Conduct a Tritium Radiation Safety Assessment on the Heating System Directly Supplied by the Steam From the Secondary Loop of the High-Temperature Gas-Cooled Reactor

Abstract With the increasingly urgent demand for industrial heating, traditional heating methods are no longer suitable for the current energy development situation. The High Temperature Gas-cooled Reactor (HTGR), as a fourth-generation advanced nuclear energy technology, has several advantages, including good inherent safety, lack of pollution, no greenhouse gas generation, as well as its unique high quality steam generation and process heat applications. These attributes will significantly contribute to the strategic transformation of industrial parks and the expansion of industrial chains. Rational, safe, and effective use of nuclear energy is an important issue for China’s future new energy development. Nuclear heating can not only meet the demand for district heating and improve the quality of life of residents, but also implement a green and low-carbon energy development strategy and help achieve the “dual carbon” goal. The current design of nuclear heating systems can be categorized into two types of schemes according to the source of the steam: the first is to use the steam in third loop for heating, which has the advantage of better safety due to the low level of radioactivity concentration in the third loop; the second is to use the steam in secondary loop directly, which can significantly improve the quality of heat supply and ultimately improve economy. No matter what type of HTGR process heat application, the influence of Tritium must be considered. Tritium is a main radioactive source item in the secondary loop of the HTGRs, if we try to use the HTGR secondary loop directly, Tritium will affect the users with much higher concentrations than third loop scheme, and the radiation safety needs to be carefully assessed. In order to maximize the utilization of heat energy, this paper studies the second type of heating systems and designs the tritium activity concentration in the supplied steam. The total emission of tritium in the radioactive effluent and the internal exposure dose of tritium for people under extreme conditions were calculated. All the assumptions of the calculations comply with the conservative principle of radiation safety design. Finally, the feasibility of the scheme is discussed by comparing the calculated results with the limit requirement specified in the national standard. The results of the study can guide industrial design and provide a theoretical basis for the heating system directly supplied by the steam from the secondary loop.