In March of 1946, the country was still struggling to come to terms with the realization that the atom had been partially mastered. When the atomic bombs of Hiroshima and Nagasaki were used to help end the war in the Pacific, the eyes of the world suddenly were opened to the fact that nothing was ever going to be the same again. But atomic energy development was being considered as an alternative to the way we made large amounts of energy. Who would control this new energy source development was very much on many people’s minds.

At the same time, the dream of using a nuclear energy source as a primary method for submarine propulsion was on a lot of expert’s minds. What if the power could be contained and made small enough to fit into a submarine?

The greatest limitation of WW2 submarines was their ability to stay under the water for great lengths of time. Even with the German snorkel system, the boats were tethered to the surface or near the surface where modern detection devices rendered them the most vulnerable. But an unlimited source of power that might be provided by a controlled reactor was the obvious way to overcome that deficiency.

The path that was developed started in March of 1946. The following excerpt from “Nuclear Navy 1946-1962” by Richard G. Hewlett and Francis Duncan details the very early beginnings of the course that would eventually lead to the development of the Navy’s nuclear submarine program.

“Among the many unsettled policy issues in early 1946, the role of the federal government in atomic energy development was probably foremost in Solberg’s thinking. The extraordinary impact of this new force, particularly as it was demonstrated at Hiroshima and Nagasaki, made complete monopoly by the government a certainty, at least until some form of international control could be devised. But three months of public debate over atomic energy legislation had confused rather than clarified the question of how the government monopoly would be managed. Atomic scientists who had manned the Manhattan project during the war had launched the first attack on the legislation drafted by the Army.

By the time Senator Brien McMahon had introduced a new bill in late December 1945, the issue had become one of “civilian” versus “military” control of atomic energy. As hearings before McMahon’s special Senate committee dragged on into 1946, the chances of establishing a new atomic energy commission during that session of Congress diminished steadily. In the meantime, Groves was trying to hold the nation’s atomic energy program together on the slender basis of his wartime authority.

Bowen had reason to complain that in the six months since the end of the war the Navy had accomplished almost nothing to advance the use of nuclear power, but his frontal assault on the Manhattan District in December and on the McMahon bill in January seemed quixotic. As Parsons had predicted, Groves felt no compunction about refusing the clearance request, and Bowen’s eagerness to attack the McMahon bill as a threat to a nuclear Navy seemed to play into the hands of the McMahon forces.

After the Senate special committee adopted the Vandenberg amendment, which assured the armed forces a voice in the new Commission through a military liaison committee, Secretary of War Robert P. Patterson and Groves decided to accept the McMahon bill as the best the Army could hope for under the circumstances. Parsons, Mills, and Solberg agreed, and they were not pleased when Bowen persuaded Forrestal to adopt his statement attacking the bill as the official Navy position. Mills and Solberg were no less interested in nuclear power than was Bowen, but they saw the realities of the situation. Groves and the Manhattan District still held tight control of all technical data on atomic energy. Alienating Groves and his staff would not help, whether the McMahon bill passed or not. It would have been prudent to wait a few months until Congress had decided the fate of the bill, but Bowen and the Naval Research Laboratory were pushing ahead under full steam.

In March 1946, the laboratory distributed a report by Abelson and two assistants proposing construction of a nuclear-powered submarine to be in operation within two years.

Because such a ship would operate underwater at high speed, Abelson suggested that the Navy use the most advanced hull which the Germans had developed for a closed-cycle system. In May 1944 the Germans had awarded a contract for construction of one hundred of these submarines, designated as Type XXVI, but none was ever built. Like other German submarines, the Type XXVI design used two concentric hulls, an inner pressure hull and an outer hull containing fuel and ballast tanks. In the Type XXVI the hydrogen peroxide for the closed-cycle system would be placed in large plastic bags which would collapse under seawater pressure as the fuel was consumed.

Abelson claimed that a nuclear-powered ship built on this design would require only minor hull changes and could retain intact most of the machinery. The reactor and the primary heat-transfer system would be mounted in the space previously occupied by fuel tanks under the main pressure hull. Many features of the proposal were questionable or vague. It was doubtful whether the reactor could be located under the main pressure hull, where it would be completely inaccessible while the ship was at sea. Furthermore, the plan contained essentially nothing about the reactor. The only feature Abelson mentioned was that the reactor would use a sodium-potassium alloy as the heat-transfer material between the reactor and the propulsion turbine, and Abelson himself admitted that this alloy had never been used in such an application. Rather than describe the reactor, Abelson and his associates concentrated on approximating the specifications for conventional submarine equipment.

The proposal was admittedly nothing more than an effort to operate a reactor in a submarine hull. The report also suggested that the use of nuclear power constituted only a modification of existing submarine propulsion equipment and did not require a completely new technology.

The proposal, in short, did not advance the cause of the independent Navy project. Over the years since 1939, Admiral Bowen had waged a hard-fought and courageous battle for a nuclear Navy. As an engineer he had the kind of practical approach necessary to produce results, but his strong convictions and tenacity bred an inflexibility that misled him.

