In this paper, we develop a symbolic representation for timed concurrent constraint (tccp) programs, which can be used for defining a new model-checking algorithm for reactive systems.  Our approach is based on using streams to extend Difference Decision Diagrams (DDDs) which generalize the classical Binary Decision Diagrams (BDDs) with constraints. We use streams to model the values of system variables along the time, as occurs in many other (declarative) languages.  Then, we define a symbolic (finite states) model checking algorithm for tccp which mitigates the state explosion problem that is common to more conventional model checking approaches. In particular, we show how the symbolic approach to model checking for tccp improves previous approaches based on the classical Linear Time Logic (LTL) model checking algorithm.