Low-level radioactive wastewater (LLW) is generated during the operation of nuclear facilities. Usually, LLW is discharged directly into the ocean in the form of liquid effluent after purification under the discharge management limits. However, discharging LLW into inland water bodies is difficult for inland nuclear facilities because of the poor dispersion and the lack of public acceptance. Thus, LLW disposal has become one of the challenges limiting the development of inland nuclear facilities. Liquid-to-gas discharge, which is based on high-pressure spray evaporation technology, is an alternative solution for LLW disposal for inland nuclear facilities.

This study aims to develop and validate a model for simulating spray flow and evaporation to assess the design feasibility.

A numerical method coupling a two-phase flow model, mass transfer model, and heat transfer model were established to describe droplet evaporation during the flow process. To validate this numerical method, a sample high-pressure spray evaporation system was developed which included three key subsystems: carrier gas generation, source term generation, and measurement systems. Finally, considering evaporation and deposition factors, three experimental cases were designed for experimental comparison of the droplet diameter, number, and deposition rate among these cases.

The comparison results show that the numerical method is highly consistent with the experimental results, with a maximum uncertainty of 15%.

The numerical model developed in this study can be used for the technological design of liquid-to-gas LLW discharge based on high-pressure spray evaporation technology.