A steam reformer for the production of a hydrogen reformate, comprising: a shell having a cavity, and a heat source configured to heat a fluid, wherein the shell comprises: a radiant conduit member at least partially disposed within the cavity and comprising at least one thermally emissive material to provide a radiation emitting surface within the cavity, the radiant conduit member comprising a first end in fluid communication with the cavity, a second end in fluid communication with the heat source, and a passage extending generally through the radiant conduit to guide the heated fluid from the heat source to the cavity; reactor modules at least partially disposed within the cavity to receive heat supplied by the heated fluid, and located about the radiant conduit member to receive radiant heat supplied by the radiant conduit member, wherein each of the reactor modules comprises a reforming catalyst bed; and at least one insulating member disposed within the cavity to reflect radiant heat from the radiant conduit member and the heated fluid back to the reactor modules, the surface of which is shaped to conform to the individual shape of the reactor modules; characterized in that an array of reactor modules surrounds the radiant conduit member, and the at least one insulating member comprises arc shapes, the number of which match the number of reactor modules; wherein the radiant conduit member is configured to radiate heat from the heated fluid traversing the passage of the radiant conduit into the cavity. a shell having a cavity, and a heat source configured to heat a fluid, wherein the shell comprises: a radiant conduit member at least partially disposed within the cavity and comprising at least one thermally emissive material to provide a radiation emitting surface within the cavity, the radiant conduit member comprising a first end in fluid communication with the cavity, a second end in fluid communication with the heat source, and a passage extending generally through the radiant conduit to guide the heated fluid from the heat source to the cavity; reactor modules at least partially disposed within the cavity to receive heat supplied by the heated fluid, and located about the radiant conduit member to receive radiant heat supplied by the radiant conduit member, wherein each of the reactor modules comprises a reforming catalyst bed; and at least one insulating member disposed within the cavity to reflect radiant heat from the radiant conduit member and the heated fluid back to the reactor modules, the surface of which is shaped to conform to the individual shape of the reactor modules; a radiant conduit member at least partially disposed within the cavity and comprising at least one thermally emissive material to provide a radiation emitting surface within the cavity, the radiant conduit member comprising a first end in fluid communication with the cavity, a second end in fluid communication with the heat source, and a passage extending generally through the radiant conduit to guide the heated fluid from the heat source to the cavity; a first end in fluid communication with the cavity, a second end in fluid communication with the heat source, and a passage extending generally through the radiant conduit to guide the heated fluid from the heat source to the cavity; reactor modules at least partially disposed within the cavity to receive heat supplied by the heated fluid, and located about the radiant conduit member to receive radiant heat supplied by the radiant conduit member, wherein each of the reactor modules comprises a reforming catalyst bed; and at least one insulating member disposed within the cavity to reflect radiant heat from the radiant conduit member and the heated fluid back to the reactor modules, the surface of which is shaped to conform to the individual shape of the reactor modules; characterized in that an array of reactor modules surrounds the radiant conduit member, and the at least one insulating member comprises arc shapes, the number of which match the number of reactor modules; wherein the radiant conduit member is configured to radiate heat from the heated fluid traversing the passage of the radiant conduit into the cavity.