reentry from orbit and impact with the earth, so that
the source will be safely contained until it is
recovered. Although existing designs have proved
more than adequately safe, the Office of the Assis-
off the rainwater that percolates through thesoil.
The hottom of the tray tapers to a pipe that runs to
the outside of the chamber so this water can he
collected.
the ERDA Division of Space Nuclear Systems con-
B. Soils
tant Director, Safety and Reliability Programs, of
tinually seeks more information ahout the heat
sources to improve their safety. As part of this
program, LAS is studying the interaction of 7°8Pu
fuel material with seawater, fresh water, and marine
organisms, and withair, soil, and rain to supply data
for design of even safer heat sources.
Several chemical forms of 2°®Pu have been used as
heat. sources. The forms now in use or being studied
for future use are plutonia-molybdenum cermet
(PMC), and various pressed shapes of pure
plutonium dioxide (PPO). We have run several
aquatic experiments using PMC, but all our
terrestrial experiments have involved PPO.
Discussions of details of the experiments are intentionally brief and will be repeated in subsequent
progress reports. The main purpose of these reports
is to compile in one convenient reference all usable
About 1.4 Mg each of loam, clay. sand, and silt
loam were obtained for terrestrial experiments.
Compositional analyses of these soils were provided
by the U. S. Soil Conservation Service Laboratory at
Riverside, California (Table I). Pressure plate
moisture measurements are planned for these soils.
C. Test Conditions and Analyses Performed
The first three experiments were started with the
chambers programmed for humid summer conditions (20 to 40°C, 87 to 96° RH). Camsinstalled
later provided humid winter conditions (0 to 17°C.
71 to 100% RH). The alternate summer and winter
data venerated in the LASL experiments. The com-
TABLE I
pilation will be updated each quarter. When an experiment or set of experiments is completed or terminated, a final topical report will be issued and
that phase of the work will not be included in sub-
COMPOSITION OF SOILS USED
IN TERRESTRIAL EXPERIMENTS?
sequent quarterly reports.
Il. BEHAVIOR
OF
*8pu
TERRESTRIAL ENVIRONMENTS
FUEL
IN
(James H. Patterson, Nicholas Vanderborgh. and
George M. Matlack)
A. Environmental Test Chambers
Meaningful data on the environmental effects of
the radiation and heat from radivisotope heat
sources can best be obtained under simpler, less
varied conditions than exist normally in nature. Use
of environmental test chambers permits selection of
the parameters to he tested and ensures control over
them.
Determination of the effects of these
parameters on the fuel material and simulation of
different climates and soils are also possible.
Each environmental test chamber has aninterior
volume of 1.8m" and can be programmedfor diurnal
temperatures of ~20 to 95°C and relative humidities
of 25 to 100%. A manually operated spray system
simulates rainfall at rates as high as 10 em/h.
Each chamber contains a 0.9- by 0.9-m tray, filled
toa depth of 0.3 m with soil. The soil is supported by
a grill covered with a thin perforated plate (o drain
Loam
Clay
Silt
Loam
Sand
Sand (%)
49,5
1.5
25.3
88.6
Silt. (%)
37.6
31.4
60.1
4.6
Clay (3)
12.9
67.1
14.6
6.8
C, organic (%)
0.6
Carbonate as CaCO3(%) trace
H20 at 15 burs (%)
7.6
H20 at saturation(%) 40
0.12
0.03
8
10
23.8
7.5
0.01
4
2.6
91
45
22
pH
Ca(neq/100 g)
8.0
16.3
7.8
43.9
8.4
20.4
9.1
17.8
Mg (meq/100 g)}
1.9
10.2
3.7
1.7
Na(meq/100 g)
0.5
4.6
3.5
0.9
K(meq/190 g)
1.0
1.1
0.5
0.5
13.6
42.0
14.7
6.0
0.6
4.2
3.3
0.6
4
te
Cation exch cap
Elect. Conductivity
maho/cim
Clzy
—
mincral ratios:
Mica
---
---
Montmorillonite 3
S
5
5
Kaolinite
3
2
3
3
"Soil analyses provided by the U. S. Soil Conservation Service Laboratory, Riverside, CA.