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At NSRRC, an electron accelerator with a beam current of 400 mA at 3 GeV and an emittance of 2 nm-rad is under planning. Four superconducting cavities are required to keep the electron energy in the storage ring and superconducting insertion magnets are used as the major devices providing the desired photon energy with high brilliance and flux. This paper shows the design features of the helium cryogenic system for superconducting devices. The cryogenic system consists of two cryogenic plants each with 450 W at 4.5 K for the cavities and one cryogenic plant with 600 W at 4.5 K for the magnets. Redundancy is achieved by switching valves and interconnection piping between the three cryogenic plants. Distribution of the liquid helium to the superconducting magnets is planned via two 250 m multichannel lines with up to 24 supplying ports for the candidate positions of superconducting magnets.

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