We examine the problem of transferring the heat from a 600 MWth nuclear reactor to a thermochemical plant that produces hydrogen by the sulfur-iodine process. In particular, we present the design for the secondary loop that transfers the heat from an intermediate heat exchanger to the thermochemical plant. The design chosen consists of internally insulated pipes made from easily obtainable materials with helium as the heat transfer fluid. The helium is moved around the loop by a gas circulator. The design is optimized to minimize cost including capital costs, operating costs, and heat losses. Energy gains from the circulator are taken into account and credited. Both a concentric-pipe design and a parallel-pipe design will be discussed.