obtained dose rates due
to cloud passage. From a plot of dose rate vs time one may esti~
mate the dose due to cloud passage. In addition, an estimate of the
infinite external dose has been made by assuming a dose rate decay
from a residual dose rate following cloud passage, A summary
of the peak exposures at populated locations is presented in Table 2.
The infinite doses following EP4 and EP5 are given as zero; any
actual deviation from this is very small.
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Table 2. Summary of whole body exposures resulting from 1965
NRDS testing.
Event
KIWI TNT
NRX-A3, EP4
NRX-A3, EP5
Location of
peak dose
(See Figure 1)
Death Valley Jet.
Hwy 95, 1.5 mi W
of Lathrop Wells
(unpopulated J
Pah rump
Goss Ranch
External whole body gamma
exposure
Due to
•AM* UC lf\J
cloud
passage
.23
5,7
<.03
<.03
in milliroentgens
Due to Total
Fallout Exposure
.44 .67
8.5 14
0 <,03
0 <.03
NRX-A3, EP6 No measurable dose rates off the test range
complex.
PHOEBUS 1-A Diablo
.04
1,2
1.2
Thyroid dose due to inhalation
Concentrations of iodine in air were detected following each
experiment. A summary of the peak concentrations of iodine,
as detected by charcoal cartridges, is presented in Table 3.
4
From data collated by P. Griffiths , one may predict the
potential thyroid dose at a downwind location.
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Table 3. Summary of inhalation thyroid exposures resulting from 1965 NRDS
experiments.
Thyroid dose conversion factors
Location
EVENT °f Peak .
concentrations
(See Figure 1}
KIWI TNT Death Valley Jet
Hwy 95, 1. o mi !
W of Lathrop
Wells f unpopulated)
131.
JL
-7 4
3.42x10 mrad
pCi-sec/m
pCi-sec Millirad
3 to
m ^ -j
thyroid
ND 0
3.6xi05 .29
9. 21xlO"8mrad4
pCi-sec/m
pCi-sec Millirad
3 to
m *i_ -j
thyroid
2.4xl05 <,1
1.7x10 .16
Thyroid
dose due
to inha-
lation of
131
•^ ~* •* 17 1
I and
I in
mrad
<. 1
3.3*
NRX-A3. EP4 Pahrump
1. 1x10'
<• 1
3.4xl05 <.l
<. 1
NRX-A3,
NRX-A3,
PHOEBUS
EPS
EP6
i-A
Hiko
Coyote Summit
([unpopulated }
Lathrop Wells
Diablo
Queen City Sum-
mitfunpopulated)
3.
4.
3,
6.
5.
0x10
0x10
6x10
0x10
5x10
<. 1
5 .14
4 <.l
4
5 .19
5.
6,
4.
2.
1.
4x10 < . 1
OxlO5 < . 1
4
2x10 <.l
OxlO5 < . 1
6x10 .15
<•. !
< 2
< . 1
< .1
.34
^Determined by in vivo thyroid counting.
Thyroid dose due to milk ingestion
Following three of the experiments conducted at NRDS there were detectable
131
quantities of I in milk collected in the test site environs. As mentioned
2 3
in the NRX-A3 and Phoebus 1-A reports c sources other than NRDS
reactors could have been responsible for a portion of the activity. If one
5
scales from data prepared by the Federal Radiation Council , it is possible
to estimate the potential dose to an infant's thyroid from the milk ingestion.
However,, scaling by this method assumes that the contamination was a result
4
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of a single event, and it is necessary to consider this possible
source of error in judging the dose estimate.
A summary of the milk sampling results is presented in Table 4.
Analyses of samples collected in Nevada and Southern California
following Kiwi TNT did not indicate the presence of I. This
probably reflects the fact that at the time of the test most of the
animals were on stored feed,, In addition, samples collected
following NRX-A3, EP4 did not contain radioiodine.
Table 4. Summary of milk ingestion thyroid exposures resulting
from 1965 NRDS experiments.
Event
NRX-A3, EP5
NRX-A3, EP6
Phoebus 1-A
Locations where
131
I was detected
in milk(see Fig. 1)
Hiko
Springdale
Alamo
Hiko
Blue Eagle
Currant
Milk radio-
assay data.
, 131_
peak I
(pCi/1)
90
70
50
60
180
20
Millirad to
thyroid(12
mrad/100
PCi ^l/l
peak) 5
11
8
6
7
22
2
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CONCLUSIONS
The levels of radioactivity encountered off the test range complex
as a result of 1965 NRDS tests were small fractions of the AEC
Radiation Protection Guides , The dose to any one location was
limited by the infrequency of testing and the varied directions of
the five experiment "hot lines"(See Figure 1).
By assuming that one roentgen exposure produces one millirad or
r b '•
one millirem absdtyed dose0 a comparison of the 1965 results with
the protection standards has been made in Table 6.
Table 6. Comparison of protection standards with 1965 NRDS
effluent effects.
Type of
Exposure
AEC Radiation Protection Standards
for individuals and population groups
in controlled areas.
Based on Expo-
sure to individ-
ual (millirem/
year)
Based on aver=
age exposure to
a suitable pop-
ulation sample
(millirem/year)
Maximum
potential
exposure
encountered
in the off-
site area
(millirem)
Whole body,,
gonads, or
bone marrow
Thyroid or
bone
500
1500
170
500
14 (unpopu-
lated)
1. 2(Diablo)
22 (Blue Eagle
Ranch)
18 (Hiko)
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A comparison of Tables 3 and 4 indicates that the contribution to
the thyroid exposure from inhalation was negligible. Table 6
shows the potential exposure, due to milk ingestion, from
Schofield Dairy at Hiko and from the Blue Eagle Ranch. The
milk from Hiko, representing 150 cows, is potentially capable
of delivering a larger integrated dose to a population, although
the Blue Eagle Ranch milk, from one cows had the higher con=
. 4- r 131r
centration of I,
The results indicate that the power integral of future routine tests
can safely be increased, provided that other factors remain equal
and that recurrent exposures to a given, populated area are avoided,,
References
1. "Final Report of Off»Site Surveillance for the Kiwi TNT
Experiment", SWRHL-17r, August 1965.
2. "Final Report of Off-Site Surveillance for the NRX-A3
Experiment", SWRHL-18r0 October 1965.
3. "Final Report of Off-Site Surveillance for the Phoebus 1-A
Experiment",, SW
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LATHROP WELLS .
•*•
Figure 1. Sampling locations arid "hot lines" of 1965 NRDS experiments.
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