Cook Plant preoperational studies 1970 / John C. Ayers ... [et al.].

-4 -

system. Figure 2 shows the detector circuit (3) which allows
a minimal number of electrical components to be located underwater. An aluminum pressure vessel is used to protect the
crystal, phototube, and voltage divider against water, pressure
and thermal and physical shock. The vessel is designed to
withstand pressures encountered in water depths up to 350 meters.
The large rubber tire, used to support and transport the
detector above the sediment, is towed by a boat. Figure 3
demonstrates the method used to position the aluminum pressure
vessel inside the tire. The vessel is mounted pendulously to
the axle which connects the tire's two steel side rims. As the
tire rotates about the stationary axle, the detector located
inside remains in a vertical attitude. The co-axial cable which
transmits signals from the submerged detector to the analyzing
equipment enters the tire through a hollow axle and connects to
the detector. The semicircular tow bar defects the tire around
obstacles protruding upward from the bottom. Drain plugs
located in each of the tire's rims are removed allowing water
to fill the tire and are replaced before the tire is lowered to
the sediment.
The signal pulse, transmitted on the same cable which
supplies the high voltage to the detector, is stripped from the
high voltage by a decoupler (Figure 1) located on the boat.
Gamma ray produced pulses from the detector are recorded in two
ways: a 256-channel pulse height analyzer sorts the pulses into
a gamma ray spectrum; and a count rate meter coupled to a strip