An installation for very long term storage of products emitting a high thermal flux. The installation comprises a container (14), in which the products to be stored are placed, and an evaporator (22) surrounding the container, to evacuate the heat through a heat-pipe effect. The evaporator (22) comprises a jacket (28), pipes (32) integral with the jacket and filled with a coolant fluid such as water, and a system for tightening the evaporator (22) on the container (14). The arrangement is such that the evaporator (22) is not maintained in close contact with the container (14) except in front of the pipes (32). Advantageously, channels (42) are provided for air circulation by natural convention between the evaporator (22) and the container (14), on both sides of the pipes (32).