Encapsulation quickly raises the specific weight 
of chemical dynamic systems for operations below 
2,000 feet. Important weight reduction for mobile 
systems could be achieved by employing systems 
in which the fuel and effluent were maintained at 
ambient pressure with only the engine and genera- 
tor enclosed in hard tanks. Ultimate development 
of a system with conversion equipment and fuel 
maintained at ambient operating pressures might 
achieve power sources weighing around 25 pounds 
per kilowatt hour. 
4. Nuclear Reactors 
a. Current Situation The nuclear reactor proved 
to be a dramatic success on Navy fleet submarines. 
Units delivering tens of thousands of kilowatts are 
in reliable service for main propulsion and auxil- 
iary loads of submarines and surface ships. The 
recent launching of NR-1 is a major milestone in 
adapting nuclear power to much smaller vehicles. 
A concept developed for the Naval Civil Engi- 
neering Laboratory of a five man, 6,000 foot 
undersea station includes a nuclear reactor for 
main power. A unit recommended for a power 
demand of 38 kilowatts was the TRIGA Oceano- 
graphic Power Supply with a steam turbine genera- 
tor power conversion system. Total weight of this 
plant (maximum capacity 100 kilowatts) was 
estimated at 145,000 pounds, more than half 
shielding. The Navy and the Atomic Energy 
Commission are working to develop yet more 
suitable nuclear reactors for other future deep 
ocean applications. 
b. Future Needs There are attractions to placing 
a nuclear power plant on the ocean floor where it 
would be away from population centers. If the 
plant were operated unmanned with most systems 
at ambient pressures, external pressure might be 
used to reduce some wall thicknesses. Waste heat 
removal problems would be reduced in the limit- 
less heat sink of the ocean. If the power plant were 
remote from manned habitats, shielding might be 
reduced by relying upon seawater, an excellent 
shielding material itself. Except for power plant 
maintenance problems and some materials devel- 
opment, current technology is adequate to provide 
submerged nuclear power plants. 
Three factors will influence decisions to build a 
nuclear power plant at an undersea site:? (1) cost 
of electricity supplied by a nuclear plant at the site 
compared with cost of long cable transmission 
from land or from surface floating plants, (2) the 
character and priority of the undersea operation, 
and (3) the leadtime for nuclear power plant 
construction and operation. 
Reactor technology considerations will not 
greatly influence the decision at shallower depths. 
For missions at 20,000 feet, there are severe design 
and engineering problems, particularly in the 
structural design of the condenser. 
Remaining problems may include a variety of 
materials and operating difficulties. Maintenance, 
for example, would be virtually impossible at 
depth. It would be difficult and expensive to raise 
a plant for repair and maintenance. Maintenance 
requirements might be minimized if static energy 
conversion systems such as thermo-electric conver- 
sion were incorporated in place of dynamic 
turbine-generator systems. Several conceptual de- 
signs for such power plants have been developed. 
Unfortunately, the much smaller power require- 
ments of current saturation diving habitats are not 
compatible with the characteristics of existing 
nuclear reactors. Technology derived from devel- 
opment programs to supply small nuclear reactors 
for space applications may be adapted to the 
undersea power problem, particularly for manned 
underwater stations at limited ocean depths. 
5. Isotope Power 
Power up to 10 kilowatts is considered achiev- 
able via radioisotope-dynamic conversion power 
systems, in which the heat of radioactive decay 
produces steam to drive a conventional turbine- 
generator or power a thermoelectric converter. 
Isotope materials with halflives ranging from 
four months to 458 years exist in varying quanti- 
ties and costs. One most promising for long 
missions, cobalt-60, has a halflife of over five years 
and an energy density of 1.7 watts per gram in 
compound form. For shorter missions, 
polonium-210 with a halflife of 138 days might be 
selected. 
3There are also reasons to locate power generating 
stations offshore to serve land needs. See Chapter 6, 
Section VII, Power Generation. 
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