A warship or combatant ship is a naval ship, built and intended for naval warfare. They belong to the armed forces of a state; as well as being armed, warships are designed to withstand damage and are faster and more manoeuvrable than merchant ships. Unlike a merchant ship, which carries cargo, a warship carries only weapons and supplies for its crew. Warships belong to a navy, though they have been operated by individuals and corporations. In wartime, the distinction between warships and merchant ships is blurred. In war, merchant ships are armed and used as auxiliary warships, such as the Q-ships of the First World War and the armed merchant cruisers of the Second World War; until the 17th century it was common for merchant ships to be pressed into naval service and not unusual for more than half a fleet to be composed of merchant ships. Until the threat of piracy subsided in the 19th century, it was normal practice to arm larger merchant ships such as galleons. Warships have often been used as troop carriers or supply ships, such as by the French Navy in the 18th century or the Japanese Navy during the Second World War.
In the time of Mesopotamia, Ancient Persia, Ancient Greece and the Roman Empire, warships were always galleys: long, narrow vessels powered by banks of oarsmen and designed to ram and sink enemy vessels, or to engage them bow-first and follow up with boarding parties. The development of catapults in the 4th century BC and the subsequent refinement of this technology enabled the first fleets of artillery-equipped warships by the Hellenistic age. During late antiquity, ramming fell out of use and the galley tactics against other ships used during the Middle Ages until the late 16th century focused on boarding. Naval artillery was redeveloped in the 14th century, but cannon did not become common at sea until the guns were capable of being reloaded enough to be reused in the same battle; the size of a ship required to carry a large number of cannons made oar-based propulsion impossible, warships came to rely on sails. The sailing man-of-war emerged during the 16th century. By the middle of the 17th century, warships were carrying increasing numbers of cannon on their broadsides and tactics evolved to bring each ship's firepower to bear in a line of battle.
The man-of-war now evolved into the ship of the line. In the 18th century, the frigate and sloop-of-war – too small to stand in the line of battle – evolved to convoy trade, scout for enemy ships and blockade enemy coasts. During the 19th century a revolution took place in the means of marine propulsion, naval armament and construction of warships. Marine steam engines were introduced, at first as an auxiliary force, in the second quarter of the 19th century; the Crimean War gave a great stimulus to the development of guns. The introduction of explosive shells soon led to the introduction of iron, steel, armour for the sides and decks of larger warships; the first ironclad warships, the French Gloire and British Warrior, made wooden vessels obsolete. Metal soon replaced wood as the main material for warship construction. From the 1850s, the sailing ships of the line were replaced by steam-powered battleships, while the sailing frigates were replaced by steam-powered cruisers; the armament of warships changed with the invention of the rotating barbettes and turrets, which allowed the guns to be aimed independently of the direction of the ship and allowed a smaller number of larger guns to be carried.
The final innovation during the 19th century was the development of the torpedo and development of the torpedo boat. Small, fast torpedo boats seemed to offer an alternative to building expensive fleets of battleships. Another revolution in warship design began shortly after the start of the 20th century, when Britain launched the Royal Navy's all-big-gun battleship Dreadnought in 1906. Powered by steam turbines, it was bigger and more gunned than any existing battleships, which it rendered obsolete, it was followed by similar ships in other countries. The Royal Navy developed the first battlecruisers. Mounting the same heavy guns as the Dreadnoughts on an larger hull, battlecruisers sacrificed armour protection for speed. Battlecruisers were faster and more powerful than all existing cruisers, which they made obsolete, but battlecruisers proved to be much more vulnerable than contemporary battleships; the torpedo-boat destroyer was developed at the same time as the dreadnoughts. Bigger and more gunned than the torpedo boat, the destroyer evolved to protect the capital ships from the menace of the torpedo boat.
