The plant arrangement, component design, and the functions of various systems are described and illustrated. Relative estimated costs of the systems and major components are indicated. The reactor core is designed around requiremouts for 254 thermal megawatts, 950 deg F maximum sodium temperature, stainless steel clad graphite moderator blocks, and low enrichment (0.015 to 0.04 U235) uranium fuel elements. The fuel cycle is described for the possible fuel elements. The fuel cost factors are discussed. Burn-up limitations encountered for metallic fuel in the SGR temperature range indicate UO2 the more desirable choice. The estimated cost of electrical energy associated with the UO2 fuel is given. (auth).