Can natural circulation be used for water flowing through the tube side of a shell and tube heat exchanger?

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Currently, I am working on a heat exchange system that consists of a molten salt heat exchanger in conjunction with a steam drum. The heat medium is molten salt, which generates a steam-water mixture that enters the steam drum to produce saturated steam. The heat load is approximately 50 kW/m², the water pressure is around 2 MPa, and the flow velocity within the pipes is kept at about 1 m/s. The owner prefers to use natural circulation as much as possible. The heat exchanger designer suggested that water should flow through the tube side while salt flows through the shell side, but I am concerned about vapor-liquid separation due to the slow flow rate of water during system startup ； Or other unfavorable factors such as a lower actual flow rate due to calculation errors. Can natural circulation be used in shell-and-tube heat exchangers with water flowing in the tube side? Are there any special requirements? I would also appreciate it if the experts could share their insights; thank you!