At this time, Britain developed the use of fuel oil to produce steam to power warships, instead of coal. While reliance on coal required navies to adopt a "coal strategy" to remain viable, fuel oil produced twice the power and was easier to handle. Tests were conducted by the Royal Navy in 1904 involving the torpedo-boat destroyer Spiteful, the first warship powered by fuel oil; these proved its superiority, all warships procured for the Royal Navy from 1912 were designed to burn fuel oil. During the lead-up to the Second World War and Great Britain once again emerged as the two dominant Atlantic sea powers. Germany, under the Treaty of Versailles, had its navy limited to only a few minor surface ships, but the clever use of deceptive terminology, such as "Panzerschiffe" deceived the British and French commands. They were surprised when ships such as Admiral Graf Spee and Gneisenau raided the Allied supply lines; the greatest threat though, was the introduction of the Kriegsmarine's largest vessels and Tirpitz
A prototype is an early sample, model, or release of a product built to test a concept or process or to act as a thing to be replicated or learned from. It is a term used in a variety of contexts, including semantics, design and software programming. A prototype is used to evaluate a new design to enhance precision by system analysts and users. Prototyping serves to provide specifications for a real, working system rather than a theoretical one. In some design workflow models, creating a prototype is the step between the formalization and the evaluation of an idea; the word prototype derives from the Greek πρωτότυπον prototypon, "primitive form", neutral of πρωτότυπος prototypos, "original, primitive", from πρῶτος protos, "first" and τύπος typos, "impression". Prototypes explore different aspects of an intended design: A Proof-of-Principle Prototype serves to verify some key functional aspects of the intended design, but does not have all the functionality of the final product. A Working Prototype represents all or nearly all of the functionality of the final product.
A Visual Prototype represents the size and appearance, but not the functionality, of the intended design. A Form Study Prototype is a preliminary type of visual prototype in which the geometric features of a design are emphasized, with less concern for color, texture, or other aspects of the final appearance. A User Experience Prototype represents enough of the appearance and function of the product that it can be used for user research. A Functional Prototype captures both function and appearance of the intended design, though it may be created with different techniques and different scale from final design. A Paper Prototype is a printed or hand-drawn representation of the user interface of a software product; such prototypes are used for early testing of a software design, can be part of a software walkthrough to confirm design decisions before more costly levels of design effort are expended. In general, the creation of prototypes will differ from creation of the final product in some fundamental ways: Material: The materials that will be used in a final product may be expensive or difficult to fabricate, so prototypes may be made from different materials than the final product.
In some cases, the final production materials may still be undergoing development themselves and not yet available for use in a prototype. Process: Mass-production processes are unsuitable for making a small number of parts, so prototypes may be made using different fabrication processes than the final product. For example, a final product that will be made by plastic injection molding will require expensive custom tooling, so a prototype for this product may be fabricated by machining or stereolithography instead. Differences in fabrication process may lead to differences in the appearance of the prototype as compared to the final product. Verification: The final product may be subject to a number of quality assurance tests to verify conformance with drawings or specifications; these tests may involve custom inspection fixtures, statistical sampling methods, other techniques appropriate for ongoing production of a large quantity of the final product. Prototypes are made with much closer individual inspection and the assumption that some adjustment or rework will be part of the fabrication process.
Prototypes may be exempted from some requirements that will apply to the final product. Engineers and prototype specialists attempt to minimize the impact of these differences on the intended role for the prototype. For example, if a visual prototype is not able to use the same materials as the final product, they will attempt to substitute materials with properties that simulate the intended final materials. Engineers and prototyping specialists seek to understand the limitations of prototypes to simulate the characteristics of their intended design, it is important to realize that by their definition, prototypes will represent some compromise from the final production design. Due to differences in materials and design fidelity, it is possible that a prototype may fail to perform acceptably whereas the production design may have been sound. A counter-intuitive idea is that prototypes may perform acceptably whereas the production design may be flawed since prototyping materials and processes may outperform their production counterparts.
In general, it can be expected that individual prototype costs will be greater than the final production costs due to inefficiencies in materials and processes. Prototypes are used to revise the design for the purposes of reducing costs through optimization and refinement, it is possible to use prototype testing to reduce the risk that a design may not perform as intended, however prototypes cannot eliminate all risk. There are pragmatic and practical limitations to the ability of a prototype to match the intended final performance of the product and some allowances and engineering judgement are required before moving forward with a production design. Building the full design is expensive and can be time-consuming when repeated several times—building the full design, figuring out what the problems are and how to solve them building another full design; as an alternative, rapid prototyping or rapid application development techniques are used for the initial prototypes, which implement part, but not all, of the complete design.
