This radioisotope powered swimsuit heater uses plutonium-238 to produce 420 watts of heat. Water, heated by the decay of ²³⁸Pu, is pumped through plastic veins partially visible in the undergarment. The cylinder under the diver’s arm contains 4 capsules of ²³⁸Pu, and a battery-pump assembly is contained in the box at his feet. After preliminary tests at the Naval Medical Research Institute in Bethesda, Maryland, the unit will be used in Sealab III, the Navy’s underwater research laboratory. The heater was developed by the AEC Division of Isotopes Development.
The ocean is both a complex and a harsh environment and its study has always demanded that designers of seaworthy instruments and sampling devices be both ingenious and experienced in shipboard requirements. Until recently, these devices tended to be rugged and simple, if not indeed crude. More refined, electronic instrumentation has begun to appear in recent years, but most designs still fail to pass the test of use at sea. Even among those that do pass, there is persistent difficulty in separating desired information-carrying signals from background and system-induced “noise”. This has been a specific problem with current meters designed to be moored in the open ocean and also with one quite sophisticated gamma-ray detector.
To meet the clear need for improved devices, as well as to support its own research and increase utilization of nuclear materials and techniques, the AEC Division of Isotopes Development encourages the development of oceanographic instrumentation. This comparatively young technology already has produced exciting results. The future may be even more revealing as nuclear energy is applied more and more to the study, exploration, and exploitation of the ocean.
Instruments that have been developed under the AEC program include a current meter, a dissolved-oxygen-content analyzer, and a sediment-density meter. A new, fast method for determining the mineral content of geological samples also has been perfected.
The DEEP WATER ISOTOPIC CURRENT ANALYZER (DWICA) was developed under a contract with William H. Johnson Laboratories, Inc. It relies on radioisotope drift time over a fixed course to measure seawater flow rates ranging from 0.002 to 10.0 knots. The device embodies 12 radiation sensors spaced equally in a circle around a radioisotope-injection nozzle. Current direction can be determined to within 15 degrees. The mass of tracer isotope injected is very small—less than 10 picograms[12] per injection—and the instrument can store enough tracer material to operate for a year. The tracer can be injected automatically at intervals from 2 to 20 minutes, depending on the current. The device sits on the sea floor, where its orientation to magnetic north can be determined within 2.5 degrees.
The Deep Water Isotopic Current Analyzer.
Isotope Reservoir and equipressure system Electric logic circuitry Pressure protective case Compass Sensor ring Flow baffle plate Isotope injection point
