Voyage of the Devilfish

MAD (MUTUAL ASSURED DESTRUCTION) The theory that a nuclear enemy will be deterred from launch of his nuclear weapons by the knowledge that if he launches, he will be destroyed by America’s nuclear arsenal.

MAIN BALLAST TANK Tank that is used solely to hold seawater ballast, weight that allows a ship to sink, or when blown allows a ship to be light enough to surface.

MAIN COOLANT AVERAGE TEMPERATURE (T-AVE) A rough estimate of in-core temperature found by averaging water inlet temperature and outlet temperature.

MAIN COOLANT CUTOUT VALVE (MCCOV) A large gate valve designed to isolate a coolant loop from the core in case of a fast leak.

MAIN ENGINES (PROPULSION TURBINES) The large turbines that extract energy from steam and convert it to power to turn the screw.

MAIN SEAWATER SYSTEM The seawater piping and pumps that force seawater through the main condensers to condense steam into water for boiler feed.

MAIN STEAM VALVES ONE AND TWO (MS-1, MS-2) Large gate valves on the port and starboard main steam headers at the forward bulkhead of AMR 2 that can isolate the main steam system in the event of a major steam leak.

MANEUVERING The nuclear control room, located in engineroom upper level. Smaller than most closets.

MANEUVERING WATCH The watch stations manned when a ship gets under way in restricted waters.

MARK 37 TORPEDO Torpedoes used in the early nuclear submarine classes. Driven by electrical motors.

MARK 49 TORPEDO (HULLBUSTER) Current version of the torpedo in use by the submarine fleet. Has a range of about 20 to 25 miles, carries a 1500 pound load of shaped charge explosives, and has a top attack speed of 50 knots. Depth limited to 3500 feet.

MARK 50 TORPEDO (HULLCRUSHER) Experimental prototype of the weapon designed to replace the Mark 49, for use against large double hulled deep diving submarines. Maximum depth is 10,000 feet. Shaped charge warhead 100 times more effective at hull rupture than the Mark 49. Maximum speed is 55 knots.

MARK I FIRECONTROL SYSTEM Full name is the CCS (Combat Control System) Mark I. The system has three positions, each capable of some two dozen displays for finding target solutions and programming weapons.

MATCH BEARINGS AND SHOOT Captain’s order to shoot a torpedo after resetting the firecontrol solution to match the actual bearing and bearing rate of the target. Used with older firecontrol systems. (See Shoot on Generated Bearing).

MELEE A condition in which two submarines in combat are aware of each other’s presence. Pirecontrol situations using passive sonar become impossible to ascertain due to constant maneuvers of the target. Both combatants tend to switch to active sonar and get weapons in the water. If the ships are too close, weapon targeting becomes nearly impossible and collisions become highly likely. In some situations, commanding officers may elect to clear datum until the battle can be controlled.

MEGATON Nuclear warhead yield equivalent to a million tons oftnt.

MELTDOWN Gross fuel element failure and melting in nuclear core, usually from overheating. Overheating can be caused by lack of cooling in a loss of coolant accident or by excess reactivity addition as in a control rod jump. Hazardous because highly radioactive products of fission are released to the environment (a typical Navy reactor midway through core life has enough radioactivity to rival the release from Chemobyl). Also dangerous because the melted fuel can collect at the bottom of the reactor vessel and melt through the metal, breaching the hull. Finally, there is a slight chance of the melted fuel mass becoming critical at the bottom of the core, leading to a prompt critical disassembly.

MOTOR GENERATOR One of two large machines located in AMR 2 upper level. It is a motor connected to a generator on the same shaft. The unit can convert DC electrical power to AC power, when the battery is supplying ship’s AC loads, or from AC power to DC power, when the turbine generators are charging the battery.

MIZ (MARGINAL ICE ZONE) An area of drift ice and icebergs in the region between open water and the polar icecap.

NESTOR SECURE VOICE A UHF radiotelephone communications system that encrypts a voice signal prior to transmission and decrypts it after reception. Can be transmitted to the satellite and beamed worldwide. Fast, secure means of communication.

NEUTRON FLUX The amount of free neutrons in a specific volume during a specific time interval. Roughly proportional to reactor power level, i.e., to the fission rate in a core.

NEUTRON LEVEL Number of neutrons per second received at a probe outside the reactor vessel. Directly proportional to reactor power level (fission rate).

NEUTRON RADIATION As a result of uranium fission, each fission yields two to three neutrons. Many of these leak from the core, irradiating neighboring compartments and people. Elaborate shields are constructed, but nothing stops all the neutrons. Also a result of spontaneous fissions in nuclear warheads.