This allows designers and manufacturers to and inexpensively test the parts of the design that are most to have problems, solve those problems, build the full design. This counter-intuitive idea—that the quickest way to build something is, f
Control rods are used in nuclear reactors to control the fission rate of uranium and plutonium. They are composed of chemical elements such as boron, silver and cadmium that are capable of absorbing many neutrons without themselves fissioning; because these elements have different capture cross sections for neutrons of varying energies, the composition of the control rods must be designed for the reactor's neutron spectrum. Boiling water reactors, pressurized water reactors and heavy water reactors operate with thermal neutrons, while breeder reactors operate with fast neutrons. Control rods are used in control rod assemblies and inserted into guide tubes within a fuel element. A control rod is removed from or inserted into the central core of a nuclear reactor in order to increase or decrease the neutron flux, which describes the number of neutrons that split further uranium atoms; this in turn affects the thermal power, the amount of steam produced and hence the electricity generated. Control rods stand vertically within the core.
In PWRs they are inserted from above, with the control rod drive mechanisms mounted on the reactor pressure vessel head. In BWRs, due to the necessity of a steam dryer above the core, this design requires insertion of the control rods from beneath; the control rods are removed from the core to allow a chain reaction to occur. The number of control rods inserted and the distance to which they are inserted can be varied to control activity. Typical shutdown time for modern reactors such as the European Pressurized Reactor or Advanced CANDU reactor is 2 seconds for 90% reduction, limited by decay heat. Chemical elements with a sufficiently high neutron capture cross-section include silver and cadmium. Other candidate elements include boron, hafnium, europium, terbium, holmium, thulium and lutetium. Alloys or compounds may be used, such as high-boron steel, silver-indium-cadmium alloy, boron carbide, zirconium diboride, titanium diboride, hafnium diboride, gadolinium nitrate, gadolinium titanate, dysprosium titanate and boron carbide - europium hexaboride composite.
The material choice is influenced by the neutron energy in the reactor, their resistance to neutron-induced swelling and the required mechanical and lifespan properties. The rods may have the form of tubes filled with neutron-absorbing pellets or powder, they can be made out of stainless steel or other neutron window materials such as zirconium, silicon carbide or cubic 11B15N. The burn up of the absorbing isotopes is another limiting lifespan factor, they may be reduced by capturing long isotope rows of the same element or by not using neutron absorbers for trimming. For example, in pebble bed reactors or in possible new type 7lithium-moderated and -cooled reactors that use fuel and absorber pebbles; some rare earth elements are less rare than silver. For example and yttrium, 400 times more common, with middle capturing values, can be found and used together without separation inside minerals like xenotime PO4, or keiviite 2Si2O7, lowering the cost. Xenon is a strong neutron absorber as a gas and can be used for controlling and stopping of helium-cooled reactors, but does not function in cases of pressure loss, or as a burning protection gas together with argon around the vessel part in case of core catching reactors or if filled with sodium or lithium.
Fission-produced xenon can be used after waiting for caesium to precipitate, when no radioactivity is left. Cobalt 59 is used as an absorber for winning of cobalt 60 for x-ray production. Control rods can be constructed as thick turnable rods with a tungsten reflector and absorber side turned to stop by a spring in less than 1 second. Silver-indium-cadmium alloys 80% Ag, 15% In and 5% Cd, are a common control rod material for pressurized water reactors; the somewhat different energy absorption regions of the materials make the alloy an excellent neutron absorber. It has good mechanical strength and can be fabricated, it must be encased in stainless steel to prevent corrosion in hot water. Although indium is less rare than silver, it is more expensive. Boron is another common neutron absorber. Due to the different cross sections of 10B and 11B, materials containing boron enriched in 10B by isotopic separation are used; the wide absorption spectrum of boron makes it suitable as a neutron shield. The mechanical properties of boron in its elementary form are unsuitable, therefore alloys or compounds have to be used instead.
