AbstractA Compact Tokamak Transmutation Reactor natural divertor design is proposed. B2 code is used for this design and edge plasma main physics parameters in the wider SOL (SOL thickness=15 cm) are obtained. The peak value of energy flux and electron temperature near the natural divertor target plate, Pmax=13.37 MW m−2 and Temax=15.55 eV, respectively, are less than in the case of conventional tokamak thin SOL (generally, SOL thickness=5 cm), Pmax=27.92 MW m−2 and Temax=78.85 eV. When radiation gas (cold He gas, energy E0=0.1 eV, flux φ=1.3×1023 m−2 s−1) is puffed into the divertor room from the bottom of the natural divertor, the Pmax value is reduced to 3.861 MW m−2. He gas puffing is applied to the design. A basic structural design has been completed and the main features or key parameters have been introduced.