The idea of an independent Navy project was a chimera. The Naval Research Laboratory possessed neither the personnel nor the facilities for such an effort. Abelson was already making plans to return to his prewar post at the Carnegie Institution of Washington, and the Bureau of Ships had taken the first steps toward a cooperative effort with the Manhattan District. Bowen had the drive and the intelligence needed to establish a nuclear project, but without a solid base in nuclear technology all his energy and enthusiasm were in vain.

The Bureau Takes Command

By the end of March 1946 it was clear that any action the Navy might take on nuclear power would have to come from the Bureau of Ships. Through Mills and Solberg the bureau had good liaison with the Manhattan District and, through Parsons, with the Chief of Naval Operations. What the bureau lacked, however, was a strong advocate of nuclear power, such as Admiral Bowen. Mills, Solberg, and Parsons were convinced that, for better or worse, the Navy would have to rely on the Manhattan District. They were prepared to adopt Groves’ suggestion that the Navy assign a small number of engineering officers full-time at Oak Ridge to learn the fundamentals of nuclear technology.

The idea really came into focus on March 26, when Charles A. Thomas of the Monsanto Chemical Company proposed to the Bureau of Ships that the Navy participate in a joint government-industry project to build an experimental power reactor at the Clinton Laboratories, which the company operated for the Army at Oak Ridge. The plan was to build a small power reactor proposed by Farrington Daniels, a chemist who had been director of the Chicago Metallurgical Laboratory during the final months of World War II. Daniels’ idea was not necessarily to achieve a practical or economic power reactor, but rather to build an experimental unit quickly by selecting a design which would require the smallest possible extrapolation from existing technology.

Daniels contended that by making this a cooperative effort involving the Manhattan project laboratories, American industry, and the armed forces, each group would soon have the basic technology needed for specific applications. Solberg, who represented the Navy at a meeting with Daniels in New York City on April 11, 1946, noted that the reactor would not apply directly to the Navy’s needs, but he told Daniels and the industrial representatives that the Navy would be glad to cooperate.

For Cochrane and Mills the Daniels proposal could not have come at a better time. During the spring of 1946, perhaps stimulated by some of Bowen’s actions, the higher echelons in the Navy had begun to think more seriously about nuclear power. In response to a request from Forrestal, the General Board had undertaken an investigation of various possibilities for advanced propulsion systems in the Navy.

In March Cochrane had received a request from the board for a study on the subject, but before the bureau could complete its reply, the board had recommended to Forrestal on April 4 that “active comprehensive study and development of atomic power for utilization in propulsion of naval units be initiated without delay. In drafting his reply to the General Board, Cochrane could now refer to the bureau’s decision to assign a group of officers to Oak Ridge to work on the Daniels project. “It is the Bureau’s opinion,” Cochrane wrote, “that the action being taken by the Manhattan District to develop an experimental power pile is the soundest possible approach to this problem and will produce the fastest results.”

Contrary to public opinion that nuclear power was just around the corner, Cochrane and his staff believed that “at least 4-5 years will elapse before it will be possible to install atomic energy in a naval ship for propulsion purposes.”

Within the bureau, one of the officers interested in nuclear propulsion was Captain Albert G. Mumma, chief of the machinery design division. A graduate of Annapolis in 1926, Mumma had early distinguished himself in engineering and had been the first Navy officer in several decades to be sent to Europe for postgraduate studies.

After two years at L’Ecole D’Application du Genie Maritime in Paris, Mumma had returned to the United States in 1936 with a new respect for French naval engineering and a strong conviction that sound technical training would be a key to American naval strength in any future war.° During World War II Mumma had specialized in machinery design and had been a member of the Alsos mission which had moved into Germany with the forward units of the allied invasion armies in 1945 to intercept any German atomic energy activities.

Poised and intelligent, with a breadth of intellectual interests unusual in engineering officers in the Navy, Mumma had become by 1946 one of the most promising officers in the Bureau of Ships and a close advisor to Admiral Mills. Mumma’s experience on the Alsos mission had given him an opportunity to obtain some information on nuclear technology, and he was convinced that nuclear power would provide an incomparably superior energy source for ship propulsion, especially in submarines. He agreed that the Navy should begin to develop some competence in nuclear technology, and he supported the proposal to send some bureau personnel to Oak Ridge for training.

Although Mumma believed it would be several years before the Navy could begin to build a nuclear propulsion system, he wanted to launch on a broad scale the kind of technical development which might eventually help that effort. One promising idea was to use liquid metals as the heat transfer medium in steam generating systems. The high thermal conductivity of these materials suggested certain theoretical advantages in steam plants. Mumma probably had seen Abelson’s study proposing the use of a liquid sodium-potassium alloy in a nuclear propulsion plant. Whatever the prospects for nuclear propulsion might turn out to be, liquid metals seemed worthy of investigation.”

Mumma originally asked to have Captain Harry Burris named as the head of the project. But Admiral Mills favored another Engineering Officer named Captain Hyman G. Rickover. In the summer of 1946, Rickover assumed his new role. He would lead the Navy’s nuclear submarine program for the next four decades.