Common choices are boron carbide. The latter is used as a control rod material in both BWRs. 10B/11B separation is done commercially with gas centrifuges over BF3, but can be done over BH3 from borane production or directly with an energy optimized melting centrifuge, using the heat of freshly separated boron for preheating. Hafnium has excellent properties for reactors cooling, it has good mechanical strength, can be fabricated, is resistant to corrosion in hot water. Hafnium can be alloyed with other elements, e.g. with tin and oxygen to increase tensile and creep strength, with iron and niobium for corrosion resistance, with molybdenum for wear resistance and machineability. Such alloys are designated as Hafaloy, Hafaloy-M, Hafaloy-N, Hafaloy-NM; the high cost and low availability of hafnium limit its use in civilian reactors, although it
The A1B reactor plant is an aircraft carrier nuclear reactor developed by the United States Navy. It is used in Gerald R. Ford-class aircraft carriers to provide electrical and propulsion energy; the A1B is the first naval reactor produced by Bechtel Corporation, which has "performed engineering and/or construction services on more than 80 percent of nuclear plants in the United States". Aircraft carriers' nuclear reactors provide the electrical and motor energy of the ship by splitting enriched uranium to produce heat and convert water to steam to power steam turbines; this process is the same as land-based nuclear reactors, although smaller naval reactors have several design differences. As Navy planners developed requirements for the Ford class, they concluded that the A4W reactors that provide propulsion and electricity for the predecessor Nimitz-class aircraft carriers offer too little power for contemporary and anticipated future shipboard needs. So they commissioned a new reactor from Bechtel.
The new reactor was named A1B, following the Navy's reactor-designation scheme of type and manufacturer: A for aircraft carrier, 1 for the maker's first-generation reactor plant design, B for Bechtel. Two A1B reactor plants will power each Ford ship, it is estimated that the total thermal power output of the A1B will be around 700 MW, some 25% more than provided by the A4W. Improved efficiency in the total plant is expected to provide improved output to both propulsion and electrical systems. Using A4W data with a 25% increase in thermal power, the A1B reactors produce enough steam to generate 125 megawatts of electricity, plus 350,000 shaft horsepower to power the four propellor shafts.^ The increased electrical generation capacity will allow for elimination of service steam on the ship, reducing staffing requirements for maintenance. Electrical aircraft catapult power will free the ship's air wing from reactor plant constraints; as well, the A1B reactor, uses modernized technology, both more advanced and adaptable than previous reactor technology, is smaller and weighs less than the A4W, has operator interfaces that are expected to be improved as well.
USS Gerald R. Ford
Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all isotopes of uranium are unstable, with half-lives varying between 159,200 years and 4.5 billion years. The most common isotopes in natural uranium are uranium-238 and uranium-235. Uranium has the highest atomic weight of the primordially occurring elements, its density is about 70% higher than that of lead, lower than that of gold or tungsten. It occurs in low concentrations of a few parts per million in soil and water, is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238, uranium-235, a small amount of uranium-234. Uranium decays by emitting an alpha particle; the half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years, making them useful in dating the age of the Earth.
Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 is the only occurring fissile isotope, which makes it used in nuclear power plants and nuclear weapons. However, because of the tiny amounts found in nature, uranium needs to undergo enrichment so that enough uranium-235 is present. Uranium-238 is fissionable by fast neutrons, is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is important in nuclear technology. Uranium-238 has a small probability for spontaneous fission or induced fission with fast neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction; this generates the heat in nuclear power reactors, produces the fissile material for nuclear weapons. Depleted uranium is used in kinetic energy penetrators and armor plating. Uranium is used as a colorant in uranium glass. Uranium glass fluoresces green in ultraviolet light.
It was used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, who named the new element after the discovered planet Uranus. Eugène-Melchior Péligot was the first person to isolate the metal and its radioactive properties were discovered in 1896 by Henri Becquerel. Research by Otto Hahn, Lise Meitner, Enrico Fermi and others, such as J. Robert Oppenheimer starting in 1934 led to its use as a fuel in the nuclear power industry and in Little Boy, the first nuclear weapon used in war. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of nuclear weapons that used uranium metal and uranium-derived plutonium-239; the security of those weapons and their fissile material following the breakup of the Soviet Union in 1991 is an ongoing concern for public health and safety. See Nuclear proliferation; when refined, uranium is a weakly radioactive metal.
