The Atom at Work in the Sea
NUCLEAR REACTOR PROPULSION
The transformation in undersea warfare tactics and national defense strategy effected by the introduction of nuclear-powered submarines is now well known. Navy submarines employing the latest reactors and fuel elements can stay at sea for more than 3 years without refueling. Polaris submarines on patrol remain submerged for 60 to 70 days. The nuclear submarine Triton, tracing Magellan’s route of 400 years earlier, traveled 36,000 miles under water, moving around the world in 83 days and 10 hours. Under-ice transits of the Arctic Ocean by nuclear submarines are now commonplace. These feats all are possible because of the nuclear reactors and propulsion systems developed by the AEC Division of Naval Reactors, which also developed the propulsion plants for the Navy’s nuclear surface vessels.[14]
USS Seadragon and Skate sit nose to nose on top of the world after under-ice voyages from the Atlantic and Pacific Oceans to the North Pole.
A frogman from the Seadragon swims under the Arctic ice in one of the first photographs made beneath the North Pole.
DEEP SUBMERGENCE RESEARCH VEHICLE On April 18, 1965, President Johnson announced that the Atomic Energy Commission and Department of the Navy were undertaking development of a nuclear-powered deep submergence research and engineering vehicle. This manned vehicle, designated the NR-1, will have vastly greater endurance than any other yet developed or planned, because of its nuclear power. Its development will provide the basis for future nuclear-powered oceanographic research vehicles of even greater versatility and depth capability.
The NR-1 will be able to move at maximum speed for periods of time limited only by the amount of food and supplies it carries. With a crew of five and two scientists, the vehicle will be able to make detailed studies of the ocean bottom, temperature, currents, and other phenomena for military, commercial, and scientific uses. The nuclear propulsion plant will give it great independence from surface support ships and essentially unlimited endurance for exploration.
The submarine will have viewing ports for visual observation of its surroundings and of the ocean bottom. A remote grapple will permit collection of marine samples and other objects. The NR-1 is expected to be capable of exploring areas of the Continental Shelf, which appears to contain the most accessible wealth in mineral and food resources in the seas. Exploratory charting of this kind may help the United States in establishing sovereignty over parts of the Continental Shelf; a ship with its depth capability can explore an ocean-bottom area several times larger than the United States.
The reactor plant for the vehicle is being designed by the General Electric Company’s Knolls Atomic Power Laboratory, Schenectady, New York. The remainder of the propulsion plant is being designed by the Electric Boat Division, General Dynamics Corporation, Groton, Connecticut.
Scientists are already beginning to implant small sea floor laboratories. In the future, when large permanent undersea installations for scientific investigation, mining, or fish farming become a reality, nuclear reactors like the one designed for research submersibles or the one already in use in Antarctica and other remote locations[15] will serve as their power plants.
ISOTOPIC POWER SOURCES
The ocean is a logistically remote environment, in the sense that conventional combustible fuels can’t be used underwater unless supplied with their own sources of oxygen. It is usually extremely costly to take anything heavy or bulky into the deep ocean. Even if the two essential components of combustion—fuel and oxygen—could be delivered economically to an undersea base or craft, the extreme back pressure of the depths would present serious exhaust problems. Yet deep beneath the sea is just where we now propose to do large amounts of work requiring huge supplies of reliable energy. The lack of reliable and extended duration power sources is perhaps one of the most critical requirements for expansion of underwater and marine technology. For example, the pressing need for measurements of atmospheric and oceanic data to support scientific, commercial, and military operations will in the future require literally hundreds of oceanographic and meteorological buoys deployed throughout the world to take simultaneous measurements and time-series observations at specific sites.
Some of these buoys will support and monitor up to 100 sensors each. These devices record a variety of physical, chemical, and radiological phenomena above, at, or below the surface. Periodically the sensor data will be converted to digital form and stored on magnetic tape for later retrieval by distant shore-based or shipboard radio command, by satellite command (for retransmittal to ground stations), or by physical recovery of the tapes. Individually, each buoy will not require a great deal of energy to operate, but will have to operate reliably over long periods of time. Conventional power sources are being used for the prototype buoys now under development and testing, but these robot ocean platforms in the future will make excellent use of nuclear energy supplied by isotopic power sources.
The world’s first nuclear-powered weather buoy located in the center of the Gulf of Mexico. This weather station, part of the U. S. Navy’s NOMAD system, is on a barge 10 feet × 20 feet, and is anchored in 12,000 feet of water.
