An Annapolis graduate, Commander E. E. Kintner was project officer for the STR Project, responsible directly to Admiral Rickover for the two crucial years which he has described in his article. Since 1955 Commander Kintner has been nuclear power superintendent at Mare Island Naval Shipyard in California, which recently delivered the first nuclear submarine to be built on the West Coast.
The highly dramatic and historic news that the submarine Nautilus had completed a passage under the roof of the world from the Pacific to the Atlantic excited the imagination of men everywhere. An equally dramatic and historic event, which proved that the Nautilus voyage could eventually be made, occurred five years earlier.
The Submarine Thermal Reactor plant (STR Mark I), the test version of the Nautilus machinery, commenced operating on May 31, 1953, in the desert of the Snake River plain, fifty-five miles west of Idaho Falls, Idaho. Its successful operation on that date, the first generation of any significant quantity of controlled atomic power, was the culmination of one of the largest, most daring, and most aggressive scientific ventures in history. No less than the polar voyage of the Nautilus, the design and operation of its prototype machinery required facing the hitherto unknown with physical courage, technical skill, and forceful and energetic leadership.
In 1946, one year after the unleashing of nuclear forces for destruction at Hiroshima, a Navy group, headed by then Captain, now Vice Admiral H.G. Rickover, was sent to Oak Ridge for a year’s study of all available information concerning production of useful power from the atom. The Navy students decided that the first practical application of nuclear power should be made in a United States submarine. They realized that the installation of an atomic power plant would be much more difficult in a submarine than in a surface ship, but they made the decision—the first example of the daring aggressiveness of Rickover’s methods—because the rewards of success would be greater in a submarine than in a surface ship. A nuclear submarine, not requiring air for combustion of fuel in its engines, would be able to divorce itself from the earth’s atmosphere and thus would be a true submarine rather than a surface ship which could submerge only for short periods. It would be an “underwater satellite.” To many in high places, however, the proposal sounded like a trip to the moon.
Upon his return to Washington in 1947, Rickover organized a unique joint agency with authority in both the Atomic Energy Commission and the Navy. Drawing on both AEC and Navy engineering experience and funds, this Naval Reactors Branch during the next three years organized and directed a huge research and development effort. Westinghouse Electric Corporation was given a contract to design and build the nuclear reactor and power plant. The Electric Boat Company of Groton, Connecticut, which had long experience in the design and construction of submarines, was chosen as a subcontractor to Westinghouse, responsible for ensuring that the reactor plant was adapted to the rigid requirements of service in a submarine.
Because so many unknowns could be solved only in theory prior to the operation of a complete atomic power system, it was decided early that a full-scale land-based model should be built at the National Reactor Testing station in Idaho. This prototype was named STR Mark I. The propulsion plant which followed in the Nautilus would be STR Mark II.
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In the early stages of design, the problems of obtaining some small amount of power from uranium fission seemed so overwhelming that it was planned to build Mark I as a “breadboard” arrangement, with machinery and piping systems spread out over a large floor area to allow easy access for installation, test, modification, or replacement. Rickover opposed this plan. He felt that years would be lost by breadboarding, since it required an additional stage in the development—the redesign of an operating breadboard model into a submarine hull. After several bitterly argued discussions within the project, Rickover made the decision to build Mark I as a land-based submarine to all the Naval specifications later to be required of Mark II. Here was the second example of courageous leadership, which contributed directly to the Nautilus success.
And so Mark I, although located almost as far from sea water as possible in the North American continent, was a true seagoing power plant—no shore-based engineering short cuts were allowed in its construction. As the Naval Reactors Branch engineers put it, “Mark I equals Mark II.” This meant that while they were designing the world’s first nuclear power plant, they also would have to meet the special problems of seagoing submarines. Some of these were:
1. At operating depths, a submarine experiences hundreds of pounds of sea pressure on each square inch of its surface—hundreds of thousands of tons on the entire vessel. This pressure must be resisted by the hull which is in contact with sea water. Mark I and all its components could withstand very high sea pressures.
2. A submarine and its machinery must be able to continue operation after enemy depth charges have exploded just outside the hull. Mark I was built to the high mechanical shock standards which resulted from the Navy’s World War II experiences. Some of its important units were shock tested to destruction in an actual submarine submerged in Chesapeake Bay, and then redesigned to strengthen the failures.
3. The Nautilus would need to take air into hr hull while submerged to refresh the atmosphere after long cruises under water and to provide oxygen to her stand-by diesel engines if her reactor failed in enemy waters. Pressure variations due to this “snorkeling” might disturb sensitive instrumentation systems. Mark I could snorkel.
4. When a submarine is submerged, the sea surrounding it tends to reflect dangerous atomic radiation back into spaces occupied by the crew. Mark I was placed in a large tank of water to test the atomic radiation problems of a submerged sub.
In short, Mark I was built to reproduce the conditions of an actual submarine power plant in every respect save one: it could not be tested in the motion of the open sea. The ability to withstand such motion was designed into the Mark I systems and components, however, and these items were individually tested for thousands of hours ashore under the conditions of ship motion experienced at sea.
As time went on and as the problems of reactor plant design became more forbidding, it became increasingly difficult for Rickover to hold the designers rigidly to the concept that the submarine problems must be faced simultaneously with the reactor problems. There were bitter technical debates between Rickover and his engineers, already hard-pressed by a tight schedule and almost insurmountable difficulties of simply obtaining atomic power for the first time and hoping to postpone the submarine problems until the Mark II design stage. An example was the discussion as to whether air conditioning should be provided in Mark I.
Surface ships ventilate heat out of boiler and engine rooms by blowing large quantities of air through them. The Nautilus, as the first vessel to be driven submerged by steam propulsion, could not be ventilated—at least not while she was submerged. All the heat escaping from her machinery would have to be pumped overboard by large air conditioning sets. This problem did not have to be settled for Mark I, which could have been adequately ventilated with cool Idaho air. But the Captain insisted that Mark I be air conditioned, and in a typical example of his uncanny engineering insight, he ordered three times as much air conditioning capacity as was required. “In 1917 the British built two submarines which used steam for surface operations,” he said, “and they were failures because they became too hot when they submerged. The Nautilus will not be a failure for such a reason.” Operating experience has proved that the Nautilus would have been unsuccessful without the extra air conditioning.