It has a Mohs hardness of 6, sufficient to scratch glass and equal to that of titanium, rhodium and niobium. It is malleable, ductile paramagnetic electropositive and a poor electrical conductor. Uranium metal has a high density of 19.1 g/cm3, denser than lead, but less dense than tungsten and gold. Uranium metal reacts with all non-metal elements and their compounds, with reactivity increasing with temperature. Hydrochloric and nitric acids dissolve uranium, but non-oxidizing acids other than hydrochloric acid attack the element slowly; when finely divided, it can react with cold water. Uranium in ores is extracted chemically and converted into uranium dioxide or other chemical forms usable in industry. Uranium-235 was the first isotope, found to be fissile. Other occurring isotopes are fissionable, but not fissile. On bombardment with slow neutrons, its uranium-235 isotope will most of the time divide into two smaller nuclei, releasing nuclear binding energy and more neutrons. If too many of these neutrons are absorbed by other uranium-235 nuclei, a nuclear chain reaction occurs that results in a burst of heat or an explosion.
In a nuclear reactor, such a chain reaction is slowed and controlled by a neutron poison, absorbing some of the free neutrons. Such neutron absorbent materials are part of reactor control rods; as little as 15 lb of uranium-235 can be used to make an atomic bomb. The first nuclear bomb used in war, Little Boy, relied on uranium fission, but the first nuclear explosive and the bomb that destroyed Nagasaki were both plutonium bombs. Uranium metal has three allotropic forms: α stable up to 668 °C. Orthorhombic, space group No. 63, lattice parameters a = 285.4 pm, b = 587 pm, c = 495.5 pm. Β stable from 668 °C to 775 °C. Tetragonal, space group P42/mnm, P42nm, or P4n2, lattice parameters a = 565.6 pm, b = c = 1075.9 pm. Γ from 775 °C to melting point—this is the most malleable and ductile state. Body-centered cubic, lattice parameter a = 352.4 pm. The major application of uranium in the military sector is
Negative feedback occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances. Whereas positive feedback tends to lead to instability via exponential growth, oscillation or chaotic behavior, negative feedback promotes stability. Negative feedback tends to promote a settling to equilibrium, reduces the effects of perturbations. Negative feedback loops in which just the right amount of correction is applied with optimum timing can be stable and responsive. Negative feedback is used in mechanical and electronic engineering, within living organisms, can be seen in many other fields from chemistry and economics to physical systems such as the climate. General negative feedback systems are studied in control systems engineering. Mercury thermostats using expansion and contraction of columns of mercury in response to temperature changes were used in negative feedback systems to control vents in furnaces, maintaining a steady internal temperature.
In the invisible hand of the market metaphor of economic theory, reactions to price movements provide a feedback mechanism to match supply and demand. In centrifugal governors, negative feedback is used to maintain a near-constant speed of an engine, irrespective of the load or fuel-supply conditions. In a steering engine, power assistance is applied to the rudder with a feedback loop, to maintain the direction set by the steersman. In servomechanisms, the speed or position of an output, as determined by a sensor, is compared to a set value, any error is reduced by negative feedback to the input. In audio amplifiers, negative feedback reduces distortion, minimises the effect of manufacturing variations in component parameters, compensates for changes in characteristics due to temperature change. In analog computing feedback around operational amplifiers is used to generate mathematical functions such as addition, integration, differentiation and antilog functions. In a phase locked loop feedback is used to maintain a generated alternating waveform in a constant phase to a reference signal.
In many implementations the generated waveform is the output, but when used as a demodulator in an FM radio receiver, the error feedback voltage serves as the demodulated output signal. If there is a frequency divider between the generated waveform and the phase comparator, the device acts as a frequency multiplier. In organisms, feedback enables various measures to be maintained within a desired range by homeostatic processes. Negative feedback as a control technique may be seen in the refinements of the water clock introduced by Ktesibios of Alexandria in the 3rd century BCE. Self-regulating mechanisms have existed since antiquity, were used to maintain a constant level in the reservoirs of water clocks as early as 200 BCE. Negative feedback was implemented in the 17th Century. Cornelius Drebbel had built thermostatically-controlled incubators and ovens in the early 1600s, centrifugal governors were used to regulate the distance and pressure between millstones in windmills. James Watt patented a form of governor in 1788 to control the speed of his steam engine, James Clerk Maxwell in 1868 described "component motions" associated with these governors that lead to a decrease in a disturbance or the amplitude of an oscillation.
