This info was borrowed from a FB group and was written by a former nuke that graduated back in 1994.

Some Basics:

 GC refers to the Goose Creek (Charleston, SC) base; BS refers to Ballston Spa, NY.

NNPTC is Navy Nuclear Power Training Command Goose Creek.  It houses A-School and Nuclear Power School (NPS), as well as two of the ‘prototype’ platforms.

 A-School doesn’t really have a meaning; it’s actually Class ‘A’ School and is the fundamental training for the respective rates (this is true for all Navy ratings, not just for nuclear personnel).  Each class is designated by the last two digits of the year and a serial number, followed by a letter indicating the rate (T for ET, E for EM, and A or B for MM, since there can be two classes of MMs at the same time).  (For example, I was A-school class 9449T:  the 49^th class of ETs to graduate in 1994.)

 After A-School, a new class number is assigned.  This number will remain the same through Prototype (assuming the sailor doesn’t roll back).  The basic format will be the same, except that the extension (for PS only) will be a number, generally 1 through 8, referring to a section.  All students in a given section will be the same rate.

 NNPS is Navy Nuclear Power School.  This is where they learn the theory involved in operating a sea-going nuclear power plant.  That includes a LOT MORE than just the theory of fission reactors.  See the classes list below for some more information.

 Prototype is somewhat of a misnomer.  These are operational, but not sea-going, plants where students (still prospective nuclear operators, at this point) get hands-on training and experience operating a plant for the Navy.  Initially, these platforms doubled as test beds for various technologies the Navy was considering implementing in the fleet (thus the name Prototype).  Today, only the two Ballston Spa platforms are used for such testing; the Goose Creek platforms are converted to training platforms from sea-going submarines.

            The Ships (Nuclear powered only)

SSN – Subsurface Ship, Nuclear; also known as the ‘Fast Boat’, these are the submarines that are often part of a battle group, hunting the other guys’ submarines out there.  If you’ve seen the movie Hunt for Red October, the USS Dallas is an SSN.

SSBN – Subsurface Ship, Ballistic Missile, Nuclear; also known as ‘Boomers’ these are the submarines that carry and can launch missiles at the other guy.  Primarily, they go out, go down, stay down and hide until they come back.  The point here is, the other guy doesn’t really know where the Boomers are, so they become a great ‘passive’ deterrent to direct attack.  The USS Alabama, from the movie Crimson Tide, is a Boomer.

SSGN – Subsurface Ship, Guided Missile, Nuclear; these guys carry short-range guided missiles, which can accurately target very specific locations.  They are relatively new to the fleet.

CVN – Carrier, Fixed Wing, Nuclear; The Carriers.  ‘Fixed Wing’ refers to what you generally think of as a jet airplane.  They also carry helicopters, which are not Fixed Wing, but the point is that they can launch and retrieve the jets.

            Some basic Navy terms

Chit – Generally, a chit is any piece of paper, particularly with some formal purpose.  A ‘request chit’ is a formal written request for… whatever: leave, liberty, see the Captain…

Liberty – Authorized time away from work.  ‘General Liberty’ is the regularly-scheduled time away from work, such as at the end of the work day or on non-working days; ‘Special Liberty’ is basically any other time away from work, such as taking time off during the week or on a duty weekend to go to a family event.

Leave – Essentially extended Liberty.  Liberty, even Special Liberty, should not be for more than 96 hours; any time longer than that should be taken as Leave.  A sailor earns 2.5 days of Leave for each month of active duty service.

‘Use-or-Lose’ – This refers to Leave that can be taken back.  Sailors are not allowed to carry more than 60 days of unused Leave over the Fiscal Year (October through September, for the Navy).  Anything over that will be lost; no sailor will have more than 60 days Leave available on October 1 of any given year. (Congress occasionally authorizes exceptions to this based on deployment schedules, but I actually have seen a sailor lose leave – 1 day of leave, to be exact)

Deployment – For a ship, departure from Home Port for a specific extended mission-oriented period of time.  For SSBNs, a Deployment is generally 3 or 4 months and is referred to as a Deterrent Patrol, or just Patrol; a period of a few to several weeks between Patrols allows for repairs and for changing crews. For SSNs, SSGNs and CVNs, a Deployment will often be 6 months or longer but the ship can often be away from Home Port for shorter periods (a few weeks or so) for ‘work-ups’, or training to crew for deployment.

Stand Down¹ – A significant reduction in manning for a particular period of time.  Generally, no more than 10% of the crew can be on leave or liberty at any given time; this allowance is even broken down and applies to various groupings within the crew.  During a Stand Down the limit may be raised to as much as 50%.  This is common during the Holiday period (mid-December through early January), and in the weeks just prior to or immediately following a Deployment.

Stand Down² – A temporary reduction in operations for a specific purpose.  A common example is a Safety Stand-down, where manning will be kept at a minimum while all other crew are required to attend a series of lectures or seminars regarding some aspect(s) of safe work on the ship.

The Rates:

MM – Machinist’s Mate; also called Mechanic

EM – Electrician’s Mate; also called Electrician

ET – Electronics Technician

The Jobs (without going into much detail as to what each one does):

MO – Mechanical Operator

EO – Electrical Operator

RO – Reactor Operator (an ET)

ELT – Engineering Laboratory Technician (chemistry and radiological controls; usually a MM, who has done some extra training)

RT – Reactor Technician

AE (AEA) – Auxiliary Electrician (Aft)

EOOW – Engineering Officer of the Watch (usually an officer)

EWS – Engineering Watch Supervisor (senior enlisted)

TH – Throttleman (usually EM or ET)

 A-School Classes

Power School Classes

HTFF – Heat Transfer and Fluid Flow

ETRO/ETEO/ETMO – Electrical Theory for Reactor Operator/Electrical Operator/ Mechanical Operator

CMR – Chemistry, Materials and Radiological Controls

RP – Reactor Principles

Prototype staff roles:

SA – Staff Advisor

SOCI – Senior Off-Crew Instructor

TC – Training Coordinator; the enlisted person who tracks the progress of every sailor in that crew

LCC – Leading Crew Chief; senior enlisted person for your sailor’s crew

SE – Shift Engineer; senior navy person for your sailor’s crew – usually a Lieutenant

SS – Shift Supervisor; civilian responsible for everything that happens when your sailor’s crew is on shift.

JSI – Junior Staff Instructor; a sailor who, upon completing prototype, stays on as a staff member rather than going to a ship.

**Adding SPU - Staff pick up (That's what my son called it when he was in prototype)