Atomic Sub: How Focus and Drive Delivered a Radical New DesignBill Schweber | January 27, 2015
The traditional diesel-electric submarine was really not a "submarine" vessel: it was a watertight, submersible boat capable of staying underwater for a few hours at most until it needed to surface to recharge its batteries.
That situation changed completely in 1954 with the launch of the first nuclear submarine, the USS Nautilus (SSN-571), which could stay underwater without any need to surface for weeks and even months.
The successful development of this boat was largely the result of one man, Captain (later Rear Admiral) Hyman G. Rickover (1900-1986), who bucked the "system" and whose vision, technical expertise, personal drive, industry contacts, intense persistence, arrogance, audacity, bluntness and even outright abrasiveness made the boat a reality.
Rickover's far-fetched idea (albeit backed with a tangible plan) and an absolute intention to put a nuclear reactor into a sub was revolutionary and so far outside what was considered feasible that it was ridiculed and labeled impossible. Experts said that reliably generating electricity from atomic fission might just be possible in a land-based facility. But using a reactor to power a vessel on extended patrol cruising in the confined, isolated, hostile environment below the ocean's surface was thought to be impossible.
Despite intense opposition and misgivings (some technical and some political), the project to launch a nuclear submarine ultimately was successful. In many ways, the steps that Rickover took were precursors for the project management style of the Apollo moon mission (some adopted consciously, some not). (Read "Lunar Lander: How One Engineer's Persistence Led to Apollo Success.")
After all, vehicles for space and undersea environments share common attributes. They operate in an inherently hostile surrounding of near-total isolation and must operate despite circumstances which are highly confining and fully unforgiving. In both moon-mission and atomic-sub designs, many new technologies had to be investigated, developed, proven and deployed in circumstances where almost any failure would almost certainly be fatal, and where calling for outside help was not possible. Further, both Nautilus and Apollo were high-risk, tight-schedule, high-visibility programs
Rejecting Conventional Wisdom
The conventional wisdom of the late 1940s was that a nuclear-powered ship should be a surface vessel. Further, wisdom was that the possible reactor technologies (pressurized water or liquefied sodium metal) should be first be evaluated and fully tested. Once a technology was chosen, then a scaled-up prototype of the reactor should be built for detailed engineering and production experience and validation.
Rickover rejected these notions. To get the project done and not get bogged down in endless evaluation/review and "paralysis by analysis" cycles, he forced a radically different approach in the face of intense and well-intentioned opposition. His approach was to have engineers scope out the basic envelope that was allowable and requirements needed for a nuclear sub's propulsion and related subsystems (with respect to size, control, weight, power and thermal issues) regardless of reactor type.
More important, he insisted that the engineering-development prototype for the actual reactor be built to the same size and layout as the final unit for the sub, rather than build a large-scale model that would have been easier to access, instrument, modify and evaluate. His reasoning was that even if the prototype was a success, there would be so many new engineering and production problems related to performance, access and maintenance when modifying it to fit into the sub, that it would be almost an entirely new project.
To add to the validity of the land-based reactor prototype for the sub, the reactor was not only built as an exact precursor of the unit to be installed, but was built inside an actual submarine hull in a saltwater tank. By doing so, the critical interaction between the reactor and surrounding sea water (such as hull pressure and thermal effects) would be part of the prototype design and evaluation. The production unit was built in close parallel with the prototype, with a time lag of little more than a week. This meant that as changes were made in the prototype, the same changes were quickly duplicated at the submarine's reactor site.
This more realistic (but far more arduous development and evaluation) approach to a completely new technology essentially was repeated in the Apollo program. The original Apollo plan was to incrementally add elements to each stage of the design, then fully test each enhanced configuration. Apollo program head George Mueller realized that this was not only going to take too long, but was fundamentally misleading, because adding a small element represented only the first of multiple changes that might be required. (Read "The 'Right Stuff' for Innovative Engineering Teams.")
Indeed, the actual effect of a single design change on the overall system was far larger: operational procedures had to be re-done, ground support requirements changed, and test rigs re-configured. In fact, many of these elements became obsolete as soon as the next step was added. As a result, Mueller decided that the only path to mission success was to adopt a counter-intuitive strategy of "all up" testing. In this way, every major stage was tested only in full, complete configuration, flight ready and fully functional, rather than as a more modest next-step enhancement.
Leadership Across Disciplines
In driving the Nautilus nuclear submarine program, Admiral Rickover drove numerous program issues, all while working through, around, or behind the official shipbuilding establishment.
First, the basic atomic-reactor technology had to be decided on, then perfected and built even as key obstacles such as required materials were identified. Very little was known about sustainable, power-generating reactor design at the time, including what materials were suitable. For example, when cadmium-plated fuel rods proved to be inadequate, hafnium was the next choice, but there were no commercial sources of hafnium. There also was a need for 20,000 pounds of zirconium, for which there was only a small industrial source. Rickover's team had to develop entirely new processes to extract and refine these elements in large quantities.