The term "feedback" was well established by the 1920s, in reference to a means of boosting the gain of an electronic amplifier. Friis and Jensen described this action as "positive feedback" and made passing mention of a contrasting "negative feed-back action" in 1924. Harold Stephen Black came up with the idea of using negative feedback in electronic amplifiers in 1927, submitted a patent application in 1928, detailed its use in his paper of 1934, where he defined negative feedback as a type of coupling that reduced the gain of the amplifier, in the process increasing its stability and bandwidth. Karl Küpfmüller published papers on a negative-feedback-based automatic gain control system and a feedback system stability criterion in 1928. Nyquist and Bode built on Black’s work to develop a theory of amplifier stability. Early researchers in the area of cybernetics subsequently generalized the idea of negative feedback to cover any goal-seeking or purposeful behavior. All purposeful behavior may be considered to require negative feed-back.
If a goal is to be attained, some signals from the goal are necessary at some time to direct the behavior. Cybernetics pioneer Norbert Wiener helped to formalize the concepts of feedback control, defining feedback in general as "the chain of the transmission and return of information", negative feedback as the case when: The information fed back to the control center tends to oppose the departure of the controlled from the controlling quantity... While the view of feedback as any "circularity of action" helped to keep the theory simple and consistent, Ashby pointed out that, while it may clash with definitions that require a "materially evident" connection, "the exact definition of feedback is nowhere important". Ashby pointed out the limitations of the concept of "feedback": The concept of'feedback', so simple and natural in certain elementary cases, becomes artificial and of little use when the interconnections between the parts become more complex... Such complex systems cannot be treated as an interlaced set of more or less independent feedback circuits, but only as a whole.
For understanding the general principles of dynamic systems, the concept of feedback is inadequate in itself. What is important is that complex systems, richly
The S5G reactor was a prototype naval reactor designed for the United States Navy to provide electricity generation and propulsion on submarines. The S5G designation stands for: S = Submarine platform 5 = Fifth generation core designed by the contractor G = General Electric was the contracted designer The S5G was a pressurized water reactor plant with two coolant loops and two steam generators, it had to be designed with the reactor vessel situated low in the boat and the steam generators high in order for natural circulation of the primary coolant to be developed and maintained. Reactor primary coolant pumps are one of the primary sources of noise from submarines, the elimination of coolant pumps and associated equipment would reduce mechanical complexity and the space required by propulsion equipment; the S5G had primary coolant pumps, but they were only needed for high speeds. And since the reactor core was designed with smooth paths for the coolant, the coolant pumps were smaller and quieter than the ones used by the competing S5W core.
They were fewer in number. In most cases the submarine could be operated without using coolant pumps at all; the quiet design resulted in a larger hull diameter but required larger primary coolant piping than the competing S5W reactor. Due to the larger size, the S5G was not used in subsequent attack submarines, but was a precursor to the S8G reactor design used in the larger Ohio-class submarines. To further reduce engine plant noise, the normal propulsion setup of two steam turbines driving the screw through a reduction gear unit was changed instead to one large propulsion turbine with no reduction gears; this eliminated the noise from the main reduction gears, but the cost was to have a huge main propulsion turbine. The turbine was cylindrical, about 12 feet in diameter, about 30 feet long; this massive size was necessary to allow it to turn enough to directly drive the screw and be efficient in doing so. The same propulsion setup was used on both the land-based prototype; the concept of a natural circulation plant was new when the Navy requested this design.
The prototype plant in Idaho was therefore given quite a rigorous performance shakedown to determine if such a design would work for the US Navy. It was a success, although the design never became the basis for any more fast-attack submarines besides the Narwhal; the prototype testing included the simulation of the entire engine room of an attack submarine. Floating the plant in a large pool of water allowed the prototype to be rotated along its long axis to simulate a hard turn, accomplished by torquing large gyroscopes mounted forward of the reactor compartment; this was necessary to determine whether natural circulation would continue during hard turns, since natural circulation is dependent on gravity whereas submarines are known to maneuver at various angles. This nuclear reactor was installed both as a land-based prototype at the Nuclear Power Training Unit, Idaho National Laboratory near Arco, on board the USS Narwhal, it was intended to test the potential contribution of natural circulation technology to submarine quieting.
The S5G prototype was permanently shut down in May 1995. Stacy, Susan M. "Proving the Principle, A History of The Idaho National Engineering and Environmental Laboratory, 1949-1999"