RADIO ANTENNA WEATHER SENSORS WARNING BEACON NUCLEAR GENERATOR
The SNAP-7D isotope power generator has been operating unattended since January 1964 on a deep-ocean moored buoy in the Gulf of Mexico. This U. S. Navy NOMAD (Navy Oceanographic and Meteorological Automatic Device) buoy is powered by a 60-watt, strontium-90 radioisotope source, which was developed by the AEC Division of Reactor Development and Technology. This weather station transmits data for 2 minutes and 20 seconds every 3 hours. This data includes air temperature, barometric pressure, and wind velocity and direction. Storm detectors trigger special hourly transmissions during severe weather conditions. The generator operates continuously and charges storage batteries between transmissions. Some power is used to light a navigation beacon to alert passing ships.
Energy from the heat of radioisotope decay has been used on a “proof-of-principle” basis in several other instances involving ocean or marine technology.
An experimental ⁹⁰Sr isotope-powered acoustic navigation beacon (SNAP-7E) now rests on the sea floor in 15,000 feet of water near Bermuda. Devices such as these not only will enable nearby surface research or salvage vessels to locate their positions precisely (something very difficult to do at sea) and to return to the same spot, but the beacons also will aid submarine navigation (see [page 48]).
A U. S. Coast Guard lighthouse located in Chesapeake Bay has been powered by a 60-watt, ⁹⁰Sr power source, SNAP-7B, for 2 years without maintenance or service. This unit was subsequently relocated for use in another application (described below).
Engineers prepare to install the SNAP-7D generator.
The first commercial use of one of these “atomic batteries” began in 1965 when the SNAP-7B 60-watt generator went into operation on an unmanned Phillips Petroleum Company offshore oil platform, 40 miles southeast of Cameron, Louisiana. The generator operates flashing navigational lights and, in bad weather, an electronic foghorn (see [page 49]). This unit will be tested for 2 years to determine the economic feasibility of routinely using isotopic power devices on a commercial basis.
Buoyancy tank Sound amplifier Nuclear-powered sound source Ocean bottom
The SNAP-7E isotopic generator powers an undersea acoustic beacon, which produces an acoustic pulse once every 60 seconds. In addition to being a navigation aid, the beacon is used to study the effects of a deep-ocean environment on the transmission of sound over long distances.
Total height: 10 ft 2 in Armored cable Pressure vessel Capacitor bank Fuel capsules Biological shield Equipment package Voltage converter Depleted uranium Thermoelectric generator System support structure
Details of the Phillips Petroleum platform, which uses the SNAP-7B nuclear generator.
The final electrical connection is made from the nuclear generator to the platform’s electronic foghorn and two flashing light beacons.
Fog Horn Beacon Beacon Snap-7B nuclear generator
The radioisotope-powered devices previously described were developed by the AEC under the SNAP-7 Program.[16] The testing of these units has demonstrated the advisability of developing reliable and unattended nuclear power sources for use in remote environments without compromise to nuclear safety standards. As a result of the success of these tests, a variety of potential oceanographic applications have been identified. A study, conducted by Aerojet-General Corporation in conjunction with Global Marine Exploration Company and Northwest Consultant Oceanographers, Inc., described ocean applications including underwater navigational aids, acoustic beacons, channel markers, cable boosters, weather buoys, offshore oil well controls along with innumerable oceanographic research applications. This study was sponsored by the AEC Division of Isotopes Development.
In order to satisfy the requirements for these and other applications, the AEC has begun developing a series of compact and highly reliable isotope power devices that are designed to be economically competitive with alternative power sources. Currently underway are two specific projects, SNAP-21 and SNAP-23.
SNAP-21 is a two-phase project to develop a series of compact strontium-90 power systems for deep-sea and ocean-bottom uses (20,000-foot depths). The first phase of design and component development on a basic 10-watt system already has been completed, and a second phase development and test effort now under way will extend through 1970. A series of power sources in the 10- and 20-watt range will be available for general purpose deep-ocean application.
The SNAP-23 project involves the development of a series of economically attractive strontium-90 power systems for remote terrestrial uses. This project will result in 25-watt, 60-watt, and 100-watt units capable of long-term operation in surface buoys, offshore oil platforms, weather stations, and microwave repeater stations.
In addition to the above, effort is underway by the AEC to develop an isotope-fueled heater that will be used by aquanauts in the Navy’s Sealab Program (see [page 12]). Future activities, now being planned, will involve the development of large isotope power sources (1-10 electric kilowatts) and small nuclear reactors (50-100 kilowatts) for use in manned and unmanned deep-ocean platforms.