Introduction  As a clean and efficient energy source, nuclear fusion promises to achieve global sustainable development in the future. For the first wall of Chinese helium-cooled solid breeder test blanket module, the temperature fields of helium, argon and nitrogen as coolants were calculated based on the design scheme of four coolant channels proposed by the Nuclear Thermal Security and Standardization Research Team.

  Method  To calculate the heat transfer of different coolants in the first wall of the cladding module of fusion reactor, the B.S. Putukhov formula is used to calculate the heat transfer.

  Result  Research indicates that the temperature field variations in the Be panel and RAFM steel are similar for helium, argon, and nitrogen as coolants. The maximum temperatures in the temperature fields are below the allowable temperature, meeting the safety requirements for temperatures. Nitrogen as a coolant offers the largest safety margin, followed by argon, with helium presenting a relatively smaller safety margin.

  Conclusion  This study provides more optimization options for selecting the coolant for the first wall of the test blanket module of nuclear fusion reactor, thereby enhancing the safety margin of the first wall of the test blanket module of nuclear fusion reactor.