Bless Your Heart
The senior enlisted person on a submarine is known as the Chief of the Boat (COB). One of the COB’s jobs is to provide training for new personnel and that training is referred to as the “School of the Boat.” This column is intended for newsletter subscribers who may have no military background and those unfamiliar with submarines and Idaho’s extensive Naval history.
Bless Your Heart
By: Rick Gilchrist, Captain, USN (ret)
If you’ve spent any time in the Southern United States or been around someone from that area, you’ve probably heard the phrase, “bless your heart”. Depending on the circumstances in which it’s being used and the tone of voice, it can be used to express gratitude, sympathy, disdain, or ridicule.
In humans, like most other animals, the heart is the primary organ in the body. It works around the clock to provide nutrients to the body in the form of oxygenated blood. Much like the human heart, a nuclear submarine’s reactor works continuously to provide electricity which runs nearly everything on the boat.
Following the successful development of atomic energy for destructive uses, i.e. the atomic bombs used against Japan to end the Second World War, scientists began exploring the use of nuclear power for ship propulsion. In 1953, they began work on a prototype at the Naval Reactors Facility. Today that facility is called the Idaho National Laboratory (INL). It’s an 890 square mile area of high desert between Arco and Idaho Falls, Idaho where more than 6,000 people can work undisturbed. That prototype was called the S1W. Reactors, like Navy ships, are given designators to describe them. The first character is the type of ship it is meant for (“A” for aircraft carrier, “C” for cruiser, “D” for destroyer, and “S” for submarine). The second character indicates whether it’s a first, second, third, etc. generation reactor. The third character denotes the designer, “W” for Westinghouse, “G” for General Electric, “C” for Combustion Engineering, and “B” for Bechtel.
By 1955 reactor design has come so far that the first nuclear-powered ship in the world, the USS Nautilus (SSN-571) entered active service in the U.S. Navy. She was powered by an S2W reactor. The Nautilus, named after Jules Verne’s science fiction submarine in Twenty Thousand Leagues Under the Seas and the World War II boat, USS Nautilus (SS-168), set many records and went to numerous places earlier submarines couldn’t. She logged more than 62,500 miles (half submerged) before she was decommissioned in 1980 and enshrined in the Submarine Force Library and Museum in Groton, Connecticut. An estimated 250,000 people visit her each year. Until 1995 the original S1W reactor in Idaho continued in use to train nearly 40,000 Navy personnel.
While the Navy still maintains a small presence at the INL, today’s nuclear Navy personnel receive their training at the Navy’s Nuclear Power School in Goose Creek, South Carolina. Before being assigned to the fleet, each of them undergoes extensive mental, physical and psychological testing second only to that of people in the astronaut program. Fewer than one person in a thousand qualifies.
Today the Navy has 12 nuclear powered aircraft carriers (each with two A2W reactors). As a sidenote: the now decommissioned USS Enterprise (CVN-65) had eight A2W reactors. The 45 submarines prior to the Virginia class boats (of which the USS IDAHO SSN-799 is one) were powered by a single S2W reactor. The Virginia-class submarines each have one of the latest, most advanced reactors, the S9G, which are designed to operate for 33 years without refueling.
Artist’s Rendition of a Chain Reaction Inside a Nuclear Reactor
Naturally occurring uranium (chemical sign - NU) is composed of about 99.2% inert (inactive) U-238 molecules and 0.72% (U-235) radioactive molecules. A complex enrichment process separates the U-235 from the U-238 to provide a concentrated, high-grade U-235 product. Navy submarines use fuel enriched to at least 93% U-235. Because of this concentration, the fuel lasts longer which enables the reactor to run ten or more years before refueling (a time-consuming and costly process that involves literally cutting the reactor out of the submarine). The concentrated material is formed into small pellets, not much larger than a sugar cube. Each pellet can contain as much energy as a ton of coal. The pellets are then assembled into sealed metal tubes called fuel rods. These rods are then bundled together into what are referred to as assemblies and several hundred assemblies are placed in each reactor core. The result is a reactor with thousands of fuel pellets, the equivalent of thousands of tons of coal.
Fuel Pellets
The reactor is in the middle of the submarine in a compartment (room) shielded by thick layers of steel, lead and water to prevent the escape of radiation. Access to this compartment can be cut off by watertight doors and hatches. The reactor, which is fundamentally a large kettle, has several safety systems that monitor/control the temperature, pressure and power. These sensors, valves, pumps and circuits can automatically cool or shut down the reactor, if needed.
Inside the reactor, a nuclear chain reaction is initiated by causing a neutron to strike a U-235 atom, momentarily converting it to an unstable U-236 atom. This atom then splits into two fragments, a process referred to as fission. Two to three free neutrons will be released which go on to strike other U-235 atoms causing a chain reaction. Lastly a burst of energy in the form of heat results. Control rods in the reactor, made of neutron-absorbing materials like silver and boron, can be raised or lowered to either speed up or slow down the number of free neutrons that are causing the chain reaction and thus control the amount of heat being produced.
The heat is removed from the reactor by an external circulating water system and used to generate steam. The steam then turns turbines to produce electricity. The electricity then powers nearly everything aboard the boat, from the stoves in the galley, to the lights to see by, to the pumps, water purification system, air filters, compressors and weapons launchers. The nuclear generated electricity even powers the boat’s pump-jet propulsors which propel the submarine on its underwater missions.
It’s no wonder that submarines like the USS IDAHO (SSN-799) are built by the Electric Boat Division of General Dynamics. Here's to the people who have built and are building these boats and to the people who serve aboard them. Bless their hearts! And God bless America!