Submarine: A Guided Tour Inside a Nuclear Warship

turbines in the machinery spaces, where the steam is condensed back into water and fed back into the steam generator. The turbines feed into a massive set of gears known as reduction gears, which turn the main propeller shaft. In addition, some of the steam is used to turn several smaller turbines that provide electrical power to the boat and its various pieces of machinery.

It may come as a surprise that other than the transit tunnel aft to the main machinery space, the reactor is not manned. The DNR limits the time a man can stay in proximity to the reactor, even how long he might stay in the transit tunnel. The actual control area for the reactor plant and the turbines, called Maneuvering, is located aft in the engine room. While it has never been shown to the press, it probably follows the convention of commercial power plants, with the controls laid out over a block diagram of the reactor/turbine system. This panel is manned at all times, even when the boat is in port and the reactor is shut down (noncritical).

The dominating feature of the machinery space is the deck, or more correctly, the mounting for all of the machinery. While it may seem solid enough, it is in fact a large platform or 'raft,' which is suspended on mounts on the inside of the hull. The mounts use at least one, probably two, sets of noise isolation mounts. These are like oversized shock absorbers designed to reduce the vibrations of the larger pieces of engine room machinery. The purpose of a raft is to take the noisiest things on the boat and isolate them from the hull, which radiates noise like a speaker into the water.

Mounted on the raft are the two main engines, the boat's electrical turbine generators, and the supporting pumps and equipment associated with moving the boat. Proceeding aft, you see the main propeller shaft leading back to the main packing seals in the stern. In addition there are a number of workbenches, as well as a limited machine shop capable of supporting many small-scale repairs. The size of the main gear, called a bull gear, would preclude repair, but virtually every other contingency in the space could be handled by the engineering team. These crew members, by the way, are recognizable by the different types of radiation monitoring devices they wear. Unlike the film badges worn by those who live and work forward of the reactor, these personnel wear a small dosimeter (which looks like a tiny flashlight), so that any dosage of radiation they receive can be assessed immediately.

To get the power plant started, the engineering officer of the watch orders the personnel at the reactor control panel to retract the control rods to a known position. This allows the core to heat up, causing the coolant to generate steam in the steam generator. From here the turbines are set turning, and so too the reduction gear train. There is a popular notion that the speed of the boat is increased by just retracting the control rods farther from the reactor core. This, in fact, is exactly the converse of what actually happens; the rods are simply retracted to a fixed point and held there. The engineers' main goal is to bring the reactor into equilibrium so that the basic amount of heat going into the primary coolant loop is constant. One can then control the speed of the boat by simply tapping more steam from the steam generator, thereby increasing the steam supply to the turbines. This results in cooling the primary coolant loop more, thus increasing the efficiency of the nuclear reaction, feeding more heat to the steam generator, and increasing the speed of the boat.

Conversely, stemming the flow of steam to the turbines not only slows down the spinning of the turbines, it also takes less heat from the primary coolant loop, and rapidly drops the efficiency of the nuclear reaction, 'cooling' it down.

Life Support and Backup Systems

The auxiliary machinery space down on the third level aft of the torpedo room is arguably the most important compartment on Miami. Here is located all of the life support equipment, as well as the auxiliary power source. As you enter the space and head down the starboard aisle, you are given a quick introduction to 'Clyde,' the big auxiliary diesel engine. This is an old favorite of the chiefs onboard, because it is a direct link with the old World War II fleet boats. Built by Fairbanks-Morse, the design dates back to the 1930s and is a scaled-down version of the model used to power all of our submarines during the war. It is reliable and the crew loves it, therefore the name Clyde, as in, '… right turn, Clyde!'

While some folks might wonder why such a dinosaur would be on one of the most advanced submarines, remember that not everything always works properly, including nuclear reactors. For example, what would happen if Miami was at sea and needed to scram the reactor plant? Restarting a reactor takes a lot of power, and while there is a large bank of batteries underneath the torpedo room, it might not prove adequate to completely restart a cold S6G plant. Thus the Fairbanks-Morse engine can provide, through a generator turned by the diesel, enough continuous power to get the tea kettle running again. It has other uses, too. In the event of a reactor casualty, the diesel provides the means for getting home. In that event, the captain orders the engineers aft to lower a small electric outboard motor, which is recessed in the lower hull aft, into the water to provide motive power to get home or to get help.

The diesel engine also has a role in firefighting onboard that might surprise some folks. In the event of a fire, one of the first things the captain might do (assuming this is not in a combat situation) is to surface and start up the diesel. This is because the diesel draws its air from within the boat, and thus it would suck up any air being polluted by the fire. Opening just the fairwater hatches from the control room will completely change the air in the boat in a matter of minutes.

This space is also where the air is made or, more properly, maintained. Several different pieces of equipment in the auxiliary machinery space help to provide the clean, fresh air that can be found onboard. First are the carbon dioxide (CO) scrubbers. CO is the gas given off by humans when they breathe and is dangerous when the concentration gets too high. The Miami utilizes a chemical scrubber to remove it from the air. The chemical absorbs CO when it is cool and releases it when it is warmed. In addition, CO and H 'burners' remove the carbon monoxide and hydrogen gas generated by equipment as well as by cigarette smoking, which is allowed onboard. Finally, filters and dehumidifiers clean the air and help keep it 'friendly' not only for the crew but also for the many pieces of equipment-especially electronic-on the Miami. In case a fire or some other emergency contaminates the onboard air, a force-fed air supply called the Emergency Air Breathing (EAB) system has attachment points throughout the boat, allowing crewmen with breathing masks to plug in to it and continue their duties.

Other life support equipment includes a device that takes water and electrically 'cracks' it into its base elements of hydrogen and oxygen. The oxygen is retained in tanks and released into the boat's atmosphere automatically by the environmental control system, and the hydrogen is vented off the ship from a small port in the aft edge of the fairwater. There is a fresh-water distillation plant that produces something over 10,000 gallons/38,000 liters of fresh water a day. Most of the water is used for drinking, cleaning, cooking, and personal hygiene. Very little water is usually required for the power plant (for charging the cooling loops and steam generators), but the reserve tanks are usually maintained near full 'just in case.' It should be said that the obsession with water conservation is mostly for contingency purposes. Most COs like to have full tanks of water before they enter a tactical situation, just in case they need to shut down the distillation plant to keep noise down. And from what I hear, some boats just choose to run the distillation plant full-time and let the crew have as much shower time as they want, particularly during runs home. On a normal day aboard Miami, the majority of the water produced would go to crew habitability.

Weapons-Torpedoes, Missiles, and Mines

While submarines are useful for covert actions like intelligence gathering and landing special operations forces, it is the threat of what they can do with their weapons that can cause so much fear and respect in an adversary. Ever since Sergeant Ezra Lee tried to sink HMS Eagle in Boston harbor back in 1776, just the potential threat of harm from a submarine has been enough to make an enemy stop and consider whether he should move his ships against you. Today the weapons can hit a wider variety of targets, and they have become even more deadly.