generator theory and maintenance instead of I&CE theory and maintenance. Due to the specialized training given at NFAS, ETNs who have trained there instead of another ET 'A' school are not qualified to be assigned to billets designed for non-nuclear ETs. Personnel who are disqualified from Navy nuclear work ('de-nuked') or who fail to qualify for Navy nuclear work later in the pipeline are reclassified and retrained into another rating in order to remain in the Navy. ETN is not eligible for direct conversion to ET. This means that for an ETN to become and ET they must attend the ET 'A' school. In the second stage of training in the Navy Nuclear Pipeline, ETNs are trained for six months at the Nuclear Power School at the NNPTC. The curriculum for ETNs at the Nuclear Power School includes a higher level mathematics (Calculus) refresher course, introduction to nuclear propulsion systems, Navy nuclear mechanical, electrical, and electronics system design, reactor theory, health physics, basic materials science, and chemistry as it applies to nuclear power plants. The curriculum is similar for MMNs, EMNs, and ETNs, except that each rating focuses more on their particular nuclear system design (for nuclear ETNs this means that they have additional training in nuclear electronics design). In the third and final stage of training in the Navy Nuclear Pipeline, ETNs are trained for six months at one of four Navy nuclear prototype training units (NPTUs). Three NPTUs are moored training ships (MTS) using a S5W reactor and two S6G reactors located at the Naval Weapons Station in Charleston, SC., and two additional NPTUs are land-based prototype units using a S7G reactor and a S8G reactor located in Saratoga Springs, NY. The curriculum for ETNs at an NPTU includes detailed health physics training, design, operation, and maintenance of electronics systems for the NPTU, nuclear watchstanding procedures, and nuclear casualty procedures. Unlike the first two stages of the Navy Nuclear Pipeline where the curriculum is presented in a typical classroom format, training at an NPTU is self-motivated training where students are required to research different aspects of a nuclear propulsion plant design, operation, or theory and demonstrate this knowledge in an oral interview with a qualified nuclear instructor. Additionally, ETNs must perform graded watches under the instruction of a qualified nuclear instructor where they operate a particular piece of nuclear equipment or respond to a casualty. The culmination of