A technique is provided to selectively control flow along shunt tubes, such as those used in gravel pack operations. The technique utilizes a swellable material valve that comprises a swellable material deployed along the shunt tube flow path. When flow through a specific shunt tube is no longer desired, the swellable material valve can be exposed to a substance that induces swelling of the swellable material. The expanded or swollen material blocks further flow along the shunt tube.