Similar stories played out for the highly specialized piping and pumps, and the hundreds of tons of specialty steels the sub would need. Rickover's personal calls and outright haranguing of many CEOs business leaders to get the R&D (research & Development) effort or materials he needed are well documented.
Because this was not just going to be a free-standing, land-based reactor but the power plant for a seagoing vessel, Rickover organized the design team as a combination of generalists and specialists. He started with experienced submarine designers and added engineers who knew nothing about subs but did know about nuclear power and fission. He then enhanced the teams with materials scientists, industrial chemists, theoretical and applied physicists and other experts.
Second, new technologies and boat designs had to be developed while managing "mission creep." Nuclear power freed the sub from the need to surface, which in turn mandated advanced desalinization systems to provide fresh water, and electrolysis and scrubber systems to provide fresh air to the crew. Since the sub would be underwater for long periods and unable to take frequent navigation sightings to correct course, the existing standard compass and gyrocompass were inadequate. Accurate inertial navigation units were needed, along with more precise sonar to measure distance to the ocean floor and to the ice-sheet above (since nuclear subs would sail under the ice near the North Pole).
At the same time, the novelty which the nuclear sub program offered tempted some designers to add features that were never feasible in conventional subs. Since the nuclear-powered boat did not need to hold huge banks of batteries or diesel fuel tanks, the internal layout could be rethought entirely, and the hull design could be optimized for submerged operation rather than for the primarily surface-cruising design of diesel subs.
Even so, Rickover was adamant that the number of new, untested technologies be kept to a minimum, since each one added installation and maintenance are such a headache, which could prove deadly for a sub in the heat of battle. Among his memos, he noted "it has been the experience of industry that to compound one experiment on another precludes the ability to forecast results successfully, and renders meaningless any concrete schedule."
Crew Selection and Training
Third, the submarine’s crew had to be selected and trained for a program that had no precedent. After all, the traditional engine-room parameters and operating rules were irrelevant in a nuclear sub. The crew members had to be technically competent, of course, but also able to live and work in tight quarters, with no sight of daylight or land for weeks at a time.
Issues arose around how to train the crew, what contingencies and emergencies needed to be included in the training process and all at a time when no one had ever done anything like this before. In short, there were no experienced-hardened teachers or even a basic manual to guide the crew or the trainers. Rickover's solution involved multiple tactics: he brought together a few nuclear-power academics, scientists and engineers and worked with MIT to set up a master's program in nuclear science, which all officers and sub designers had to complete.
He also tapped experienced submariners to define and then vet any possible operational scenarios and responses. And the less-experienced submariners were used to participate in extensive simulation scenarios.
Fourth, issues arose around reliability and managing and risks. Despite all the unknowns, unproven technologies and inherent risks, the absolute rule was to anticipate everything and ignore nothing in an effort to ensure design and operational perfection. Rickover set up a flat organization with minimal bureaucracy and used personally trained staff committed to the project – easier said than done. He demanded that any potential or observed problem be reported, analyzed and resolved to the team's (and perhaps more important, to his) satisfaction, no matter how small or seemingly insignificant, with no exceptions.
Every design concept and implementation was subject to severe design reviews and every part was tested and re-tested to all imaginable circumstances. For example, tests were done with the reactor and its control rods at severe angles (a sub can roll up to 45⁰ and dive or surface at 30⁰ to 40⁰); all reactor-related components (pumps, fittings, and piping runs) also were tested for operation in a radioactive environment, as well as for performance under the shock impact of depth charges.
Schedule Met, Goals Exceeded
Given all the unknowns and uncertainties, this project could easily have taken a decade or more, yet its timeline was remarkably short. The nuclear submarine program was formally authorized in 1950, after just a few years of preliminary work. The Nautilus' keel was laid in 1952, and despite the technical challenges (plus complicated Navy, Defense Department and congressional politics), it launched on schedule two years later, becoming fully operational immediately with only minor issues.
A WWII-vintage diesel-electric sub was roughly 300 feet long and 22 feet wide, could make about 20 knots on the surface and perhaps up to half that for fairly short bursts when submerged, and stay submerged for a few hours at most. By contrast, the Nautilus was 317 feet long with a 27-foot beam, could do 22 knots on the surface and cruise at more than 20 knots for extended periods under water.
The success and demonstrated capability of this nuclear-power submarine led to a fleet of dozens of these vessels as well as ballistic-missile subs. These were followed by much-larger subs which today may remain on patrol for up to six months without surfacing. The nuclear Navy extends to surface ships such as aircraft carriers that are powered by up to eight independent reactors, which only need annual refueling (in contrast, a conventional carrier needed to be refueled approximately every week).
Rear Admiral Rickover received Presidential and Congressional awards acknowledging his role as "the father of the nuclear submarine." In this case, it is not just excessive hype and zeal, but the real thing. The Nautilus was retired in 1980, and this unique vessel is available for inspection at the Submarine Force Museum in Groton, Conn. There it offers a true sense of the unique design and production challenges that had to be addressed.
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